published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / abstract / toc / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

No description available.

Predictors of response of AIDS-associated Kaposi-Sarcoma to standard chemotherapy Overview: Kaposi Sarcoma is the most common HIV-associated cancer. Its etiology and pathogenesis is not fully understood. Little is known about what predicts prognosis, survival and therapeutic response in HIV-KS. In South Africa given the high seroprevalence rates of HIV-l and human herpes virus 8 (HHV 8), Kaposi's sarcoma is a significant problem. The majority of patients have been treated solely with palliation due to the poor outcome associated with a diagnosis of HIV-KS, more so in the absence of highly active antiretroviral therapy (HAART). Since the national ARV rollout programme and the availability and accessibility of HAART to all patients with a diagnosis of HIV-KS, a new strategy has to be established to enable adequate patient selection for chemotherapy. There have been a few published studies addressing the predictors of response to chemotherapy in the first world. However, this is the first study of these factors in HIV-l infected African patients with Kaposi's sarcoma. Aim: To identify and assess the potential value of several parameters predictive of outcome, survival and therapeutic response in HIV- infected patients with KS. Clinical, hematological, biochemical, immunological and virological variables were evaluated. Methods: We collected data from 25 patients with AIDS-KS who were enrolled in a phase III randomized controlled trial comparing HAART alone with the combination of HAART and chemotherapy. All patients were from the combination therapy arm. The following variables were evaluated as predictors of prognosis and therapeutic response: age, gender, ethnic origin, Haemoglobin (Hb), white blood cells (WBCs), lymphocytes, neutrophils, platelets, S.albumin, ALP, GGT, CD4 count, HIV viral load. These variables were assessed in patients at baseline and month 6 of therapy. Patients were staged into good risk and poor risk according to the AIDS clinical trial group (ACTG) criteria. The outcomes assessed were response to treatment and mortality. Results: A total of 25 patients participated to the study. Of these 16(64%) were males and 9(36%) were females, with male: female ratio of 2.7:1. Median age was 34 years (24-47); all patients were of Black African origin. Of the 21 patients, 15 (71.4%) were of good prognosis and 6(28.6%) were of poor prognosis. At baseline the median values of the different variables were as follows: Hb 10.9 g/dl, WBCs 5.95x109/L, lymphocytes 1.7 x109/L, neutrophils 3 x10 9 /L, platelets 272 x10 9 /L, S.albumin 30 gil, total protein 88 gil, ALP 64 U/L, and GTT 21 U/L, CD4 count was 255 cells/mm 3 , HIV-RNA viral load was 42000( 4.610gs). At month 6, 22 patients remained alive, their median values were: Hb 12.2 g/dl, WBCs 4.65 x109/L, lymphocytes 1.5 x109/L, neutrophils 3 x10 9 /L, platelets 301 x109/L, S.albumin 36.5 gil, total protein 84.5 gil, ALP 78.5 U/L, GTT 44.5 U/L, CD4 count 288 cells/mm3 , HIV-RNA viral load was 50500( 4.6910gs). The baseline median CD4 and HIV-RNA viral load counts for the 3 patients who died before month 6 were 47 cells/mm3 and 31000(4.610gs); respectively. Response to therapy was evaluated in 21(84%) patients as 4(16%) patients were missing, of the 21 patients 3 (14.3%) had complete response and 18(85.7%) had partial response. With respect to sex 2(14.3%) males had complete response and 12(85.7%) had partial response, 1(14.3%) female had complete response and 6 (85.7%) had partial response. Non-parametric statistics were used because of the small sample size and the skewness of the data. Variables were described using medians and ranges, and compared between two independent groups using Mann-Whitney tests. Baseline and month 6 comparisons were done using Wilcoxon signed ranks tests. Receiver Operating Characteristic (ROC) curves were used to analyze cut points to optimize sensitivity and specificity of a quantitative variable for a dichotomous outcome. Discussion In the univariate analysis age and sex didn't influence prognosis and therapeutic response, the influence of ethnic origin couldn't be assessed as all patients were of the same ethnic origin. Baseline WBCs (P= 0.004) and lymphocytes (P=0.026) were significantly associated with complete response. Higher values of GGT (p=O.OOl); ALP (P=0.006) were associated with more deaths. Baseline CD4 count and HIV viral load were not of predictive value, lthough change CD4 (P=002) and VL (p=.OOO) over time was significant and most likely attributed to response to therapy. 90.9 % of patients reached undetectable HIV-l Viral loads at month 6. CONCLUSION: Neither CD4 count nor HIV viral load at baseline predicted prognosis or survival; however there was a borderline significance of CD4 (P=0.058) towards a better survival. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2006.

This KwaZulu-Natal (KZN) based study investigates hypertension, glomerulonephritides and the rarity of IgA Nephropathy (IgAN) in Africans in association with the Human Leukocyte Antigen (HLA). A retrospective hypertensive study found a positive association with HLA-B40 (P c<0.05) and HLA-B15 (Pc<0.02) in Indians and Africans respectively. No association was found in Whites. A prospective study showed glomerulonephritides to be positively associated with HLA-A33 in Indians (Pc 0.049). No associations were found with glomerulonephritides in Africans and Whites. Combined Race groups show no HLA associations. HLA-A30; HLA-A34; HLA-A29; HLA-B42; HLA-B58; HLA-B70 and HLA-DR11 were extremely significantly higher in Africans compared to Indians and Whites (all P<0.0001). In conclusion, HLA-B40 and I 1LA-B15 are possible disease susceptibility markers in Indian and African hypertensives; HLA-A33 is a possible disease susceptibility marker for glomerulonephritides in Indians and alleles in linkage might be responsible for the rarity of IgAN in Africans but further studies need to be employed. / Thesis (M.Med)-University of KwaZulu-Natal, 2007.

Certain HLA-B-restricted CD8+ T cell responses are associated with control of viremia whereas HLA-Cw* restricted responses, including Gag epitopes are associated with high viremia. To better understand the role of HLA-Cw* restricted epitopes in viral control, HLA-Cw* restricted epitopes were optimally defined. Seventy eight study subjects from a cohort of 451 chronically infected participants had HLA-Cw* restricted CD8+ T cells responses as quantified by intracellular cytokine staining assessing IFN-γ secretion. Fine mapping and HLA restriction of the optimally defined HLA-Cw* restricted epitopes were performed using ELISPOT assay. Functional avidity of responses was assessed by peptide dilution in an ELISPOT assay. Two novel HLA-Cw* restricted epitopes Cw*04- TF10 (in reverse transcriptase) and Cw*08-RM9 (in gp120) were optimally defined. A previously described epitope, Cw*07- KY11 (Nef) was the most frequently targeted epitope in this cohort (30/78) and has high functional avidity compared to other HLA-Cw restricted CD8+ T cell responses. The polyfunctionality of HLA-B*57/5801-restricted Gag-specific HIV-1 CD8+ T cell responses and HLA-Cw*07-KY11 restricted CD8+ T cell responses within the same study subject was determined. Polyfunctionality of CD8+ T cell responses to HLAB* 57/5801 and HLA-Cw*07 restricted epitopes were determined in nine study subjects assessing IFN-γ, TNF-α, IL-2, MIP-1β, and CD107a by multicolour flow cytometry. Additionally gag and nef genes were sequenced from plasma. HLA-B*57/5801-restricted IFN-γ-producing CD8+ T cell responses were of lower magnitude than HLA-Cw*07 responses (p=0.0012) for the nine subjects. The majority of responses were monofunctional (75%), irrespective of HLA restriction. HLA-B*57/5801 and HLACw* 07 restricted CD8+ T cells did not differ significantly in polyfunctionality (p=0.84). Possession of ≥3 functions correlated positively with CD4+ T cell counts (r=0.85; p=0.006). The percentages of monofunctional CD8+ T cells inversely correlated with CD4+ T cell counts (r=-0.79; p=0.05). There was no correlation between polyfunctionality and viral load and sequence variation within targeted epitopes did not impact polyfunctionality. These results suggest that polyfunctionality of HIV-1-specific CD8+ T cells is associated with disease progression independent of restricting HLA alleles, and that loss of these polyfunctional cells correlates with increased in the frequency of monofunctional virus-specific CD8+ T cells. In addition, sequence variation does not appear to significantly impact CD8+ T cell polyfunctionality in chronic HIV infection. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2010.

Here we report the identification of 15 potential MSP-like proteins from the P. falciparum 3D7 genome using a bioinformatics-based approach. One candidate, renamed URF1, was further characterized by cloning into the Gateway system. We were able to demonstrate expression of URF1 during the blood stage, especially the trophozoite, early and late schizont phases, by immunofluorescence on infected RBC using antisera raised in mice with an URF1 DNA vaccine. URF1 expression in the merozoite stage could not be confirmed in this study. Future co-localization and immunosorbent electron microscopy (EM) experiments would help us determine the exact localization of URF1 on the parasite before officially categorizing URF1 as a merozoite surface protein. As a whole, this research project demonstrates the success of using bioinformatics in identifying potential new MSP-like proteins found in the malaria genome. Further characterization and sequence analysis of the other 15 candidates may reveal other novel antigens expressed during the erythrocytic stage, especially in the merozoite stage. Such antigens may prove to be good vaccine candidates.

The research investigated the combined effects of protein deficiency (PD) and a gastrointestinal nematode infection, Heligmosomoides bakeri , on immunopathology and nutritional status in BALB/c mice. The acute phase of a primary infection reduced resting metabolic rate, but PD did not. Early challenge infection led to temporary anorexia and cessation of weight gain in both protein-sufficient (PS) and PD mice. / Among PS mice, a challenge dose of 200 L3 caused more active worm expulsion than infection with 100 L3. Both serum monocyte chemotactic protein-5 and gut fluid leakage were positively correlated with worm expulsion whereas numbers of mucosal mast cells, eosinophils, goblet cells and Paneth cells were unaffected by doses. Among PD mice, worm survival was prolonged and no dose-dependent worm expulsion was observed. In addition, a wide range of Th1 inflammatory cytokines including leptin was elevated in infected PD mice suggesting (1) that PD mice are unable to mount the appropriate Th2 inflammation and (2) that infection in PD mice induces a Th1 inflammation that allows continuing persistence of the parasite. / The shift to Th1 inflammatory responses in PD mice may also explain modifications in mineral distributions in tissues. Despite adequate dietary intakes of minerals in both PD and PS mice, serum iron concentrations were lower after H. bakeri challenge infection. Infection also reduced calcium and iron concentrations as well as the Ca/Zn ratio in the spleen. In contrast, PD resulted in increased iron and calcium concentrations as well as increased Ca/Zn ratio in the spleen and Fe/Zn ratio in the liver, but reduced calcium, zinc, copper and sulfur concentrations, and the Cu/Zn ratio in the liver. / Re-feeding PD mice with a PS diet restored parasite expulsion, regardless of whether the PS diet was provided during the primary or challenge infection. Thus, although PD mice have suppressed Th2 responses and elevated Th1 inflammation, their response to the primary infection is sufficient to ensure that parasite expulsion occurs once protein status is restored. / Together, these studies show that the shift toward Th1 inflammation plays a key role in prolonged parasite survival and mineral redistribution in protein deficient, infected mice.

The purpose of this study was to separate acute and chronic effects of moderate exercise on the immune system by analyzing three sets of experimental and control groups; (1) 72 hours, (2) 1 week, (3) 2 weeks post exercise. Mice swam 5 days per week for 3 weeks accumulating a total of 125, 225, and 225 minutes of exercise in weeks 1, 2, and 3, respectively. Moderate swimming exercise did not result in a significant increase in SDH levels (p > 0.05). There was no change in tissue cell responses as measured by mitogen responsiveness, nor in splenic and thymic cell counts in response to the training regimen at any time point (p &ge; 0.05). Total, CD4, CD8, and T cell counts in the lymph nodes were significantly suppressed at 72 hours and 2 weeks post exercise (p &le; 0.05). It appears that chronic exercise resulted in an increased trafficking of lymphatic cells, which could be interpreted as a sign of heightened immune reactivity.

Studies using Mongolian gerbils found that during a primary infection with Giardia lamblia trophozoites, disaccharidase activities were decreased from day 10 post-infection (p.i.) until well past elimination of the parasite. However, during a challenge infection, enzyme deficiencies were short-lived. A challenge with a soluble extract of G. lamblia trophozoites also resulted in reductions in disaccharidase activity. The degree of these reductions in enzyme activity was dependent on the extract dose. Gel filtration of the trophozoite crude extract resulted in fractions F1, F2, and F3. However, only a challenge with F1 led to disaccharidase deficiencies. Further separation of F1 resulted in fractions F1a and F1b. Impairments of enzyme activity were obtained only in gerbils challenged with F1b. Protein analysis of F1b revealed several high and low molecular weight bands. When gerbils previously exposed to G. lamblia were challenged with an extract of Entamoeba histolytica trophozoites, disaccharidase activities remained comparable to controls. Moreover, enzyme levels in gerbils challenged with excretory/secretory G. lumblia products were affected in a manner which was inconsistent with the live parasitic challenge. Results suggest that the disaccharidase deficiencies in giardiasis are parasite-specific and are induced by a heat-stable constituent(s) of fraction F1b, possibly through an immune response to an antigenic component of this parasite fraction.