Browsing by Issue Date, starting with "2009-03"
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- In vivo selection of plasmodium falciparum parasites carrying the chloroquine-susceptible pfcrt K76 allele after treatment with artemether-lumefantrine in AfricaPublication . Sisowath, Christin; Petersen, Ines; Veiga, Maria Isabel; Martensson, Andreas; Premji, Zul; Bjorkman, Anders; Fidock, David A.; Gil, José PedroBackground. Artemether-lumefantrine (AL) is a major and highly effective artemisinin-based combination therapy that is becoming increasingly important as a new first-line therapy against Plasmodium falciparum malaria. However, recrudescences occurring after AL treatment have been reported. Identification of drug-specific parasite determinants that contribute to treatment failures will provide important tools for the detection and surveillance of AL resistance. Methods. The findings from a 42-day follow-up efficacy trial in Tanzania that compared AL with sulfadoxine-pyrimethamine (SP) were analyzed to identify candidate markers for lumefantrine tolerance/resistance in the chloroquine resistance transporter gene (pfcrt) and multidrug resistance gene 1 (pfmdr1). The findings were corroborated in vitro with genetically modified isogenic P. falciparum parasite lines. Results. Treatment with AL selected for the chloroquine-susceptible pfcrt K76 allele (P < .0001) and, to a lesser extent, the pfmdr1 N86 (P = .048) allele among recurrent infections. These genotypes were not selected during SP treatment. No pfmdr1 gene amplifications were observed. Isogenic pfcrt-modified parasite lines demonstrated a 2-fold increase in susceptibility to lumefantrine, which was directly attributable to the K76T mutation. Conclusions. Our findings suggest that the pfcrt K76T mutation is a drug-specific contributor to enhanced P. falciparum susceptibility to lumefantrine in vivo and in vitro, and they highlight the benefit of using AL in areas affected by chloroquine-resistant P. falciparum malaria.
- Effect of copper exposure on growth, condition indices and biomarker response in juvenile sole Solea senegalensisPublication . Fonseca, Vanessa; Serafim, Angela; Company, Rui; Bebianno, Maria João; Cabral, HenriqueJuvenile Solea senegalensis were exposed to different concentrations of waterborne copper (Cu) for 15 days ill static conditions with continuous aerated artificial salt water at 20 degrees C (+/- 0.8 degrees C with a normal photoperiod (10 h/14 h light/dark) and daily feeding. Several measures of exposure and effects were determined: 1) biomarkers - metallothioneins and lipid peroxidation level; 2) mass indices - growth rate and morphometric condition indices; and 3) biochemical condition indices - RNA:DNA ratio and lipid and protein content in fish tissues. Copper exposure triggered the response of the biomarkers and resulted in reduced growth and condition (RNA:DNA and lipid content), but the morphometric indices did not vary. The physiological costs of Cu contamination on condition Suggested that lipid reserves were allocated as an energy Source to enable exposed fish to respond to Cu toxicity as well as to maintain positive growth rates and protein synthesis throughout the experiment, although with lower growth rates than the control fish. This study showed the importance of selecting suitable biomarkers according to contaminant source, fish Species and their life-history stage. In addition, the use of several biomarkers of exposure, growth and specific condition indices call improve fish health determination and should be considered in evaluations of the effects of environmental contaminants on fish.
- Beach litter managementPublication . Inthisang, Kitima; Newton, AliceSolid waste and wastewater pollution issues in Ko Chang Island, a MNP in the eastern region of Thailand have been of concern recently due to rapid growth in tourism. Plastics in the coastal zone are a problem and the major source of input has been land-based litter. The objectives of this study was to: (a) identify source of plastics litter on beaches, (b) investigate local and visitors’ perception on the impacts of beach litter on tourism, and (c) explore and assess the present beach litter management of Ko Chang Island. Best management plans that could be used in Ko Chang, Thailand, were sought through surveying the litter management at Faro, Portugal (holding a Blue Flag award) and through literature survey to form guidelines for plastic litter management. Beach litter survey indicated plastics to be the major source of litter (63.1%) on beaches coming as drink and food-related (39.6%) mainly contributed by the Recreational and Beach visitor (62%). Tourists and shop vendors were thus considered to be two main litter distributors to environment. Survey results complimented to the interviewees’ perceptions. Inappropriate coastal scenic view was major impact of beach litter and beach cleanliness was important for tourism in Ko Chang. Although, serious management of beach litter was found to be lacking, majority of interviewees were satisfied with the management present. Emphasis should prioritize education, provision of waste facilities followed by legislations for effective feasibility in tackling tourism-related litter. Beach clean-up activities were found to be one of the good methods of education at regional level. A campaign was proposed as part of the guidelines.
- Evaluation of poly(sodium 4-styrenesulfonate) film coating in thin mercury film electrodes for lead determinationPublication . Silva, C. P.; Carapuça, H. M.; Rocha, L. S.; Pinheiro, J. P.In this work, polyelectrolyte coatings assembled on glassy carbon/thin mercury film electrodes, as an adsorbed layer of poly(sodium 4-styrenesulfonate) (PSS), were studied. The goal was to search for the best conditions for the production of stable PSS-coated electrodes that could present high negative charge densities within the thin polymeric film, providing a fast and significant electrostatic cation accumulation. Square-wave anodic stripping voltammetry was applied to measure the amount of incorporated lead used as the reference cation. The influence of the composition of the PSS solution, the amount of deposited PSS, molecular weight and of the ionic strength of the electrolyte solution, on the features of the PSS coatings for ion-exchange voltammetry was studied. The PSS films morphology was assessed by SEM. The best PSS coating performance was found for the electrodes prepared from water solutions with a molecular weight of at least 70,000, and a mass loading of ca. 8 μg mm−2. In these conditions a three fold increase was observed in low ionic strength (0.0032 M) media. However, this improvement was not sufficient for the application of direct ion-exchange voltammetry, thus different strategies to obtain polymer films with higher charge densities have to be envisaged.
- Eutrophication assessment in China's coastal watersPublication . Yunjun Yu; Newton, Alice; Ferreira, João GomesThe cause and effect related to coastal eutrophication have been well defined. However, the approaches to assess trophic status of coastal systems are still under development. Over the past two decades, some attempts have been conducted with the purpose of improving the assessment and management of coastal eutrophication. An example is the ASSETS screening model, which has been applied around the world. As the population grows and economy develops further in China, coastal zones are under more pressure. Issues related to coastal eutrophication are becoming more frequent and becoming a public concern, which creates a need to assess the trophic status of its coastal systems. Previous studies on the application of ASSETS in China’s coastal waters have shown its fitness for the purpose of trophic assessment and management definition. The present thesis attempts to review the China’s coastal waters and eutrophication status there, and investigate potential trophic assessment methods for the system. The case study of Jiaozhou Bay and the estimation of nutrient inputs from to this waterbody will be discussed after the review of the status quo of China’s coastal systems. The watershed of the Jiaozhou Bay and nutrient loads are mapped. The update application of the ASSETS model in Jiaozhou Bay found that the eutrophic status in the bay is moderate. In the conclusion and recommendation section, the extensive application of the ASSETS model was discussed, and the integrated approach of coastal zone and river basin management (ICARM) was proposed to the Dagu River-Jiaozhou Bay system.