Thesis (M. Sc.)(Chemistry)--University of Pretoria, 2005. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Proefschrift Universiteit Maastricht. / Auteursnaam op omslag: Pim Martens. Met lit. opg. - Met een samenvatting in het Nederlands.

Thesis (MSc (Mathematics))--University of Stellenbsoch, 2009. / Please refer to full text for abstract

abstract: Infectious diseases are a leading cause of death worldwide. With the development of drugs, vaccines and antibiotics, it was believed that for the first time in human history diseases would no longer be a major cause of mortality. Newly emerging diseases, re-emerging diseases and the emergence of microorganisms resistant to existing treatment have forced us to re-evaluate our optimistic perspective. In this study, a simple mathematical framework for super-infection is considered in order to explore the transmission dynamics of drug-resistance. Through its theoretical analysis, we identify the conditions necessary for the coexistence between sensitive strains and drug-resistant strains. Farther, in order to investigate the effectiveness of control measures, the model is extended so as to include vaccination and treatment. The impact that these preventive and control measures may have on its disease dynamics is evaluated. Theoretical results being confirmed via numerical simulations. Our theoretical results on two-strain drug-resistance models are applied in the context of Malaria, antimalarial drugs, and the administration of a possible partially effective vaccine. The objective is to develop a monitoring epidemiological framework that help evaluate the impact of antimalarial drugs and partially-effective vaccine in reducing the disease burden at the population level. Optimal control theory is applied in the context of this framework in order to assess the impact of time dependent cost-effective treatment efforts. It is shown that cost-effective combinations of treatment efforts depend on the population size, cost of implementing treatment controls, and the parameters of the model. We use these results to identify optimal control strategies for several scenarios. / Dissertation/Thesis / Ph.D. Applied Mathematics for the Life and Social Sciences 2011

Malaria continues to be an enormous health-threat in the developing world and the emergence of drug resistance has further compounded the problem. The parasite-specific enzyme, 1-deoxY-D-xylulose-S-phosphate reductoisomerase (DXR), has recently been validated as a promising antimalarial drug target. The present study comprises a combination of synthetic, physical organic, computer modelling and bioassay techniques directed towards the development of novel DXR inhibitors. A range of 2-heteroarylamino-2-oxoethyl- and 2- heteroarylamino-2-oxopropyl phosphonate esters and their corresponding phosphonic acid salts have been synthesised as analogues of the highly active DXR inhibitor, fosmidomycin. Treatment of the heteroarylamino precursors with chloroacetyl chloride or chloropropionyl chloride afforded chloroamide intermediates, Arbuzov reactions of which led to the corresponding diethyl phosphonate esters. Hydrolysis of the esters has been effected using bromotrimethylsilane. Twenty-four new compounds have been prepared and fully characterised using elemental (HRMS or combustion) and spectroscopic (1- and 2-D NMR and IR) analysis. A 31p NMR kinetic study has been carried out on the two-step silylation reaction involved in the hydrolysis of the phosphonate esters and has provided activation parameters for the reaction. The kinetic analysis was refined using a computational method to give an improved fit with the experimental data. Saturation transfer difference (STD) NMR analysis, computer-simulated docking and enzyme inhibition assays have been used to evaluate the enzyme-binding and -inhibition potential of the synthesised ligands. Minimal to moderate inhibitory activity has been observed and several structure-activity relationships have been identified. In silica exploration of the DXR active site has revealed an additional binding pocket and information on the topology of the active site has led to the de novo design of a new series of potential ligands. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

Introduction Malaria retinopathy is a set of visible changes in the retina which are specific to falciparum malaria. Studies to date have been mostly limited to comatose African children. Retinal changes in adults with severe malaria and severely unwell patients without malaria have been less well studied and the specificity, pathogenesis, diagnostic and prognostic value of malarial retinopathy in adults are not known. Methods A series of observational studies of retinopathy in Bangladesh, India and Malaysia were done from 2008-2012. The aims were to describe the spectrum of retinal changes in falciparum and knowlesi malaria in adults, determine their specificity for severe falciparum malaria, quantify the impact of malaria retinopathy on visual function, understand its pathogenesis and assess the potential contribution of retinopathy to confirming diagnosis of malarial coma, predicting prognosis and understanding pathogenesis of cerebral malaria. Results 495 patients were enrolled and underwent retinal photography (305 with P. falciparum malaria (112 cerebral, 68 noncerebral severe, 125 uncomplicated), 44 P. knowlesi, 43 sepsis, 41 encephalopathy and 62 healthy). Retinal whitening and white-centred haemorrhages were common and specific to severe falciparum malaria. Retinopathy was most common and severe in cerebral (88%) and fatal (91%) falciparum malaria. Moderate-severe retinopathy was 95% specific for cerebral malaria in comatose patients, and its severity correlated with depth of coma. Vessel whitening was not seen and papilloedema was rare. In noncerebral severe falciparum malaria, retinopathy predicted increased likelihood of later development of coma and death. Retinal findings in Bangladeshi children were similar to those in adults. Optic nerve sheath diameter was mildly increased and brain swelling minimal on MRI. Severity of retinopathy correlated with plasma lactate, serum bicarbonate, sequestered parasite load and red cell stiffness suggesting a central role for microvascular obstruction in the pathogenesis. Severity of retinal whitening correlated with decreased visual acuity. Conclusions Retinal changes seen in severe P. falciparum malaria in Asian adults is similar, but not identical, to that seen in African children. They have potential to help with diagnosis and prognosis of Asian adults with severe falciparum malaria. Microvascular obstruction is prominent in the pathogenesis of retinopathy and coma in adults whereas raised intracranial pressure is not.

In regions endemic for malaria, natural exposure results in an acquired immunity which protects individuals from severe disease. However, no vaccine against the blood-stage of malaria, against which naturally-acquired immunity is targeted, currently exists that is capable of emulating, or out-performing, natural protection. To rationally direct the next generation of blood-stage malaria vaccine development, a greater understanding of the immunological mechanisms involved in clinical protection is required. To date, the assessment of naturally-acquired and vaccine-induced immunity to the blood-stage of malaria has suffered from a paucity of in vitro immunological assays that are both robust and reproducible, whilst allowing for assessment of anti-parasitic activity induced by antibodies, either alone, or in conjunction with immune cells. Thus this Thesis describes the development of the antibody-dependent respiratory burst (ADRB) assay, for assessment of blood-stage immunity against Plasmodium falciparum, as well as the Duffy antigen receptor for chemokines (DARC) – Duffy binding protein (DBP) binding inhibition assay, for assessing antibody mediated immunity to P. vivax. A reproducible and standardised assay of ADRB activity was developed here and applied to studies of immunity in both mice and humans. ADRB activity, which assesses antibodies' ability to activate oxidative burst in neutrophils via Fc receptor (FcR)-dependent pathways, was shown to associate with clinical protection in a cohort from Mali where FcR-independent immunological assays, such as the assay of growth inhibition activity, did not. This work thus elucidates the importance of FcR-dependent immunity to P. falciparum malaria and establishes the ADRB assay as a useful tool for future vaccine development. In addition, the DARC-DBP binding inhibition assay was established and utilised to assess inhibitory activity of antibodies induced in the first Phase I clinical trial of this antigen. Results identify the need for significant improvements in vaccine design, and show the utility of the assay as a tool for assessing future blood-stage vaccine development efforts against this neglected parasite.

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Brigita Mányová Supervisor: PharmDr. Marie Vopršalová, CSc. Supervisor-specialist: PharmDr. Vendula Hepnarová, Ph.D. Title of diploma thesis: Development of insecticides inhibiting acetylcholineseterase Pest insects cause problems and damage all over the world. They are vectors of serious diseases such as malaria, dengue fever, yellow fever, Zika virus disease and chikungunya disease. They cause huge damage to agricultural crops and are annoying to everyday life in living spaces. The aim of this diploma thesis was in vitro testing of selected compounds from the group of bis-isoquinoline and bispyridinium acetylcholinesterase inhibitors as potential insecticides. Another goal was also to create relationships between structure and effect. The ability of these compounds to inhibit both human (hAChE) and fly acetylcholinesterase (MdAChE) was evaluated. The modified Ellman spectrophotometric method was used. The half inhibitory concentration (IC50) values were obtained for both enzymes and the selectivity indexes (SI) were then calculated. Compounds having IC50s in micromolar or nanomolar range and exhibiting selectivity for MdAChE were most desirable. During the testing of these inhibitors, three...

Made available in DSpace on 2012-05-07T14:46:37Z (GMT). No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) 000015.pdf: 12430663 bytes, checksum: 67e3744dee25168d8c765fcc7b7a50c8 (MD5) Previous issue date: 2008 / Este trabalho analisa a história da saúde pública no governo de Juscelino Kubitschek (1956-­1961). A análise desse período inicia pela descrição e discussão do Programa de Saúde Pública do candidato Juscelino Kubitschek, documento político, no qual são divulgadas as metas e as promessas da campanha presidencial para a área da saúde. Como primeira ação no cumprimento do seu programa, Juscelino cria em 1956 o Departamento Nacional de Endemias Rurais (DNERu), instituição centralizadora dos serviços nacionais de saúde. Nessa empreitada, JK teve o apoio imprescindível do sanitarista e político Mario Pinotti. Principal personagem nacional da saúde pública na década de 1950, Pinotti cria um método de combate à malária. O sal c1oroquinado nomeado de "Método Pinotti" foi reconhecido internacionalmente como importante contribuição brasileira para erradicação mundial da malária. A doença, que estava controlada no início do governo JK, toma-se a mais importante endemia em 1958, quando o Brasil assumiu o compromisso com a Organização Mundial de Saúde (OMS) de converter seus programas de controle em programas de erradicação. Para isso foi instalado um Grupo de Controle e Erradicação da Malária sob a direção de Pinotti. A malária seria uma importante moeda de negociação no contexto da política de desenvolvimento de JK

Artemisinin-resistant Plasmodium falciparum parasites have been reported in the Greater Mekong Subregion since 2007. Artemisinin combination therapy (ACT) is the mainstay of antimalarial treatment and is responsible for decreases in malaria-related morbidity and mortality over the past fifteen years. The slowed parasite clearance rates following ACT indicates resistance to artemisinin derivatives. This resistance places increasing selective pressure for variants or traits that confer resistance to the partner drug used in combination and has led to the rapid failure of several partner drugs. While a single nucleotide polymorphism (SNP) in kelch13 has been shown to mediate some resistance phenotypes, the complete mechanism of artemisinin resistance is poorly understood. The known mechanisms of resistance hint at a connection to autophagy, an intracellular pathway that cells use to degrade waste molecules or organelles in response to stress and starvation, which is poorly characterized in Plasmodium. In this doctoral thesis project, I investigated the role of an autophagy-like mechanism in P. falciparum in the mechanism of artemisinin resistance. I found a SNP in autophagy-related gene 18 (atg18) that was associated with clinical delayed parasite clearance half-life following ACT. This gene encodes PfAtg18, a protein that I characterized as being similar to mammalian/yeast homologues in terms of structure, binding abilities, and ability to form puncta in response to stress. In order to investigate the contribution of the mutation in this protein, I edited the atg18 gene using CRISPR/Cas9 and screened the mutant and parent parasites against a drug library of over 6000 unique compounds. I discovered that while the SNP did not change the mutant parasite's susceptibility to any of the antimalarial compounds using a 72-hour drug pulse, it did alter the susceptibility to 227 other compounds. Further, I found that the SNP offers parasites a fitness advantage by allowing them to grow better in nutrient-limited settings. Finally, I determined that neither this atg18 SNP nor several polymorphisms in kelch13 modulate a dormancy phenotype that appears to be involved in the artemisinin-resistance mechanism.