Submitted in fulfilment for the Degree of Masters in Technology: Clinical Technology, Durban University of Technology, 2010. / Cardiovascular disease (CVD) is one of the major causes of premature deaths worldwide. In South Africa, approximately 195 people die from cardiovascular diseases each day. The earlier coronary artery disease (CAD) is detected, the better the prognosis. NT- pro- brain natriuretic peptide (NT-proBNP) is a cardiac neurohormone that is secreted in the cardiac ventricles in response to excessive stretching of heart muscle cells. Brain natriuretic peptide (BNP) is currently being used as a marker of left ventricular dysfunction but limitations are evident in patients with sepsis, volume overload, stroke and acute mitral regurgitation. OBJECTIVES: The main objective of this study was to identify a possible value of NT- proBNP level which indicates CAD. It also aimed to compare NT- proBNP levels with the number of diseased vessels; to assess the association between proBNP levels and patients’ age and gender; to determine the percentage of false positive proBNP levels; to determine the probability of false positive exercise stress testing and to correlate NT- proBNP levels with LVEDP. METHODS: Sixty patients were recruited from the Cardiology Department at St Anne’s hospital to participate in this trial. They were divided into two groups; Group A, the control group, consisted of thirty patients with a positive EST and Group B, the experimental group, consisted of thirty patients with an inconclusive EST. After the EST, all patients from both groups were required to have a NT- proBNP blood test, a left and right coronary angiogram and a left ventriculogram. iii RESULTS: Results of the study showed that post EST NT- proBNP levels, in both groups, increased in the presence of CAD (p<0.001). For the positive EST group, the area under the ROC curve was 0.975 which was highly statistically significantly different from the null hypothesis value of 0.5 (p<0.001) and a cut- off value of 120 pg/ml was identified with the highest sensitivity (95.7%) and specificity (100%). For patients in the inconclusive EST group, the area under the ROC curve was 0.912 which was highly statistically significantly different from the null hypothesis value of 0.5 (p<0.001) and a cut-off value of 85 pg/ml was identified with the highest sensitivity (87.5%) and specificity (86.4%). There was a statistically significant difference between the median NT- proBNP values of males and females in the group of patients with positive EST (p=0.048). The values were higher in males. However, there was no significant difference between the genders in the group with an inconclusive EST. A strong and significant correlation (p<0.001) between left ventricular end diastolic pressures (LVEDP) and number of disease vessels was demonstrated. The probability of a false positive result for EST was 24.1%. and the probability of a false negative result was 25.8%. CONCLUSION: Results of the study showed that post EST NT- proBNP levels, in both groups, increased in the presence of CAD and could accurately predict the presence of CAD. Cut- off values of 120 pg/ml for the positive EST group and 85 pg/ml for the inconclusive EST group were identified with the highest sensitivity and specificity. In the positive EST group, a trend of increasing NT-proBNP with age was and NT-proBNP values were higher in males. The positive EST was relatively accurate at predicting CAD; however, 75.9% of patients with an inconclusive EST did not have CAD.Exercise stress testing in this regard, is therefore relatively inaccurate at predicting CAD in patients with inconclusive ESTs, and the need for an additional tool, such as NT-proBNP measurements post inconclusive EST is warranted in the determination of the presence of CAD. / DUT Postgraduate office

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No description available.

Abstract not available

Traumatic brain injury (TBI) today remains a major health and social problem for both developed and developing countries. It is the leading cause of death and disability under the age of 40, and despite the significance of this public health problem, no effective therapy exists. While a number of factors have been shown to be associated with the development of irreversible tissue injury after TBI, the formation of oedema and opening of the blood brain barrier (BBB) have been shown to be of major significance to outcome. Oedema formation in the brain, when left uncontrolled, results in increased intracranial pressure that may lead to a decrease in brain tissue perfusion, localised hypoxia and ischemia, and ultimately tissue herniation and death. The mechanisms associated with the development of oedema are largely unclear, and accordingly, current therapies are generally ineffective, often resulting in dehydration, hypotension and renal problems. This thesis describes the characterisation of neurogenic inflammation in the development of post-traumatic brain oedema and functional deficits, and particularly the role of substance P (SP) in mediating their development, using rodent models of both focal and diffuse TBI. Results from this thesis demonstrate that increased SP immunoreactivity, particularly at the level of the vasculature, is a ubiquitous feature of TBI implying a potential role in the breakdown of the blood brain barrier (BBB) following TBI. This was confirmed through the use of the NK[subscript 1] receptor antagonists, which attenuated BBB and oedema formation as well as deleterious morphological events such as dark cell change and axonal injury. The NK[subscript 1] receptor antagonists also resulted in an associated improvement in both motor and cognitive deficits, as assessed using a battery of functional outcome tests. Possible mechanisms of action of the NK[subscript 1] receptor antagonist included effects on the BBB, SP release, intracellular free magnesium concentration and aquaporin-4 channels. Neuroprotection could be facilitated with administration of a non-lipid permeable NK[subscript 1] receptor antagonist in the immediate postinjury period, or up to 12 h after TBI with a lipid permeable NK[subscript 1] receptor antagonist, suggesting that this class of drugs have a clinically viable therapeutic window. We conclude that SP has a significant role in the secondary injury process following TBI and may offer a novel target for the development of interventional pharmacological strategies. / Thesis (Ph.D.)--School of Medical Sciences, 2006.

The neuropeptides galanin and neuropeptide Y (NPY) play an important role in the reproduction of rodents, e.g. by modulating the release of gonadal hormones, the nutritional status by effects on feeding behavior and also by influencing mating behavior. There are age- and gender- differences in galanin- and NPY- like immunoreactivities (LIs) in brain areas important for higher functions including the hippocampal formation (HiFo) and cortex, that are related to the concentrations of 17β-estradiol. Neuropeptides in general are currently not considered critical in normal integrative neuronal functions but are rather thought to act as slow modulators during periods of stress or injury. In the present thesis we attempted to investigate, if the normal cyclical changes in the female sex-hormone 17β-estradiol can affect neurotransmission in brain areas important for memory, cognition and mood. We studied not only ”long term” (days and weeks) but also ”short-term” (one hour) effects on galanin and NPY concentrations in 17β-estradiol-primed ovariectomized (ovx) rats and mice. Radioimmunoassay (RIA) of galanin-LI in extracts of brain tissues from ”long-term” 17β-estradiol-treated ovx rats showed that its effects on galanin are dependent on boththe dose and on duration. Galanin - and NPY-LI in brain tissues of young ovx rats and mice increased in response to 17β-estradiol treatment in the HiFo, frontal cortex and striatum already within hours. This effect was not blocked by Tamoxifen® in rats. The mechanism of the 17β-estradiol effects on galanin levels in the rat HiFo may be related to decreased release of galanin into the extracellular fluid, since galanin-LI decreased in microdialysis samples two hours after a single injection of 17β-estradiol. Species differences were observed with regards to galanin, possibly due to tissue and species differences in the distribution of estrogen receptors. In the HiFo and caudate nucleus of mice, we found an increase in NPY-transcript after two hours by means of insitu hybridization, perhaps a compensatory up-regulation of NPY mRNA after increased 17β-estradiol-induced release in these areas. Taken together with no effects of Tamoxifen® on the levels on galanin in the HiFo of rats, the short duration, and the fact that the density of classical estrogen receptors seems to be limited in the striatum, we suggest that these effects are mediated through a membrane-related mechanism perhaps not involving the classical ER route. With an antiserum raised against the C-terminal end of the first 16 aminoacids of galanin- the sequence important for binding of intact galanin to its receptor - we found a novel compound which appears to be a homologue to galanin. Chromatographical analysis revealed that it was not galanin(1-29) or the galanin related peptide, galaninlike peptide (GALP), but appeared with immunohistochemistry in the galanin systems in the brain and was further influenced by 17β-estradiol in the HiFo and frontal cortex in a similar manner as galanin(1-29). In conclusion, tissue concentrations of galanin, a putative galanin homologue and NPY can be altered already after one hour by 17β-estradiol treatment e.i. in the HiFo. These ”short-term” effects are most likely to be due to effects on estrogen-primed peptide release which might influence mechanisms important for memory, cognition and mood.

Canadians live in a society where the sun does not dictate the workday. Our lifestyles must shift to cater to the 24-hour demands of a fast paced global community. As a result our circadian rhythms are altered, leading to dysregulation of key physiological processes responsible for the maintenance of essential functions like energy homeostasis. Energy homeostasis is controlled by neuropeptide-expressing neurons within the hypothalamus. These neurons are affected by circulating hormone and nutrient levels in addition to their endogenous molecular clock machinery that controls cellular processes. Therefore, hypotheses were generated that non-SCN hypothalamic neurons express orexigenic neuropeptides in a rhythmic fashion without external influence from the SCN as a result of internal rhythmicity; and that elevated concentrations of palmitate, a ubiquitous saturated FFA common in a high fat diet, have direct influence on the mRNA levels of circadian clock components Bmal1, Clock, Per2, Rev-erbα and the potent orexigenic neuropeptides NPY, AgRP and ppGhrelin through mechanisms related to HAT, SIRT1 and AMPK. Using the mHypoE-44 neurons, a well characterized cell line that expresses the molecular clock and specific neuropeptides these hypotheses were explored in four studies. Neuropeptide expression within the mHypoE-44 neurons was determined to be rhythmic. NPY and NT demonstrate significant 24-hour rhythms. CRH and ppGhrelin mRNA cycled significantly in an ultradian fashion, oscillating approximately every 18 h. AgRP mRNA did not show a significant rhythm. We identified rhythmic binding of BMAL1 to the NPY promoter, suggesting clock-mediated control of neuropeptide expression. Bmal1 and Clock mRNA levels were elevated with palmitate, whereas Per2 and Rev-erbα mRNA showed significant decreases following palmitate treatment. Palmitate increased the acetylation of both BMAL1 and PER2 proteins. Alteration of AMPK activity altered the mRNA levels of all clock genes assayed and AMPK activation diminished the palmitate-induced changes in Bmal1 mRNA. Palmitate significantly elevated both NPY and ppGhrelin mRNA levels. Chemical modifiers that decrease acetylation altered these systems. AMPK activation reduced the palmitate-induced changes in NPY mRNA levels. These findings demonstrate that non-SCN neurons have rhythmic neuropeptide transcript levels. This thesis elucidates a direct effect of palmitate on the molecular clock and neuropeptide expression at the level of the hypothalamic neuron; and these findings highlight a role for HAT/SIRT1 activation and AMPK in these important processes, which ultimately contribute to the understanding of circadian dysregulation and energy balance.

Canadians live in a society where the sun does not dictate the workday. Our lifestyles must shift to cater to the 24-hour demands of a fast paced global community. As a result our circadian rhythms are altered, leading to dysregulation of key physiological processes responsible for the maintenance of essential functions like energy homeostasis. Energy homeostasis is controlled by neuropeptide-expressing neurons within the hypothalamus. These neurons are affected by circulating hormone and nutrient levels in addition to their endogenous molecular clock machinery that controls cellular processes. Therefore, hypotheses were generated that non-SCN hypothalamic neurons express orexigenic neuropeptides in a rhythmic fashion without external influence from the SCN as a result of internal rhythmicity; and that elevated concentrations of palmitate, a ubiquitous saturated FFA common in a high fat diet, have direct influence on the mRNA levels of circadian clock components Bmal1, Clock, Per2, Rev-erbα and the potent orexigenic neuropeptides NPY, AgRP and ppGhrelin through mechanisms related to HAT, SIRT1 and AMPK. Using the mHypoE-44 neurons, a well characterized cell line that expresses the molecular clock and specific neuropeptides these hypotheses were explored in four studies. Neuropeptide expression within the mHypoE-44 neurons was determined to be rhythmic. NPY and NT demonstrate significant 24-hour rhythms. CRH and ppGhrelin mRNA cycled significantly in an ultradian fashion, oscillating approximately every 18 h. AgRP mRNA did not show a significant rhythm. We identified rhythmic binding of BMAL1 to the NPY promoter, suggesting clock-mediated control of neuropeptide expression. Bmal1 and Clock mRNA levels were elevated with palmitate, whereas Per2 and Rev-erbα mRNA showed significant decreases following palmitate treatment. Palmitate increased the acetylation of both BMAL1 and PER2 proteins. Alteration of AMPK activity altered the mRNA levels of all clock genes assayed and AMPK activation diminished the palmitate-induced changes in Bmal1 mRNA. Palmitate significantly elevated both NPY and ppGhrelin mRNA levels. Chemical modifiers that decrease acetylation altered these systems. AMPK activation reduced the palmitate-induced changes in NPY mRNA levels. These findings demonstrate that non-SCN neurons have rhythmic neuropeptide transcript levels. This thesis elucidates a direct effect of palmitate on the molecular clock and neuropeptide expression at the level of the hypothalamic neuron; and these findings highlight a role for HAT/SIRT1 activation and AMPK in these important processes, which ultimately contribute to the understanding of circadian dysregulation and energy balance.

Thesis (M.Sc.-Res.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references: leaf 60-80.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Ependymin; anti-oxidative enzyme SOD. Includes bibliographical references (p. 65-69).