3. Electronic Theses and Dissertations (ETDs) - All submissions
Permanent URI for this communityhttps://wiredspace.wits.ac.za/handle/10539/45
Browse
11 results
Search Results
Item Lung cancer in Johannesburg(2010-09-29) Mukansi, Murimisi DemmyIntroduction: cancer remains the most common malignancy, with an estimated 1.04 million new cases each year worldwide, accounting for 12.8% of new cancer cases. Of these cases, 58% occur in the developing world. Lung cancer is the most common cancer among men, with an incidence of approximately 37.5 new cases per million. The incidence is lower in women, at 1.08 cases per million population. Lung cancer is the leading cause of morbidity and mortality in the world. There is evidence in the literature of racial and gender differences in the distribution of lung cancer. However data from South Africa is sparse. Aim: The primary objective of this study was to investigate whether differences existed in demographic and histological features of lung cancer when comparing black versus white patients with cancer of the lung in Johannesburg Methods: A retrospective case record review of 817 patients presenting to the pulmonology units of the three hospitals, between January 1992 and December 1998, was undertaken. Demographic, clinical, laboratory and histological features were captured and analyzed, using the GraphPad InStat 3.10 program for Windows. The histological cell types of lung cancer were characterized using the 1981 WHO classification. Results: A total of 817 patients with lung cancer were enrolled in the study. The age group of the total sample ranged between 26-92 years with a mean±SEM of 61.0±0.04 years. There were 574 (70.3%) male patients versus 222 (27.2%) female patients. The remaining 21 (2.6%) patients had no data recorded with respect to their gender. The racial stratification of these patients in decreasing order of frequency was whites 441 (54.0%), blacks 337 (41.3%), mixed race 24 (3.0%) and Indians 15 (1.8%). The study group consisted of the 778 black and white patients. The black patients were younger (mean ±SEM, 57.3±0.5years) than the white patients (mean ±SEM, 64.0±9.9) irrespective of gender (p <0.001). Overall 632 patients were smokers, either current or ex-smokers. The amount of cigarettes consumed was significantly higher in white patients compared to black patients (mean pack years for white patients was 52.7 ± 27.1 versus 21.7± 14.3 pack years for black patients (p <0.001)). This difference was irrespective of gender. The mode of diagnosis in the 778 lung cancer patients was bronchoscopy in the majority 479 (54.0%), followed by sputum cytology in 152 (18.3%) and fine needle aspiration in 105 (12.7%). Tissue biopsy was utilized to diagnose 23 (2.7%) of the lung cancers. In some cases more than a single modality of diagnosis was utilized. The radiological features of the 778 lung cancer patients varied. The majority had a mass on chest radiograph; a lung mass in 357 (46.5%) patients, a hilar mass in 166 (21.6%), and a mediastinal mass in 18 (0.3%) patients. Pleural effusions were found in 82 (10.7%), lung atelectasis in 78 (10.2%), an infiltrate in 29 (3.8%) and consolidation in 25 (3.3%). Histological cell types of lung cancer in the 778 patients consisted of the following, in descending order of frequency; squamous cell carcinoma in 341 (43.8%), adenocarcinoma in 167 (21.5%), small cell carcinoma in 129 (16.6%) and large cell carcinoma in 68 (8.7%) of the cases. Other histological cell types accounted for 73 (9.4%) of the patients. Small cell carcinoma was overall more common amongst white patients especially males and in black patients it was exclusively in females (p<0.0005). However the black female patients tended to have more small cell carcinoma (40 (45.5%)), compared to the white female patients who had more squamous cell carcinoma (54 (45.0%)) in the majority. There was a small proportion of patients considered to be operable with intent to cure -74 (9.5%). This was a poor operability rate compared to an expected operability rate of 15-20%. This rate was as distressing when divided along racial lines; 29 (8.6%) of black patients and 45 (10.2%) of white patients being considered operable. Discussion: The demographics of the study group were different. The black patients tended to be significantly younger and smoked less cigarettes compared to the white patients. There was a significantly greater number of male patients with lung cancer than female patients. This difference was irrespective of race. The ranked frequency of histological subtypes was similar in both race groups. However, the black female had more small cell carcinoma, compared to white females with a preponderance of squamous cell carcinoma. The operability of all lung cancer patients, irrespective of gender and race, was dismal at 9.5%, compared to the standard norm of 15-25% operability rate. This is worrying when one considers the fact that surgery is the means to a cure. It either suggests there is a delay in seeking medical care and/or the lack of medical resources to permit screening and early diagnosis of the malignancy. Conclusions: This study did not demonstrate any ranked frequency differences in histological cell type distribution between black and white patients. Squamous cell carcinoma was the most common histological cell type regardless of race. Small cell carcinoma was significantly more common among white patients, especially the males while among the black patients it was exclusively found in the females. Black patients with lung cancer tended to present at an earlier age. Black females were less likely to develop lung cancer when compared with the white females. The black patients smoked fewer cigarettes than the white patients irrespective of gender. The operability of our patients, in the study, was poor in all race groups.Item Characterization of mutants and splice variants of hepatitis B virus isolated from South African black hepatocellular carcinoma patients(2010-02-15T09:36:37Z) Skelton, MichelleHepatitis B virus (HBV) infection is endemic in Africa. As many as 98% of black Africans are infected during their lives and about 10% (65 million) have chronic HBV infection, which is the cause of 70-80% of all hepatocellular carcinoma (HCC) cases. Despite this high prevalence of HBV and the high incidence of HCC in Africa, relatively few complete HBV genomes from African HCC cases have been deposited in international data bases. In order to gain a clearer understanding of the role of genetic variants and mutants in the development of HCC, the complete genomes of HBV isolated from southern African HCC patients were amplified and molecularly characterized. HBV DNA was extracted from the serum forty HBsAgpositive HCC patients. Twenty six complete genomes were successfully amplified, cloned and sequenced from nine HCC patients. Phylogenetic analyses of the complete genomes and the individual open reading frames of HBV isolates from the HCC patients, led to the classification of all the isolates within subgenotype A1. No isolates belonging to subgenotype A2 and genotype D were identified, even though these genotypes/subgenotypes have been shown to circulate in South Africa. Three patients contained the uncommon combination of serological subtype ayw1 in the subgenotype A1 strain. This combination has been found previously in South Africa and the Phillipines. Seventy-eight percent of the patients carried HBV strains with the double basic core promoter (BCP) mutation (1762T/1764A), previously shown to reduce HBeAg expression. Furthermore, complete genome sequence analysis has revealed a complex combination of mutations, which include at least three or five of these residues 1753C1762T1764A1766T1768A1809T1812T occurring as the dominant HBV strains isolated from 5/9 HCC patients. These mutations have previously been shown to regulate gene expression at various levels, to enhance viral replication and simultaneously decrease HBeAg expression. All five HBV genomes isolated from one patient contained novel complex BCP rearrangements, which introduced 2 HNF1 and 1 putative HNF3 transcription factor binding sites. These mutations can enhance viral replication and simultaneously abolish HBeAg expression at a transcriptional level. Furthermore, truncated core proteins would be expressed from 4/5 isolates and none would express wild-type HBx. Several mutations were identified in the pre-S/S genes of 2/5 isolates, which would result in the expression of novel 3’ truncated medium surface proteins (MHBst) and large surface proteins (LHBst). The majority of the mutations would contribute to hepatocyte pathogenesis and transformation by activating cell proliferating pathways. Two patients also contained rare HBV variants not previously identified in HBV strains from southern Africa. These included an HBV splice variant and a poly (dA) variant from patient 10 and patient 6, respectively. These variants occurred in combination with other isolates within the respective patients. The envelope genes were characterised in a total of 18 HCC patients, the pre-S gene of HBV contained deletions in 72% of the patients. Deletions across pre- S1/pre-S2, pre-S2 initiation codon mutations with internal deletions, and S gene nonsense mutations were prevalent. Mutated envelope proteins have been shown to accumulate within the hepatocyte endoplasmic reticulum (ER) and are a characteristic histopathological hallmark of HCC known as ground glass hepatocytes. HBV induced ER stress has been shown to dysregulate several cell cycle regulatory pathways, which contribute to HCC. In addition several novel LHBst and MHBst have been described. These potential transactivators require further investigation. The HBV mutations described in this study have been associated with increased risk for HCC. Despite the obvious heterogeneity HBV displays within and between patients, there are common characteristics shared between the HBV variants which emerge during the development of HCC. These include the BCP and pre-C (1753C1762T1764A1766T1768A1809T1812T) mutations and the pre-S/S mutations. These mutations are able to affect HBV replication and gene expression, and may work synergistically to promote liver dysfunction and HCC.Item The identification of differentially expressed cell cycle -related genes in breast and colon cancer cell lines in response to chemotherapeutic drugs(2010-01-27T11:15:07Z) Rupnarain, CharleenWith the high prevalence and high mortality rate of cancer in the global community, it is increasingly essential to accelerate our understanding of the disease, to identify new genetic targets for therapy, and to pursue avenues for improving on the therapies in development and in current use. The aim of this study is to identify cell cycle-related genes whose expression is influenced by the chemotherapeutic drugs curcumin, SAHA, lycopene and thalidomide in breast and colon cancer and normal cell lines. These drugs are currently not in clinical use for cancer in South Africa, and while there have been investigative studies of these chemotherapeutic agents, this study aims to identify the specific genes that are influenced by the drugs. The result of this is that several genes that were not previously documented as targets of these drugs are highlighted. The cell cycle pathway is the area of focus as loss of regulation in the cell cycle is one of the important factors involved in promoting cancer initiation and progression. In the first instance, flow cytometry was used to identify optimal drug concentrations relative to the cell cycle stages. Following this, alterations in gene expression were assessed using a PCR-based differential display after each drug treatment. Subsequently, a more focussed approach was taken in a PCR-array analysis of panels of cell cyclerelated genes. A subset of genes is identified that is implicated in oncogenic transformation in breast cancer. This has the potential to inhibit the genetic pathways involved in breast malignancy by providing targets that perhaps may not be manipulated in current therapies. The gene expression studies here suggest that lycopene and thalidomide function in inhibiting this transformation, and play significant roles in suppressing the oncogenic state of breast cancer. Curcumin and SAHA also exhibit important functions in inhibiting tumourigenesis in colon cancer. While the results propose that the drugs have clear roles in inhibiting breast and colon cancer, they are also implicated in promoting cancer. This research has defined the genes that must be carefully monitored during drug administering as they may promote these and other cancers. The availability of these results to researchers will aid in selecting the criteria for assessing the success rate of these drugs.Item Mechanisms of cancer initiation/progression: an investigation of chromosomal "hot spots" in South African cancer patients(2009-10-14T10:46:36Z) Willem-Belot, Pascale SylvieThe human chromosome complement contains nonrandom genomic regions that are prone to breaks and recurrently altered in tumors. These chromosomal “hot spots” are preferentially involved in early events of genomic instability and point to genes in their vicinity that may participate to carcinogenesis. Amplicons and deletions are frequently generated at “hot spots”, including common fragile sites (CFS), and are thought to host cancer genes whose rearrangements drive cell proliferation and promote the initiation and progression of cancer. Chromosomal “hot spots” in South African cancer patients, were investigated in this study with a view to characterizing underlying gene alterations. A chromosome 12p amplicon was mapped and array comparative genomic hybridization (aCGH) was pioneered to identify candidate genes in the amplicon. Genes of the 12p stem cell gene cluster (NANOG, STELLAR and GDF3) were involved in striking similarity to what has been reported in testicular germ cell tumors and suggest that they may be more commonly involved in different types of cancer. Two tumor suppressor genes, FHIT and WWOX, are located at the two most commonly expressed fragile sites, FRA3B and FRA16D respectively. Alterations in these fragile site associated genes have been reported in a variety of tumors including lung, esophageal, gastric, breast and cervical cancers most frequently as a result of submicroscopic deletions. Genomic deletions at CFS have been mostly investigated using loss of heterozygosity assays that do not necessarily inform on gene exon deletions. A new method was developed based on multiplex ligation-dependent probe amplification (MLPA) that screens for exon deletions/amplifications of genes at CFS. The assay was validated on five esophageal squamous carcinoma cell lines and showed deletions in the FRA3B-associated gene FHIT in four of the cell lines. Two geographically distinct South African cohorts of esophageal squamous cell carcinoma were then screened for FHIT/WWOX exon deletions and a visual basic (VBA) encoded program was written to automate MPLA products analysis. A high frequency of intragenic deletions in FHIT and/or WWOX (73%) was observed in the Eastern Cape cohort. FHIT deletions were seen in 27% of specimens from the Gauteng cohort, which by contrast did not show WWOX deletions. This difference may however reflect a difference in sampling collection. The breakpoints of a translocation t(3;11)(p14;p15.1) present in an ovarian carcinoma cell line was characterized using the above MLPA assay, aCGH and the polymerase chain reaction. The translocation was found to interrupt the FHIT gene making it the 5th cancer associated translocation involving FHIT. The evaluation of gene relative copy number by aCGH and MLPA were highly correlated further validating the power of the MLPA assay in fresh tissue. The involvement of critical genes at “hot spots” in SA cancer patients was high in the context of this study raising questions about the possible role of environmental exposure. The new MLPA assay may assist to expand the screening of critical genes at fragile sites in the future.Item An exploration of the post-treatment psychosocial experiences of female adult cancer patients(2009-05-28T10:07:52Z) Kraut, LisaABSTRACT This study explores the post-treatment psychosocial experiences of female adult cancer patients. In particular, this study aims at identifying common themes in the nature of their experiences. This research was exploratory in nature and took place within the context of the qualitative paradigm. The focus group method was utilised in collecting data. The six participants were white Christian females between the ages of 50 and 62 who had completed treatment (either chemotherapy, radiation or both) not more than four months prior to the study. Data were analysed by means of categorical content analysis. Four out of the six participants reported relief as well as mixed emotions after discovering they had survived cancer. A major finding of this research was that all of the participants were experiencing anxiety that the cancer might recur. Five out of the six participants reported ample support from their partners and other family members. The entire group of participants admitted that their genuine friends remained supportive throughout treatment, while some friends avoided them when they had cancer, but were willing to continue the friendship after treatment. This impacted negatively on their friendship. The entire group mentioned negative social experiences due to the stigma attached to having cancer. It was also found that the participants preferred spending time with people who have insight into the meaning of life. All of the participants agreed that without their relationship with God and the social support structure including churches and acquaintances at church, they would not be able to get through their experiences during and after treatment. The entire group mentioned the experience of a greater appreciation for life after having completed treatment and survived cancer. It is evident that the experiences of cancer survivors in the South African context necessitate further research and that an understanding of these experiences plays a crucial role in the development of successful interventions for survivors, their families and the wider social community in regard to cancer.Item Molecular characterisation of the peripheral Benzodiazepine receptor in various human cancer tissues(2008-03-07T08:41:53Z) Bhoola, Nimisha HarshadraiABSTRACT Background: The Peripheral Benzodiazepine Receptor (PBR) can be classified as a distinct receptor from the central benzodiazepine receptor. The PBR gene has been located to chromosome 22q13.31 in humans and has been found to consist of four exons, with the first and half of the fourth exon being untranslated to form the PBR protein. PBR is involved in numerous biological conditions including the regulation of cellular proliferation and apoptosis, steroidogenesis, heme biosynthesis, anion and porphyrin transport and mitochondrial functions such as oxidative phosphorylation and translocation of cholesterol from the outer to the inner mitochondrial membrane. Recent studies showed that the expression of PBR correlated with tumour malignancy and patient survival. Aim: The objectives of this research were to determine the expression pattern and level of PBR mRNA in various types of human normal and cancer tissues and to isolate the PBR protein.Item Breast cancer prevention: The knowledge and skills of final-year undergraduate nursing students(2006-11-20T09:57:33Z) Mayet, ZakeeyaA quantitative research study in the form of a descriptive survey was undertaken with the aim of determining the level of knowledge and skills of final-year undergraduate nursing students relating to breast cancer prevention. The research objectives were as follows: to determine the awareness of, and orientation toward breast cancer preventative measures of final-year undergraduate nursing students; to determine the level of knowledge regarding breast cancer prevention of final-year undergraduate nursing students; to assess their psychomotor skills in performing a clinical breast examination; and to identify critical knowledge and skill deficits, with regard to breast cancer prevention. Data were collected from a sample of final-year undergraduate nursing students (n=62) from three universities in Gauteng. A self-administered questionnaire was used to collect data relating to theoretical knowledge. Direct, structured observation, using a self-compiled checklist, enabled the collection of data relating to psychomotor skills in clinical breast examinations. Data analysis was done with the aid of two computer software packages, namely MoonStats and Microsoft Excel. The findings of the research revealed that, although the students were positively orientated to the issue of breast cancer prevention, their theoretical knowledge regarding it was not largely below the level that would deem them competent. The mean score for theoretical knowledge regarding breast cancer prevention was 56%. In addition, the scores for their psychomotor skills in carrying out a clinical breast examination were generally poor. The mean score in this component of the study was 45%. Major theoretical and skill deficits were identified from the findings of the study. Recommendations proposed comprehensive educational coverage of breast cancer prevention in nursing curricula. It was suggested that nursing students become more actively involved in the promotion of breast cancer prevention in underserved communities. Furthermore it is suggested that nurses and nursing students become more involved in ongoing research in the field of breast cancer prevention.Item The effect of differentiation on the expression of phosphoprotein phosphatase in the human promyelocytic leukaemic cell line HL-60(2006-11-16T07:30:27Z) Bhoola, RajeshDynamic cellular activity is fundamental to all life. Virtually all life processes, are modulated by the reversible phosphorylation of proteins, mediated by protein kinases and phosphoprotein phosphatases, respectively. This thesis focuses on three enzymes, namely: phosphoprotein phosphatase 1, phosphoprotein phosphatase 2A and protein tyrosine phosphatase-1B. Temporal variations in the expression of the enzyme proteins were examined in the human acute promyelocytic leukaemic cell line, HL-60. The cells were induced to differentiate along the macrophage pathway using phorbol-12-myristate- 13-acetate and along the granulocytic pathway using dimethyl sulfoxide, all-trans retinoic acid and 9-cis retinoic acid. Modulation of the rhythmic patterns of protein and messenger RNA was monitored in the absence and presence of inducing agents. Expression of protein in cell extracts prepared at various time intervals was determined by western immunoblotting, while mRNA expression was assessed by northern blotting and RT-PCR. The probe used for northern blotting was generated during the RT-PCR procedure. In addition, PTP-1B mRNA was cloned into an expression vector to produce recombinant protein. Results indicate that the expression of phosphoprotein phosphatase 1, phosphoprotein phosphatase 2A and protein tyrosine phosphatase-1B protein is dynamically regulated in proliferating HL-60 cells and modulated after being induced to differentiate along either the macrophage or granulocytic pathway. Similar changes were also noted with PTP-1B mRNA when using northern blot analysis. Using molecular cloning techniques, PTP-1B mRNA was successfully cloned into pGex-4T-1 expression vector to produce recombinant PTP-1B protein, which was checked by sequence and western blot analysis.Item Characterization of the novel domain with no name gene in colon cancer(2006-03-23) Rupnarain, CharleenNormal colonic epithelium bombarded by a range of molecular changes, affecting cell proliferation and apoptosis, result in the initiation of an adenoma and consequently an invasive carcinoma, which is usually lethal. One of the main characteristics of tumour progression is the loss of regulation between the cell cycle and apoptosis. Under normal circumstances, these processes are strictly controlled by a number of regulators and inhibitors. Previous studies have implicated the novel Domain With No Name gene in apoptosis. This study aimed to characterize the expression patterns and levels of the gene in colon cancer and to determine its role in apoptosis. In situ hybridisation, immunocytochemistry and quantitative PCR localised the gene and its products in cancerous and normal colon tissue. Combined with apoptosis detection studies, proliferation assays and Bcl-2 assays, the results suggest that the gene is involved in promoting apoptosis in cancerous cells i.e. the targeting of undesirable cells. Helicobacter pylorus was implicated in the progression of noninvasive colon cancer to the invasive state. From this study DWNN is proposed to be a pro-apoptotic participant in programmed cell death and classification studies such as these allow for potential manipulation of the apoptotic system to serve as a therapeutic corridor.Item Characterization of a novel cell death related gene, DWNN, in cervical cancer(2006-03-13) Ledwaba, Ramatsobane JohannaDWNN-deficient Chinese Hamster Ovary cells have been found to be resistant to staurosporine-induced apoptosis. The human DWNN gene is located on chromosome 16p21, with 18 exons and is 36 kb long. It is alternatively spliced at exon 16 and makes two major mRNA transcripts, 1.1 and 6.1 kb, encoding 13 kDa and 200 kDa proteins respectively. The purpose of the study was to elucidate the possible role of DWNN in cervical cancer and apoptosis, to establish tissue distribution and expression levels of DWNN at protein and mRNA levels in cervical cancer. In situ hybridization studies showed elevated levels of the three mRNA transcripts in cervical cancer as compared to the normal tissues. The transcripts were localized in the nuclei of invaded stroma, moderately differentiated islands of tumours, dysplastic epithelium and some infiltrating lymphocytes. Immunocytochemistry showed that DWNN proteins were highly expressed in the dysplastic epithelium, dysplastic endocervical glands, moderately and well differentiated islands of tumours and the invaded stroma. Image analysis indicated elevated expression levels in the islands of tumours. Apoptosis detection by TUNEL revealed high apoptotic levels in the invaded stroma and moderately differentiated islands of tumours and this significantly correlated with DWNN localization. Proliferation assay using Ki67 antibody was found to be indirectly directly proportional to DWNN expression. Antiapoptotic Bcl-2 expression levels were found to be inversely proportional to the expression levels of DWNN. The up-regulated levels of DWNN in cervical cancers in contrast to normal tissues suggest DWNN to be proapoptotic, as there were elevated levels of apoptosis in the same sites where there were high levels of DWNN expression and Bcl-2 was down-regulated in the same sites. DWNN expression significantly correlated with apoptotic levels and was indirectly proportional to ki67 in human cervical cancers. Real Time PCR also confirmed the up-regulation in levels of DWNN in cervical cancer. This study suggests that the DWNN gene may be involved in apoptosis. Further characterization of this gene could lead to its manipulation as a diagnostic marker and a potential therapeutic target for cancer treatment.