Investigating the molecular participants of programmed cell death in plamodium falciparum

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy University of the Witwatersrand, Johannesburg, 2014Malaria, a disease resulting from infection by members of the Plasmodium genus, accounted for an estimated 627 000 deaths globally in 2012. The majority of these mortalities were due to P. falciparum infections and thus the species of focus in this study. Due to the rapid emergence of drug-resistant strains, novel avenues for research evaluating parasite survival and population regulation within the human host are now needed. Programmed cell death (PCD) is a well characterised means of self-regulation in metazoans, where a plethora of proteins and signals result in the destruction and/or removal of unnecessary, damaged or dangerous cells. A key protein participant is MDM2 which, via its SWIB/MDM2 domain, binds to the nuclear transcription factor p53 to promote p53 degradation and prevent apoptosis. SWIB/MDM2 domains additionally play key roles in transcription-dependent stress survival. No proven PCD molecular participants for P. falciparum exist but two SWIB/MDM2 homologues (PF3D7_0611400 (PfSWIB) and PF3D7_0518200 (PfMDM2)) and a putative p53 homologue (PF3D7_0522400 (Pfp53)) have been identified by bioinformatics. These were assessed experimentally in this study. Structural features of the SWIB/MDM2 domains of PfMDM2 and PfSWIB, suggested that they are chromatin remodelling factors. The domains were amplified from 3D7 P. falciparum genomic DNA, directionally cloned into the pGEX-4T-2 vector, and used for recombinant GST-fusion protein expression in E. coli. The soluble, tagged, domains were isolated and purified by affinity chromatography (PfMDM2, ~33kDa and PfSWIB, ~42kDa) and used, in conjunction with P. falciparum phage display library technology, for the identification of several novel binding partners. Two of these interactions were verified with in vitro binding assays, proving concentration dependent interactions between PfMDM2 and a conserved protein of unknown function; and PfSWIB and a putative Investigating the Molecular Participants of Programmed Cell Death in Plasmodium falciparum serine-threonine protein kinase (PfARK3). Transgenic P. falciparum parasites were created by transfection with pARL2-GFP vector constructs containing the PfSWIB and PfMDM2 genes. PfMDM2-GFP localized to the mitochondria under the control of an N-terminal signal sequence, under normal and heat stress conditions, the latter triggering PCD in the asexual intraerythrocytic parasite. PfSWIB-GFP localized to the cytoplasm under normal and heat stress conditions, but in a subpopulation of trophozoites it moved to the nucleus after exposure to elevated temperatures. PfMDM2 is hypothesized to play a role within the parasite mitochondrion, although its involvement in PCD is uncertain and may be unconventional, while PfSWIB is suggested to be involved in a stage-specific heat stress response. Pfp53 was found to have a putative DNA binding and tetramerization domain, based primarily on sequence alignments. A recombinant GST-tagged form (~87kDa) of these two domains was expressed in E. coli and purified by affinity chromatography. The ability of the recombinant protein to tetramerize was inconclusive, while in an electromobility shift assay it did not bind to a canonical p53 DNA binding consensus sequence identified in the parasite’s genome. The precise cellular function(s) for this protein requires further evaluation. This study represents the first characterisation of these three P. falciparum proteins. Several novel activities were identified for each and their role in PCD was evaluated by exposing parasites to febrile temperatures, which provided new information regarding heat stress regulation in P. falciparum

Results of geoelectrical surveys in the area of Crater 70, Deception Island, Maritime Antarctica

Deception Island is horse-shoe shaped stratovolcano with 15 km diameter and a large caldera that opens towards the southeast, forming a bay about 7 km wide. The maximum altitude is at Mount Pond (539 m a.s.l.). About 57% of the island area is covered by glaciers. In geological terms Deception Island is composed of volcano-sedimentary deposits, including pyroclastic flows and deposits, strombolian scoriae and lava, volcanic and hypo-volcanic indurated ashes, and phreatomagmatic deposits. Recent eruptions took place in the interior of the island in 1967, 1969, and 1970. Permafrost is widespread in the island but its characteristics are still poorly studied. In this study we present geoelectrical data collected in the Crater 70 area of Deception Island which was formed during the eruptions of 1970. The study area is located in the southern slope of a volcanic cone and the objective of the geoelectrical survey was to determine if there were any permafrost aggradation after the eruptive event and to assess the thickness of the frozen body. Two electrical resistivity tomography (ERT) profiles and a vertical electrical sounding (VES) were done (Fig. 1). Geoelectrical methods are particularly well adapted to study the spatial distribution of permafrost because of its high electrical resistivities in comparison with the electrical resistivities of soil and rocks with water and above 0 oC

Regional Differences in Returns to Education in Portugal

This paper analyses differences in the return to education in Portugal across regions. For this purpose, we use an extended Mincer-type wage equation. OLS regression results indicate that differences in the rewards to education are substantially different across regions. In particular, they are much higher in Lisbon than in other regions. Since the average level of education in Lisbon is much higher in Lisbon than elsewhere such a differential is attributed to the fact that the demand for educated labour is much higher in Lisbon, likely due to differences in technology. A quantile regression analysis reveals that the return to education is not constant across the whole conditional wage distribution. This is valid for the 18 regions examined, although once again the impact of education on wages is higher in Lisbon regardless the quantile we examine.

The impact of asthma on the gastrointestinal tract (GIT)

The gastrointestinal tract (GIT) of vertebrates is composed of several distinct compartments and glands as well as an extensive mucosal surface. Its primary function is that of chemical and physical digestion of food and the absorption of nutrients; however, due to its continual antigen exposure, the GIT also has an important defensive immunological function. The GIT’s immunological participation is facilitated by the mucosa-associated lymphoid tissues, thought to share the mucosal immunological system with the respiratory mucosa-associated lymphoid tissues. As a result of this shared mucosal immunity, it has been hypothesized that bronchial asthma may be able to affect the body’s GIT in the same pathophysiological manner as the airways and lungs. Here we discuss the link between bronchial asthma and pathophysiological features in the GIT – including leukocyte influx, goblet cell alterations, fibrosis, and epithelial and villous atrophy

Vocabulary in foreign-language learning explorations of a neglected area

Dissertação(mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e ExpressãoExploração de questões preliminares com vistas a uma teoria da aquisição de vocabulário em língua estrangeira - LE e uma terminologia correlata. Investiga-se a produção local (Pós-Graduação em Inglês/UFSC) em áreas afins destacando-se o enfocado e o ignorado. Observações da literatura internacional permitem enfatizar a importância da proficiência lexical em vários aspectos do desempenho comunicativo e línguo-aquisicional de aprendizes de LE. Contraditoriamente, a literatura também aponta um certo descaso pelo assunto, relacionado a disputas lingüísticas teóricas sobre as relações entre léxico e gramática. Em descaso mais gritante está, em Lingüística Aplicada, o enfoque específico do conhecimento lexical e do processo de aquisição de vocabulário em LE. Um esquema das áreas de interesse ligadas a este objeto de descaso descortina um vasto 'campo' de assuntos interconexos e atividades correlatas. Deste campo, num segundo passo de aproximação, analisam-se as dimensões lingüísticas e psicológicas da proficiência lexical. Por fim, apontam-se ulteriores linhas de continuidade lógica desta investigação que é feita a partir do escrutínio de cerca de 150 trabalhos listados na bibliografia

Análise da variabilidade espacial do rendimento de culturas e de propriedades do solo em pequenas parcelas agrícolas

[Abstract] The objective of this study was to assess spatial variability of soil properties and crop yield under no tillage as a function of time, in two soil/climate conditions in São Paulo State, Brazil. The two sites measured approximately one hectare each and were cultivated with crop sequences which included corn, soybean, cotton, oats, black oats, wheat, rye, rice and green manure. Soil fertility, soil physical properties and crop yield were measured in a 10-m grid. The soils were a Dusky Red Latossol (Oxisol) and a Red Yellow Latossol (Ultisol). Soil sampling was performed in each field every two years after harvesting of the summer crop. Crop yield was measured at the end of each crop cycle, in 2 x 2.5 m sub plots. Data were analysed using semivariogram analysis and kriging interpolation for contour map generation. Yield maps were constructed in order to visually compare the variability of yields, the variability of the yield components and related soil properties. The results show that the factors affecting the variability of crop yield varies from one crop to another. The changes in yield from one year to another suggest that the causes of variability may change with time. The changes with time for the cross semivariogram between phosphorus in leaves and soybean yield is another evidence of this result

Noncompliance with tuberculosis treatment involving self administration of treatment or the directly observed therapy, short-course strategy in a tuberculosis control program in the city of Carapicuíba, Brazil

OBJECTIVE: To determine treatment noncompliance rates among patients participating in a municipal tuberculosis control program and to identify the variables related to noncompliance depending on the type of treatment strategy used. METHODS: A longitudinal non-concurrent cohort study was carried out involving two cohorts of patients participating in the Tuberculosis Control Program of the city of Carapicuíba, Brazil. The first cohort comprised 173 patients with tuberculosis treated from January 1, 2003 to December 31, 2003 using self administration of treatment, and the second comprised 187 patients with tuberculosis treated from July 1, 2004 to June 30, 2005 using the directly observed therapy, short-course strategy. RESULTS: Noncompliance rates decreased from 13.3% (self administration of treatment) to 5.9% (directly observed therapy, short-course), a significant difference (p < 0.05). For the self administration of treatment strategy, the variables significantly associated with treatment noncompliance were as follows: being an unregistered worker (relative risk [RR] = 3.06); retreatment (RR = 2.73); alcoholism (RR = 3.10); and no investigation of contacts (RR = 8.94). For the directly observed therapy, short-course strategy, no variables were significantly associated with noncompliance. CONCLUSION: The directly observed therapy, short-course strategy decreased noncompliance rates and produced better treatment outcomes, even when the risk factors for noncompliance were the same.OBJETIVO: Verificar as taxas de abandono e identificar as variáveis relacionadas ao abandono do tratamento, segundo o tipo de estratégia utilizada em pacientes matriculados no Programa de Controle da Tuberculose do município de Carapicuíba (SP) Brasil. MÉTODO: Estudo longitudinal não concorrente de duas coortes de tratamento de tuberculose, a primeira de 1 de janeiro a 31 de dezembro de 2003 com a estratégia tratamento auto-administrado (173 casos) e a segunda de 1 de julho de 2004 a 30 de junho de 2005 com a estratégia tratamento supervisionado (187 casos). RESULTADOS: A taxa de abandono diminuiu significativamente (p < 0,05), de 13,3% (tratamento auto-administrado) para 5,9% (tratamento supervisionado). Na estratégia tratamento auto-administrado, as variáveis associadas significativamente ao abandono foram: estar trabalhando na informalidade (risco relativo [RR] = 3,06); ser caso de retratamento (RR = 2,73); ser alcoolista (RR = 3,10); e não ter os contatos examinados (RR = 8,94). Não houve variável associada ao abandono para os casos sob a estratégia tratamento supervisionado. CONCLUSÃO: A estratégia tratamento supervisionado reduziu a taxa de abandono e produziu bons resultados quanto ao desfecho do tratamento, mesmo nos pacientes com fatores de risco para abandono como na coorte tratamento auto-administrado.Universidade Bandeirante de São PauloSecretaria de Saúde e Medicina Preventiva do Município de Carapicuíba Programa de Controle da TuberculoseUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Medicina PreventivaUNIFESP, EPM, Depto. de Medicina PreventivaSciEL

Commitment and loyalty: are they two constructs or two constructs from the same concept? A reply to Prado and Santos (2003)

Alguns pesquisadores utilizam os conceitos de lealdade e comprometimento como construtos distintos em seus modelos. Outros, como Prado e Santos (2003), argumentam que eles são de fato um único conceito. A literatura a respeito de tal distinção por vezes é confusa. Nesse contexto, este trabalho visa analisar a relação entre comprometimento e lealdade no ambiente virtual, especificamente no processo de compra pela Internet. Os resultados indicaram que ambos os construtos convergem fortemente para um mesmo conceito. Adicionalmente, a validade discriminante sugerida por Fornell e Larcker (1981) foi realizada e os resultados demonstraram que não existe distinção entre ambos os conceitos. Considerações finais e limitações da pesquisa finalizam o artigo.Some researchers use loyalty and commitment as different constructs in their models. Others', as Prado and Santos (2003), argue that these two are in fact just one concept. The literature about that is sometimes obscure. In this context, this paper tries to analyze the association between loyalty and commitment in the virtual environment, specifically in e-commerce. The results indicated that both constructs are just one. In addition, using Fornell and Larcker (1981) suggestion, the data again confirmed the only construct. Final considerations and research limitations end the paper