abstract / Biological Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Master / Master of Philosophy

Probiotics are defined as live microorganisms that confer beneficial effects to health when administered in a sufficient amount. In previous studies about the beneficial effects of probiotic bacteria to health, particularly in the fields of intestinal mucosa defence responses, specific probiotics, in a strain-dependent manner, show some potential to reinforce the integrity of intestinal epithelium and/or regulate some immune components. However, the mechanisms involved in the interactions between probiotics or bioactive components of probiotics with the intestinal epithelium are still not yet clearly defined or systematically studied. Among all possible routes of modulation by probiotics of intestinal epithelial cell–mediated defence responses, modulations of mucin and trefoil factor expression as well as the cytokine profiles are important components of the innate and adaptive mucosal immune responses of the intestinal epithelial cells and are considered to play important role in the intestinal defence responses against pathogenic bacteria. This thesis examined and characterized the in vitro modulation effects by metabolic products of two commonly studied probiotics bacterial strains, Lactobacillus rhamnosus GG (LGG) and Escherichia coli Nissle 1917 (EcN), on the intestinal epithelial cell-mediated defence responses. It was found that the metabolic products of EcN decreased the transcriptional levels of secretory mucins MUC5AC, MUC5B and MUC2 while LGG metabolic products only down-regulated that of MUC5AC. In partial agreement with the reduction of mucin gene expression levels, intracellular MUC5B and MUC2 mucin expression was reduced by EcN metabolic products and MUC5AC and MUC2 by the metabolic products of LGG. In contrast, the extracellular MUC5AC and MUC2 mucin expression tended to increase upon the effects of both LGG and EcN metabolic products, which might result from accumulative effects of the modulation on extracellular mucin secretion during the time of treatment or the differential responsiveness of cellular mucin gene and protein expression upon stimulation. The expression of trefoil factor 3 in both gene and protein levels upon the effects of EcN metabolic products while those of LGG enhanced the transcriptional but not protein level. As for the modulation of cytokine profiles, LGG metabolic products mainly influence the secretion of anti-inflammatory cytokines such as IL-4, IL-5 and IL-10 in a moderate manner while EcN metabolic products exerted broad pro-inflammatory potential to the intestinal epithelial cells by inducing the secretion of pro-inflammatory cytokines such as IL-8, MCP-1, TGF-α, TNF-α and GM-CSF, which indicated that the metabolic products of LGG and EcN might initiate differential signaling pathway to influence the intestinal epithelial adaptive immune responses. To conclude, the present research provides evidence to substantiate that LGG and EcN display differential modulation mechanisms of the intestinal epithelial cell-mediated defence responses that involve intestinal-cell mediated mucin and trefoil factor secretion as well as pro- and anti-inflammatory cytokine expression. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

This study was carried out to investigate different aspects of the epidemiology of the common intestinal protozoan infections in children in KwaZulu-Natal. The main aspects studied were to: i . monitor changes in the prevalence and intensity of the common intestinal protozoons in children after receiving antihelmintic drugs, ii. determine whether environmental and/or socio-economic factors are important in the prevalence of the common intestinal protozoons, iii. determine the occurrence of Cryptosporidium parvum in stool samples of paediatric patients with gastroenteritis and in healthy school children. Intestinal protowan species often co-occur with intestinal nematodes in infected children and it is important to determine the effect that anti-nematode treatment has on concomitant protozoan infections. The study included the analysis of stool samples by the Formol-Ether Concentration Technique, exam ination of the obtained sediments for intestinal helminths and protozoan species, and treatment of nematode-infected individuals. Four surveys were carried out to determine the prevalence and intensity of intestinal protozoons in school children before and after anthelmintic chemotherapy, and the X(2) test was used to determine significant changes. Prevalences and intensities of helminths were determined for significant changes after treatment using the Student's t-test. Additional pre- and post-treatment prevalence data were obtained from four schools in Health Region A of KwaZulu-Natal. The prevalence of Ascaris lumbricoides decreased significantly from 75.2% to 9.7% after the first treatment, that of Trichuris trichiura decreased from 77.7% to 62. 1%, and hookworm infections (presumably Necator americanus) dropped fromI2.7% to 1.0% and remained very low for the rest of the study. Very few individuals were infected with protozoan species and for statistical analysis, these were combined. The prevalence of protozoan infections increased from 33.0% to 50.3% after the first treatment and from 35% to 42% after the second treatment. The prevalence of A. lumbricoides decreased significantly again after the second treatment while there was no significant decrease in the prevalence of T. trichiura. The intensities (number of eggs/gram of feaces) of the three nematodes also decreased significantly after the two treatments. It is recommended that children who have been treated for nematode infections should also be examined for protozoan infections, and these should also be treated accordingly. A retrospective analysis of protozoon prevalence data from different surveys in KwaZulu-Natal was done in order to detennine the importance of environmental and/or socio-economic factors in the distribution of intestinal protozoons. These data were plotted on the map of KwaZulu-Natal using Geographic Information System (GIS). Univariate analysis was carried out to determine significant correlations between the prevalences of protozoan species and selected variables. The significant correlations obtained were moderate and no strong correlations were obtained. Univariate stepwise regression analysis was performed to determine the factors that combine best in facilitating the transmission of protozoan species and significant associations were obtained between the prevalence of protozoon species and a combination of environmental and socio-economic factors. In most cases, the association between prevalence and mid-summer temperature and rainfall were the most significant. This is an indication of increased summer transmission. Altitude was significantly correlated only with the prevalence of Endolimax nana. The fact that moderate correlations were obtained between prevalence of intestinal protozoons and climatic and socio-economic factors indicates that these factors are important in the distribution of the common intestinal protozoons. However, lack of strong correlations suggests that in addition to climatic and socio-economic factors, there are other factors that have an effect on the distribution of intestinal protozoan species. In the multivariate analysis where the variables were simultaneously considered, the presence of electricity was the only factor that was significantly associated with the variation seen in the prevalence of intestinal protozoons in the different study locations. Cryplosporidium parvum is a parasitic protozoon that is associated with severe fatal diarrhoea in children and immunocompromised individuals. Oocysts of this parasite were found in 18.2% of stool samples collected from children (aged 6 to 48 months) who were admitted in the paediatric wards at King Edward VIII Hospital, Durban. The stool samples were firstly concentrated using the Formal-ether method and the obtained sediment was mixed with the Sheather's Sucrose solution and examined microscopically. No oocysts were found in stool samples collected from older primary school children. Although the diarrhoea in these children might have also been due to other causes, the results obtained further show the importance of C. parvum as a cause of diarrhoea in children below the age of five years. Knowledge of the epidemiology of C. parvum is crucial in the control of this parasite as there is currently no effective treatment. More intensive surveys are needed in detennining the epidemiology of this pathogen in the South African population. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

Made available in DSpace on 2014-11-10T11:09:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-21Bitstream added on 2014-11-10T11:57:43Z : No. of bitstreams: 1 000785387.pdf: 1004100 bytes, checksum: 60651dd50c503ca75c5c206fb2da89b0 (MD5) / A resistência anti-helmíntica em bovinos se tornou um problema global, e no Brasil tem sido relatada em alguns estados. Devido à necessidade de métodos mais precisos de diagnóstico da resistência anti-helmíntico, o objetivo deste trabalho foi avaliar duas técnicas (McMaster e Flotac) e duas fórmulas matemáticas (FECRT1 - de acordo com a média de OPG e FECRT2 - de acordo com o número total de ovos contados) para calcular o teste de redução de ovos nas fezes (FECRT). O anti-helmíntico testados foram ivermectina (0,2 mg/kg), moxidectina (0,2 mg/kg) , sulfóxido de albendazol (2,5 mg/kg) e fosfato de levamisol (4,7 mg/kg) , administrada na dose recomendada pelo fabricante. Dez propriedades foram avaliadas, quatro visitas em cada, pré-tratamento (D - 2), processamento (D 0), 10 dias pós-tratamento (D10) e 28 dias póstratamento (D28). Em todas as propriedades foi observada resistência a um ou mais agentes anti-helmínticos testados, independentemente da técnica ou da fórmula matemática avaliada. Os gêneros/espécies encontradas com resistência a um ou mais anti-helmínticos foram Haemonchus placei, Cooperia spp., Trichostrongylus spp. e Oesophagostomum radiatum. Em conclusão, a resistência anti-helmíntica está presente em todos os rebanhos avaliados. A técnica Flotac e a fórmula matemática FECR2 foram mais precisas do que a técnica de McMaster e fórmula FECR1. Há necessidade de maior conscientização dos produtores sobre o uso de anti-helmínticos. Portanto, em estudos futuros de resistência anti-helmíntica em bovinos, recomenda-se a utilização do método de diagnóstico com uma maior precisão, como é o método Flotac. Na interpretação dos resultados, nosso estudo indica que o cálculo pela fórmula FECR2, o que elimina o uso de um grupo de controle, deve ser recomendada / The anthelmintic resistance in cattle has become a global problem, and in Brazil it has been reported in some states. Due to the need for more accurate methods of diagnosis of anthelmintic resistance the purpose this work was to evaluate two techniques (McMaster and Flotac) and two mathematical formulas (FECRT1 - according to the average EPG and FECRT2 - according to the total number of eggs counted) to calculate the faecal egg count reduction test (FECRT) in the diagnosis of anthelmintic resistance in cattle. The anthelmintic tested were ivermectin (0.2 mg/kg), moxidectin (0.2 mg/kg), albendazole sulfoxide (2.5 mg/kg) and levamisole phosphate (4.7 mg/kg), administered at the dose recommended by the manufacturer. Ten farms were assessed, four visits in each pre-treatment (D -2), processing (D 0), 10 days post-treatment (D 10) and 28 days post-treatment (D 28). In all of the properties was observed resistance to one or more anthelmintics tested, regardless of the technique (McMaster or Flotac) or FECRT the mathematical formula (1 and 2). The genera/species found with resistance to one or more anthelmintics were Haemonchus placei, Cooperia spp., Trichostrongylus spp. and Oesophagostomum radiatum. In conclusion, the anthelmintic resistance is present in all herds evaluated. The Flotac technical and mathematical formula FECR2 were more accurate than the McMaster technique and formula FECR1. Need is greater awareness of the producers on the use of anthelmintics. Therefore, in future studies on anthelmintic resistance in cattle, use of the method of diagnosis with higher accuracy, it is recommended, as is the case FLOTAC method. In interpreting the results, our study indicates that the calculation by formula FECR2 %, which eliminates the use of a control group, should be recommended

Orientador: Alessandro Francisco Talamini do Amarante / Banca: Cyntia Ludovico Martins / Banca: Helder Louvandini / Resumo: A resistência anti-helmíntica em bovinos se tornou um problema global, e no Brasil tem sido relatada em alguns estados. Devido à necessidade de métodos mais precisos de diagnóstico da resistência anti-helmíntico, o objetivo deste trabalho foi avaliar duas técnicas (McMaster e Flotac) e duas fórmulas matemáticas (FECRT1 - de acordo com a média de OPG e FECRT2 - de acordo com o número total de ovos contados) para calcular o teste de redução de ovos nas fezes (FECRT). O anti-helmíntico testados foram ivermectina (0,2 mg/kg), moxidectina (0,2 mg/kg) , sulfóxido de albendazol (2,5 mg/kg) e fosfato de levamisol (4,7 mg/kg) , administrada na dose recomendada pelo fabricante. Dez propriedades foram avaliadas, quatro visitas em cada, pré-tratamento (D - 2), processamento (D 0), 10 dias pós-tratamento (D10) e 28 dias póstratamento (D28). Em todas as propriedades foi observada resistência a um ou mais agentes anti-helmínticos testados, independentemente da técnica ou da fórmula matemática avaliada. Os gêneros/espécies encontradas com resistência a um ou mais anti-helmínticos foram Haemonchus placei, Cooperia spp., Trichostrongylus spp. e Oesophagostomum radiatum. Em conclusão, a resistência anti-helmíntica está presente em todos os rebanhos avaliados. A técnica Flotac e a fórmula matemática FECR2 foram mais precisas do que a técnica de McMaster e fórmula FECR1. Há necessidade de maior conscientização dos produtores sobre o uso de anti-helmínticos. Portanto, em estudos futuros de resistência anti-helmíntica em bovinos, recomenda-se a utilização do método de diagnóstico com uma maior precisão, como é o método Flotac. Na interpretação dos resultados, nosso estudo indica que o cálculo pela fórmula FECR2, o que elimina o uso de um grupo de controle, deve ser recomendada / Abstract: The anthelmintic resistance in cattle has become a global problem, and in Brazil it has been reported in some states. Due to the need for more accurate methods of diagnosis of anthelmintic resistance the purpose this work was to evaluate two techniques (McMaster and Flotac) and two mathematical formulas (FECRT1 - according to the average EPG and FECRT2 - according to the total number of eggs counted) to calculate the faecal egg count reduction test (FECRT) in the diagnosis of anthelmintic resistance in cattle. The anthelmintic tested were ivermectin (0.2 mg/kg), moxidectin (0.2 mg/kg), albendazole sulfoxide (2.5 mg/kg) and levamisole phosphate (4.7 mg/kg), administered at the dose recommended by the manufacturer. Ten farms were assessed, four visits in each pre-treatment (D -2), processing (D 0), 10 days post-treatment (D 10) and 28 days post-treatment (D 28). In all of the properties was observed resistance to one or more anthelmintics tested, regardless of the technique (McMaster or Flotac) or FECRT the mathematical formula (1 and 2). The genera/species found with resistance to one or more anthelmintics were Haemonchus placei, Cooperia spp., Trichostrongylus spp. and Oesophagostomum radiatum. In conclusion, the anthelmintic resistance is present in all herds evaluated. The Flotac technical and mathematical formula FECR2 were more accurate than the McMaster technique and formula FECR1. Need is greater awareness of the producers on the use of anthelmintics. Therefore, in future studies on anthelmintic resistance in cattle, use of the method of diagnosis with higher accuracy, it is recommended, as is the case FLOTAC method. In interpreting the results, our study indicates that the calculation by formula FECR2 %, which eliminates the use of a control group, should be recommended / Mestre

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Most bacterial infections can be correlated to contamination of consumables such as food and water. Upon contamination, boil water advisories have been ordered to ensure water is safe to consume, despite the evidence that heat-killed bacteria can induce genomic instability of exposed (intestine) and distal cells (liver and spleen). We hypothesize that exposure to components of heat-killed Escherichia coli O157:H7 will induce genomic instability within animal cells directly and indirectly exposed to these determinants. Mice were exposed to various components of dead bacteria such as DNA, RNA, protein or LPS as well as to whole heat-killed bacteria via drinking water. Here, we report that exposure to whole heat-killed bacteria and LPS resulted in significant alterations in the steady state RNA levels and in the levels of proteins involved in proliferation, DNA repair and DNA methylation. Exposure to whole heat-killed bacteria and their LPS components also leads to increased levels of DNA damage. / xiv, 132 leaves : ill. (chiefly col.) ; 29 cm