Theses and Dissertations Collection

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    Interactions oe host immune responses, iron status and genetic backgrounds in the pathogenesis of malarial anaemia in children
    (Sokoine University of Agriculture, 2008) Moses, Gwamaka
    In search for pathophysiological mechanisms of malarial anaemia, this study investigated several serum soluble factors (cytokines, growth factors, iron markers) and mechanisms (red cell aging, complement regulation, genetic red cell disorders) that may explain why some children with malaria develop anaemia. Among anaemic malaria patients, children with inappropriate reticulocyte responses were compared to those with normal reticulocyte responses for the differences in serum soluble factor levels. Serum soluble factors were analyzed by multiplex bead-based platform with custom sandwich or competitive assay kits. Children with inappropriate reticulocyte responses had higher IL-1, IL-6, TNI-'-a. IL-10 and TNF-a/IL-10 ratio, and lower erythropoietin levels. In multivariate logistic regression analyses, only erythropoietin remained significantly associated and inversely related to poor reticulocyte response suggesting that erythropoietin influences rcticulocytosis during malaria. RBC membrane surface molecules were measured by cytolluorometry and analyzed for their relationship with cytokine levels. RBC age and anaemia during acute malaria. Phosphatidylserine. IgG, CD35. CD55 and CD59 levels were not associated with cytokine levels, whereas TNF-a/IL-10 ratio associated positively with CD59 only. Loss of CD55 and CD59 occurs during erythrocyte ageing but this effect docs not explain the changes occurring during malarial anaemia. CD55 levels were significantly lower in anaemic children and correlated positively with haemoglobin level, suggesting that the loss of CD55 may contribute to malarial anaemia. Immune responses to P.falciparum malaria in children with different genetic backgrounds were studied before and during first malaria episodes. Haemoglobin levels did not varyiii according to the genetic backgrounds before malaria infection. Parasitemia. haemoglobin and cytokine levels (IL-1. IL-6. IFN-y and IL-5) were significantly higher in age-matched children with normal haemoglobin than sickle cell carriers during malaria. Levels of TNF-a and ferritin varied on the basis of thalassemia status, and none of the serum soluble factors levels varied on the basis of G6PD genotypes. The results suggest that genetic red cell disorders vary in their effects to modulate immune response and these variations may be influencing disease outcomes. From these data it is concluded that several host factors interact to contribute to acute malarial anaemia including EPO response, CrP levels on RBC and genetic backgrounds.
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    The potential of immunohistochemistry in diagnosis of contagious bovine pleuropneumonia in apparently healthy animals
    (Sokoine University of Agriculture, 2013) Mlay, John Didas Mbereliye
    Diagnosis of contagious bovine pleuropneumonia (CBPP) in asymptomatic animals is a big challenge towards control of the disease. This is because most, if not all, of the available diagnostic methods are incapable of detecting the disease in such animals. In this study, an immunohistochemistry protocol was developed and employed to detect Mycoplasma mycoides subspecies mycoides Small Colony (M/wwSC) type, the causal agent of CBPP, in apparently healthy animals slaughtered at Morogoro urban abattoir. Lungs (n=13) with CBPP-like lesions were collected from the abattoir, kept in cool boxes, and transported to the veterinary pathology laboratory for investigation. After thorough gross examination, the lung samples were prepared for bacteriology, histology and immunohistochemistry using monoclonal antibodies 3H12 and 6E3. Grossly, the lungs were non-collapsing, marbled with widened interlobular septa, oedematous and fibrinous. They were also consolidated and had areas of sequestration. Cultures from two samples showed growth of small colonies with “fried egg” appearance on Mycoplasma Experience medium. Histological examination revealed expanded alveoli containing fibrin, oedema and inflammatory cells such as lymphocytes, plasma cells, macrophages and alveolar epithelial cells in all samples. In more severe cases the inflammatory cells occupied the lost architecture of the alveoli. There was also fibrinous vasculitis and bronchiolitis with peripheral leukocytic infiltration. In immunohistochemistry, MmmSC antigens were detected from the sections prepared from all collected lung samples in the alveolar lumen and wall, bronchial and bronchiolar lumina, epithelium as well as bronchial glands and cartilage. It is concluded that immunohistochemistry is efficient in detecting MmmSC antigens in apparently healthy slaughtered animals. Its employment could be a sound option in diagnosis of CBPP in carrier asymptomatic animals and could thus aid in a long run, the control of the disease.