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The purpose of the present study was to determine if persons who had made a recent decision would be selective in seeking information related to their decisions. Also under consideration were the explanation for any selectivity exhibited, and the explanation for any variance in the degree of selectivity manifested.

This thesis investigates changes in the oscillatory dynamics in key areas of the pain matrix during different modalities of pain. Gamma oscillations were seen in the primary somatosensory cortex in response to somatic electrical stimulation at painful and non-painful intensities. The strength of the gamma oscillations was found to relate to the intensity of the stimulus. Gamma oscillations were not seen during distal oesophageal electrical stimulation or the cold pressor test. Gamma oscillations were not seen in all participants during somatic electrical stimulation, however clear evoked responses from SI were seen in everyone. During a train of electrical pulses to the median nerve and the digit, a decrease in the frequency of the gamma oscillations was seen across the duration of the train. During a train of electrical stimuli to the median nerve and the digit, gamma oscillations were seen at ~20-100ms following stimulus onset and at frequencies between 30-100Hz. This gamma response was found to have a strong evoked component. Following a single electrical pulse to the digit, gamma oscillations were seen at 100-250ms and between 60-95Hz and were not temporally coincident with the main components of the evoked response. These results suggest that gamma oscillations may have an important role in encoding different aspects of sensory stimuli within their characteristics such as strength and frequency. These findings help to elucidate how somatic stimuli are processed within the cortex which in turn may be used to understand abnormal cases of somatosensory processing.

In a series of experiments, we tested category-specific activation in normal parti¬cipants using magnetoencephalography (MEG). Our experiments explored the temporal processing of objects, as MEG characterises neural activity on the order of milliseconds. Our experiments explored object-processing, including assessing the time-course of ob¬ject naming, early differences in processing living compared with nonliving objects and processing objects at the basic compared with the domain level, and late differences in processing living compared with nonliving objects and processing objects at the basic compared with the domain level. In addition to studies using normal participants, we also utilised MEG to explore category-specific processing in a patient with a deficit for living objects. Our findings support the cascade model of object naming (Humphreys et al., 1988). In addition, our findings using normal participants demonstrate early, category-specific perceptual differences. These findings are corroborated by our patient study. In our assessment of the time-course of category-specific effects as well as a separate analysis designed to measure semantic differences between living and nonliving objects, we found support for the sensory/motor model of object naming (Martin, 1998), in addition to support for the cascade model of object naming. Thus, object processing in normal participants appears to be served by a distributed network in the brain, and there are both perceptual and semantic differences between living and nonliving objects. A separate study assessing the influence of the level at which you are asked to identify an object on processing in the brain found evidence supporting the convergence zone hypothesis (Damasio, 1989). Taken together, these findings indicate the utility of MEG in exploring the time-course of object processing, isolating early perceptual and later semantic effects within the brain.

This study examines the invention, innovation, introduction and use of a new drug therapy for coronary heart disease and hypertensio~; beta-blockade. The relationships between drug introductions and changes in medical perceptions of disease are analysed, and the development and effects of our perception of heart disease through drug treatments and diagnostic technology is described. The first section looks at the evolution of hypertension from its origin as a kidney disorder, Bright's disease, to the introduction and use of effective drugs for,its treatment. It is shown that this has been greatly influenced by the introduction of new medical teChnologies. A medical controversy over its nature is shown both to be strongly influenced by the use of new drugs, and to influence their subsequent use. The second section reviews the literature analysing drug innovation, and examines the innovation of the beta-blocking drugs, making extensive use of participant accounts. The way in which the develcpment of receptor theory, the theoretical basis of the innovation,was influenced by the innovation and use of drugs is discussed, then the innovation at ICI, the introduction into clinical use, and the production of similar drugs by other manufacturers are described. A study of the effects of these drugs is then undertaken, concentrating on therapeutic costs and benefits, and changes in medical perceptions of disease. The third section analyses the effects of other drugs on heart disease, looking at changes in mortality statistics and in medical opinions. The study concludes that linking work on drug innovation with that on drug effects is fruitful, that new drugs and diagnostic technology have greatly influenced medical perceptions of the nature and extent of heart disease, and that in hypertension, the improvement in drug treatment will soon result in much of the popUlation being defined as in need of it life-long

This is a study of the manner in which death is organised in the city of Belfast. It is concerned with the analysis of the principles, practices, and forms of knowledge which serve to organise the dead from the moment at which physical death is pronounced until the moment of disposal. The thesis is presented in two parts. Part One is entitled Public Bodies. It focuses, in the main, upon the discourse through which individual deaths in particular, and mortality patterns in general, are explained, described, and analysed by state agents and agencies. Chapter One examines the principles according to which causes of death are discovered and allocated. Chapter Two switches attention to modes of death, and examines the use of categories of natural and unnatural death. Chapter Three focuses upon the discourse of modern pathology as it operates within the confines of the city mortuary. And, Chapter Four, concentrates upon the General Register Office, and the principles according to which it collects, collates, and produces data on Belfast mortality patterns. The second part of the thesis is entitled Private Death. Here, the point of focus shifts to the examination of the activities and forms of thought which operate outside of, and beyond the official state agencies. Chapter Five presents an investigation of the organisational principles through which death is ordered within the cemetery, the city, and the hospital. Chapter Six, investigates the ways in which sentiments of the bereaved are structured in relation to the dead. Whilst Chapter Seven focuses upon the organisation of body, soul, and social being during the phase of disposal. The final chapter examines the interpenetration of Belfast politics and political ideologies with the social practices which surround the disposal of the dead. The methodological basis of the study is outlined in Appendix A.

The properties of the cell surface of Aeromonas salmonicida were studied, with particular emphasis on the additional surface layer (A-layer), found on virulent strains. This was identified by electron microscopy, as having a tetragonal subunit morphology; and by + ejectrophoresis of membrane components as a 51 kdal protein on A strains. A and A- strains, (the latter isolated by growth at elevated temperature), were compared biochemically and their interactions with various cell types investigated. Strains of A. salmonicida possessing the A-layer were shown to be more hydrophobic than those devoid of this protein. The influence of culture age, medium composition and subculture on hydrophobicity were investigated and hydrophobicity related to culture characteristics. No difference in enzyme susceptibility between A+ and A A. salmonicida was found and both phenotypes showed similar tolerance to other environmental conditions. The interactions between A. salmonicida and cells in vitro were studied using adhesion and association assays involving rädiolabelled bacteria, viable count determinations, haemagglutination and chemiluminescence. A+ A. salmonicida were found to adhere to a greater extent than A bacteria to tissue culture cell lines and to isolated fish tissue by non-specific hydrophobic interactions. Adhesion was maximal to a fish epithelial cell line and the effects of various environmental conditions on adhesion were determined. A- bacteria more commonly exhibited haemagglutination which was inhibited by specific sugars. A+ bacteria associated more than A- organisms with mouse peritoneal macrophages and rainbow trout phagocytes when in salts solutions. The effects of opsonization on A. salmonicida were strain dependent. Incubation in a variety of sera resulted in a decrease in A+ surface hydrophobicity, often accompanied by abolition of characteristic autoagglutinability, whereas opsonized A cells became more hydrophobic. These properties directly influenced the chemiluminescence response of trout macrophages.

MMed (Paediatrics), Faculty of health Sciences, University of the Witwatersrand / AIM: To evaluate aspects of the PMTCT programmes at selected hospitals and clinics in Gauteng. METHOD: A cross sectional survey of post partum women in Gauteng was undertaken during April- June 2006. Data was collected at four hospitals and eight Midwife Obstetric Units (MOUs) in four regions in Gauteng. Mothers, irrespective of HIV status, who delivered in the previous 48 hours were interviewed. This was followed by a review of the mother’s and infant’s records as well as relevant registers. RESULTS: Interviews with, and record reviews, of 182 mother-infant pairs were conducted/obtained; 69 (38%) at MOUs and 113 (62%) at hospitals. The majority (172 [95%]) of mothers were “booked” of whom 155 (85%) had undergone an antenatal HIV test. Forty-two mothers (23%) were HIV positive. Nevirapine was issued antenatally to 37/42 (89%) of eligible mothers; 30/42 (71%) took it during labour. Three women (8%) received the drug for the first time during labour; thus 33/42 (79%) of eligible mothers received nevirapine. Thirtytwo (76%) of babies born to HIV positive mothers received nevirapine. However, in only 24/42 of mother-infant pairs (57%) was receipt of nevirapine by both parties, recorded. There was no significant difference in nevirapine administration rates to mothers at clinics compared to hospitals (76% vs. 81%, p=0.71). Infants were more likely to receive nevirapine at clinics compared to hospitals (90% vs. 62%, p= 0.03). CONCLUSION: Four years after introduction of a PMTCT programme in Gauteng, nevirapine uptake and administration rates remained sub-optimal, with at least a quarter of eligible (identified) women and infants not receiving the intervention. The findings highlight the need to prioritise and consolidate PMTCT activities in the province.

A dissertation submitted to the Faculty of Health Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Masters of Science in Medicine, 2014 / Many loci coding for xenobiotic metabolising enzymes, especially those involved in carcinogen metabolism, confer susceptibility to various types of cancers. These genes have been poorly investigated in sub-Saharan African populations, where the genetic variation that exists is relatively unknown. The primary objectives of the study are to determine the frequency variation among 15 loci in sub-Saharan Africans, the level of genetic diversity, and the genetic affinities among sub-Saharan Africans. Secondary, the study aims to evaluate the implication of these variants in disease susceptibility, especially cancer. The study population comprised of 1880 unrelated individuals from 18 sub-Saharan African populations. DNA samples were used to examine genetic variation for phase I metabolism genes CYP1A1, CYP1A2, CYP2A6, CYP2D6, CYP2E1, and phase II metabolism genes GSTM1, GSTT1, GSTP1 and NAT2. A single base extension (SBE) method was designed and used to genotype single nucleotide polymorphisms (SNP): CYP1A1*2A and *2C; CYP1A2*1C and *1F; CYP2A6*7 and *8; CYP2D6*3A (2549delA) and CYP2D6*4(1846G>A); CYP2E1*5B(PstI) and CYP2E1*5B(RsaI); GSTP1*Ile105Val and *Ala114Val; and NAT2*14A. To investigate the presence of null mutations GSTM1*0 and GSTT1*0 a previously reported multiplex PCR method was used. The distribution of mutations in the sample was interpreted and compared with data from literature respectively. Mutations CYP1A1*2A, CYP1A2*1C, CYP1A2*1F, CYP2A6*7, CYP2D6*4 and GSTP1*Ile105Val mutations was found in most sub-Saharan Africans, while CYP1A1*2C, CYP2A6*8, CYP2D6*3A and GSTP1*Ala114Val mutations were almost non-existent. Both GSTM1*0 and GSTT1*0 mutations were present in all populations, with GSTT1*0 most frequent. The distribution of NAT2*14A confirms previous reports of its exclusive existence in Africans. Hardy-Weinberg Equilibrium (HWE) and Tajima’s D statistic tests showed none of the mutations were under selection. The genetic affinities of sub-Saharans were analysed. Bantu-speakers were closely related with little correlation to their geographic locations. Khoisan-speakers were closely related, genetically most distinct and oldest among populations. Pygmies were similarly distinct from most populations and one of the oldest surviving populations. The data further supports previous reports that the Khwe are descendants of an east African pastoralist group. AMOVA analyses revealed language as a major confounder among sub-Saharans. Haplotypes were inferred to determine their distribution and to understand their significance in populations with respect to their functional relevance. The study has confirmed previous reports of genetic histories of these sub-Saharan African populations. In unravelling the distribution of these mutations, the study has added to the global picture of these mutations. In doing so, the data may add value to the design of future cancer studies and pharmacological studies. The study also highlights the importance of elucidating ancestral relations of populations, more specifically linguistic and anthropological relationships, and to include in the design of future clinical trials in Africa.

MFamMed, Faculty of Health Sciences, University of the Witwatersrand, 2009 / BACKGROUND Until recent years, uptake of voluntary counselling and testing for HIV (VCT) and enrolment into the programme of prevention of mother-to-child transmission of HIV (PMTCT) was very poor among pregnant women. This study aims to identify factors influencing enrolment into the programme of PMTCT among post-partum women. METHODS Cross sectional interview of 200 consecutive post-partum women was conducted using an interviewer-administered questionnaire. Forms of those who declined to participate were kept and marked “refusal”. Data was analysed using Epi info software. RESULTS The response rate was 84.5%. VCT uptake was 96.9% among participants and PMTCT uptake among HIV+ve mothers was 90.9%. The mean age of participants was 25 years, ranged from 14 to 41 years. Women in the age-group 20-29 were more likely to accept VCT and enroll for PMTCT than women in the other age-groups (p=0.0114). CONCLUSIONS AND RECOMMENDATIONS Provision of clear and well-defined policy guidelines and strong commitment to implementation of these guidelines have been largely responsible for impressive uptake of VCT among participants and high rates of satisfaction with PMTCT programme among HIV-infected women. Training of more lay-counsellors is recommended for its cost-effectiveness.