404 results for Undergraduate

  • St. Margaret's College : a study of women students in relationship to their environment.

    McClymont, Maris Laline (1940)

    Undergraduate thesis
    University of Otago

    With: Simplex Group Intelligence scale. (13 p.)

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  • Research on theoretical framework and implementation of Local Government Act 2002

    Li, Xiaotong (Bob) (2006)

    Undergraduate thesis
    University of Otago

    Focusing on the Special Consultative Procedure (SCP), Long Term Council Community Plan (LTCCP) and LTCCP audit processes, this research studies the underlying theories and assumptions of Local Government Act (LGA) 2002’s theoretical framework. A case study is conducted in Dunedin to test whether the implementation of LGA 2002 in practise is consistent with its theoretical framework. Research results indicate that many theories and assumptions behind LGA 2002’s theoretical framework are not valid. The gap between SCP, LTCCP and LTCCP audit causes difficulties in implementing LGA 2002. Empowering communities, the ultimate purpose of LGA 2002, has not been realised. However, improvement of LGA 2002 implementation is expected when SCP, LTCCP and LTCCP audit become more efficient in the future.

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  • Kia tū ko taikākā: Let the heartwood of Māori identity stand - An investigation into the appropriateness of the legal definition of ‘Māori’ for Māori

    Coates, Natalie (2008)

    Undergraduate thesis
    University of Otago

    A dissertation submitted in partial fulfilment of the degree of Bachelor of Arts (Honours), in Māori Studies at the University of Otago, Dunedin, New Zealand.

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  • Understanding Postpartum Mood Disorders: Characterization of Brain Nuclei Activated by Prolactin Induced Signalling

    Wojciechowski, Isabella Teresa (2011)

    Undergraduate thesis
    University of Otago

    "November 2011". University of Otago department: Anatomy

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  • Sympathetic hyperexcitation in obesity may be protective against pulmonary hypertension

    Diong, Crystal Theerin (2014)

    Undergraduate thesis
    University of Otago

    Pulmonary hypertension (PH) is a disease characterised by an elevation of mean pulmonary arterial pressure due to excessive vasoconstriction and pulmonary arterial remodelling. Despite the many negative health implications of obesity, epidemiological evidence suggests the presence of an ‘obesity paradox’ in PH, whereby obesity is associated with a lower mortality rate in patients with PH. The physiological mechanism underpinning this paradox is currently unknown. However, it is well established that pulmonary sympathetic nerve activity (pSNA) is an important modulator of pulmonary arterial pressure due to β-adrenergic mediated vasodilation of pulmonary vessels. Sympathetic hyperexcitation, or increased SNA in obesity has been shown to occur in some organ systems but has yet to be investigated in the lungs. Thus, this study aimed explore whether pSNA is increased in obesity and PH and if so, whether pSNA plays a greater role in vasodilating pulmonary vasculature in obesity with or without PH. Experiments were performed on four groups of anaesthetised male Zucker rats: lean control rats (lean-C), lean rats with PH (lean-PH), obese control rats (obese-C), and obese rats with PH (obese-PH). In vivo electrophysiology experiments directly recorded activity from the pulmonary sympathetic nerve in order to establish any differences in pSNA in obesity and PH. The pSNA in obese-C animals (2.4 ± 0.4 µV.s, mean ± SEM, n = 7) was significantly elevated compared to lean-C animals (0.5 ± 0.1 µV.s, P < 0.001, n = 7) while the pSNA in the obese-PH group (7.1 ± 2.5 µV.s, n = 4), was also significantly greater compared to their lean counterparts (lean-PH, 2.0 ± 2.5 µV.s, P < 0.01, n = 4). The development of PH was also associated with a 3-fold increase in pSNA in obese rats (P < 0.05). To determine the effect of differing pSNA on vessel diameter, synchrotron radiation microangiography was performed. This technique facilitated the visualisation of dynamic changes in vessel internal diameter during acute hypoxic pulmonary vasoconstriction (HPV, 8% O2 for 5 minutes), before β-adrenoceptor (β-AR) blockade, after β1-AR blockade (atenolol, 3 mg/kg) and after combined β1- and β2-AR blockade (propranolol, 2 mg/kg). Before β-AR blockade, the magnitudes of HPV were similar between all experimental groups. After β1-AR blockade, a greater magnitude of vasoconstriction was observed in the obese-C animals compared to lean-C. Upon combined β1- and β2-AR blockade, the magnitudes of HPV in obese animals both with and without PH (obese-PH, 33 ± 4% and obese-C, 24 ± 4%) were significantly exacerbated compared to their lean counterparts (lean-PH, 16 ± 3% and lean-C, 12 ± 3%, P < 0.05). These differences were primarily observed in resistance arterioles (< 300 µm), critical in modulating pulmonary arterial pressure. This study shows for the first time, differential sympathetic regulation of pulmonary vascular tone in obesity and PH. Sympathetic hyperexcitation in obese rats, both with and without PH plays a larger role in ‘protecting’ the pulmonary vasculature against constriction during HPV compared to lean counterparts, suggesting sympathetic hyperexcitation in obesity may be a potential mechanism underlying the obesity paradox in PH.

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  • Take nothing but photos, leave nothing but footprints : major issues affecting the Fiordland tramping industry since 1952, using the Routeburn, Hollyford and Milford tracks as case studies.

    Patterson, Lewis J. (1995)

    Undergraduate thesis
    University of Otago

    69 leaves ; 31 cm. Includes bibliographical references (leaves 64-69). Typescript (photocopy)

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  • Hydrography and photommetry : tools for artificial surfing reef studies?

    Scarfe, Bradley Edward (1999)

    Undergraduate thesis
    University of Otago

    xi, 104 leaves, [18] leaves of plates :ill., maps (some folded) ; 30 cm. Includes bibliographic references. University of Otago department : Surveying. Cover title. "November 1999."

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  • The other class of women : maternity services available for destitute women in Dunedin, c.1886-1897

    McKay, Willow Reay (2002)

    Undergraduate thesis
    University of Otago

    98 leaves :ill. (some col.), maps (some col.) ; 30 cm. Includes bibliographical references. Typescript (photocopy).

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  • Rugby, racism and fear : the reaction of Invercargill people to the 1981 Springbok tour of New Zealand

    Arthur, Lucy (1998)

    Undergraduate thesis
    University of Otago

    iii, 93 leaves :ill., ; 30 cm. Includes bibliographical references (leaves 89-93). Typescript (photocopy).

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  • Exploring Molecular Links between Obesity and Breast Cancer

    Crake, Rebekah Lee Isla (2015)

    Undergraduate thesis
    University of Otago

    Obesity is associated with a high risk of incidence of, and mortality for, postmenopausal breast cancer. Despite this well-established link, the molecular and mechanistic basis of the obesity and breast cancer association still remains unclear. In obesity research, genetic variation due to copy number differences has become increasingly popular. The salivary amylase gene, AMY1, is well-known for its extensive copy number variation (CNV) in the human genome and has previously been correlated with a genetic predisposition toward obesity; however, research surrounding this association is controversial. Despite an established relationship between obesity and breast cancer risk, the recently reported genetic association between AMY1 CNV and obesity has not yet been examined in normal and obese breast cancer patients. Furthermore, gene expression changes in breast tumours from obese women remain poorly characterised. We hypothesise that obese breast cancer patients are associated with (1) low AMY1 copy number and (2) differential expression of candidate genes in the breast tumour. This study included 55 post-menopausal breast cancer patients from The Cancer Society Tissue Bank, with a BMI (body mass index)> 30 (obese; n=28) or BMI < 25 (healthy; n=27). Quantitative PCR (qPCR) assessment of germline AMY1 copy number status from blood showed that obese breast cancer patients have a lower average copy number of AMY1 compared to normal weight patients. Examining breast tumour expression profiles of obese and non-obese patients from two published studies, identified four candidate genes (GRIA2, DUSP4, NR2F1, and ADH1B) shared between both studies. Analysis of gene expression data from The Cancer Genome Atlas (TCGA) indicated that these four genes are differentially expressed within clinically relevant breast tumour subtypes characterised by oestrogen receptor, progesterone receptor and HER2 status. qPCR analysis of each candidate gene within our study cohort showed that the average expression of GRIA2, DUSP4, NR2F1 and ADH1B was lower in obese compared to healthy breast tumours, but these results were not statistically significant. My study indicated that BMI may be associated with lower germline copy number of AMY1 in post-menopausal breast cancer patients; however, further work with a larger cohort is needed to establish if GRIA2, DUSP4, NR2F1 and ADH1B are associated with obesity related breast cancer.

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  • Development of a Metabolic Syndrome Mouse Model of Breast Cancer

    Mandani, Anishah Nanji Devji (2015)

    Undergraduate thesis
    University of Otago

    Metabolic syndrome is a cluster of disorders, including obesity, atherosclerosis, inflammation and insulin resistance. It is associated with increased risk of various types of cancers including breast cancer. Obesity in particular is a risk factor for an aggressive tumour phenotype and reduced survival of patients with breast cancer. To understand the underlying mechanisms I aimed to develop and characterise a metabolic syndrome mouse with an orthotopic model of breast cancer. Apolipoprotein E (ApoE) is involved in the catabolism of triglycerides and cholesterol, and the ApoE knockout mouse model is prone to obesity and development of atherosclerosis. The double knockout ApoE/ArKO mouse displays all features of metabolic syndrome. At 6 months of age, wild type, ApoE and ApoE/ArKO C57BL/6 mice were inoculated with the murine breast cancer cell line E0771. Growth of tumours in the mammary fat pad and mouse weight were measured until tumours reached ethical endpoint. The hypoxia marker, pimonidazole, was injected 90min prior to euthanasia, and plasma, organs and tumours were harvested and weighed. Half of each tumour was formalin fixed and paraffin embedded for Immunohistochemical (IHC) analysis of cancer associated adipocytes (perilipin), proliferation (phosphohistone-H3), estrogen receptor status (ERα) and hypoxia (pimonidazole adducts). The other half was frozen and processed for tumour lysates, which were used to measure hypoxia inducible factor 1 (HIF-1α) by Western blotting, and adipokines, using an antibody array. Vascular endothelial growth factor (VEGF) and Insulin-like growth factor binding protein 5 (IGFBP5) concentrations were further analysed by an ELISA assay. HIF-1α levels in EO771 cells were analysed by subjecting the cells to hypoxic conditions. ApoE mice weighed more than wild type and ApoE/ArKO mice, and showed increased cellular proliferation. ApoE/ArKO mice had the least omental fat and the smallest tumours. IHC analysis showed that EO771 tumours in ApoE mice had the highest number of intratumoral, perilipin positive adipocytes (p<0.01). My findings show that breast tumours grown in ApoE/ArKO mice have an aggressive tumour phenotype, with increased proliferation, tumour hypoxia and VEGF concentration. These models represent valuable tools for research that will bridge the gap between cell culture models and breast cancer patients.

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  • Serum biomarkers and paracetamol during post-chemotherapy infections

    Bowden, Emily Ellen (2015)

    Undergraduate thesis
    University of Otago

    Background: Febrile neutropenia (FN) is a common complication of cancer chemotherapy defined as fever with neutropenia below 1.0 x109 /L. Prompt antibiotic treatment is life-saving. Antipyretics (e.g. paracetamol) are commonly used during antibiotic treatment to reduce temperature and discomfort. A phase II randomised, placebo-controlled double-blinded trial of paracetamol during FN was completed at Wellington Hospital. This study aimed to determine whether paracetamol affects temperature or quality of life (QoL) during FN, and to assess biomarkers as potential secondary endpoints. Methods: Participants received 1g oral paracetamol or placebo six hourly for 42 h. Tympanic temperature was monitored four hourly. Blood was taken 0, 4, 24 and 72 h after FN presentation. In the current study cytokine bead array was used to determine levels of TNF-α, IL-6, IL-8 and IL-10, procalcitonin (PCT) was assessed by ELISA, and C-reactive protein (CRP) using an immunoturbidimetric method. Participants completed the EQ-5D-5L QoL questionnaire daily and the FACT-N questionnaire on day 3. Results: Of 37 enrolled patients, 22 participants developed FN and received at least one dose of paracetamol (n = 13) or placebo (n = 9). Treatment groups had comparable demographics and vital signs at baseline. Per pre-determined criteria, 23% and 33% of patients had successful treatment in the paracetamol and placebo groups respectively (not significant). Peak temperature was significantly lower in paracetamol- than placebo-treated patients on days 1 and 2 (difference 0.7°C and 0.6°C, respectively, p < 0.01 and p = 0.03), but not on day 3. Average daily temperature was also significantly lower in the paracetamol than placebo group. IL-6, IL-8, IL-10 and TNF-α were raised at baseline and/or 4 h and declined thereafter. PCT peaked at 24 h. Presentation and 4 h levels of IL-6, IL-8, IL-10, PCT and TNF-α, as well as 24 h PCT and 72 h IL-8 levels, were associated with adverse outcome. IL-6 was higher in the placebo than paracetamol group at 24 h (p <0.02). QoL scores were worse in the paracetamol group during the first two days of treatment (difference not significant). Conclusions: Paracetamol was an effective antipyretic during FN. Serum biomarkers change during FN, and IL-6 and IL-8 are promising secondary outcome measures for future trials. The adverse impact of paracetamol on QoL scores was unexpected and requires confirmation in a larger study.

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  • Searching for a Functional Variant in a Non-Coding Genomic Region Associated with Serum Urate

    Dowdle, Amy Evaline (2015)

    Undergraduate thesis
    University of Otago

    Gout was historically known as the king of diseases and disease of kings, reserved for those of wealthy, extravagant lifestyles. Far from being resigned to history books, gout is on the rise worldwide and in New Zealand – where we have the highest rate of gout in the world – Maori and Polynesian populations have a greatly elevated risk of experiencing the debilitating disease. Gout arises as a direct result of increased urate in the blood, and as such many studies worldwide have investigated gout, using serum urate levels as a proxy measure. Recently, two important genome-wide association studies were published – these compare the genomes of those with elevated serum urate to the genomes of control subjects and identify differences. Single nucleotide polymorphisms (SNPs) were identified upstream of MAF, a gene that had not before been associated with serum urate levels. These SNPs were in what is known as a non-protein-coding region, which often play an important role in gene regulation. MAF is a transcription factor that is expressed in the lens of the eye and immune cells, and many studies into MAF have focused on these aspects. However, MAF has also been shown to be expressed in the developing kidney (in zebrafish and mice), which is of great relevance in a study of gout. Therefore, it was hypothesised that one or more of the SNPs upstream of MAF alter regulation of the MAF gene in the kidney, resulting in a change in serum urate levels. An in silico analysis was carried out, using publicly available datasets to produce candidate causal variants upstream of the MAF gene. When multiple datasets were combined and meta-analysed, no specific candidates were produced – however, some SNPs approached significance. This is noteworthy in such a small sample set (n = 18,503, versus 71,149 and >140,000 in the GWAS analyses), and the analysis needs to be repeated on a larger scale. Based on ENCODE annotations, candidate SNPs were selected in areas that looked to be involved in regulation of gene expression. To investigate the putative cis-regulatory role of SNPs, reporter constructs were used in human cell lines. This enhancer assay indicated that one element acts to enhance gene expression, and that the SNPs within this element increased this effect. Finally, a chromosome conformation capture (3C) experiment aimed to determine the interactions occurring between the MAF promoter and these upstream regions, but unfortunately the results were inconclusive. This study contributes to a growing field of research investigating the effects of non-coding DNA on gene expression, in the context of an important disease affecting the lives of New Zealanders everyday. Future findings may provide a novel mechanism by which non-coding variants affect serum urate levels in a system that has not previously been characterised.

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  • Determining biomarkers for a diagnostic test of Chronic Fatigue Syndrome / Myalgic Encephalomyelitis

    Denny, Lisa (2015)

    Undergraduate thesis
    University of Otago

    Chronic fatigue syndrome / Myalgic encephalomyelitis (CFS/ME) is an unexplained chronic multi-system illness, which leads to a lifetime of impairment. Symptoms indicative of the disease include immunological dysregulation, incapacitating fatigue, cognitive impairments, pain in the lymph nodes, and post-exertional sickness. The pathophysiology of CFS/ME is unknown, however several potential causes of development of the disease have been speculated. Consequently, due to a lack of understanding both medically and scientifically, there are no validated laboratory tests for diagnosis or management. Filling this gap of knowledge by finding an appropriate biomarker would aid the medical community in determining appropriate treatment. This pilot study aims to evaluate whether certain molecules in the blood of CFS/ME patients may be biomarkers to aid in diagnosis. This involves analysis of cytokine levels in CFS/ME patients with matched controls, and changes in cytokine levels following a pre-determined exercise regimen, in which patients are known to perform poorly. Additionally, the ratio of translational initiation factor eIF2α, to its stress activated phosphorylated peIF2α derivative, will be examined in white blood cells of patients and controls. We hypothesise that these molecules have the potential to be informative in relation to immune deterioration, a hallmark of CFS/ME. To test this hypothesis we obtained blood samples from 10 CFS/ME patients and 10 matched controls according to the International Consensus Criteria. In addition, following a separate exercise study with 11 CFS/ME patients and 3 MS patients as controls, all samples were fractionated to separate plasma, lymphocyte and neutrophils. The prepared plasma samples from all participants were simultaneously examined for expression of 27 cytokines. Statistical analysis revealed Interleukin-9 (IL9) and vascular endothelial growth factor (VEGF) expressed at significantly higher levels in CFS/ME patients compared to healthy controls (P<0.05). IL-9 and IL-13 were represented in both analyses, which indicates their potential as biomarkers for CFS/ME. Western analysis of proteins isolated from white blood cells detects both phosphorylated and unphosphorylated states of eIF2α with respective purified antibodies. Western analysis showed protein peIF2α to be slightly higher in patient lymphocytes compared to controls, though further experiments will need to be undertaken to determine the value of this result. This work suggests potential biomarkers that can be seen in blood, and Western blot analyses of additional patient and control samples will define whether a change in molecular state of eIF2α could be developed into a diagnostic test. This study gives a means to form a larger cohort for analyses on CFS/ME patients to enhance on current results in terms of identifying a possible biomarker for the disease.

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  • Impact of G-quadruplex structures and DNA methylation on allelic drop-out during in vitro amplification of imprinted genes

    Taylor, Millie Grace (2015)

    Undergraduate thesis
    University of Otago

    Diagnostic testing for genetic disorders or techniques such as preimplantation genetic diagnosis (PGD) both require accurate PCR genotyping (1). The failure of amplification of one allele, referred to as allelic drop-out (ADO) can confound genotyping results by falsely identifying heterozygotes as homozygous (2). A unique ADO mechanism has previously been demonstrated to occur consistently in the imprinted MEST gene, where both DNA methylation and G-quadruplex (G4) DNA structure contributed to allele loss (3). G4s are alternative DNA structures that form in G-rich regions due to the self-associating ability of guanine. Under certain ionic conditions, four guanine residues bind together either within or between strands to form a G-quartet, which can then stack upon one another to form the higher order structure. Such structures have the ability to act as a steric block to Taq polymerase. This effect is exacerbated when the G4 is methylated due to an increased thermal stability (4). This thesis explored the hypothesis that ADO via this mechanism occurs more widely throughout the imprinted genome. To test this, 22 target loci containing G4-DNA motifs were selected from 16 imprinted genes and an assay designed to detect ADO during PCR was developed. This required the creation of two variant alleles via the introduction of a single nucleotide polymorphism (SNP) with differential primer design. Both variants were then subjected to in vitro methylation and template mixing PCR experiments followed by Sanger sequencing to reveal mono-allelic or bi-allelic amplification. Of the 22 amplicons initially selected, only 14 were able to be consistently amplified and were thus used for this analysis. This method revealed that MEST is not alone in being susceptible to ADO events, with nine other amplicons showing either complete or partial mono-allelic amplification when methylated G4s were present. To confirm that the predicted G4 motifs did adopt the structure, CD spectroscopy was used. This revealed that these motifs were capable of forming the secondary structure and therefore contributing to ADO events. This work confirms that the effect of cytosine methylation and G4 regions on ADO that was previously observed (3) occurs more widely throughout the imprinted genome, and further highlights the need for diligence in both a diagnostic and research setting when analysing imprinted genes or other methylated regions.

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  • Identifying the functional role of miRNA-34a in diabetic cardiac stem cells

    Gandhi, Sophie (2015)

    Undergraduate thesis
    University of Otago

    Transplantation of resident cardiac stem cells (CSCs) to the injured myocardium presents the potential to improve functioning of the diabetic heart in patients post-myocardial infarction. However, this therapy is not effective in people with diabetes due to reduced number and impaired functionality of CSCs and the molecular mechanisms underlying this impairment remain obscure. Recent studies have shown marked modulation of microRNAs (miRs) before the development of structural and functional changes in the diabetic heart. Among several miRs, microRNA-34a (miR-34a) is highly expressed in the diseased heart and differentially expressed in various stem cells. The aim of this study is to determine the role of miR-34a in diabetic CSCs in both acute and chronic diabetic states. We hypothesised an increase in miR-34a expression under both conditions and detrimental effect of miR-34a activation on CSC function. CSCs isolated from Type 2 diabetic (BKS.Cg-m+Leprdb/J) db/db mice demonstrated a 3 fold increase in miR-34a expression (p<0.05). Surprisingly, after miR-34a inhibition, CSCs in the acute and chronic diabetic models demonstrated a trend towards a 3.5% and 13% increase in apoptosis respectively. Furthermore, the acute and diabetic models demonstrated a trend towards a decrease in proliferation following miR-34a inhibition. Interestingly, expression of senescent gene marker TP53, a gene encoding for p53 protein, showed a trend towards a 15% decrease in TP53 expression in the non-diabetic model following miR-34a inhibition. Unexpectedly, the acute and chronic diabetic models demonstrated trend towards a 30% and 90% increase in TP53 respectively. However, we observed a decrease in p53 protein expression in the non-diabetic and diabetic models following miR-34a inhibition. Interestingly, these findings suggest miR-34a plays a dual role in the regulation of TP53 in non-diabetic and diabetic conditions. Findings from this study suggest a protective role of miR-34a in CSCs of the diabetic heart and modulation of miR-34a expression may improve diabetic CSC function.

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  • Viral proteins as novel therapeutics in chronic horse wounds.

    Wakelin, Kirsty Anne (2015)

    Undergraduate thesis
    University of Otago

    This study examined the effects of two Orf virus-derived proteins, vIL-10 and VEGF-E, on chronic wounds in horses, to determine if they can improve vascularisation and re-epithelialisation while reducing scarring.

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  • Inactivation of a Thiol-Dependent Enzyme by Urate Hydroperoxide

    Hamzah, Melanie Rosina (2015)

    Undergraduate thesis
    University of Otago

    There are links between high serum urate (hyperuricemia) and many inflammatory diseases, yet the mechanism is obscure. Urate, the product of purine and ATP break down, builds up in plasma because humans lack the enzyme uricase to convert it to allantoin, which is freely excreted. Urate may benefit health by acting as an antioxidant that scavenges reactive oxygen species. However, hyperuricemia is associated with gout, metabolic syndrome and cardiovascular disease. Oxidative stress is also associated with all these inflammatory diseases. During oxidative stress urate is converted to several reactive electrophiles, including urate hydroperoxide. This novel oxidant could contribute to the adverse effects of urate. Urate hydroperoxide is formed when urate is oxidized to a radical that subsequently combines with superoxide. Activated white blood cells called neutrophils, and xanthine oxidase along with myeloperoxidase/lactoperoxidase, can produce urate hydroperoxide. Previous studies characterized the formation of urate hydroperoxide and its oxidation of small biomolecules. In this investigation, I explored oxidation of thiols and the thiol-dependent enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by urate hydroperoxide. The effectiveness of urate hydroperoxide as a thiol oxidant was compared with taurine chloramine. Ellman’s assay for reduced thiols was used to measure depletion of cysteine residues on GAPDH by urate hydroperoxide and taurine chloramine. GAPDH was exposed to oxidants in a dose-dependent manner, then assayed by measuring its ability to catalyse the production of NADH. Mass spectrometry was used to identify specific modifications of GAPDH. Urate hydroperoxide oxidized exposed thiols on GAPDH and fully inactivated the enzyme at a ratio of about 5:1. Half of its activity was recovered by reduction with DTT. In comparison, taurine chloramine inactivated GAPDH at approximately 10:1 and DTT reduction recovered all activity. Hence, urate hydroperoxide inactivates GAPDH by reversible and irreversible routes. GAPDH increased in molecular mass by 132 Da with exposure to urate hydroperoxide, indicating the formation of a GAPDH-urate adduct. However, I could not identify which residue was modified with a tryptic digest. Formation of urate hydroperoxide during inflammation and its subsequent oxidative reactions may explain some of the adverse effects of hyperuricemia.

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  • Association of Interleukin-23 Receptor (IL-23R) gene variants with Gout and Rheumatic Heart Fever (RHF)

    Leaupepe, Keresoma (2015)

    Undergraduate thesis
    University of Otago

    Gout is an increasingly common form of inflammatory arthritis caused by the deposition of urate, leading to the formation of monosodium urate (MSU) crystals in joints and other body tissue. This results in subsequent recurrent acute inflammation attacks (1). Gout prevalence is increasing worldwide and has a particularly high prevalence in the Māori and Pacific populations of New Zealand (9.3 to 13.9% of Māori men and 14.9% of Pacific Island men) (2). Risk factors for gout development can be either genetic or environmental. The risk of gout is different between ancestral groups, suggesting that they have genetic differences (3). Rheumatic heart fever (RHF) is a systemic auto-inflammatory disease that is caused by infection of the upper respiratory tract (mainly the throat) by group A β-haemolytic streptococci (GABHS). RHF happens via antigen molecular mimicry and cross reactivity mechanisms between the host and bacteria. Cross reactivity of antibodies and/or T cells stimulates recognition between the S.pyrogenes peptides and the host protein and leads to inflammation and autoimmunity (4). RHF incidence and prevalence has steadily declined in developed countries since the early 1900s. However, it remains a leading cause of morbidity and mortality among young individuals (6 – 15 years) in developing countries. The risk of RHF can be familial or environmental e.g. as poor housing conditions, crowding, and poor health knowledge (5, 6). The IL23R gene codes for the interleukin 23 receptor. The receptor is located on the cell membrane of cells that are involved in the immune system, which provide defence mechanisms against infection and disease from foreign microbes. During the TH17 immune response, activation of IL23R from interaction with its subunit (IL23) initiates inflammation (7). Previous studies have shown that genetic variants derived from IL23R are associated with auto-inflammatory related diseases, such as rheumatoid arthritis, ankylosing spondylitis and inflammatory bowel disease. A study by Liu et al (2015) showed that the IL23R SNP rs7517847 minor allele G confers an association with gout in Chinese Han male population. 4 Our aim was to test IL23R gene variants (rs11209026, rs7517847 and rs11465804) for association with gout and RHF in European and Polynesian populations using case-control sample sets recruited within New Zealand and (for gout) Europe. To test this hypothesis, SNPs were genotyped using Taqman assay and statistical analysis was carried out using R studio logistic regression to test for association of SNPs with gout and RHF. Common confounders including ancestry, sex and age were adjusted for in the regression analysis. Gout results revealed that rs11465804 and rs11209026 in both European and Polynesian were not significantly associated with gout. However, the rs7517847 minor allele (G) showed a significant association with gout in Polynesian (Polynesian OR = 0.85, P = 0.04) (European OR = 0.94, P = 0.53), which is consistent with the Lui et al (2015) findings. These data replicate the Liu et al (2015) findings and support the claim that IL23R has a causal role in gout in people with Polynesian ancestry. Hence, the IL23R pathway is a target for gout treatment in the Polynesian population. RHF results revealed that only SNP rs11209026 shows evidence of association with a protective effect for the minor allele (A) (OR = 0.07, P-value = 0.002) after adjustment. Therefore the rs11209026 major allele (G) is in a susceptible direction. This provides evidence that IL23R has a casual role in RHF development risk in Polynesian people.

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  • The role of retromer in the epithelial sodium channel trafficking pathway

    Geda, Anna Caterina (2015)

    Undergraduate thesis
    University of Otago

    The epithelial sodium channel (ENaC) is a protein located at the apical membrane of polarised epithelial cells, primarily expressed in the epithelia of the gastrointestinal tract, lungs and kidney. ENaC's main function is that of absorbing sodium and it is strongly involved in regulating and maintaining total-body salt and water homeostasis, acting as the rate-limiting step for sodium reabsorption into the body. Its activity, therefore, is crucial for determining blood volume and, as a consequence, blood pressure. The sorting and trafficking of ENaC to the apical membrane is a tightly controlled process, requiring the interaction of multiple proteins and organelles. Although ENaC has been well-characterised, there are certain aspects about its trafficking which need to be clarified, such as defining the many proteins involved in the recycling of the channel to and from the apical membrane. A potential, novel candidate involved in ENaC recycling is the retromer complex. This endosome-associated protein complex has been shown to have a role in protein recycling, as well as maintaining cell polarity by assisting in the transport of proteins to and from their appropriate membrane. The aim of this study was to investigate whether retromer is involved in the recycling of ENaC in polarised epithelia, focusing on three specific proteins, namely ccdc22, Snx4 and KIBRA. Whilst ccdc22 is an established component of the retromer complex, Snx4 and KIBRA were hypothesised to be part of retromer, a plausible concept given their cellular localisation and proposed function. To test whether ccdc22, Snx4 and KIBRA were involved in ENaC recycling, their function was altered (via protein knockdown or overexpression) and the effects on ENaC trafficking were measured. Using transiently transfected HEK293 (human embryonic kidney) and FRT (Fischer rat thyroid) cells, semi-quantitative analysis was carried out with Western blots to visualise whether the knockdowns/overexpression of the proteins of interest were occurring. Then, Ussing chamber experiments were conducted to detect any changes in the ENaC channel’s activity at the apical membrane when a retromer protein was knocked down or over-expressed. Finally, GST-pulldown assays were performed to visualise whether the ENaC channel interacted with retromer through the protein KIBRA. Significant knockdowns were obtained of both Snx4 (ps blood pressure.

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