<p>In 1980, cholecystokinin (CCK) was demonstrated to co-exist with dopamine (DA) in certain neurons of the CNS. Since the animal studies were carried out on rodents, little was known about CCK in the brain of higher mammalian species. In the present study, CCK receptors were characterized in the brains of higher mammalian species. The pharmacological characteristics of CCK receptors appear to have been well preserved in the mammalian brain. However, marked differences in the distribution of CCK receptors were observed in several brain areas. There were basically two main types of species-specific differences. The absence or presence of CCK receptors in a given structure and differences in the distribution within a given structure. Although the reasons for such species-specific differences in receptor distribution are not clear at the present time, this evidence cautions against simple extrapolation of data obtained in animal models directly to clinical applications. Moreover, although some animals studies provided evidence of an inhibitory effect of CCK on DA function, which would be compatible with a potential antischizophrenic action, others reported a lack of modulation or an enhancement of DA function. Circling behaviour is commonly used to assess DA function. In the present study, unilateral intracranial microinjections of CCK₈ induced a dose-dependent contraversive circling bias in rats. This CCK₈-induced contraversive circling bias was attenuated by the DA receptor antagonist haloperidol. To further elucidate the mechanism(s) underlying this CCK-induced circling behaviour, the effects of CCK peptides on ligand binding at DA receptors and on DA-stimulated adenylate cyclase were investigated in the rat striatum. Under the assay conditions employed, CCK₈ has no significant acute effects on binding at the DA receptor or on DA-stimulated adenylate cyclase. It is possible that CCK induced its acute facilitatory influence on DA function in the circling behaviour paradigm by altering DA turnover or release. Another problem with the animal studies which were used as the basis for the clinical application was that the vast majority were of an acute nature. In the present study, long-term administration of CCK₈ did not significantly alter DA D₂ receptor densities nor the expression of DA D₂ receptor mRNA. In contrast, long-term haloperidol administrations significantly increased CCK binding in the nucleus accumbens, olfactory tubercle, and frontal cortex. (Abstract shortened by UMI.)</p> / Doctor of Philosophy (PhD)

<p>The pharmacology of 2-(¹²⁵I) iodomelatonin ((¹²⁵I) MEL) binding was investigated in Syrian hamster brain regions. Both kinetic and saturation binding analysis revealed a site with an affinity of ≅2 nM in the hypothalamus. Correlation of the pharmacological profiles in different brain regions indicated this site also to be present in the cerebral cortex and hippocampus. This binding site appeared to be present throughout the CNS and peripheral tissues of the hamster and is distinct from the picomolar-affinity melatonin receptor. Using the technique of radiation inactivation, the molecular sizes of the chick retinal picomolar-affinity melatonin receptor (Mᵣ = 44 kDa) and hamster hypothalamic low (nanomolar)-affinity binding site (Mᵣ = 30 kDa) were found to be significantly (p<0.04) different. This, along with the pharmacological differences, supports the notion of two separate melatonin binding sites. Binding studies indicated that the continuous cell line RPMI 1846 (Syrian hamster melanoma) possesses a melatonin binding site similar to that found in the hamster CNS. A high correlation was observed for a series of compounds between the Kᵢ in hamster hypothalamic membranes vs RPMI 1846 membranes. Scatchard-Rosenthal analysis of saturation binding of (¹²⁵I) MEL to membranes indicated a site of similar affinity to that in brain. This cell line was used to study potential signal transduction mechanisms for the site. No effect of melatonin was seen on basal or forskolin-stimulated membrane adenylate cyclase activity. Using (³H) adenine and (³H) myo-inositol prelabelling of cells, melatonin was found to be without effect on in situ basal or stimulated cAMP or basal IP₃ levels. In ⁴⁵Ca-flux experiments, melatonin was without effect on basal or K⁺-stimulated uptake in hamster brain synaptosomes or basal uptake in RPMI 1846 cells. This nanomolar-affinity melatonin binding site therefore does not seem to be coupled to the adenylate cyclase or inositol phosphate second messenger systems and its biochemical and physiological function(s) remain(s) unknown.</p> / Doctor of Philosophy (PhD)

<p>This study was designed to compare the effects of two weight training systems, the Interval Circuit and High Intensity systems on muscular strength, cardio-respiratory endurance, girth measures and self-concept of high school boys.</p> / Master of Science (MSc)

<p>Direct VIP-nerve and indirect ICC-mediated inhibitory control of colon motility were studied using biochemical techniques. In order to define a basis for VIP action in colon, longitudinal muscle, ICC-poor circular muscle and ICC-rich layers separated by dissection were characterized by electron microscopy and subcellular fractionation using markers for synaptosomes, smooth muscle membrane and mitochondria. Synaptosmal, mitochondrial and smooth muscle enriched membrane fractions were isolated but a putative ICC membrane enriched fractions has the highest 5'nucleotidase, Mg2+ATPASE activities and density of 125 I-VIP binding followed by synaptosome and smooth muscle membranes. High VIP binding density can be used as a marker for ICC membrane.</p> <p>The study of nitric oxide production in fractions from ICC-rich and-poor preparation by measuring nitrite levels showed that mitochondrial, synaptosome and ICC-rich membrane fractions produced nitric oxide but greater levels were seen in the ICC-membrane rich fraction. Nitric oxide synthase activity on ICC membrane was constitutive and calcium-dependant. VIP increased (2-fold) nitric oxide production in ICC-rich strips which was inhibited by L-NAME, reduced by EGTA and increased by exogenous calcium. Partial inhibition of VIP-induce nitric oxide production by ω-Conotoxin GVIA was recorded in the absence (22%) and presence (32%) of L-arginine suggesting that the source of nitric oxide was in large part non-neural, from ICC.</p> <p>I conclude that direct nerve-mediated control of longitudinal and circular muscle occurs through VIP binding on membrane receptors while indirect control of circular muscle occur through VIP-nerve induced production of nitric oxide from ICC to cause smooth muscle relaxation.</p> / Doctor of Philosophy (PhD)

<p>Language acquisition in relation to sex, manual motor skill and laterality was studied in forty-nine middle class normally developing children. A longitudinal design was employed and testing was done at 18, 24 and 30 months of age. Measures of language function, motor function, lateral asymmetry and general cognitive ability were used. It was predicted that: (a) girls would perform better than boys on the language measures, (b) children who scored high on manual motor tasks would talk better, (c) handedness would not be related to language ability, and that, (d) handedness and motor asymmetries would be observed at 18 months and not change at 24 and 30 months. The girls performed better than the boys on almost all the language measures. There were no sex differences for any of the other tests given. A weak association was found between manual motor skill and language productivity, but handedness and language ability were not related. Hand preference and motor asymmetries were observed at 18 months and maintained at 24 and 30 months. These results further our understanding of language development in young children and may help the assessment and treatment of children with developmental language problems. The measurement of handedness and lateral behaviors in young children permits inferences about hemisphere specialization in the young child. The results of this research support the position that hemispheric specialization does not develop with age but is present from a very early age.</p> / Doctor of Philosophy (PhD)

published_or_final_version / Medicine / Master / Master of Medical Sciences

Phase 1 of the new class 61 Medical Sciences was completed early in 2009 and the work on Phase 2 is now well under way. In phase 1, a framework for the new class was established using the organization of facets provided in Class H of the Bliss Bibliographic Classification. Bliss terminology was used in the captions together with UDC notation and formatting as needed. Concepts and terms, the common auxiliaries, and classes related to medicine were used insofar as they were appropriate. There was heavy use of common auxiliary tables of general characteristics (Table 1k) -02 Properties, -04 Relations and Processes and -05 Persons as they became available. As needed, other tools were consulted including Medical Subject Headings (MeSH) and the World Health Organization’s International Classification of Diseases (ICD). At the end of Phase I the result was a framework for medicine which itself needed revision to be compatible with UDC. In Phase 2 the principal goal is to update the proposed Medical Sciences class to bring it into line with UDC as it exists today and to add new diseases and other terms which are covered in neither Bliss (1981) nor the present UDC 61 (which has not been revised for many years).

Embalming fluid contains substances such as formalin, ethanol, phenol, and other solvents to prevent decomposition temporarily. These agents disinfect, preserve, and/or sanitize. The risk of contracting a disease such as tuberculosis (TB) among persons, who are in close contact with recently deceased people, is high and the risk varies according to occupation. Workers at Anatomy Departments and embalmers are some of those people who are at a greater risk of contracting tuberculosis carried by cadavers. The question thus arises whether the penetration of formalin and other embalming agents into the tissue infected with Mycobacterium tuberculosis (MTB) is sufficient to render the bacilli non-infectious. The aim is to test the efficacy of the embalming fluid used at the department of Basic Medical Sciences (UFS) on eliminating Mycobacterium tuberculosis in human cadaver lung tissue. The cadavers were accompanied by their death certificates indicating the cause of death. Only cadavers whose death certificate indicated that the cause of death was TB, was selected to be included in the study. Closed needle biopsies were performed on 20 cadavers to obtain lung tissue from the apical and hilar areas. With the use of a pro-cut biopsy needle, a sample of lung tissue was obtained by inserting the needle through the 3rd intercostal (hilar sample) and the supraclavicular space (apical sample). The first sample was taken before embalming. The second sample 3 weeks after embalming. Tissue was then retrieved and deposited into a sterile specimen container, with saline as transport medium, and transported to Pathcare Laboratory (Drs Dietrich, Voigt, Mia, and partners) in Bloemfontein. The following diagnostic tools were used by Pathcare: direct microscopy from aspirates (lungs in the case of Pulmonary TB or from granulomatous lesions), MGIT culture, identification using PCR techniques, if positive. Before embalming 50% of the apical samples tested positive for MTB and 3 weeks after embalming none tested positive for MTB. Before embalming 40% of the samples taken from the area close to the hilus (perihilar), tested positive for MTB, 3 weeks after embalming none tested positive. The results show that 3 weeks after embalming none of the tested lung samples contained viable MTB. Thirteen of the 20 cadavers tested did have a viable strain of MTB before embalming occurred. It is of special interest to mention that one cadaver still had viable MTB 36 days after death. According to previous studies, after death, MTB can remain infectious for about 8 days in unembalmed lung tissue and up to 14 days if stored between 2 - 4oC. From this result, it is clear that MTB can survive in dead bodies with significant post-mortem intervals. It is evident from the results that the embalming fluid used at the department of Basic Medical Sciences (UFS) renders the bacilli non-infectious, because no growth was indicated 3 weeks after embalming

This thesis starts with what the House of Lords Third Report (2000) has identified as a “crisis of trust” between science and society. It explores ways of addressing this crisis by examining stem cell researchers’ discourses about their work and public engagement, and suggests ways of improving scientists’ engagement with publics. My journey from natural to social sciences started with an in-depth critical analysis of constructive (or critical) perspectives on public understanding of science (e.g. Irwin and Wynne). This highlighted the importance of investigating scientific institutions and scientists, and their embedded assumptions about publics, engagement and science. My research expands upon the limited empirical research on this topic and draws upon data from interviews and discussions with 54 stem cell researchers (of different levels of seniority and field of research, in Australia and the UK). Using informants’ discourse as a “topic” and a “resource” (Gilbert and Mulkay), the thesis explores in detail the strategic and socially contingent definitions and boundaries (Gieryn) in stem cell research (SCR). Analysis of the empirical material develops four main themes. Firstly, the language and conceptual fluidity of SCR is emphasised and shown to enable scientists to conduct “boundary-work” in a variety of ways. Secondly, discourses and performances of (un)certainty are examined to highlight a diversity of socially contingent identities SCR professionals can draw upon. This examination draws on MacKenzie’s “certainty trough” but also improves it by problematising the concept of “distance from knowledge production”. Thirdly, scientists’ expressions of trust and ambivalence are analysed as interactions with particular “expert systems” such as processes of informed consent, commercialisation or legislation in conditions of increased globalisation. By highlighting hermeneutic aspects of trust, this analysis is sharpened and shows that there are elements of “counter-modernity” as well as “reflexive modernisation” in SCR. It is argued that, to further explore the reflexive potential of stem cell professionals’ critiques of their work, these need to be further discussed in public. The forth and final theme focuses more specifically on engagement. Stem cell researchers’ accounts are shown to construct and perform publics, scientists and engagement – and thus “scientific citizenship” – in a variety of ways. This variety can be made sense of by reflecting on conceptions of expertise, democracy, and power. This enables the development of six “ideal-types” of engagement that can be used heuristically to study performances of citizenship. The thesis concludes by discussing its main contributions to knowledge. It highlights how social scientists can encourage greater “interpretative reflexivity” (Lynch) on the part of scientists; this can, in turn, lead to improved science-public relations.

Type-2 diabetes (T2D), a multi-factorial disease characterised by chronic hyperglycaemia, is caused by a complex interaction between genetic and environmental factors. Genetic and phenotypic characterisations of diabetic patients suggest that a combination of &beta;-cell failure, culminating in defective insulin secretion, as well as impairment of glucagon secretion in &alpha;-cells is central to the aetiology of the disease. Mouse models represent a valuable tool in such investigations. With the advent of large-scale genetic tools, a myriad of novel susceptibility loci associated with T2D have been identified. For many of these genes, it is unclear how genetic variation is linked to increased disease susceptibility. Our first study elucidates the implication of a transcription factor, SOX4, which is believed to underlie a T2D susceptibility locus (CDKAL1) in human. Using an N-ethyl-N-nitrosourea (ENU) mouse model, we explored &beta;-cell function in mice carrying a point mutation in Sox4 (Sox4mt mice). This mouse strain displayed a significant reduction in glucose-stimulated insulin secretion (GSIS) that was associated with a 2-fold increase in wild-type Sox4 expression. The exocytotic events in mutant &beta;-cells, as measured by single-vesicle (on-cell) capacitance measurements, suggested the presence of a persistent fusion pore. Subsequent failure of fusion pore expansion beyond the initial 1–2 nm results in an incomplete insulin release due to steric hindrance (insulin diameter: 3–4 nm). The proportion of full fusion events diminished in favour of kiss-and-run events in mutant &beta;-cells. Stxbp6, which encodes amisyn, was shown to be the target gene of Sox4. Increased expression of amisyn, a protein previously shown to be involved in the stabilisation of the fusion pore in chromaffin cells, was observed in islets isolated from Sox4mt mice. The possible involvement of amisyn is further suggested by the finding that overexpression of amisyn mimicked the effect of the Sox4 mutation and resulted in reduced insulin secretion. Knockdown of amisyn expression restored the secretory defect in Sox4mt-overexpressing cells. Importantly, the effect of the Sox4 mutation was recapitulated by the overexpression of Sox4. Similar effects were obtained in the human &beta;-cell line EndoC-&beta;H2. We also observed a negative correlation between SOX4 expression and GSIS in a large collection of human islet preparations. There was also a positive correlation between SOX4 expression and STXBP6 (amisyn) expression and a tendency towards increased SOX4 expression in islets from organ donors with T2D. The second part of the thesis focuses on the role of the Krebs cycle enzyme fumarate hydratase (FH) in insulin release. Ablation of the Fh1 gene (which is initially implicated as a tumour suppressor in hereditary leiomyomatosis and renal cell cancer) in pancreatic &beta;-cells led to a complete loss of GSIS, as determined by ex vivo pancreatic perfusion studies, although this was not associated with any detectable abnormalities in [Ca²⁺]_i homeostasis, ATP production or glucose oxidation. The phenotype was rescued by the introduction of the human orthologue FH into the cytosol alone or in both the cytoplasm and mitochondria of Fh1 knockout (Fh1KO) mice, confirming the role of Fh1 in insulin secretion. Moreover, the addition of exogenous glutamate, previously implicated as a 2^nd messenger between glucose metabolism and insulin secretion, corrected the insulin secretory defect in Fh1^-/- &beta;-cells. We hypothesise that the loss of GSIS in Fh1KO mice results from enhanced anaplerosis, which is necessary to replenish Krebs cycle reactants. Consequently, this is followed by the depletion of the intracellular amino acid pool (including glutamate). Thus, our study demonstrates that the pancreatic Fh1KO mouse is a novel model of severe hyperglycaemia that harbours dysregulated metabolic features at the interface between both cancer and diabetes. The final study investigates the effect of ageing, a risk factor for T2D, on glucose-stimulated insulin and glucagon release. However, GSIS increased rather than decreased with ageing in both human and mouse islets (6 and 20 mmol/l glucose). Notably, ageing was not associated with reduced insulin content. Normal calcium homeostasis was observed in old (24-month-old) mice, demonstrating that the glucose sensing machinery was intact. In human islets, the inhibitory effect of glucose on glucagon secretion deteriorated with age. In the oldest group (>60 years of age), the inhibitory effect was completely abolished with 20 mmol/l glucose, while 6 mmol/l glucose only achieved less than 20% inhibition (which was not statistically significant). Our study reports the exciting possibility that hypersecretion of glucagon represents a link between senescence and increased diabetes risk.