3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item The role of the polymerase chain reaction in the routine haematology laboratory.(1993) Gunther, Karen ElizabethThe Polymerase Chain Reaction (PCR) provides a means of amplifying target sequences of DNA exponentially and it is rapidly becoming an indispensable tool in the research laboratory. Many other molecular genetic techniques used for research are far too laborious and expensive to be used for routine diagnostic purposes but PCR has the potential to be different. This Research Report assesses the possible role of PCR as a routine diagnostic tool in the haematology laboratory. In the context of haematology, PCR can be used to detect both "pathological" and "physiological" target sequences present within the genome. Pathological sequences of interest would include mutations, deletions, insertions or translocations not present within the normal genome but which may arise either as a result of an hereditary abnormality or be acquired somatically. Sensitive detection of such sequences is useful for diagnostic purposes and can also be relevant in determining prognosis, evaluating response to therapy and following up minimal residual disease in the context of haematological malignancies. PCR detectable physiological sequences would include the immunoglobulin and T cell receptor gene rearrangements normally present within the genome of cells of the appropriate lineage. These rearrangements differ for each lymphocyte within a polyclonal population but are identical among members of a clone arising by proliferation of a single precursor cell. They can therefore be of value not only in determining cell lineage but also as markers of clonality. In this study the practical aspects of using PCR were assessed by setting up the technique of amplification of immunoglobulin gene rearrangements. The cost of reagents and disposable equipment, as well as that of major items of equipment required which are not usually available in a routine laboratory was also determined. In addition, peripheral blood and bone marrow samples reaching the Haematology Laboratory of the Johannesburg Hospital were analysed to assess the potential demand for such investigations. Once appropriate reaction conditions for the primers used had been established, PCR was found to be quick, technically simple and relatively inexpensive. Sufficient numbers of appropriate samples for which PCR analysis could potentially be of value were received in the Johannesburg Hospital Haematology Laboratory in the periods assessed, to indicate that diagnostic PCR, if available, would be well utilised. Some problems were encountered, particularly with regard to variability in the extent of amplification obtained. Thus for routine diagnostic purposes, extensive research and development of each set of primers to be employed will be necessary to make the technique more reliable and consistent. Adequate quality control will also be essential if PCR is to be used for diagnostic purposes. However, once these issues have been addressed, PCR should definitely find a place as a routine diagnostic tool in the haematology laboratoryItem Avian haemoparasite prevalence in Kruger National Park and the surrounding human settlements(2018) Pori, TinotendasheThe drivers and implications of avian haemoparasite infection in wild birds are complicated to understand and predict, especially in areas where infections are endemic and the parasites have co-evolved together with their hosts. I studied the prevalence of avian haemoparasite infections in the Kruger National Park and the impact of haematozoa on host immune response. Six sites were sampled and blood from 685 birds of 87 species was microscopically screened for parasites. Haemoproteus, microfilariae, Trypanosoma, Plasmodium, Leucocytozoon, Aegyptianella and Hepatozoon spp. were detected. Overall prevalence was 27.33 % with 29 cases of mixed infections, which were mostly in association with Haemoproteus. Prevalence was similar for all sites and seasons, with no apparent influence of host life history traits on infection. Interestingly, immune status and body condition were better in infected than uninfected individuals. These findings reveal the complex relationship between parasites and their avian hosts in a southern African environment.Item Validation of haematology peripheral blood slide review rules at various tiers of diagnostic laboratories in South Africa(2017) Bouwer, NikkiAutomated analysers in the haematology laboratory have vastly improved since their inception in the mid-20th Century. The capability of these analysers to provide information exceeding a numerical output have made them allies in the clinical laboratory field. These analysers generate suspect flags and additional differential parameters with enhanced sensitivity and specificity which can assist in reducing manual peripheral blood smear (PBS) review rates and increasing laboratory productivity. In 2005, the staffing pressures faced by clinical laboratories prompted the International Consensus Group (ICGH) for Haematology Review to establish a set of criteria (consensus rules) to guide manual smear review of automated full blood counts (FBC) and white blood cell differential counts (Diff) in order to reduce unnecessary smear review rates. The usefulness of these rules is dependent on the patient population, laboratory criteria for PBS review and the specifications of the analyser. The aim of this study was to apply ICGH rules to FBC samples (with and without Diffs) from tertiary, regional and district diagnostic laboratory tiers, to evaluate their efficiency, and to optimise their performance in the South African context. In this study, the ICGH rules were compared to the individual representative laboratory standard operating procedures (SOP) for smear review in 600 samples from laboratories representing the tertiary, regional and district health tiers. Manual PBS review was the reference method. The rules were analysed for sensitivity, specificity and efficiency. False negative (FN) and false positive (FP) rates were also recorded for the rule set collectively, as well as for individual parameter and morphology flags. In order to optimise the ICGH rules for our setting, samples with FP flagging were then more closely analysed to determine if exclusion or modification of the flags triggered in these samples would be beneficial. Smear review rates were substantially reduced on implementation of the ICGH rules in the tertiary laboratory as compared to the current laboratory SOP (82% vs 70%; p=0.022), were not iv significantly altered in the regional laboratory (72% vs 80%; p = 0.198), while review rates increased on implementation of the rules in the district laboratory (67.1% vs 79.3%; p <0.0001). FN rates were reduced in all three sites, with the greatest reduction occurring in the district laboratory (dropping from 32% to 5%; p < 0.0001). Efficiency rates of the rule set were similar to those reported in the literature in the tertiary laboratory (78.1%), but were poorer in the regional (74.5%) and district laboratories (68.6%). Leukopenia and thrombocytopenia were the most common parameter flags triggered in the tertiary hospital (20.7% and 25% of samples respectively), while anaemia and microcytosis were most prevalent in the regional facility (22.5% and 17.5% of samples respectively). The most common abnormal parameter in the district laboratory was leucopenia (WCC<4 x 109/L) (16.4%). The analysers from the different tiers triggered morphology flags variably. The findings of this study indicate the need for optimisation of the rules. Recommendations were made for each tier individually, each of which could reduce smear review rates further without increasing the clinically significant FN rates. In the tertiary laboratory, request for a Diff alone should not be a criterion for smear review and the white cell threshold for smear review should be reduced from 4 x 109/L to 2 x 109/L. Recommendations for the regional laboratory include modification of the WCC threshold to that of <2 x 109/L and exclusion of the platelet clumping (PCL) rule when the platelet count is normal/increased. In the district laboratory the nucleated red blood cell (NRBC) flag and PCL flag in samples with normal/high platelet counts should be excluded.Item A description of splenomegaly in a hospital haematology setting(2017) Venter, MichelleBackground This study entails a retrospective review and description of splenomegaly in a Hospital Haematology setting. Underlying diagnoses and radiological classification, as well as laboratory parameters were used to further describe the splenomegaly encountered in the Clinical Haematology Unit, Department of Medicine, at Chris Hani Baragwanath Academic Hospital over a 10-year period. There is a paucity of data with regards to the occurrence of splenomegaly associated specifically with haematological disorders in the South African context. This study aims to better define the clinical, radiological, and laboratory parameters associated with splenomegaly in the setting of haematological disorders encountered in a hospital setting. Patients and Methods This study is a retrospective review of adult patients seen at the Clinical Haematology Unit, Department of Medicine at Chris Hani Baragwanath Academic Hospital during a 10-year period (01/01/2004 to 31/12/2013). The aim of the study was to determine the profile of patients who presented with splenomegaly, in particular to assess the demographics, clinical presentation, radiological and laboratory findings in association with splenomegaly. A total of 1976 files were reviewed. Splenomegaly was evident in 367 patients (15,6%), who were included in the study. There were 194 males (52,8%) and 173 females (47,2%), with a male to female ratio of 1,38:1. Results and Discussion In keeping with other studies on the subject of splenomegaly within a haematological setting, the vast majority of patients included in this study had neoplasms of the myeloid (43,3%) and lymphoid (16,6%) lineage, which together accounted for 89% of all patients. Myeloid neoplasms that were complicated by splenomegaly include CML (89,4%), PMF (100%), PRV (61,5%), ET (44,4%), while lymphoid neoplasms that manifested with splenomegaly include NHL (14,9%), HL (21,1%), CLL (45,9%) and ALL (17%). Interestingly, the traditional haematological aetiologies of splenomegaly such as sickle cell anaemia and thalassaemia did not contribute to the numbers of patients included in the study. Within the lymphoid neoplasm group in particular, the association with HIV seropositivity remained strong. This was not the case for neoplasms of the myeloid lineage. Conclusion There is currently no South African data available regarding the detection and quantification of splenomegaly specifically with regard to underlying haematological disorders. Traditional haematological causes of splenomegaly may not be entirely applicable to the African population, as the added impact of (HIV) on the profile of local hematological disorders within the African continent may not be considered. With this paucity of information, there is currently no knowledge on the reproducibility of studies relating to the relative frequencies of haematological aetiologies leading to splenomegaly. However, the results from this study clearly demonstrate the overlap in the South African setting between predominantly neoplastic and infectious (including HIV-associated malignancies) aetiologies. These results may be extrapolated to better define the haematological settings in which splenomegaly is encountered in the South African context. Finally, as the study was conducted in a haematology setting, other causes of splenomegaly that may generally not be encountered in haematology patients such as TB, schistosomiasis, portal hypertension, infiltrative disorders and storage diseases do not feature in this review.Item Studies on haemolytic complement(2014-08-19) Bernstein, Ralph Ernest