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1
Jaegle, Christophe. "Giardia lamblia : risque hydrique." Strasbourg 1, 1988. http://www.theses.fr/1988STR15084.
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2
Crouch, Alan Arthur. "Immunodiagnosis of Giardia Lamblia." Thesis, Queensland University of Technology, 1988. https://eprints.qut.edu.au/36772/1/36772_Crouch_1988.pdf.
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Giardia lamblia is the most frequently reported protozoan parasite of the human intestine, causing significan morbidity worldwide. The method currently used in diagnostic medical laboratories for the detection of Giardia lamblia is the microscopic examination of stool specimen or duodenal fluid for the presence of cysts or trophozoites. This technique has been reported as insenstive, with less than 50% of infections diagnosed by the exmaination of one stool specimen.
3
Weiland, Malin. "Immunodominant proteins in Giardia lamblia /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-158-X/.
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4
Bertrand, Sylvie. "Macrophage functions in Giardia lamblia infections." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61867.
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5
Cevalloas, Gaos Ana Maria. "Biological differences between Giardia lamblia isolates." Thesis, Queen Mary, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309122.
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Bertrand, Isabelle Schwartzbrod Janine. "Détection et génotypage des kystes de Giardia lamblia à partir de matrices environnementales et d'échantillons biologiques." [s.l.] ([s.n.]), 2005. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2005_0210_BERTRAND.pdf.
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7
Bertrand, Isabelle. "Détection et génotypage des kystes de Giardia lamblia à partir de matrices environnementales et d'échantillons biologiques." Nancy 1, 2005. http://docnum.univ-lorraine.fr/public/SCD_T_2005_0210_BERTRAND.pdf.
Full textAbstract:
Dans les pays industrialisés, les nombreuses épidémies d'origine hydrique dues aux protozoairesont souligné l'importance de ces micro-organismes longtemps sous-estimés par rapport aux bactéries et aux virus. Parmi ces protozoaires, Giardia lamblia est une espèce complexe composée de sept génotypesdont seulement deux sont considérés comme pathogènes pour l'Homme, mais aussi pour de nombreux mammifères. Les méthodes de référence actuelles font appel à l'immunofluorescence qui autorise uniquement la détection de l'ensemble des kystes du genre Giardia. Dans ce contexte, notre étude a pour objectif de développer des outils permettant une détection spécifique des espèces et des génotypes, puis de les transférer à l'analyse d'échantillons environnementaux et biologiques. La première partie de notre étude est réalisée uniquement à partir de kystes en suspensions purifiées. Dans un premier temps, nous avons sélectionné et validé un système de détection par PCR en temps réel permettant d'augmenter la spécificité de détection pour l'espèce Giardia lamblia par rapport à l'immunofluorescence. Au-delà de la mise en évidence de cette espèce, nous avons également mis en place deux PCR en temps réel assurant la détection spécifique des génotypes A et B pathogènes pour l'Homme, ainsi que deux PCR analytiques destinées à la mise en évidence des génotypes C et E spécifiques respectivement d'animaux domestiques et d'élevage. La sensibilité, la spécificité et la rapidité de détection constituent les avantages majeurs de ces différents outils. La deuxième partie de nos travaux vise à transférer ces techniques de détection à l'analyse d'échantillons environnementaux suite à l'évaluation de protocoles de concentration et de purification des kystes. Les techniques basées sur la détection du génome sont en effet sensibles à de nombreux composés inhibiteurs présents à des concentrations élevées dans les échantillons biologiques et surtout environnementaux, et pouvant alors entraîner une sous-estimation de la contamination par ces micro-organismes. Différentes techniques de purification basées sur la densité des éléments à purifier (flottation et gradients de densité), la séparation immunomagnétique (IMS), mais aussi des procédés destinés à limiter l'effet des inhibiteurs de PCR lors de l'extraction des acides nucléiques ou de leur amplification sont évalués au cours de cette étape. Le protocole sélectionné suite à ces expérimentations comporte une concentration par centrifugation suivie par une purification des kystes par séparation diphasique à l'acétate d'éthyle et une flottation sur solution de PercollTM-saccharose (d : 1,10). L'étape d'extraction des acides nucléiques est également modifiée au niveau de la digestion de protéines et de la purification des acides nucléiques. La troisième partie constitue l'étape majeure de notre étude puisqu'elle concerne tout d'abord la détection de l'espèce Giardia lambha suivie par une analyse plus fine au niveau des génotypes. La détection de l'espèce G. Lamblia s'avère alors positive pour l'ensemble des prélèvements. Des disparités sont ensuite mises en évidence pour les génotypes. Le génotype A est ainsi isolé au niveau des stations d'épuration et de l'abattoir, alors que le génotype B, plus rarement mis en évidence, n'est détecté dans aucun échantillon provenant de l'abattoir. La détection du génotype E confirme la différence observée entre ces sites puisqu'il est détecté uniquement dans les eaux usées de l'abattoir et apparaît comme un marqueur potentiel de contamination non-humaine. Les systèmes spécifiques des génotypes A et B ont également permis de génotyper des kystes de Giardia lamblia isolés de selles humaines. Le génotype B apparaît alors comme nettement majoritaire pour l'ensemble des prélèvements quelque soit leur origine. Cette première étude réalisée en France permet de détecter les génotypes B et A dans 64 % et 36 % des cas sporadiques respectivement. L'analyse de cas regroupés aboutit également à la mise en évidence du génotype B. Ces expérimentations démontrent l'intérêt des techniques de biologie moléculaire pour une détection rapide, sensible et spécifique, mais aussi pour le génotypage de ce protozoaire au niveau environnemental et biologique.
8
Villazana-Kretzer, Diana L. "Giardia lamblia genomic and molecular analyses of flippase /." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Fernandes, Tayane Gonçalves. "Efeito da ciclohexilamina sobre trofozoítos de Giardia lamblia." Centro de Pesquisas Gonçalo Moniz, 2014. https://www.arca.fiocruz.br/handle/icict/9955.
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Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil
A giardíase é uma doença causada pelo protozoário flagelado Giardia lamblia, e sua sintomatologia é caracterizada pela eliminação de fezes esteatorréicas, dores abdominais e náuseas. Segundo o CDC estima-se que há cerca 1,2 milhões de casos por ano de giardíase, acometendo principalmente crianças em idade escolar. Atualmente, o tratamento da giardíase é realizado principalmente pelo uso do fármaco da família dos 5-nitromidazóis, metronidazol (Flagyl®), secnidazol e tinidazol em particular. Estes são confrontados em casos de resistência clínica causada pelo frequente uso inadequado do medicamento e/ou abandono do tratamento. Além disso, o metronidazol pode apresentar efeito carcinogênico em longo prazo em humanos. Desta forma, novos estudos com análogos e/ou inibidores de poliaminas podem levar à elucidação dos mecanismos de ação envolvidos, favorecendo o estabelecimento de novos regimes terapêuticos mais seguros e eficazes. Em nosso trabalho, foram testadas as substâncias ciclohexilamina (CHA) e o metronidazol que são produtos sintéticos, com o objetivo de avaliar os seus efeitos na proliferação celular, caracterização dos moduladores do metabolismo de poliaminas, avaliação nas mudanças no potencial redox e elucidação de seus possíveis mecanismos de ação nos trofozoítos de Giardia lamblia. Foi realizada uma avaliação da proliferação celular na presença de CHA para trofozoítos de Giardia lamblia, onde observamos que a substância demonstrou ter ação siginficativa apresentando um efeito dosedependente. Observamos que os trofozoítos de G. lamblia apresentam uma inibição significativa do crescimento em presença de concentrações milimolares do CHA, cujo IC50 em 72 horas foi de 1,646 mM. Ao avaliar a produção de lipoperóxidos nos trofozoítos foi observado o possível papel do CHA como promotor de estresse oxidativo neste parasito. Ao realizar microscopia eletrônica de varredura (MEV) os trofozoítos apresentaram morfologias completamente irregulares em diferentes concentrações da CHA, com internalização do disco adesivo, sendo corroborado com os resultados da microscopia eletrônica de transmissão (MET) que mostram o processo de encistamento seguido de necrose celular. Esses resultados indicam que a CHA é possível candidata para o uso terapêutico contra a giardíase.
Giardiasis is a disease caused by the flagellate protozoan Giardia lamblia, and its symptomatology is characterized by steatorrhea, abdominal pain and nausea. According to the CDC, an estimate number of 1.2 million cases of giardiasis happen every year, affecting especially schoolchildren.Nowadays, giardiasis treatment is based on drugs from the 5-nitroimidazole family, particularly metronidazole (Flagyl), secnidazole and tinidazole. Those drugs are indiscriminately used by the population, and it's not uncommon to find them causing clinical resistance due to inappropriate utilization and/or tratment abandon. Besides that, metronidazole can present longterm carcinogenic effect in humans. Thus, new studies with analogs and/or polyamines inhibitors can lead to the clarification of the drugs action mechanis, favouring the establishment of new, safer and more efficient therapeutic regimens.Our work tested cyclohexylamine (CHA) and metronidazole, wich are synthetic products, in order to evaluate their effects on cell proliferation and on changes in redox potential, characterize polyamines metabolism modulator and describe their possible action mechanisms on Giardia lamblia trophozoites. We evaluated Giardia lamblia trophozoites cell proliferation in the presence of CHA; it was observe that the substance shows significant action, presenting dose-dependent effect. We also observed that G. lamblia trophozoites presented significant growth inhibition when exposed to millimolar concentrations of CHA - its IC50 in 72 hours was 1,646mM. When assessed the lipoperoxides production in trophozoites, we observed a possible role of CHA as an oxidative stress promoter in the parasite.Under Scanning Electron Microscopy, trophozoites showed completely irregular morphologies in different CHA concentrations, with internalization of the adhesive disc; this results are corroborated by the Transmission Electron Microscopy results, wich showed the process of encystment followed by cell necrosis. This makes CHA a possible candidate for therapeutic use against giardiasis.
10
Davey, Robert Andrew. "Characterization of nucleoside transport in the intestinal protozoan parasite Giardia intestinalis." Title page, contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phd248.pdf.
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Includes copies of other papers co-authored by the author at end of thesis. Includes bibliographical references (leaves 241-265) A rapid sampling technique has been adapted and used to measure nucleoside transport in a human-derived isolate of the intestinal protozoan parasite Giardia intestinalis (syn. G. lamblia)
11
Lenaghan, Scott Sundermann Christine A. "Molecular responses of Giardia lamblia to gamma-irradiation." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Biological_Sciences/Dissertation/Lenaghan_Scott_38.pdf.
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12
Oliveira, Ana Isabel de Freitas Tavares de. "Caracterização genética de isolados axénicos de Giardia lamblia." Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/3518.
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Mestrado em Microbiologia MolecularAs parasitoses intestinais continuam a constituir um grave problema de saúde pública, a nível mundial. Giardia lamblia, também denominada G. duodenalis ou G. intestinalis é um protozoário frequentemente responsável por patologias entéricas, representando, nos seres humanos, o principal agente causal de gastroenterites parasitárias. A giardiose é, assim, tida como a mais frequente das parasitoses de índole protozoária. Tendo em conta a escassez de trabalhos, em Portugal, sobre esta patologia, com este trabalho pretende-se contribuir para o enriquecimento do conhecimento nesta área. Assim, efectuou-se um estudo epidemiológico, nas cidades do Porto e Viseu, no qual foram pesquisados diversos parasitas, entre os quais, G. lamblia. A inexistência de isolados levou à caracterização molecular, por PCR – RFLP, de outros, criopreservados, o que conduziu à optimização de um protocolo que poderá ser usado rotineiramente no Laboratório de Investigação.
Parasitic diseases continue, knowadays, to be a major concern and health problem, all over the world. The protozoa Giardia lamblia (also kwoned as G. duodenalis or G. intestinalis) is responsible, in humans, for the most of parasitic gastroenteritis. Giardiasis is, therefore, the parasitic gastric infection with the higher prevalence. The lack of published articles and studies, in Portugal, about this organism and its pathology, dictates the pertinence of this work. With it we wish to enrich the knowledge in this area. Therefore, a field study was performed to access the prevalence of several parasites (within those was G. lamblia), on the cities of Porto and Viseu. As a consequence of the results of this study (concerning G. lamblia) the work changed its course. The next step consisted in the molecular characterization by PCR – RFLP, of isolates previously axenized and criopreserved, that lead to a protocol optimization, that can be, therefore, used in our laboratory practice.
13
Allmen, Nicole Eva von. "Molecular analysis of antigenic variation in Giardia lamblia and influence of intestinal inflammatory reactions on a Giardia lamblia infection in mice /." [S.l.] : [s.n.], 2005. http://www.zb.unibe.ch/download/eldiss/05vonallmen_n.pdf.
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Chochillon, Christian. ""Giardia intestinalis" : dékystement et culture "in vitro", implantation chez le souriceau." Paris 5, 1988. http://www.theses.fr/1988PA05P503.
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15
Grignard, Lynn. "DNA replication initiation in the protozoan parasite Giardia lamblia." Thesis, St George's, University of London, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559383.
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In this thesis the Giardia lamblia origin recognition proteins, GiOrc1/cdc6 and GiOrc4 (GiORC) are under investigation. We set out to do a basic molecular characterisation of the GiORC proteins as well as determining origins of DNA replication in the protozoan parasite. The sequences for both GiORC were successfully identified from genome databases and analysed using bioinformatics tools. Furthermore, the GiORC proteins were successfully over-expressed in a bacterial system. In a first strategy, pure protein with or without an affinity tag was used for antibody production, for the use in western blotting, immuno precipitation (interacting partners), chromatin immuno precipitation (identification of origins of DNA replication) and microscopy (protein localisation). Three antibodies against the GiORC were generated. Unfortunately, none of the antibodies recognised the native GiORC. GST-tagged GiOrc4 for GST pull down experiments was used to identify interacting partners, without success. In a second strategy, the GiORC were cloned into Giardia over-expression vectors. Two novel vectors were constructed, pV5.pac and ProtORCtet. Both vectors had not been used previously in the parasite. In addition GiORC sequences were cloned into pGFP.pac, a GFP fusion vector. Six different constructs, three for each GiORC sequence, were generated. In four of the constructs, GiORC/pGFP.pac and GiORC/pV5.pac, expression could not be detected in transgenic cell lines. In ProtOrc4tet, expression of V51HA tagged GiOrc4 was detected by western blot and immuno fluorescence microscopy. In a third strategy, the interaction of GiOrcl/cdc6 and GiOrc4 was shown by yeast two hybrid. We were also interested in the effects of GiORC gene knockdown by RNA interference. The results from the DNA based RNAi vector, however, were inconclusive. In summary, we managed to compile information on the DNA replication proteins m Giardia lamblia and to set up additional tools to further study DNA replication initiation in the parasite.
16
Štefanić, Saša. "Biogenesis and dynamics of Golgi equivalents in "Giardia lamblia" /." Bern : [s.n.], 2009. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Marteau, Catherine. ""Giardia intestinalis" : modéles animaux, leurs caractéristiques et leurs apports à la connaissance de la giardiose humaine." Paris 5, 1991. http://www.theses.fr/1991PA05P130.
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Monis, Paul T. "Molecular systematics of the protozoan parasite Giardia intestinalis : identification of cryptic species /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phm744.pdf.
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Anjos, Karla Graziela Santana dos. "Efeitos do dietilditiocarbamato em trofozoítos de giardia lamblia: uma nova ferramenta na terapia contra a giardíase." reponame:Repositório Institucional da FIOCRUZ, 2008. https://www.arca.fiocruz.br/handle/icict/4227.
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Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, Bahia, Brasil
O protozoário microaerófilo Giardia lamblia coloniza o trato intestinal de hospedeiros vertebrados, onde é exposto a diferentes concentrações de oxigênio. Apesar do metabolismo fermentativo, trofozoítos de Giardia consomem oxigênio e mecanismos de detoxificação são requeridos. Desprovido de glutationa, Giardia expressa altas concentrações de proteínas ricas em cisteína (CRP, também conhecidas como proteínas variantes de superfície ou VSP), como defesa antioxidante. Este mecanismo envolve ciclagem redox para a manutenção de um ambiente intracelular reduzido e proteção contra o estresse oxidativo. Neste contexto, substâncias que interfiram na resposta antioxidante deste protozoário podem compreender uma poderosa estratégia quimioterápica contra a giardíase. Neste estudo, nós analisamos os efeitos do dietilditiocarbamato (DETC), um inibidor de superóxido dismutase (SOD), na proliferação do parasito, expressão de tióis totais, lipoperoxidação, produção de radicais livres e arquitetura celular. DETC inibiu a proliferação celular em níveis semelhantes ao metronidazol e induziu a peroxidação de membranas neste parasito, possivelmente pelo aumento de espécies reativas. Alterações ultraestruturais também foram observadas neste protozoário. Células tratadas com DETC apresentaram alto grau de extração citoplasmática, além de estruturas indicativas de autofagia. As vesículas periféricas também se encontravam maiores, sugerindo confluência. Estes efeitos são independentes de SOD, já que Giardia não apresenta esta enzima. Detecção de grupos tiol com a sonda fluorescente o-phthaldialdeído (OPA) foram significantemente moduladas negativamente pelo DETC. Estes dados nos indicam que DETC aumenta o estresse oxidativo em trofozoítos de Gardia lamblia pela reação com grupos tiol.
The microaerophilic protozoan Giardia lamblia inhabits the upper small intestine mucosa of vertebrate hosts, where it is exposed to different concentrations of oxygen. Despite the fermentative metabolism, Giardia trophozoites consume O2 and produce oxygen free radicals and therefore mechanism for detoxification are required. Devoid of glutathione, Giardia express high concentrations of cystein-rich proteins (CRP, also known as variable surface protein or VSP), as an antioxidant defense. This mechanism involves redox cycling for maintenance of a reduced intracellular environment and protection from oxidative stress. In this regard, substances that interfere in the antioxidant response of this protozoan could comprise a powerful chemotherapeutic strategy for Giardia lamblia infection. Here, we analyzed the effects of DETC, a superoxide dismutase (SOD) inhibitor, on parasite proliferation, thiol expression, lipid peroxidation, free radicals detection and cell architecture. DETC inhibited parasite proliferation at levels similar to metronidazole and induced peroxidation of membrane, possibly by the increase of reactive species.Ultrastructural alteration were also observed. Since this protozoan is devoid of SOD, here present data indicate SOD-independ DETC effects. Thiol groups detection with the fluorescent probe o-phthaldialdehyde (OPA). Cells treated with DETC displayed washed out cytoplasm and structures indicative of autophagy. The peripheral vesicles also had an increased volume, presumably caused by homophilic fusion. Taken together these data indicate that DETC enhance the oxidative stress in Giardia trophozoites by reacting with thiol groups.
20
Bertrand, Isabelle. "Détection et génotypage des kystes de Giardia lamblia à partir de matrices environnementales et d'échantillons biologiques." Nancy 1, 2005. http://docnum.univ-lorraine.fr/public/SCD_T_2005_0210_BERTRAND.pdf.
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Dans les pays industrialisés, les nombreuses épidémies d'origine hydrique dues aux protozoairesont souligné l'importance de ces micro-organismes longtemps sous-estimés par rapport aux bactéries et aux virus. Parmi ces protozoaires, Giardia lamblia est une espèce complexe composée de sept génotypesdont seulement deux sont considérés comme pathogènes pour l'Homme, mais aussi pour de nombreux mammifères. Les méthodes de référence actuelles font appel à l'immunofluorescence qui autorise uniquement la détection de l'ensemble des kystes du genre Giardia. Dans ce contexte, notre étude a pour objectif de développer des outils permettant une détection spécifique des espèces et des génotypes, puis de les transférer à l'analyse d'échantillons environnementaux et biologiques. La première partie de notre étude est réalisée uniquement à partir de kystes en suspensions purifiées. Dans un premier temps, nous avons sélectionné et validé un système de détection par PCR en temps réel permettant d'augmenter la spécificité de détection pour l'espèce Giardia lamblia par rapport à l'immunofluorescence. Au-delà de la mise en évidence de cette espèce, nous avons également mis en place deux PCR en temps réel assurant la détection spécifique des génotypes A et B pathogènes pour l'Homme, ainsi que deux PCR analytiques destinées à la mise en évidence des génotypes C et E spécifiques respectivement d'animaux domestiques et d'élevage. La sensibilité, la spécificité et la rapidité de détection constituent les avantages majeurs de ces différents outils. La deuxième partie de nos travaux vise à transférer ces techniques de détection à l'analyse d'échantillons environnementaux suite à l'évaluation de protocoles de concentration et de purification des kystes. Les techniques basées sur la détection du génome sont en effet sensibles à de nombreux composés inhibiteurs présents à des concentrations élevées dans les échantillons biologiques et surtout environnementaux, et pouvant alors entraîner une sous-estimation de la contamination par ces micro-organismes. Différentes techniques de purification basées sur la densité des éléments à purifier (flottation et gradients de densité), la séparation immunomagnétique (IMS), mais aussi des procédés destinés à limiter l'effet des inhibiteurs de PCR lors de l'extraction des acides nucléiques ou de leur amplification sont évalués au cours de cette étape. Le protocole sélectionné suite à ces expérimentations comporte une concentration par centrifugation suivie par une purification des kystes par séparation diphasique à l'acétate d'éthyle et une flottation sur solution de PercollTM-saccharose (d : 1,10). L'étape d'extraction des acides nucléiques est également modifiée au niveau de la digestion de protéines et de la purification des acides nucléiques. La troisième partie constitue l'étape majeure de notre étude puisqu'elle concerne tout d'abord la détection de l'espèce Giardia lambha suivie par une analyse plus fine au niveau des génotypes. La détection de l'espèce G. Lamblia s'avère alors positive pour l'ensemble des prélèvements. Des disparités sont ensuite mises en évidence pour les génotypes. Le génotype A est ainsi isolé au niveau des stations d'épuration et de l'abattoir, alors que le génotype B, plus rarement mis en évidence, n'est détecté dans aucun échantillon provenant de l'abattoir. La détection du génotype E confirme la différence observée entre ces sites puisqu'il est détecté uniquement dans les eaux usées de l'abattoir et apparaît comme un marqueur potentiel de contamination non-humaine. Les systèmes spécifiques des génotypes A et B ont également permis de génotyper des kystes de Giardia lamblia isolés de selles humaines. Le génotype B apparaît alors comme nettement majoritaire pour l'ensemble des prélèvements quelque soit leur origine. Cette première étude réalisée en France permet de détecter les génotypes B et A dans 64 % et 36 % des cas sporadiques respectivement. L'analyse de cas regroupés aboutit également à la mise en évidence du génotype B. Ces expérimentations démontrent l'intérêt des techniques de biologie moléculaire pour une détection rapide, sensible et spécifique, mais aussi pour le génotypage de ce protozoaire au niveau environnemental et biologique.
21
Waight, Sharma Agnes Phyllis. "The intestinal immune response to Giardia in the rat." Title page, abstract and contents only, 1988. http://web4.library.adelaide.edu.au/theses/09PH/09phw138.pdf.
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CTORZA, FRANCINE. "Arthrite reactive a giardia : etude a propos d'un cas." Aix-Marseille 2, 1988. http://www.theses.fr/1988AIX20482.
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Guy, Rebecca Ann. "Giardia lamblia : an analysis of trophozoite antigens using monoclonal antibodies." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55696.
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Mohammed, Shawn Rasheed. "Disaccharidase deficiencies in gerbils (Meriones unguiculatus) immune to Giardia lamblia." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55514.
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Studies using Mongolian gerbils found that during a primary infection with Giardia lamblia trophozoites, disaccharidase activities were decreased from day 10 post-infection (p.i.) until well past elimination of the parasite. However, during a challenge infection, enzyme deficiencies were short-lived. A challenge with a soluble extract of G. lamblia trophozoites also resulted in reductions in disaccharidase activity. The degree of these reductions in enzyme activity was dependent on the extract dose. Gel filtration of the trophozoite crude extract resulted in fractions F1, F2, and F3. However, only a challenge with F1 led to disaccharidase deficiencies. Further separation of F1 resulted in fractions F1a and F1b. Impairments of enzyme activity were obtained only in gerbils challenged with F1b. Protein analysis of F1b revealed several high and low molecular weight bands. When gerbils previously exposed to G. lamblia were challenged with an extract of Entamoeba histolytica trophozoites, disaccharidase activities remained comparable to controls. Moreover, enzyme levels in gerbils challenged with excretory/secretory G. lumblia products were affected in a manner which was inconsistent with the live parasitic challenge. Results suggest that the disaccharidase deficiencies in giardiasis are parasite-specific and are induced by a heat-stable constituent(s) of fraction F1b, possibly through an immune response to an antigenic component of this parasite fraction.
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Oliveira, Rita Mónica Ferraz Ferreira de. "Avaliação, in vitro, da sensibilidade de Giardia lamblia ao metronidazol." Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/906.
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Mestrado em ToxicologiaG. lamblia, agente causal da giardiose, é considerado o parasita protozoário patogénico mais frequente no intestino do Homem, associado a situações de grande morbilidade em todo o mundo e a causa mais comum de diarreia em humanos. De todos os compostos disponíveis, o metronidazol continua a ser considerado o fármaco de eleição no tratamento desta parasitose. Contudo, o número crescente de casos de resistência registados tem vindo a justificar a necessidade de desenvolver metodologias que permitam avaliar a sensibilidade de G. lamblia aos fármacos disponíveis. Espera-se com este estudo contribuir para o desenvolvimento e implementação de metodologias expeditas que permitam avaliar, in vitro, a susceptibilidade deste parasita aos fármacos habitualmente prescritos. Pretende-se obter uma metodologia de simples execução, em microescala e portanto menos dispendiosa, que permita alcançar resultados mais rápidos e mais fiáveis. Neste sentido, este trabalho teve como objectivo determinar a sensibilidade de G. lamblia ao metronidazol recorrendo às metodologias de inibição de aderência (ADE), diacetato de fluoresceína (FDA), iodeto de propídio (PI) e um derivado tetrazolium (XTT). Foram obtidos valores de IC50 de 2,99μM, 9,87μM e 8,93μM para a metodologia ADE, FDA e XTT, respectivamente. A metodologia PI não foi considerada uma vez que apresentou resultados incongruentes. Os resultados permitiram observar que as metodologias FDA e XTT apresentaram valores de IC50 mais próximos. Na metodologia ADE, registaram-se valores cerca de três vezes inferiores. A selecção da melhor metodologia deve ter em conta o mecanismo de actuação do fármaco em estudo bem como a disponibilidade de equipamento necessário à execução das diferentes metodologias. ABSTRACT: G. lamblia, giardiasis cause, is the most frequent pathogenic protozoan found in human, associated with great morbility in the whole world and most common cause for diarrhea. Metronidazole is the most often drug used in giardiasis treatment. However, the increasing number of metronidazole resistance cases justifies the need to develop G. lamblia viability assessment methodologies to other available drugs. It is hoped that this study contributes to the development and implementation of resourceful methodologies of in vitro susceptibility assessment of this parasite to commonly prescribed drugs. The aim is to obtain a simple methodology for microscale implementation, therefore less expensive, and to achieve faster and more reliable results. This study wanted to determine G. lamblia sensitivity to metronidazole using inhibition of adherence method (ADE), fluorogenic dyes fluorescein diacetate (FDA) and propidium iodide (PI) and a tetrazolium derivate (XTT) reduction. Sensibility results estimated IC50 values of 2,99μM, 9,87μM and 8,93μM for ADE, FDA and XTT, respectively. PI was not considered due to inconsistent results. FDA and XTT IC50 values were similar. Values obtained with ADE were three times lower. The best methodology selection must take into account the drug mechanism of action and the equipment availability to different methodologies implementation.
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Yichoy, Mayte. "Lipid uptake and metabolism in the parasitic protozoan giardia lamblia." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Narla, Nirmala Priya. "Allelic Heterozygosity Within and Among Giardia Lamblia Genotype B Isolates." Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/146616.
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Giardia lamblia is a binucleate intestinal pathogen belonging to an early diverging eukaryotic lineage. It is responsible for many cases of diarrheal disease worldwide, with two distinct Giardia genotypes, A and B, known to infect human hosts. The level of genetic diversity among genotype B isolates is not sufficiently understood. Thus, we attempt to analyze what is happening at a population genetics level to produce unique allelic sequence heterozygosity patterns. In this report, I analyzed an 869 bp region on the chromosome 3 locus and a 532 bp region on chromosome 5, by comparing multiple cloned PCR products from the reference genotype B isolate GS and 6 genotype B field isolates. We found a total of 44 and 19 SNP sites at the chromosome 3 and 5 loci, respectively. Each of the seven isolates had much higher numbers of haplotypes at the two chromosomal loci than could be explained by allelic sequence heterozygosity (ASH), and haplotype ratios did not suggest ASH as the reason for the diversity. We narrow down the reasons for allelic divergence, and implicate the potential accumulation of sequence variability in individual lineages. A comprehensive understanding of the genetic diversity within and among genotype B organisms will be important in evaluating parasite variation, the mechanisms for genetic exchange among early eukaryotes, and the taxonomic classification of Giardia genotypes.
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Araujo, Torres William Andrés. "Prevalencia de Giardia sp. en Canis familiaris de la provincia constitucional del Callao." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2004. https://hdl.handle.net/20.500.12672/1564.
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El objetivo de este trabajo fue determinar la prevalencia de Guardia sp. en la población canina doméstica en los 6 distritos que conforman la Provincia Constitucional del Callao en el Perú. Para tal fin se colectaron 385 muestras fecales de perros aparentemente normales de ambos sexos, de diferentes edades y de acuerdo a la zona en donde habitaban sus propietarios. Las muestras fueron procesadas mediante la técnica de sedimentación espontánea; encontrándose una prevalencia de 9,35 ± 2% de Guardia sp. Mediante la prueba de regresión logística se cuantificó la asociación entre la presencia del parásito y las características físicas de las heces, estrato distrital de procedencia, sexo y edad del canino; se determinó una relación estadísticamente significativa entre el hallazgo de quistes de Guardia sp. y las características físicas de las muestras. Los resultados de nuestro estudio denotan una parasitosis moderada de Guardia sp. en los caninos, evidenciando un riesgo zoonótico, por lo que se hace necesario el establecimiento de programas educativos para prevenir la posibilidad de contagio especialmente en la población infantil. Asimismo, debido a que la ocurrencia del parásito es más frecuente en heces diarreicas o pastosas que en heces normales, se debe consultar al Médico Veterinario para que determine la causa y un adecuado tratamiento a ese trastorno digestivo.The aim of this study was to determine Guardian sp. prevalence in household dog population on different districts that form Provincia Constitutional del Callao in Peru. Fecal samples were collected from 385 apparently healthy dogs of different ages that were selected depending on the zone where their owners lived. Stool samples were processed by spontaneous sedimentation technique and we found that 9,35 ± 2% (36/385) of the canine population in this study were positive to Giardia sp. cysts. Relationships between cysts detection and stool samples characteristics, provenience, sex and age of the dogs were analyzed by logistic regression; significant statistical relationship was found between Giardia sp detection and stoll samples physical characteristics. Results show a moderate Giardia sp. infection in dogs which evidences a zoonotic risk that makes necessary the setting of educational programs in order to prevent Giardia sp. transmission especially to infant population. Giardia sp. is more frequently detected in diarrheic or soft stool samples that in normal ones, this is the reason why owners of dogs with that stool characteristic should ask veterinarian to determine the cause and to give an appropriate treatment to that problem.
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Rust, Colleen Frances. "Removal of the human pathogen Giardia intestinales from groundwater." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/C_Rust_120506.pdf.
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Teoh, Désiree Ann. "The role of cytoskeletal proteins in Giardia lamblia-induced epithelial injury." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0025/MQ48048.pdf.
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Carnaby, Simon. "DNA typing of the human small intestinal protozoan parasite Giardia lamblia." Thesis, Queen Mary, University of London, 1995. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1400.
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At present there is no satisfactory means of typing strains of Giardia lamblia which can explain the broad range of clinical symptoms seen in giardiasis or which can identify genotypes in epidemiological studies. This thesis attempts to address these problems by developing DNA based typing systems sensitive enough to be able to identify many different Giardia genotypes and which may be applied to the organisms found in clinical samples. Four different techniques were assessed for their ability to identify multiple polymorphic loci in the Giardia genome which may be used to genotype and identify isolates of Giardia and upon which the future development of PCR-typing protocols may be based. These techniques included RFLP analysis, random amplified polymorphic DNA (RAPD) analysis, M13 DNA fingerprinting and minisatellite DNA fingerprinting. Minisatellite DNA fingerprinting proved to be the most discriminatory, recognising many hypervariable loci within the Giardia genome which proved useful for in vitro studies on genotypic heterogeneity within Giardia isolates. This approach would require further development in order to be used on in vivo infections where it could directly assess the relationship between genotype and pathogenicity. Therefore the variable repeats recognised on Giardia fingerprints were sought by constructing and screening a Giardia genomic DNA cosmid library. Once cloned these repeats would form the basis of sensitive and specific PCR-based fingerprinting protocols ideal for typing large numbers of infections. The repeat sequences cloned in this way turned out to be Giardia variable surface protein genes with short, imperfect tandem repeats in their 3' flanking DNA. This work has important implications for the future development and use of fingerprinting techniques on Giardia and may be useful in the study of chromosome rearrangement in Giardia which is likely to be involved in surface antigen switching.
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Adam, Rodney, Anuranjini Nigam, Vishwas Seshadri, Craig Martens, Gregory Farneth, Hilary Morrison, Theodore Nash, Stephen Porcella, and Rima Patel. "The Giardia lamblia vsp gene repertoire: characteristics, genomic organization, and evolution." BioMed Central, 2010. http://hdl.handle.net/10150/610013.
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BACKGROUND:Giardia lamblia trophozoites colonize the intestines of susceptible mammals and cause diarrhea, which can be prolonged despite an intestinal immune response. The variable expression of the variant-specific surface protein (VSP) genes may contribute to this prolonged infection. Only one is expressed at a time, and switching expression from one gene to another occurs by an epigenetic mechanism.RESULTS:The WB Giardia isolate has been sequenced at 10x coverage and assembled into 306 contigs as large as 870 kb in size. We have used this assembly to evaluate the genomic organization and evolution of the vsp repertoire. We have identified 228 complete and 75 partial vsp gene sequences for an estimated repertoire of 270 to 303, making up about 4% of the genome. The vsp gene diversity includes 30 genes containing tandem repeats, and 14 vsp pairs of identical genes present in either head to head or tail to tail configurations (designated as inverted pairs), where the two genes are separated by 2 to 4 kb of non-coding DNA. Interestingly, over half the total vsp repertoire is present in the form of linear gene arrays that can contain up to 10 vsp gene members. Lastly, evidence for recombination within and across minor clades of vsp genes is provided.CONCLUSIONS:The data we present here is the first comprehensive analysis of the vsp gene family from the Genotype A1 WB isolate with an emphasis on vsp characterization, function, evolution and contributions to pathogenesis of this important pathogen.
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Mariano, Ana Paula Melo. "Prevalência de Cryptosporidium spp. e Giardia lamblia em crianças menores de 6 anos de creches/pré-escolas de zona urbana de um município do interior da Bahia, Brasil." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/22/22133/tde-19022015-161453/.
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A crescente urbanização associada à multiplicação do número de cidades e o aumento populacional, especialmente nos países em desenvolvimento, têm favorecido o surgimento e o crescimento desordenado das comunidades com consequente dificuldade de acesso aos serviços básicos, inadequadas condições de moradia e exposição a diversos contaminantes ambientais que contribuem para a baixa qualidade de vida e saúde. As parasitoses intestinais apresentam íntima relação com as condições sanitárias, constituindo um relevante problema de saúde pública com maior prevalência entre indivíduos de baixo nível socioeconômico. A ocorrência e manifestação da sintomatologia decorrente de uma infecção parasitária também se associa, principalmente, com a imaturidade do sistema imunológico em crianças com idade ntre 0 e 6 anos, que têm no ambiente de creches e pré-escolas outro importante fator que pode contribuir para a contaminação. Embora sejam crescentes os relatos de parasitismo intestinal em crianças que frequentam creches, ainda são escassas as pesquisas direcionadas aos pré- escolares da região Sul da Bahia, Brasil. Por essa razão, o objetivo deste estudo foi identificar a prevalência de Cryptosporidium spp. e Giardia lamblia em crianças de 0 a 6 anos que frequentam creches municipais de Itabuna, cidade localizada na região Sul do estado da Bahia. Para atender aos objetivos propostos foram aplicados dois questionários, um as diretoras das creches/pré-escolas, visando realizar o levantamento das condições de saneamento e práticas de higiene alimentar no ambiente escolar e outro aos responsáveis legais das crianças, com o intuito de conhecer as condições individuais e familiares dos participantes. Para pesquisa de Cryptosporidium spp. e Giardia lamblia foram coletadas três amostras fecais por sujeito da pesquisa, processadas e analisadas pelos métodos de Ziehl- Neelsen adaptado e Mariano & Carvalho, respectivamente. A prevalência de Cryptosporidium spp. e Giardia lamblia foi de 39,10% e 29,49%, respectivamente. A grande maioria das crianças é de famílias de baixa condição social e baixo nível de escolaridade, possuem alta quantidade de moradores por residência (transmissão interpessoal). Estes aspectos constituem fatores facilitadores para a disseminação desses parasitas na população estudada. O hábito de não lavar as mãos com água e sabão também se mostrou um fator facilitador a infecção por Giardia lamblia e Cryptosporidium spp., manter as unhas cortadas e limpas diminui a exposição dos indivíduos a infecção por Giardia lamblia. Diante dos resultados, a investigação das enteroparasitoses, em especial da criptosporidíase e giardíase em pré- escolares de Itabuna, Bahia, Brasil é fundamental, devido o alto índice de positividade dos exames coproparasitológicos. Tal aspecto, aliado à escassez de estudos sobre o tema nessa região, mostra claramente que se trata de um problema de saúde pública e que se tornam necessárias melhorias no planejamento estratégico da aplicação dos recursos financeiros em prol do controle das parasitoses no municípioIncreasing urbanization linked to the multiplication of the number of cities and population growth, especially in developing countries, have favored the emergence and the uncontrolled growth of communities resulting in poor access to basic services, inadequate housing conditions and exposure to several environmental contaminants that contribute to poor quality of life and health. The Intestinal parasitosis shows a close relationship with sanitary conditions representing an important public health problem with higher prevalence among individuals of low socioeconomic status. The occurrence and presenting of symptoms resulting from a parasitic infection are also mainly associated with the immune system immaturity in children aged between 0 and 6 years, who have in their daycare and kindergarten environment another important determinant that could contribute to contamination. Although the reports about intestinal parasitism in children attending day care centers are increasing, there is still scarse research addressing kindergarten children in Southern Bahia, Brazil. Therefore, the aim of this study was to identify the prevalence of Cryptosporidium spp. and Giardia lamblia in children aged fron 0 to 6 years old who are attended in some of Itabuna\'s daycare centers. Itabuna city is located in the southern area of Bahia state. To meet the objectives proposed two questionnaires were applied , one to the daycare / kindergarten directors, in order to survey the conditions of sanitation and food hygiene practices in the school environment and other to the legal guardians, in order to find out the individual and family conditions of the participants. For the detection of Cryptosporidium spp. and Giardia lamblia three fecal samples were collected for each research subject, processed and analyzed by the Ziehl-Neelsen adapted, and Mariano & Carvalho methods, respectively. The prevalence of Cryptosporidium spp. Giardia lamblia were 39,10% and 29,49%, respectively. The large majority of children come from families of low social status, and educational level, live in enviroment with a high number of residents per household (person transmission). These aspects are factors that facilitate the spreading of these parasites in the studied group. The habit of not washing hands with soap and water was also a facilitating factor to infection by Giardia lamblia and Cryptosporidium spp., keep nails clean and cut decreases the exposure of individuals to infection by Giardia lamblia. Given the results, the investigation of intestinal parasites, especially giardiasis and cryptosporidiosis in the kindergarten schools Itabuna, Bahia, Brazil is critical, because of the high rate of positive results of fecal examinations. This aspect, together with the scarcity of studies on the subject in this region, clearly shows that it is a public health problem and that improvements are required in the strategic planning of the financial resources uses to the control of parasitic diseases in the city
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Pablo, Jota Olguita Susana. "Giardia sp. en caninos y niños de comunidades campesinas de tres distritos de Puno." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2010. https://hdl.handle.net/20.500.12672/713.
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El objetivo del estudio fue determinar la prevalencia de Giardia sp. en caninos y niños de comunidades campesinas de los distritos de Ajoyani, Palca y Santa Lucía en Puno. Se recolectaron 130 muestras fecales tanto de niños como de canes. Las muestras fueron conservadas en formol al 10%, siendo luego enviadas al Laboratorio de Parasitología de la FMV-Lima para su procesamiento. Para el diagnóstico de Giardia sp. cada muestra fue analizada mediante las técnicas de Sedimentación Espontánea y Sheather. Considerando como positivo el hallazgo del parásito en una de las dos técnicas usadas, se obtuvo una prevalencia global de 14.6+6.1% y 28.5+7.8% en caninos y niños respectivamente. En caninos se hallaron prevalencias de 31.8%, 18.2% y 9.3% en los distritos de Ajoyani, Palca y Santa Lucía, respectivamente; las prevalencias en machos y hembras fueron de 14.6% y 17.4% respectivamente y según los grupos de edad de 0-6 meses, >6-12 meses, >12-72 meses y >72 meses fueron de 7.7%, 21.7%, 11.4% y 16.0% respectivamente. En niños se obtuvieron prevalencias de 36.4%, 13.6% y 30.2% en Ajoyani, Palca y Santa Lucia, respectivamente; los niños presentaron prevalencias de 14.6% y las niñas 17.4%; según los grupos etarios de 0-3años, >3-7años, >7-12 años fueron de 33.3%, 29.7%, 25.9% respectivamente. Para el análisis estadístico se empleó la prueba de chi cuadrado, con un nivel de significancia de 0,05%. No se encontró asociación estadística significativa (p>0,05) entre la presencia de Giardia sp. y las variables estudiadas. Además la técnica de sedimentación espontánea demostró ser la técnica más eficaz para el diagnóstico del parásito. Las prevalencias halladas en caninos y niños sugieren infecciones independientes. Sin embargo, sólo se esclarecería con futuros estudios moleculares, para descartar posible riesgo zoonótico.
Palabras clave: Giardia sp., Puno, Sedimentación espontánea, Sheather, zoonosis--- The aim of this study was to determine the prevalence of Giardia sp. in dogs and children in rural communities of the districts Ajoyani, Palca and Santa Lucía in Puno. We collected 130 fecal samples from both children and dogs. The samples were preserved in formaldehyde at 10%, then sent to the Laboratory of Parasitology of the FMV-Lima for processing. For the diagnosis of Giardia sp. each sample was analyzed by spontaneous sedimentation techniques and Sheather. Considering as positive the parasite founding in one of two techniques used, we obtained an overall prevalence of 14.6+6.1% and 28.5+7.8% in dogs and children respectively. In dogs, were found prevalences of 31.8%, 18.2% and 9.3% in the districts of Ajoyani, Palca, and Santa Lucía, respectively; the prevalences in males and females were 14.6% and 17.4% respectively and according to age groups from 0-6 months,> 6-12 months, > 12-72 months and > 72 months were 7%, 21.7%, 11.4% and 16.0% respectively. In children, were obtained 36.4%, 13.6% and 30.2% prevalences in Ajoyani, Palca and Santa Lucía, respectively; boys had prevalences of 14.6% and girls had 17.4%, according to the age groups from 0-3years,> 3-7years, > 7-12 years were 33.3%, 29.7%, 25.9%, respectively. For statistical analysis we used the chi square test with a significance level of 0.05%. There was not significant association (p> 0.05) between the presence of Giardia sp. and the variables studied. Furthermore, the spontaneous sedimentation technique proved to be the most effective technique for the diagnosis of the parasite. The prevalence found in dogs and children suggest independent infections. However, only molecular studies would clarify in future to rule out possible zoonotic risk. Keywords: Giardia sp., Puno, spontaneous sedimentation, sheather, zoonosis
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Jimenez, Artigas Juan Carlos. "Rôle des antigènes d'excrétion/sécrétion de giardia intestinalis dans la réponse immune et la pathogenèse de la giardiose." Lille 2, 2004. http://www.theses.fr/2004LIL2S008.
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Le parasite flagellé Giardia intestinalis (syn. G. Lamblia ou duodenalis) est responsable d’une infection chez l’homme et d’autres mammifères qui provoque une réponse inflammatoire transitoire de la muqueuse intestinale, associée parfois à malabsorption ou a des allergies digestives. Cependant les molécules impliquées dans ces phénomènes sont inconnues. Cette thèse tente d’étudier le rôle des protéines d’excrétion/sécrétion (E/S) de G. Intestinalis dans la réponse immune et la physiopathologie de la giardiose. L’administration par voie orale des protéines E/S chez la souris Balb/c stimule une réponse humorale (IgG1, IgG2, IgA et IgE), qui est parfois cytotoxique in vitro contre des trophozoïtes. Des bandes de 15, 63, 72 et 83 kDa ont été reconnues par les sérums des souris immunisées et caractérisée comme des cystéine-protéases. Les protéines E/S provoquent aussi des altérations histologiques de la muqueuse intestinale. L’immunisation systémique avec des antigènes E/S stimule une réponse de cytokines de type Th1/Th2 (IFN-, IL4, IL5 et IL10). Cependant, l’inhibition de leur activité cystéine-protéase induit une inhibition de la réponse immune. Nous avons observé que l’infection expérimentale par G. Intestinalis chez la souris stimule une réponse humorale et cellulaire plus intense vis-à-vis des antigènes E/S que des antigènes somatiques. Les patients infectés ont montré une intense réactivité sérique contre les antigènes E/S. L’ensemble de ces résultats suggère que les protéines E/S de G. Intestinalis, en particulier celles exprimant une activité cystéine-protéase, jouent un rôle important dans la réponse immune et la pathogenèse de la giardioseGiardia intestinalis (syn. G. Lamblia or duodenalis) is a causative agent of intestinal infection in man and other mammals. This infection causes transient gastrointestinal complaints and allergic reactions. However, the parasite molecules related with these effects are unknown. In teh present study, we evaluated the role of excretory/secretory proteins (E/S) of G. Intestinalis In the immune response and the physiopathology of giardiasis. The oral administration of E/S proteins to Balb/c mice elicited a humoral response (IgG1, IgG2, IgA et IgE). The specific antibody exhibited a cytotoxic effect in vitro on the Giardia trophozoites. Proteins of 15, 63, 72 et 83 kDa were recognized by the serum of immunized mice and characterized as cystein-proteases. Histological perturbations after oral administration of E/S proteins were also observed. The systemic immunization with E/S proteins induced the production of cytokines Th1/Th2 (IFN-, IL4, IL5 et IL10). However, the inhibition of their enzymatic activity reduced the immune response. These results suggest that the enzymatic activity of E/S proteins is directly involved in the immune response. In infected mice, E/S proteins stimulated a higher immune response than somatic extracts. Consistently, serum samples from Giardia infected patients showed a higher reactivity against E/S proteins than against somatic antigen. Taken together, our results indicate that E/S proteins of G. Intestinalis, particularly, those with cysteine-protease activity, play a key role in the immun response, and contribute with the pathogenesis of Giardia infection
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Bennett, Helen Victoria. "Giardia lamblia : a genome comparison of three reference strains using microarray technology." Thesis, Royal Holloway, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538294.
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Eduardo, José Machado da Costa. "Caracterização genética de Giardia lamblia de origem humana e animal em Portugal." Master's thesis, Universidade de Aveiro, 2008. http://hdl.handle.net/10773/866.
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Mestrado em Micrbiologia Molecular e CelularGiardia lamblia é um organismo protozoário capaz de infectar o tracto intestinal de diversas espécies de animais onde se incluem os mamíferos. A heterogeneidade genética de G. lamblia está devidamente comprovada mas o seu potencial zoonótico continua ainda por esclarecer. Neste trabalho, analisaram-se 68 amostras de DNA obtidas a partir de fezes de origem humana e canina, com o objectivo de identificar os assemblages/genótipos que circulam no nosso país. Os resultados obtidos mostraram que os isolados humanos correspondiam aos assemblages A ou B, enquanto que os isolados caninos pertenciam aos assemblages A, C ou D, tendo por base o estudo do locus do gene da β-giardina pelas técnicas de PCR-RFLP e sequenciação de DNA. As prevalências dos diferentes assemblages nas amostras humanas foram de 94,1 % (32/34) para o assemblage A e de 5,9 % (2/34) para o assemblage B, enquanto que nas amostras caninas foram de 67,7 % (21/31) para o assemblage A, 6,5 % (2/31) para o assemblage C e de 6,5 % (2/31) para o assemblage D. Foram ainda identificadas 2 amostras caninas coinfectadas com os assemblages A e C (6,5 %) e 4 amostras caninas coinfectadas com os assemblages A e D (12,9 %). De realçar a identificação de um isolado A2, normalmente associado aos humanos, numa amostra de origem canina. A análise filogenética revelou que os isolados do assemblage A provenientes de humanos e animais eram idênticos entre si. Estes dados sugerem que os cães podem desempenhar um papel importante em ciclos zoonóticos de transmissão do parasita. ABSTRACT: Giardia lamblia is a protozoan organism that can infect the intestinal tract of many animal species including mammals. Genetic heterogeneity of G. lamblia is well described but the zoonotic potential is still unclear. In this study, we analysed 68 DNA samples isolated from human and canine stool specimens, to get more insight in the different G. lamblia assemblages/genotypes present in our country. Results showed that the human isolates were divided into two main assemblages, A and B, while the canine isolates belonged to the assemblages A, C and D, on the basis of PCR-RFLP assays and DNA sequence analysis of the β-giardin gene. The prevalence of the different assemblages in the human samples was 94.1 % (32/34) for the assemblage A and 5.9 % (2/34) for the assemblage B, while in the canine samples was 67.7 % (21/31) for the assemblage A, 6.5 % (2/31) for the assemblage C and 6.5 % (2/31) for the assemblage D. We also identified 2 co-infections including the assemblages A and C (6.5 %) and 4 co-infections including the assemblages A and D (12.9 %) in dogs. An interesting finding was the identification of an A2 genotype, traditionally linked to human G. lamblia infections, in a dog sample. Phylogenetic analysis revealed a close relationship between human and animal assemblage A isolates. These findings suggest that dogs may play an important role in zoonotic transmission cycles of the parasite.
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Busatti, Haendel Goncalves Nogueira Oliveira. "Avaliação dos efeitos de análogos do metronidazol sobre o protozoário giardia lamblia." Universidade Federal de Minas Gerais, 2010. http://hdl.handle.net/1843/SAGF-8TNPN4.
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Uma variedade de agentes quimioterápicos pode ser utilizada para o tratamento da giardíase. Porém, a maioria desses agentes apresenta efeitos adversos consideráveis e são muitas vezes contra-indicados. Além disto, a Giardia parece ter uma grande habilidade para desenvolver resistência a estes agentes, o que torna a investigação de novos fármacos uma área atrativa e promissora. Neste trabalho, avaliamos a atividade giardicida de algumas substâncias obtidas a partir da modificação da cadeia alifática do metronidazol (MTZ), que constitui hoje a droga mais usada no tratamento da giardíase. Escolhemos estas substâncias não só pelo valor promissário, no que tange a atividade giardicida, concedido pelo MTZ, mas também pela facilidade de modificação da cadeia lateral do MTZ para obtenção destes análogos. O efeito do MTZ e seis de seus análogos (MTZ-MS, MTZ-I, MTZ-Br, MTZ-N3, MTZ-NH2.HCl e MTZ-Tr) sobre o crescimento dos trofozoítos de G. lamblia, cepa Portland-1, foi determinado in vitro. Os análogos MTZ-MS, MTZ-I, MTZ-Br e MTZ-N3, apresentaram atividade inibitória maior, ou seja, IC50 menor que o MTZ. Entre eles o MTZ-Br e MTZ-I foram os mais ativos. Os análogos MTZ-Tr e MTZ-NH2.HCl foram os que apresentaram menor atividade anti-giardia. Visando investigar o potencial citotóxico dos análogos sintetizados, avaliamos o efeito dos mesmos sobre a proliferação de células mononucleares do sangue periférico humano (CMSP) comparado ao MTZ. Os análogos nitroimidazóis não apresentaram efeito citotóxico sobre CMSP. O efeito dos análogos MTZ-I e MTZ-Br em infecções experimentais de gerbils foi obtido determinando a DE50 (dose necessária para matar 50% dos trofozoítos de G. lamblia) comparada a do MTZ. Os animais infectados experimentalmente por trofozoítos de G. lamblia foram tratados com concentrações que variaram de 0.1 a 6.0 µmol/kg do MTZ e dos análogos. MTZ-I e MTZ-Br apresentaram atividade giardicida superior a do MTZ. Os efeitos dos análogos sobre a morfologia e ultra-estrutura dos trofozoítos foram avaliados por Microscopia Eletrônica de Transmissão. Vacuolização, dilatação de vesículas periféricas, internalização de flagelos e de disco adesivo, formação de figuras de mielina e extração citoplasmática foram as principais alterações observadas em trofozoítos incubados com os análogos do MTZ. Alterações similares foram observadas em trofozoítos tratados com MTZ, sinalizando a eficácia dos análogos. Estes resultados somados à excelente atividade giardicida do MTZ-I, MTZ-Br, MTZ-Ms e MTZ-N3, comprovam que esses análogos nitroimidazóis são importantes opções terapêuticas.
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Baker, David Andrew. "Production of a cDNA library and studies on gene sequences encoding antigens from the flagellite Giardia intestinalis (Lamblia)." Thesis, University of Hull, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328859.
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Palm, Daniel. "Adaptive responses during Giardia-host interactions /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-207-1/.
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Djamiatun, Kis. "In vitro studies on induction of lymphocyte and cytokine responses to the gut protozoans Giardia lamblia and Giardia muris." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23882.
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In mice infected with 10$ sp4$ Giardia muris cysts, a peak lymphocyte proliferation in the spleen and Peyer's patches in response to Giardia extract occurred during the elimination and latent phases, respectively. This shows that the Peyer's patch cells are more responsive than the spleen to Giardia infection. Th2-type cytokines produced by Peyer's patch cells may play a protective role during the latent and acute phases. Th1-type cytokines may contribute to this production during the elimination phase. Cytokine production in response to Giardia extract in vitro was observed in mice immunized with this extract, but not in control mice. Therefore, Giardia antigen can induce cytokine production in vitro in a specific manner.
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Suharto, Adrian Rinaldi Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Structural studies of giardial arginine deiminase." Awarded by:University of New South Wales. Biotechnology and Biomolecular Sciences, 2006. http://handle.unsw.edu.au/1959.4/26293.
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Recombinant giardial arginine deiminase (rADI) was characterized. The enzyme was found to have a specific activity of 12 U (mg protein)-1under at pH 7.4 and 1 mM arginine. The maximum velocity was 14.75 U (mg protein-1) and the KM was 0.167 mM. The specific activity and maximum velocity values are significantly lower than the values reported previously for giardial rADI, while the KM value is quite similar. The optimum pH for the giardial rADI was 6-9, a broad range compared to other arginine deiminases. Recombinant ADI is very specific in its binding specificity, with canavanine (KI 2.4 mM) and ornithine (KI 2.1 mM) being the only substrate analogues giving significant inhibition from the wide variety of analogues tested. None of the analogues could be shown to act as alternative substrates. The contribution of conserved, catalytic and C-terminal residues proposed by previous research towards ADI activity was investigated by site-directed mutagenesis. Mutations of catalytic site residues Asp175, Glu226, His280 and Cys424 decreased the rADI activity to below 2%. Conservative mutations showed significant activity for Asp175 to Glu175 (DE175) and Glu226 to Asp226 (ED226). Site directed mutagenesis on the conserved non-catalytic site Leu46 showed activities below 15%, with the highest activity observed for the mutation to Val46 (LV46), which differs in one CH2 to Leu46 on its side chain. The KM of the mutant LV46 was 3.64 mM while for LA46 (Leu to Ala mutation) was 1.33 mM. Excising 5, 13, 16 amino acids from the C-terminal residues resulted in activity decreasing to 0.8% of the wild type, while excising 54 amino acids caused the rADI to be insoluble. Sequence alignment of Giardia and Dictyostelium suggests a homologous area within the C-terminal extension. Site directed mutagenesis on the Tyr567 residue in this region resulted in a decrease in activity, with the highest activity observed for a Tyr to Phe mutation. Studies using specific cysteine protease inhibitors demonstrated partial protection against proteolysis of ADI against giardial proteases. Degradation of ADI by giardial proteases was more rapid at pH 6 than at pH 7.4.
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RODRIGUES, Rúben Miguel. "Aplicação de métodos moleculares ao diagnóstico de Giardia lamblia e de Entamoeba spp." Master's thesis, Instituto de Higiene e Medicina Tropical, 2011. http://hdl.handle.net/10362/14015.
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Entamoeba histolytica e Giardia lamblia são protozoários com distribuição mundial que frequentemente infectam o Homem, sendo causadores de elevada morbilidade associada com quadros de diarreia.
Este estudo consistiu na utilização de métodos moleculares na detecção e identificação destes parasitas em amostras de fezes recebidas no Laboratório de Patologia Tropical do Instituto de Higiene e Medicina Tropical (Lisboa, Portugal), no período decorrente entre Setembro de 2007 e Agosto de 2009. .
Foi igualmente avaliada a eficácia e custo-benefício de um método alternativo de conservação para material biológico fecal – o papel de filtro, para subsequente extracção de DNA.
Foram analisadas microscopicamente 80 amostras, 23,8 % (19/80) das quais positivas para Giardia e 27,5% (22/80) positivas para Entamoeba spp.. Através do método molecular da PCR, amplificou-se com sucesso DNA de Giardia para o gene ssurRNA em 94,7% (18/19) das amostras microscopicamente positivas. No que se refere às amostras positivas por exame microscópico para Entamoeba spp foi detectada E. dispar em 50,0% (11/22) das amostras após amplificação de parte do gene 16S rRNA. Adicionalmente foi também detectado DNA de E. histolytica em 20,0% (4/20) das amostras analisadas, microscopicamente negativas para Entamoeba spp..
Neste estudo realizou-se a genotipagem de G. lamblia utilizando parte dos genes bg (beta-giardina), tpi (triose-fosfato isomerase) e gdh (glutamato desidrogenase), que revelou haver 61,5% (8/13) dos isolados pertencentes ao genótipo B e 38,5% (5/13) do genótipo A.
A determinação de subgenótipos através da análise de SNP’s para os 3 genes só foi possível para o gene bg do genótipo A, revelando 3 amostras correspondentes ao subgenótipo A2 e uma para o subgenótipo A3. Para os restantes genes não foi possível a determinação de subgenótipos devido à presença de polimorfismos genéticos para ambos os genótipos A e B.
Realizou-se também a análise filogenética concatenada que apenas permitiu a integração de três amostras identificadas com o genótipo A no subgenótipo AII.
Os resultados obtidos neste trabalho demonstram que a microscopia associada às técnicas moleculares possibilita a diferenciação das espécies do complexo Entamoeba favorecendo o correcto diagnóstico desta patologia e consequente tratamento. Para além disso, o uso dos métodos moleculares contribuiu para o esclarecimento e compreensão dos genótipos de Giardia em humanos.
Neste estudo a utilização do método de conservação, papel de filtro apresentou um menor custo e elevada eficácia em relação aos métodos normalmente utilizados, conservação a -20ºC. Sugerindo a sua utilização com sucesso em estudos epidemiológicos em especial em zonas endémicas de condições precárias.Entamoeba histolytica and Giardia lamblia are two protozoa that are worldwide distributed commonly infecting men and causing elevated morbidity associated with diarrheal disease. In this study we used molecular techniques to detect and identify these parasites in the fecal samples received in the Pathology Laboratory of the Institute of Tropical Medicine and Hygiene (Lisbon, Portugal) in the period of September 2007 and August 2009. We equally evaluated the efficiency and cost-effectiveness of the stool sample conservation method – FTA filter paper and subsequent DNA extraction. A total of 80 samples were examined by microscopy. The protozoan parasite Giardia lamblia was detected in 23,8 % (19/80) of the isolates and Entamoeba spp. in 27,5% (22/80). G.lamblia and E.dispar were detected by PCR in 94,7% (18/19) and 50,0% (11/22) of the microscopy positive isolates, respectively. Additionally it was detected DNA of E.histolytica in 20,0% (4/20) of the samples microscopically negative for Entamoeba spp. Genotyping of G. lamblia for the genes β–giardin (bg), triose phosphate isomerase (tpi) and glutamate dehydrogenase (gdh) has shown that genotype B (61.5% - 8/13) was more prevalent that genotype A (38,5% - 5/13). A Single Nucleotide Polymorphism’s (SNP) analysis for the three genes of Giardia was conducted in order to assess the subassemblage level of the tested samples. However we were only able to determine the subassemblage level for samples of bg gene belonging to genotype A, where three samples corresponded to subassemblage A2 and one to subassemlage A3. In the remaining genes, due to the high genetic polymorphisms for both genotypes A and B the subassemblage level was not possible to determine. Phylogenetic concatenated analysis was also carried out allowing the association of three samples with subassemblage AII. The results of our study show that the microscopy in combination with molecular techniques allow the differentiation of Entamoeba species favoring the correct diagnosis and subsequent treatment of this disease. In addition, the use of molecular methods contributed to the clarification and understanding of the genotypes of Giardia infections in humans. In this study, the use of the FTA filter paper preservation method showed a lower cost and high effectiveness when compared to the commonly used methods, (storage at -20 ° C), suggesting that it can be successfully I epidemiological studies used in endemic areas with poor laboratory conditions.
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Boone, James Hunter M. S. "Evaluation of a Monoclonal-based EIA for the Detection of Giardia lamblia and the Identification of the Antigen." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36676.
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I. A number of commercial enzyme immunoassay (EIA) tests are available for the diagnosis of giardiasis. In a time of rising health-care costs, there is a need for diagnostic tests that are rapid, specific, sensitive and inexpensive. In the first phase of this study, I developed a monoclonal-based EIA, the GIARDIA TEST, with these qualities in mind. This assay's performance characteristics were determined by a comparison study using conventional ova and parasite examination, immunofluorescence antibody test (IFA) and other commercial EIA tests. Studies were done in-house at TechLab, Inc. and at various U.S. medical facilities. Results were statistically analyzed to determine sensitivity (ability of the assay to detect a positive result), specificity (amount of crossreactivity), predictive positive value (the confidence in a positive result), predictive negative value (the confidence in a negative result) and overall correlation with the reference assay.
II. There remain many questions to be answered about the various antigens produced by Giardia lamblia and how they can be utilized as diagnostic markers. In the second phase of this study, I identified and partially characterized the antigen (Ct7 Ag) that reacts with the Ct7 monoclonal antibody (MAb). This MAb is an IgM class mouse immunoglobin that is utilized by the GIARDIA TEST and by an immunofluorence antibody test (IFA) which detects Giardia cysts in water and feces. The results of this study will provide physicians and researchers with detailed information about the Ct7 Ag and why it is a useful marker for giardiasis.
Master of Science
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FONTENELE, Ana Lúcia Arruda. "Avaliação da resposta imune em crianças infectadas com Giardia lamblia e com alergias das vias respiratórias." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16505.
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A resposta imune contra Giardia lamblia e as alergias, em área endêmica para infecções por helmintos e este protozoário. tem sido estudada. IgE e isotipos IgG anti-Ascaris lumbricoides (Asc) podem modular a atopia e a alergia. Neste estudo, avalia-se a presença de anticorpos IgE ,IgG1, IgG4 anti Asc e a produção de citocinas Th1 (IL-2/IFN-γ/TNF-α), Th2 (IL-4/IL-10), Th17 (IL-17/IL-6) em crianças infectadas por G.lamblia, sem infecção concomitante por helmintos, bem como a frequência de asma e/ou rinite. Para isso, um estudo caso-controle aninhado em um estudo transversal utilizando questionário padrão para a alergia de vias aéreas, análises coproparasitológicas. Realizou-se testes imunoenzimáticos para detecção de anticorpos anti-Asc e cultura de células de sangue para mensuração dos níveis de citocinas em sobrenadante e intracelular. A amostra foi composta por 211 crianças: 53 infectadas / asma/rinite (GA); 39 não infectadas/asma/rinite (A); 62 infectadas / não / asma / rinite (G); 57 não asma/rinite/não infectadas (NA+NG), com idades entre 2-10 anos. Infecção por G.lamblia foi acompanhado pelo aumento dos níveis de IgG1, mas não IgE ou IgG4.anti Asc. A produção de IL-6 foi semelhante entre os grupos, mas a produção de IL-2, IL-4 e IFN- foi maior em crianças infectadas. TNF-α foi produzido em níveis mais elevados em crianças alérgicas, enquanto que a IL-10 esteve em níveis elevados em crianças infectadas/asma/rinite. Em crianças infectadas com IgG1 anti-Asc positivo houve maior produção do TNF-α e IL-10 e menor frequência de alergia quando comparou com IgG1 anti-Asc negativo (OR = 0,392; IC = ,168-,914; p = 0,02). Para análise do coteúdo de citocinas intracelular, foi observada menor frequência de células CD4+/IFN-+ e CD4+/IL-17+ no grupo GA, quando comparado com o grupo NG+NA. Não houve diferença na frequência de células CD4+/IL-4+ entre os grupos. A frequência de células CD4+/IL-17+ foi inferior em crianças somente infectadas (G). Em conjunto, um perfil Th1/Th2 foi estimulado nos pacientes infectados, com IgG1 anti-Asc circulante e houve maior produção de IL-10 e TNF-α com frequência de alergia vias aéreas mais baixa. Além disso, estes achados apontam um perfil predominante de Th2 (IL-4 acompanhada de menor nível de IFN-) com baixo potencial inflamatório (menos IL-17) em crianças infectadas por G. lamblia com asma e/ou rinite. Estes resultados destacam a importância de uma melhor avaliação dos subtipos de IgG em A. lumbricoides e G. lamblia em áreas endêmicas, especialmente no que diz respeito à estratégia de prevenção ou dessensibilização para reações alérgicas.
Immunity to Giardia lamblia and allergies in endemic area for helminths/protozoa infections had been studied. Anti-Ascaris lumbirocides (Asc) IgE and IgG isotypes can modulate the atopic and allergy. In this study, we evaluate the presence of anti-Asc IgE, IgG4, IgG1 antibodies and Th1 (IL-2/IFN-γ/TNF-α), Th2 (IL-4/IL-10), Th17 (IL-17/IL-6) cytokine production in G. lamblia-infected children, without concomitant helminths infection, as well as asthma and/or rhinitis frequency. For this, a case-control nested in a cross-sectional study was conducted using standard questionnaire for airway allergy, parasitological analyses, immunoassay tests for anti-Asc antibodies and blood cell culture for cytokines measurement in supernatant and intracellular. The sample comprised 211 children (53 allergic/infected (GA); 39 allergic/uninfected (A); 62 non-allergic/infected (G); 57 non-allergic/non-infected (NA+NG) aged 2-10 years. Protozoan infection was accompanied by increased of anti-Asc IgG1 levels, but not IgE or IgG4. There were similar IL-6 production, but IL-2, IL-4 and IFN- were higher in infected children. TNF-α was produced in higher levels for allergic children, whereas the IL-10 was high levels in allergic/infected children. For positive anti-Asc IgG1 and allergic/infected children, higher TNF-α and IL-10 production and lower allergy frequency was observed when compared to negative anti-Asc IgG1 (OR=0.392; IC=0.168-0.914; p=0.02). For intracellur cytokine content, was observed lower frequency of IFN-+CD4+ and IL-17+CD4+ cells in the GA group when compared to the NG+NA group. There was no difference in IL-4+CD4+ cells frequency among the groups. The IL-17+CD4+ cells frequency was lower in infected children only (G). Take together, the a Th1/Th2 profile was stimulated in the infected patients, which with circulating anti-Asc IgG1 the production of IL-10 and TNF-α was strengthened and there was lower frequency airway allergy. Besides of this, the finding point out a predominant Th2 profile (IL-4 accompanied of less IFN-) with low inflammatory potential (less IL-17) in G. lamblia infected children with asthma and/or rhinitis. These findings highlight the importance of improved evaluation of IgG subtypes in A. lumbricoides and G. lamblia endemic areas, especially with regard to the prevention strategy or desensitization for allergic reactions.
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Campbell, John Darren. "In vitro and in vivo studies on the immunobiology of encysting Giardia lamblia trophozoites." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69576.
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Gerbils, experimentally infected with Giardia lamblia trophozoites, had trophozoites and encysting trophozoites in all 3 equal sections of the small intestine and in the colon at necropsy. Cysts were found in the second and third sections of the small intestine and in the colon. WB strain derived trophozoites (WB, D1, WB-C6, and V1) differed in levels of encystation in vitro but not in gerbils. Passage in gerbils increased the in vitro encystation levels of WB and D1 but decreased that of WB-C6 and V1. No differences were found in the total protein profiles or isoenzyme patterns of these G. lamblia populations. Immunization of mice with in vitro cysts produced monoclonal antibodies (mAbs) recognizing cyst protein antigens. In Immunofluorescence (IFA), mAb 5A4.G6 recognized cyst walls. This mAb reacted with a 38 kD band on Western blots. IFA results showed that mAb 8C5.C11 reacts with vesicles in encysting trophozoites and with cyst walls. It recognized 26, 28, 42 and 46 kD bands in Western blots. When mAb 8C5.C11 and Guinea pig complement were added to 0-9 hour encysting cultures, the numbers of cysts produced were significantly reduced compared to control. MAb 5A4.G6 did not affect in vitro encystation.
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Nigam, Anuranjini. "Assembly and promoter analysis of variant-specific surface protein (vsp) genes of Giardia lamblia." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1209%5F1%5Fm.pdf&type=application/pdf.
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Cooper, Margarethe. "Molecular Typing of Giardia lamblia in Humans and Dogs and Evidence for Sexual Recombination." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195546.
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Giardia lamblia is a eukaryotic parasite that causes diarrhea in humans worldwide. Diarrheal diseases cause stunting and mental retardation in children in developing nations, therefore it is important to understand the molecular epidemiology of G. lamblia. Compounding this, it is not clear if companion animals such as dogs contribute to infections in humans through zoonotic transmission. The genotypes of G. lamblia that have been found in humans are A1, A2 and B, while those in dogs have been on rare occasions all three human genotypes, but largely C and D, which have only been reported in dogs and appear to be species-specific. The molecular epidemiology of G. lamblia in humans and dogs was assessed in an endemic region of Lima, Peru. With one exception, dogs were found to harbor the C and D dog genotypes of G. lamblia. A single family dog was found to harbor a human genotype of G. lamblia. A2 and B genotypes of G. lamblia, but not A1, were found in humans in the endemic region. Previous literature reported that A2 and B typing within genotype tools were available, however the A2 samples from the endemic region could not be distinguished from one another through nucleotide polymorphism sequence analysis. A molecular typing technique was developed to type A2 samples. The extensive sequence analysis performed on two chromosomes of G. lamblia, yielded different phylogenetic tree groupings for the same samples. This lead to algorithmic analysis, which demonstrated a significantly high probability that meiotic recombination is occurring in the A2 samples of G. lamblia. As G. lamblia is largely believed to be asexual, the conclusion of doctoral research performed in this study yielded controversial, yet significant evidence that sex in G. lamblia A2 genotype samples is indeed occurring.
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Souza, Doris Sobral Marques. "Avaliação de técnicas de diagnóstico de Cryptosporidium spp. e Giardia lamblia em fezes humanas." Florianópolis, SC, 2002. http://repositorio.ufsc.br/xmlui/handle/123456789/84452.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em Farmácia.Made available in DSpace on 2012-10-20T09:27:37Z (GMT). No. of bitstreams: 0
A diarréia é responsável por mais de 3 milhões de mortes ao ano no mundo e a maioria dos casos ocorre em crianças de países em desenvolvimento. A diarréia em crianças, além dos problemas relacionados à desidratação, ainda pode ocasionar má absorção dos nutrientes causando um quadro de desnutrição afetando, até mesmo, as funções cognitivas. Muitos patógenos causadores de diarréia podem ser veiculados pela água e por alimentos contaminados. Eles podem ser vírus, bactérias e parasitas. Os protozoários Cryptosporidium spp. e Giardia lamblia são importantes causadores de diarréia, principalmente em crianças. Estima-se que no Brasil a prevalência destes patógenos seja de 8% e 28,5%, respectivamente. Devido a cistos de Giardia e oocistos de Cryptosporidium serem estruturas muito pequenas, sua detecção torna-se difícil, já que as fezes naturalmente possuem muitos detritos e microrganismos que podem mascarar ou ser confundidos com estes protozoários. Para facilitar e tornar mais eficiente este diagnóstico, este trabalho teve por objetivo padronizar a Técnica de Imunoseparação Magnética (IMS) acoplada à Imunofluorescência (IFA) para o diagnóstico de Cryptosporidium spp. e Giardia lamblia em fezes humanas, além de avaliar sua eficiência quando comparada às Técnicas Clássicas descritas por Faust et al. (1939) e por Lutz (1919), ou Hoffman Pons & Janner (1934), quando utilizadas para o diagnóstico da giardíase; e por fim avaliar as prevalências de Cryptosporidium spp. e Giardia lamblia em uma creche e em ambulatórios de dois Hospitais da Grande Florianópolis-SC. Os resultados da Padronização da Técnica, utilizando-se 4 tratamentos com 3 repetições para cada, demonstraram que a IMS-IFA foi capaz de recuperar oocistos de Cryptosporidium spp. (média de 4,7%) e cistos de Giardia lamblia (média de 1,3%) em fezes humanas. Quando comparadas, as recuperações das duas espécies, não apresentaram diferenças significativas (F > 0,05). Ao se comparar o desempenho das Técnicas de IMS-IFA com a de Faust et al. e a de Lutz no diagnóstico de G. lamblia, utilizando-se 127 amostras de fezes de crianças, percebeu-se que a primeira deteve vantagem quando comparada às outras duas técnicas em conjunto, mas quando se comparou a recuperação de cistos pela primeira em relação à soma dos resultados da segunda (confirmados ou não pela Técnica de Lutz) observou-se que as diferenças não foram significativas (?2< 0,05). Avaliando-se as prevalências de Cryptosporidium spp. e Giardia lamblia encontradas em 77 crianças de uma creche e de 50 crianças de ambulatório, ambos na Grande Florianópolis, observou-se que para Cryptosporidium spp. estas foram baixas e próximas nas duas populações (1,3% e 2% respectivamente). Para Giardia lamblia, elas se comportaram de forma bastante distinta (45,5% e 2% respectivamente) e estatisticamente significativa. Também se detectou diferenças quando foram comparadas crianças menores com as maiores de 5 anos de idade dentro da mesma população (creche ou ambulatório) e na prevalência de giardíase comparando-se as faixas etárias analisadas das duas populações. A IMS-IFA mostrou-se capaz de detectar cistos de Giardia e oocistos de Cryptosporidium em fezes humanas e, devido a sua especificidade, não se fez necessária a confirmação através de outras metodologias de diagnóstico para Cryptosporidium.
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Osman, Asiah. "Structural and Functional Investigation of Two Parasite Protein Systems, Alpha Giardins from Giardia lamblia and Pathogenesis-Related Proteins from Ancylostoma caninum." Thesis, Griffith University, 2012. http://hdl.handle.net/10072/365706.
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Investigation of structure and function of parasite proteins is the major goal of this thesis. The two protein systems studied in this work, parasite annexins and pathogenesis-related proteins (PRPs), have both been speculated to be involved in host-parasite interactions. Parasite annexins are members of the annexin superfamily; the hallmark feature of annexins is their calcium-dependent binding to phospholipid membranes. PRPs are among the excretory/secretory (ES) products that are highly up-regulated in the transition from a developmentally arrested free-living form to a tissue-penetrating larva (L3 stage) of the parasite. Some parasite annexins and PRPs have been reported to have immunogenic properties, thus making them potential vaccine candidates.
The first part of the thesis covers the structural and functional investigation of parasite annexins. The expression, purification and biophysical properties of alpha-1 giardin and alpha-3 giardin (from G. lamblia) and Anx(Sm)1 from S. mansoni are discussed in chapter 3. This chapter describes an efficient expression and purification protocol that was used to successfully produce large amounts of highly pure untagged alpha-1 and alpha-3 giardins. A liposome affinity and anion exchange chromatography were used for purification of alpha-1 giardin, whereas ion exchange chromatography was used to purify alpha-3 giardin. The identity and molecular mass of all parasite annexins were validated using mass spectrometry and SEC-MALS, and were found to be in excellent agreement with the theoretical value of each protein. SEC-MALS results also showed that alpha-1 giardin is monomeric, whereas alpha-3 giardin and Anx(Sm)1 exist as a monomer-dimer mix in solution. CD spectroscopy was used to investigate the effect of phospholipid vesicles and calcium on the conformational and thermal stability of parasite annexins. Differential effects on the alpha-helical content of alpha-1 and alpha-3 giardin are observed with varying lipid compositions. While calcium induced conformational change of alpha-1 giardin, it has no effect on the CD spectra of alpha-3 giardin. Calcium was also found to destabilise the folding stability of alpha-1 giardin and alpha-3 giardin, but had no significant effect on the folding stability and conformation of Anx(Sm)1. The destabilisation effect of calcium on protein folding stability was also observed in annexins that lack type II calcium in some of their repeats.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
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