6,766 results for Otago University Research Archive

  • Cohesin and CTCF in early zebrafish embryogenesis

    Meier, Michael (2018)

    Doctoral thesis
    University of Otago

    Early embryonic development in metazoans is characterised by extensive changes in gene expression and chromatin remodelling at all levels. In most metazoans, zygotic genomes are transcriptionally repressed for a species-dependent length of time. Embryonic developmentis temporarily reliant on maternal factors,until the genome becomes actively transcribed during zygotic genome activation (ZGA).This transition period from maternal to zygotic control, is marked by extensivechromatin changes and the clearance of maternal products. The molecular mechanisms underlying this major event in embryogenesis are not fully understood. A growing body of evidence suggests that the chromatin structure, the 3D architecture of the DNA in the nucleus, can regulate gene expression by mediating physical interactions of regulatory regions to their target genes over long genomic distances. Two highly conserved proteins, CCCTC binding factor (CTCF) and cohesin have been found to play a central rolein facilitating long range DNA contacts, thereby regulating gene expression in a variety of cellular contexts. In this thesis, I have sought to investigate the roles of cohesin and CTCF in regulating transcription in developing embryos of the zebrafish (Danio rerio) during the maternal to zygotic transition (MZT). Using a genomics approach, I found that depletion of cohesin subunit Rad21 delays ZGA without affecting cell cycle progression. In contrast, CTCF depletion has little effect onthe timing ofZGA, butcomplete abrogation is lethal. Genome-wide profiling of Rad21 binding reveals a change in distribution from pericentromeric satellite DNA sequences and few locations including the miR-430 locus (whose products are responsible for maternal transcript degradation), to gene regulatory elements as embryos progress through the MZT. After MZT, a subset of Rad21 binding occurs at genes dysregulated upon Rad21 depletion and overlaps pioneer factor Pou5f3, which activates early-expressed genes. Rad21 depletion disrupts the formation of nucleoli and RNA polymerase II foci, suggestive of global defects in chromosome architecture. I propose that Rad21/cohesin redistribution to active areas of the genome is key to the establishment of chromosome organization and the embryonic developmental program. Rad21 binding profiles from pre-and post-gastrulation embryos were compared to identify stage-specific and constitutive binding sites. Stage-specific Rad21 binding sites are correlated with the timely activation of associated genes, but lack canonical enhancer marks. In contrast, constitutive sites are strongly enriched for active chromatin marks and show characteristics of topological domain boundaries with high enrichment of divergent CTCF binding sites and well-positioned nucleosomes.

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  • Transition metal complexes of pyrazine-based bis-terdentate diamide ligands

    Hausmann, Julia (2004-08-21)

    Post-doctoral thesis
    University of Otago

    The four symmetrical, closely related pyrazine-based bis-terdentate diamide ligands N,N'-bis(2-pyridylmethyl)pyrazine-2,3-dicarboxamide (H2 LM1), N,N'-bis[2-(2-pyridyl)ethyl]pyrazine-2,3-dicarboxamide (H2 LM2), N,N'-bis(2-pyridylmethyl)-pyrazine-2,5-dicarboxamide (H2 LS1) and N,N'-bis[2-(2-pyridyl)ethyl]pyrazine-2,5-dicarboxamide (H2 LS2) have been synthesised and characterised. Their coordination chemistry towards first row transition metal ion has been investigated. Several dinuclear copper(II) complexes of (HLM1)-, (H2 LM2)-, (LS1) 2-- and (LS2)2- have been obtained, of which six were structurally characterised, namely [CuII2(HL M1)(MeCN)4] (BF4 )3 · MeCN, [CUII2(LS1)(H20)2(MeCN)2] (BF4 )2 · H2O, [CuII2(LS1)(H20)4](SiF6) · 0.5 H2O, {[CuII2(LS1)(H20)2(SiF6)] · 4 H2O}∞,[CuII2(LS2)(H20)2(MeCN)2](BF4)2 and [CuII2(LS2)(H20)4(BF4)2] · 2 H2O. Curiously, only one complex of (LS2)2- contained six-coordinate copper(II) ions, whereas all other structures contained five-coordinate copper(II) ions. The preparation of the dinuclear copper(II) complexes {[CuII2(LS1)(H20)4(SiF6) · 0.5 H2O and {[CuII2(LS1)(H2O)2(SiF6)] · 4 H2O}∞, was carried out in water, employing Cu(BF4)2, which resulted in the formation of SiF62- ions, by hydrolysis of the BF4- anions and attack of the resulting HF onto the glassware. Under identical reaction conditions, two structurally very different complexes have been obtained with the homologous ligands H2LM1 and H2LM2, namely the dimeric dinuclear copper(II) complex [CuII2(H2LM1)2(MeCN)2](BF4)4 of a zwitterionic form of H2LM1 and the square-like tetranuclear copper(II) complex [CuII4(H2LM2)2(HLM2)2](BF4)6 · 3 MeCN · 0.5 H2O incorporating (HLM2 )- and a zwitterionic form of H2LM2. The conversion of the dimeric dinuclear copper(II) complex of H2LM1 into a [2 x 2] grid-type structure of (HLM1)- in solution with base was monitored by UV/VIS spectroscopy. The [2 x 2] grid-type complex [CuII4(HLM1)4](BF4)4 · 3.5 MeCN of (HLM1)- has been structurally characterised. The related square-like tetranuclear copper(II) complex of (HLM2)- [CuII4(HLM2)4](BF4)4 has also been obtained and structurally characterised by X-ray crystallography. Furthermore, the nickel(II) [2 x 2] grid [NiII4(HLM2)4](BF4)4 · 10 MeCN and the cobalt(III) [2 x 2] grid [CoIII4(LS2)4](BF4)4 · 12.75 MeCN have been obtained and structurally characterised. A nickel(II) [2 x 2] grid-type complex of (HLM1)- was also obtained, but not structurally characterised. Two mononuclear cobalt(III) complexes of zwitterionc forms of H2LM1 and H2LM2 have been obtained. The H2LM2 containing complex [CoIII(H2LM2)2](BF4)3 · 2 EtOH has been structurally characterised. Azido bridged copper(II) complexes of (HLM1)- and (HLM2)- have been prepared. The dimeric tetranuclear μ(1,1)-azido bridged complex [CuII4(HLM1)2(μ1,1)- N3) 2(N3)3(MeCN)2](BF4)2 · MeCN of (HLM1)- and the μ(1,3)-azido bridged polymeric chain compound l[CuII2(HLM2)(μ(1,3)-N3)2](BF4) · MeCN}∞ of (HLM2)- have been structurally characterised. IR, UV /VIS spectroscopic, cyclic voltammetric and magnetic studies have been carried out on several of the complexes mentioned above. The results are presented in this thesis.

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  • A limnological study of some New Zealand lakes

    Jolly, Violet Hilary (1959)

    Post-doctoral thesis
    University of Otago

    Freshwater surveys in New Zealand have not been numerous. This is understandable when we consider that it has been settled for little more than a century, and is still sparsely populated. The only comparative study of a group of lakes published to date is the work of Cunningham et al. (1953) which is a contribution on the dune lakes of the western coast of the North Island. In a country so richly endowed with a wide variety of lakes there is therefore a welcome opening for limnological surveys. This thesis is a comparative study of the physical and chemical conditions and the phytoplankton and zooplankton of a number of lakes. It is based mainly on monthly records made over a twelve-monthly period on seven lakes in the Rotorua-Taupo thermal area namely, Okataina, Rotoehu, Rotoiti, Rotorua, Tarawera, Taupo and Tikitapu. Data from Ngapouri, Okareka, Okaro, Rerewhakaitu, Rotokakahi, Rotomahana, Rotongaio, Waikaremoana and Waikareiti which were studied less consistently is also included. Lakes Waikaremoana and Waikareiti are the only North Island lakes outside the thermal area to have been observed. Waikaremoana could not be neglected since it is the deepest and most elevated lake of size in that island. Comparable information derived during an earlier survey of some South Island lakes is offered to provide comparison between two genetically and geographically isolated groups. Lakes Hayes, Te Anau, Wakatipu and Wanaka were sampled seasonally, that is four times over a twelve-monthly period while Kilpatrick, Moke and Manapouri received less study. The aim of this investigation was to achieve a means of assessing biological productivity. It is doubtful if this goal has been reached. However, the data collected on these seventeen North Island and seven South Island lakes which includes the largest and deepest of both Islands makes it possible to draw some comparisons and reach some conclusions, and it is hoped that the information here collected may provide a basis for further observations. [Preface]

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  • Problem solving as an approach to the teaching and learning of mathematics

    Lau, Paul Ngee Kiong (1998-12-12)

    Post-doctoral thesis
    University of Otago

    This thesis presents the findings of a research project, which examined ways in which the participating teachers learned to teach mathematics effectively using a problem-solving approach. The research also examined the interactions between students during group work that were productive to their mathematical learning so that the educational aims of the problem solving lessons could be realized. The research was collaborative, and was guided by a naturalistic inquiry and an action research philosophy. The pilot study for this research was conducted in the month of August 1996, during which one teacher and a sixth form class from a school in the city of Dunedin, New Zealand were involved. The data collection period of this research spanned six months, from early May 1997 to early November 1997. Two teachers, two sixth form classes and a third form class from the same school, participated in the research. A total of 62 mathematics lessons were video-taped and the researcher also took running records of interactions in the classroom. On top of these, numerous informal discussions were held between the researcher and the teachers to resolve the dilemmas encountered by the teachers in the classroom. A number of these discussions were audio-taped. A framework was developed to analyze the data. The framework involved an initial identification of patterns of interest. Segments of the tapes where these patterns were observed were transcribed throughout the research and grouped under these patterns. This was followed by episode-by-episode analyses, which were guided by a number of themes. Finally, the comparative analysis involved a meta-analysis of the episodes to develop an overview of the progress under the various themes. Even though the participating teachers had the mathematical knowledge and the pedagogical skills required for a problem-solving approach to the teaching and learning of mathematics, a number of weaknesses were identified in their problem solving lessons at the beginning of the research. These, together with the numerous situations they encountered in the classroom that conflicted with their previous practice, and the informal discussions held to resolve them, created a context for the teachers to learn. Not only did the teachers progress dramatically in ways such as devising rich problems for a lesson and scaffolding students' learning, they were also motivated to carefully consider the appropriate classroom context required of a problem-solving approach. The professional development demonstrated by the participating teachers provides considerable support for an action research approach. Even though the use of new instructional material by the teachers themselves might accomplish certain educational objectives, the involvement of the teachers in developing new teaching skills and approaches and understanding conceptually what happens in the classroom brought about a radical change in the classroom programmes. The reciprocal obligations and expectations for the problem solving lessons were constantly negotiated between the teachers and the students. As such, the students improved in group work. The research identified the nature of exchanges between students during group work that were productive for their mathematical learning. As the teachers progressed in teaching through problem solving, they were able to capitalize on the outcomes of group work to realize the educational aims of their problem-solving lessons. The findings offer considerable support for group work as a strategy to implement problem solving in the classroom.

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  • Vision screening in the Southern and Tairawhiti DHBs: An audit of the B4 School Check

    Muller, William (2018)

    Undergraduate thesis
    University of Otago

    Amblyopia, or ‘lazy eye’, describes visual impairment occurring due to abnormal cortico-visual development as a child, and is the most common ophthalmological condition in children. The critical period for visual development in the human extends from birth to the around the ages of 7-9 years, and the development during this time occurs competitively between fellow eyes. Thus, any impairment in retinal image quality, neuronal function or misalignment of the eyes can lead to neuronal suppression of an eye, which may cause impaired visual acuity of that eye. Amblyopia can lead to issues later in life, such as limitation of occupational choices, poorer functional vision if something happens to the better-seeing eye, and an increased risk of vision loss in the better eye compared to individuals without amblyopia. Amblyopia treatment is effective, however, so long as it occurs before the critical period of child cortico-visual development, and so, many societies have some form of child vision screening, so that children with amblyopia can be treated whileeffective treatment is still an option. In 2008, a nationwide screening programme was introduced in New Zealand: the B4 School Check (B4SC), and, currently, there is little data regarding the efficacy of the vision screening portion of the B4SC. This study primarily aimed to assess the accuracy of the B4SC vision screening, by determining the positive predictive value, negative predictive value, sensitivity, and specificity of the programme. This was done by collecting data regarding visual acuity and referral status for all children screened by the B4SC within the Southern and Tairawhiti DHBs, and cross-matching this to data collected regarding these children who also presented to community optometrists and DHB eye clinics in the Southern and Tairawhiti DHB regions for comparison. This study found that the positive predictive value for the B4SC was 53.5%. The negative predictive value was found to be between 96.1 and 99.9%, sensitivity was between 35.3 and 95.1%, and specificity was between 93.5 and 97.0%. It found that visual acuity testing is accurate, while it does have a low positive predictive value, the screening is performing its function of identifying cases of reduced visual acuity, without missing many cases.

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  • Oral health care protocols and practices in New Zealand rest homes and long term care facilities

    Kelsen, Andrea (2010-12-11)

    Post-doctoral thesis
    University of Otago

    Introduction: New Zealand's population is aging. Research in New Zealand (NZ) has reported that older people are retaining their natural teeth for longer than before. Approximately 7% of New Zealand's older adults reside within Rest Homes (RH) and Long Term Care (LTC) facilities. They depend on nurses and care-aides for assistance with multiple activities of daily living (ADL); this includes oral care. If older adults are retaining their teeth for longer it is imperative that they have access to adequate daily oral care, as poor oral health can lead to dental neglect resulting in crippling pain and loss of quality of life. Aim: The purpose of this study was to identify whether RH/LTC facilities within NZ have written oral health care (OHC) plans and policies for the maintenance of the oral health of their residents and to document the level of OHC understanding of the LTC staff. Methods: A two-part survey was designed and sent to 425 randomly selected LTC facilities in NZ. Part one recorded the number of residents, staff and location of the facilities. It then examined whether or not the facility had written OHC policies, if they were drafted with the assistance of a dental professional and whether or not the staff had problems with adhering to the policies. Part two investigated the core level of oral health knowledge of staff, and their personal dental habits and oral hygiene practises. Results: Written policies for oral care were in place in 35.9% of (n=139) facilities. Of those with policies, 15.4% had a dental professional assist in drafting it (5.5% overall). Only 14.0% of facilities had ever had a dental professional in to give a demonstration in oral care, and 90.2% of facilities felt that a demonstration in oral care would be beneficial. Most facility management teams were satisfied with the way in which they dealt with basic oral care for their residents, and the way in which they manage dental emergencies (85.1 % and 82.2% respectively). Baseline oral examinations were a low priority for facilities; only one in nine reported to provide them for residents on entry. The staffs level of oral health knowledge appeared to be adequate. With regards to daily oral hygiene habits: 88.6% reported brushing twice daily or greater, 59.2% flossed on a regular basis and 34.6% used mouthwash regularly. Where dental visiting was concerned, 63. 7% reported a regular dental attendance pattern. Conclusion: Ultimately the findings expressed a low level of policy in place to protect the oral health of older people residing in L TC facilities. There is lack of initiative by facilities to provide baseline oral examinations to document poor levels of oral health in residents on admission. Staff personal practices appeared to be positive and conform to evidence based recommendations. Many facilities identified that there was a need for improvement but due to lack of financial incentive and time constraints, were generally satisfied with the level of care they were able to provide for their residents.

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  • Spatiotemporal patterns of prokaryotic communities in New Zealand agricultural soils

    Kaminsky, Rachel (2018)

    Doctoral thesis
    University of Otago

    New Zealand pasture soils are an important resource, contributing significantly to the economy and global food security. However, the sustainability of current land management practices is of great concern, leading researchers to investigate indicators of soil health. Soils house a wealth of microbial diversity that contributes significantly to ecosystem function. However, questions remain about the ecology of soil microbes, and how intensification of land management practices such as oversowing, increased stocking rate and fertilization impact soil microbial populations. In order to address these concerns, it is important to establish a baseline characterization of microbial community ecology in managed soils. To this end, the current work aims to identify factors that influence microbial community diversity, structure and composition over space and time, and in response to disturbance. This work employs high throughput sequencing of the 16S rRNA gene in order to capture a preponderance of prokaryotic diversity in order to link community shifts to physicochemical properties of interest. This thesis employs a landscape-scale field study, exploring a group of 24 sites representing the three main land uses in New Zealand (dairy, sheep and beef and high country) in order to explore community differences in land uses of differing intensities. Samples were also taken over a seasonal cycle, after treatment with two fertilizers (phosphate and lime) to observe temporal and disturbance dynamics. The study integrates a number of physicochemical properties, revealing insights into the relative impacts of pH, land use, soil order, season and fertilization on prokaryotic communities. Results reveal strong relationships between community diversity, structure and composition and physicochemical factors (pH, land use intensity and soil order) showing landscape-scale relationships with pH and land use intensity that are sustained across time and with treatment, supporting previous results that show a strong relationship between pH and global prokaryotic communities. Links between prokaryotic communities and soil order when controlling for land use intensity provide insight into the impact of intensification on belowground communities, showing that the connection between prokaryotic communities and inherent soil properties (i.e. bedrock) weakens with increased intensification. This study also provides insight into the underexplored rare biosphere, showing that conditionally rare taxa in soils may not be responsible for overall community patterns, a result that does not match with findings for other environments. Overall, this thesis provides new insights into patterns of prokaryotic communities in pasture soils, highlighting the ways in which microbes may reflect the condition of the soils they inhabit, and consequently, general soil health.

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  • Cardiorenal syndrome in a transgenic hypertensive rat model

    Leader, Catherine (2018)

    Doctoral thesis
    University of Otago

    Hypertension is a leading cause of cardiovascular disease and myocardial infarction (MI), and these are strongly associated with renal injury. However, the impact of MI additional to the effect of hypertension on renal injury is not clearly described. Further, while mineralocorticoid blockade with spironolactone (SP) has been shown to reduce cardiac fibrosis and improve cardiac re-modelling post MI; its effects on the kidney are unknown. We aimed to explore the effects of SP on renal fibrosis in hypertensive rats post MI. Methods: Adult male transgenic Cyp1a1Ren2 rats were divided initially into two groups, normotensive (N) and hypertensive (H), and each further divided into five experimental groups: control animals, animals fed SP daily (50 mg.day-1) (+SP), animals that underwent sham operation (as a surgical control) (sham), animals with surgically induced MI (permanent left anterior coronary ligation) (+MI) and animals with surgically induced MI with additional daily administration of SP (+MI+SP). Hypertension (>160 mmHg systolic) was induced by addition of 0.167 % (w/w) indole-3-carbinol to the rat chow. Systolic blood pressure (SBP), urine collection and echocardiograms were recorded every four weeks. Cardiac and renal tissues were harvested for analysis either one month or three months. Results: SBP was lower in the H+MI group (p=0.05) compared with the other H groups (155 ± 24 and 173 ± 11mmHg respectively). SBP was not significantly reduced by SP in either of the treated groups. Ejection fraction (EF) was significantly (p<0.001) reduced by MI induction, but not improved by SP treatment in both N and H groups. Glomerulosclerosis indices (GSI) were significantly raised in all hypertensive groups against normotensive values of 0.2 ± 0.1. SP significantly (p=0.002) decreased GSI in the H+SP group (0.9±0.04) from H controls (1.2 ± 0.07) and in the H+MI+SP (1 ± 0.1; p=0.04) from the H+MI group (1.3±0.1). The degree of renal cortical interstitial fibrosis in all hypertensive groups was not however modified by SP following one month, but did show a significantly slowed progression in induced hypertensive animals following three months. Conclusion: Malignant hypertension produced extensive renal glomerulosclerosis and interstitial fibrosis over one month, which was increased further by three months. SP improved GSI scores, and reduced the extent of cardiac and renal fibrosis in hypertensive Cyp1a1Ren2 rats. No effect of SP administration was seen on SBP or cardiac EF. Further work will aim to better define the relationship between cardiac injury and renal damage.

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  • What monitoring strategies are most successful for promoting weight loss? A randomised controlled trial

    Jospe, Michelle; Roy, Melyssa; Brown, Rachel; Williams, Sheila; Osborne, Hamish; Meredith-Jones, Kim; McArthur, Jenny; Fleming, Elizabeth; Taylor, Rachael (2017-04-01)

    Conference item
    University of Otago

    Objectives: While tracking progress is one of the strongest predictors of success in healthy eating and physical activity interventions, it is uncertain whether it matters which behavior (diet, activity or weight) is being tracked. The aim of this study was to determine the effectiveness of four different monitoring strategies on weight loss, body composition, blood markers, and psychosocial indices in overweight and obese adults undertaking a 12-month weight loss program. Methods: 250 overweight or obese adults were randomized to track either a) their weight daily, b) dietary intake using My Fitness Pal, c) hunger (using a novel method called “hunger training”), d) progress via regular face-to-face meetings, or a control group for 12 months. All participants received diet and exercise advice and 171 participants completed the study. Results: All groups lost weight over the course of the intervention (typically 3.9–6.8kg) with no difference between the intervention groups and the control (all p ≥ 0.084). However, participants who tracked hunger lost significantly more weight at 1-year than those who tracked dietary intake (3.2kg, 0.1–6.4kg, p=0.046), or who met regularly with a support person (2.9kg, 95% CI 0.8–5.1kg, p=0.008). Few significant differences were observed in eating behavior (all p≥0.111), although the face-to-face and hunger tracking groups reported more favorable effects on depression and anxiety at 1-year than control participants. Adherence to the monitoring strategies (% recommended days) ranged from 29.6% for hunger training to 63.6% for attendance at the monthly face-to-face sessions. Conclusions: Daily tracking of weight, food, or hunger, or regular face-to-face support did not result in significantly greater weight loss compared with diet and exercise advice alone. However tracking hunger may be a promising approach for encouraging weight loss.

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  • Taphonomic alteration to juvenile porcine bone after exposure to a marine environment

    Hughes, Jennifer (2018)

    Doctoral thesis
    University of Otago

    Research into the effects of different aquatic environments, particularly marine environments, on the taphonomic alteration of the skeleton, is an under-studied area of forensic research. Taphonomic alteration is environment-driven and, as such, geographically specific research is critical to develop a clear understanding of the range and degree of diagenetic processes to bone when exposed to a marine environment. Bone density is probably the most well studied intrinsic factor to bone survivability and differs greatly pre- and post-puberty, with bone thickness also fluctuating during growth. Because of these age-related differences in bone, it can be expected that juvenile remains would be modified at a different rate, and perhaps in a different way, to mature adult bone. This work aimed to explore the impact of depositional marine environment on the taphonomic alteration to juvenile porcine skeletal remains. In particular, this research focused on the impact of time and seasonal variation based on initial exposure (summer and winter). Partial remains of 80 mixed breed white domestic piglets (Sus scrofa domesticus) were exposed to two marine environments: submerged and intertidal. Remains were exposed for 6 to 24 weeks, in the Otago Harbour, Dunedin, New Zealand. The experiment involved deposition in summer (January) and winter (July). Long bones (74 femora and 68 tibiae) were recovered from the two environments and analysed using three different analytical techniques: morphological assessment, Fourier transform (FT)-Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). Exposed bones were also compared to 14 non-exposed controls (7 femora and 7 tibiae) macerated in laboratory conditions. The presence of algae on newly recovered intertidal bones and possible iron sulphide (FeS2) and hematite (Fe2O3) discolouration on submerged bones were characteristics that differentiated the two depositional environments. Permanent staining of various colours persisted on bones once dried from all submerged and intertidal samples after at least 12 weeks exposure. Whereas the pattern of increased scavenging and general bioerosion over time was similar between samples from the submerged and intertidal zones and matched the patterns of algal growth during the summer and winter experiments. Using principal component analysis (PCA), sample-specific spectral indicators could be identified within the FT-Raman spectra of exposed bone samples. Intertidal samples had greater spectral variation than submerged and control samples and were generally defined by the presence of carotenoid peaks combined with amide degradation and a broadening of the phosphate peak, associated with increased carbonate substitution in the bioapatite. Quadratic discriminant function analysis (QDA) of an independent test set achieved 84% overall correct classification for environment, and 42% total correct classification for environment and length of exposure. Importantly, using FT-Raman spectroscopy, exposed and non-exposed bones were not misclassified as each other. Examination of the chemical composition of bone through SEM-EDS confirmed the presence of key marine sediment elements such as Al, Si, and Fe. The presence of these, or other, unique depositional elements may be of particular use in confirming the depositional environment if the sedimentology of the local marine environment is known. However, SEM-EDS offered little evidence for systematic depositional context-related diagenetic change over time. While many aspects of marine taphonomy remain unknown, this research has shown that there is a need for more environment- and age-specific research into taphonomic alteration. In addition, this research has demonstrated the potential of three different methods that could be further developed to improve early exposure interval estimates. FT-Raman spectroscopy combined with PCA has shown its ability as a tool for defining taphonomic alteration in bones exposed to a marine environment and warrants further research.

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  • Influence of Risk Factors on Incidence, Management, Recurrence, and Follow-up of Acute Diverticulitis.

    Sharma, Prashant Vinay (2018)

    Masters thesis
    University of Otago

    Acute Diverticulitis is a significant problem, accounting for up to one third of acute surgical admissions. Despite significant and rapid advances in medical knowledge, it remains a poorly understood disease. Practice is influenced by historical studies which have significant flaws. Current practice may be a reflection of limitations of the past e.g. the lack of accurate Cross Sectional Imaging. Technology is advancing and historical practices such as routine colonoscopy after diverticulitis may not be required. Risk factors for acute diverticulitis and recurrent diverticulitis remain unclear. With western society changing, diseases such as obesity are increasing. These may have influence on acute diverticulitis, its course and recurrence. Similarly other poorly understood risk factors include use of Non-Steroidal and Steroid medications, and the influence of Diabetes and autoimmune diseases. This thesis is an attempt to clarify these questions. Chapter 1 addresses the historical research and evidence that formed the basis of current practice. In Chapter 2 we address the effect of BMI and other risk factors on acute diverticulitis, and found that obese patients may be at increased risk. In chapter 3 we addressed the role of colonoscopy and found that the risk of malignancy after a confirmed episode of uncomplicated diverticulitis is not significantly different to that of a screened asymptomatic population, while complicated diverticulitis still carries a significant risk. In chapter 4, we looked at recurrent diverticulitis, and found that uncomplicated disease at initial presentation, having an autoimmune disease and taking regular NSAIDS increased risk of recurrent disease.

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  • People’s Interaction with Public Art in Public Spaces within New Zealand

    Jagannath, Thejaswini (2018)

    Masters thesis
    University of Otago

    Public art is an attractive feature for public spaces worldwide. From fountains to sculptures, public art colours and influences public spaces. It supports interaction, suggesting meanings and symbolism to people. This study looks at six public spaces within New Zealand, two each in Auckland, Christchurch and Dunedin. The aim of this research is to investigate how public spaces influence and promote people’s interaction with public art. To achieve this aim, the research objectives of this study are to understand: 1) How is public art structured and organised within public spaces? 2) What is people’s interaction with public art in public spaces? 3) What is the connection between public art and urban regeneration? 4) What are the public art policies of Auckland, Christchurch and Dunedin? To achieve the research objectives, semi-structured interviews and an observational matrix with video recordings were undertaken in each of the six public spaces. An observational matrix was designed by the author of this thesis. The findings from its application indicated that people are more likely to interact with public art based on factors such as the time of day and the weather. The number of people interacting with the public art in each of the public spaces varied depending on the amenities and facilities that the public spaces offered around the public art. Semi-structured interviews were undertaken which provided valuable information on stakeholders’ perspectives on people’s interaction with public art in New Zealand and how the public space can be made successful to support this interaction. The study found that for public art to be successful, it is important to have an interactive component in the public realm. The effect that public art has on people can be determined by the public or authorities such as artists and council members who initiate the public art. Some interview participants indicated that if people do not have a public space they can enjoy and feel comfortable in, suggesting conviviality, then it is unlikely that members of the public will find the public space interactive. People’s interaction with public art can create contemplation with deeper meanings, a sense of place where they re-visit the public space and contribute to activity around the public art. People’s interaction with public art significantly contributes to building a public realm on a human scale.

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  • Seeing is Believing: Revelation, Emotion, and Film Images

    Goodwin, Richard Vance (2018)

    Doctoral thesis
    University of Otago

    One of the most theologically interesting aspects of cinema is its apparent capacity to mediate revelation. While the primary agent of revelation is God, without whom revelation cannot happen, certain films seem to elicit claims of revelation more consistently than do other films. This project seeks to elucidate the relationship between revelation and film form, examining the stylistic, especially visual, features of films that commonly occasion purported experiences of revelation. Moreover, this project aims to offer an account of how formal strategies might be said to be conducive to revelatory experience without compromising the essential primacy of God’s agency in revelation. This research is presented in two parts. Part One lays the theoretical foundations by examining revelation from several vantage points. The doctrine of general revelation speaks to how revelation may take place outside ecclesial contexts and without explicit reference to Jesus Christ, yet the dominant Protestant perspectives on the matter have been too pessimistic about sinful humanity’s capacity to rightly receive general revelation to allow for the possibility of revelation through film. Thus, a revised, pneumatologically oriented account of general revelation is offered, generous enough to accommodate the particular, affective experiences that often characterise film-mediated revelation but that have historically been overlooked in traditional formulations of the doctrine. I address the possibility of revelation specifically through film, assess empirical data on the phenomenon of spiritual or religious experience through film, and critically engage with an influential theory of film form with respect to viewers’ experiences of the Transcendent, “transcendental style”. A model of revelation based on Jacob’s divine encounter in Gen 28 is proposed, the “Bethel paradigm”, in which film form invites particular affective responses that guide the viewer’s attention to those aspects of the environment through which God reveals Godself. Part Two consists of case studies of specific films, each one an exploration of visual and other stylistic strategies of films that seem to regularly elicit religious, even revelatory, experiences. Aside from the form, affective impact is also considered. The films analysed are Ordet and Silent Light (considered together) with a particular focus on lighting and wonder; 2001: A Space Odyssey with a particular focus on mise-en-scène and awe; and Magnolia with a particular focus on editing and connectedness. In each case, these concepts are considered with regard to possible resonances with theological tradition. Though a study in revelation like this permits only provisional claims, the widely attested religious reception of the films examined in this study makes it plausible that some viewers have had experiences that could be categorised as revelatory. That certain films appear to elicit these sorts of responses more consistently than others suggests that there are objective factors that correlate with film-mediated revelation. The Bethel paradigm proposed in this thesis provides an account of revelation that gives space for consideration of film form as being conducive to revelatory experience while still preserving the essential primacy of God’s agency in revelation. It seems reasonable to suggest, therefore, that certain visual and other stylistic components may contribute towards providing the optimal conditions for revelation to be experienced.

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  • Hydrologic Implications of Woody Vegetation Change in Indigenous Snow Tussock Grasslands: A Case Study at Glendhu

    Mills, Florence (2018)

    Masters thesis
    University of Otago

    Shrub encroachment in grassland ecosystems is an increasingly pressing issue globally and locally in New Zealand. New Zealand’s grassland ecosystems, specifically tussock grasslands, are also experiencing woody vegetation change from both native and exotic shrub species. Tussock grasslands are important landscape features as they offer a range of essential ecosystem services, in particular, clean freshwater for downstream users is a key hydrologic service provided by indigenous snow tussock grasslands. Increased water yield has been attributed to low evapotranspiration (ET) rates as tussock plants have the ability to reduce transpiration under water limited conditions. It is unknown whether shrub species have the same ability to repress transpiration as tussock and, therefore, may reduce water yields from tussock dominated catchments. Research was undertaken at Glendhu, Eastern Otago, to assess the potential impacts on water yield associated with the woody vegetation change from snow tussock (Chionochloa rigida) to mānuka (Leptospermum scoparium) that is occurring in the catchment. Water loss, in terms of evapotranspiration, was compared between mānuka and snow tussock. Meteorological equipment, including automatic weather stations and eddy covariance towers, were deployed for a nine-month sampling period, from late spring 2016 through to winter 2017, to collect environmental inputs for ET equations and actual evapotranspiration data respectively. Mānuka evapotranspiration rates were 2.4 mm day-1 compared to snow tussock average ET rates of 1.2 mm day-1. Across all evapotranspiration methods, mānuka was found to have higher ET rates than snow tussock vegetation which, potentially, could have a significant impact on the water yield from the catchment. A 30% cover of mānuka in the catchment could result in a decline in annual catchment water yield of at least 4%. Results from this research indicate that woody vegetation at Glendhu will likely have adverse implications for the hydrological services associated with tussock headwater catchments. Three management options are considered to address the implications of woody vegetation change in tussock dominated catchments; 1) ‘do nothing’ and allow the vegetation change to continue, which may result in a compositional shift in vegetation cover of these catchments towards a mosaic of exotic and native species, and a loss of ecosystem services associated with indigenous land cover, 2) partially manage grasslands to preserve values associated with indigenous vegetation and reduce the occurrence of exotic species, and 3) actively manage the grasslands through removal of native and exotic shrub species to preserve the ecosystem values associated with tussock vegetation, specifically the hydrological services. Implementation of the second management option is recommended to move towards restoring these grasslands to the native shrub and forest vegetation that would have once dominated the mid-altitudinal slopes of Glendhu, prior to anthropogenic disturbance. Findings offered from this research may help in defining future management agendas in tussock grasslands which will be dependent upon the vegetation that is deemed to hold the highest societal values.

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  • The impact of heat, pulsed electric fields and pH on the properties of ovomucin-depleted egg white

    Liu, Yafei (2018)

    Doctoral thesis
    University of Otago

    The thesis aimed to understand the effect of pH combined with either heat or pulsed electric fields (PEF) processing on protein aggregation and subsequent pepsin-pancreatin hydrolysis of ovomucin-depleted egg white (OdEW) solutions. The OdEW hydrolysates obtained from the simulated in vitro gastrointestinal digestion were assessed for their antioxidant and anti-inflammatory activity through in vitro experiments. OdEW solutions (10% v/v, pH 4, 5, 7, and 9) were exposed to either isothermal heating at 50-85°C for 10 min or PEF at 1.4-1.8 kV/cm under low (259-288 kJ/kg), intermediate (453-503 kJ/kg), and high (653-695 kJ/kg) specific energy input. Solution turbidity was spectrophotometrically determined and distribution of proteins in soluble and insoluble fractions of OdEW solutions was analyzed using qualitative sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). OdEW proteins were more prone to both heat- and PEF-induced protein aggregation at pH 5 than at other pH values studied. OdEW solutions showed no or minimal turbidity at low or intermediate PEF energy inputs. At the highest PEF energy input, OdEW solutions varied in their turbidity which was similar or lower than solution turbidity after heat treatment at 60°C, depending on solution pH. Heat treatment at 65°C and above resulted in s higher turbidity in the OdEW solutions. Upon simulated gastrointestinal digestion, protein digestibility of untreated and treated OdEW solutions was determined by measuring the production of peptides during hydrolysis. PEF treatment at 695 kJ/kg (1.7 kV/cm) at pH 4 significantly enhanced the digestibility of OdEW proteins. Heat treatment did not affect protein digestibility at 60°C but significantly enhanced the digestibility of OdEW proteins at 80°C. Furthermore, OdEW solutions at pH 4, exposed to PEF at 695 kJ/kg (1.7 kV/cm) or heat at 80°C (10 min), had a similar protein digestibility, with PEF treatment resulting in a much lower solution turbidity. Qualitative sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was utilized to monitor changes in proteolysis patterns of major OdEW proteins following either heat or PEF treatment. Ovotransferrin was more susceptible to pepsin hydrolysis than lysozyme. Ovalbumin showed the highest proteolysis resistance to both pepsin and pancreatin. Qualitative sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) combined with matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF MS/MS) was utilized to identify both intact proteins and hydrolyzed protein fragments during the digestion. Ovalbumin produced several proteolysis fragments, and a ~ 40 kDa fragment showed comparable digestive stability to intact ovalbumin, persisting till the end of pancreatin hydrolysis. Antioxidant activity of the OdEW hydrolysates was determined using 2,2-Di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH), oxygen radical absorbance capacity (ORAC), 2,2-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and Ferric reducing antioxidant power (FRAP) methods. PEF treatment of OdEW solutions at pH 4 and 695 kJ/kg (1.7 kV/cm) enhanced the antioxidant activity of OdEW hydrolysates, to similar or even higher levels than heat treatment at 80°C (10 min), by the DPPH or ORAC method. PEF (1.7 kV/cm, 695 kJ/kg) or heat (80°C, 10 min) treatments of OdEW solutions at pH 4 significantly enhanced the anti-inflammatory activity of OdEW hydrolysates. At a concentration of 1 mg/mL, OdEW hydrolysates showed 35.9% and 35.5% inhibition of interleukin-8 (IL-8) production of lipopolysaccharide-stimulated HT-29 cells due to prior heat and PEF treatment, respectively. This study demonstrated that PEF treatment of the thermolabile OdEW solutions had advantages over conventional heat treatment as it enabled the retention of high solution clarity, while significantly enhancing the gastrointestinal digestion of OdEW proteins. PEF treatment provides the potential for wider utilization of OdEW including the use in protein-fortified drinks with desirable qualities such as high visual clarity and good digestibility.

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  • The Role of Analytics in Higher Education

    Mahroeian, Hamidreza (2018)

    Doctoral thesis
    University of Otago

    Higher education institutions are increasingly accumulating a significant amount of data on students, teachers, facilities and curricula (Bichsel, 2012; Gantz & Reinsel, 2012, Siemens & Long, 2011). In the last decade, analytics has become an important area of research within the educational technology area. This research presents a current conception of analytics and its possible contribution to better support decision-making and possible challenges relating to the deployment of analytics in the higher education sector in New Zealand. Seven research-intensive public universities in New Zealand participated in a survey. Respondents were recruited from institutional senior management responsible for executing operational and strategic initiatives, as well as individuals whose portfolios are related to the management of data and analytics (n=82). The study found inconsistent understanding of the meaning of analytics across respondents. In particular, three forms of conception of analytics were identified: structural, functional and structural-functional. These kinds of conception have, to a larger extent, influenced respondents’ views on the value of analytics in shaping policy and practice. Also, respondents mentioned some challenges related to institutional uptake and implementation of analytics in higher education. These challenges were: difficulties in extracting data from multiple databases, maintaining data quality, ethical and privacy issues, and lack of professional development opportunities. In addition, surprising findings revealed that across institutions, universities in New Zealand see the potential use of analytics in such areas as student services support and institutional research administration. Respondents also saw potential in building institutional capability in analytics to manage performance. Overall, the research found that the higher education sector in New Zealand primarily views the potential use of analytics in monitoring, performance, and in the extraction of transactional data from siloed database systems that can be used to examine learning and teaching environments. Respondents widely acknowledged the potential role of analytics in supporting institutions to meet their strategic objectives. This study broadly contributed to a better understanding of the current conception and value of analytics in higher education, and in particular within the New Zealand context. Also, the current study contributes to our overall understanding of how higher education institutions engage with analytics to support various initiatives. Furthermore, the research presents the overall place regarding the use of analytics in higher education within the New Zealand context.

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  • Perceptions and acceptability of Low Carbohydrate, High Fat (LCHF) diets among Māori whānau in Dunedin

    Arthur, Te Huri (2018)

    Masters thesis
    University of Otago

    OBJECTIVE: Low carbohydrate, high fat (LCHF) diets are currently much debated in both the media and the academic literature. However, little is known about the acceptability of these diets among Māori, who commonly consume diets high in carbohydrates, and how they might interpret recommendations to follow these diets. This study aims to investigate how LCHF diets are perceived by members of the Māori community (Dunedin) and some of the barriers and facilitators to following this type of diet. METHODS: Face-to-face interviews was conducted with n=18 Māori participants, (13 females, 5 males). They were recruited by word of mouth around the University of Otago and door approaches in low decile neighborhoods. Interviews focused on their perceptions about carbohydrates, such as how often they ate carbohydrates, and their food habits including high carbohydrate and high-fat foods. Other questions included the participants' thoughts on the LCHF diet, and if they would be willing to try an LCHF diet. Interview transcripts were analysed by inductive thematic analysis. RESULTS: Māori are highly motivated to living healthy lives. Motivating factors include family, culture, achieving a desired body weight and fear of developing diet-related diseases experienced by other family members. Participants’ knowledge and views of dietary fat are diverse. Saturated fat is still considered by many as unhealthy however, saturated fat from natural (less processed) sources is perceived by a significant number of participants as being healthy. As a staple food in Māori diets, starchy carbohydrates appeal because they are cheap, satiating and convenient. LCHF diets are viewed positively because it emphasizes eating fewer processed foods, which are associated with poor health outcomes and resembles diets of pre – colonised Māori. Barriers to LCHF diets were the cost of foods, concern for children’s food preference, lack of time, information, understanding and meal ideas. CONCLUSION: Our study suggests that perceptions of the LCHF diet by Māori adults is divided and their understanding is not based on sound evidence. Significant barriers and facilitators cause indecision in the application of the LCHF diet. Further research is needed to determine whether Māori perception of LCHF is accurate. KEYWORDS: Carbohydrates, High Fat, Diet, Nutrition, Processed foods, Saturated fat, Māori, Health, Traditional foods

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  • The life and times of Cakobau : the Bauan state to 1855

    Heasley, Murray (1983-05-24)

    Post-doctoral thesis
    University of Otago

    This thesis is divided into eleven chapters. The first of these, Sa Cadra Na Matanisiga: the acculturation of a Tui Kaba Chief, traces the major rites of passage which transformed Cakobau from a child to a Tui Kaba chief, in line to the title Vunivalu. The Second Chapter, The Origins of the Vunivalu: from Bulu to Ulunivuaka, is an investigation of the Bauan state from its mythical beginnings until the shift to Bau islet. It attempts to place Cakobau in the context of the Bauan historical experience. The Bauan Confederacy, it is argued, was built on the successful marriage of interests between the agriculturalist and the seafarer. The Third Chapter, The Epidemics: assault on the fertility cult, investigates the impact of two devastating epidemics. The writer believes that these diseases were a serious blow to Fijian perceptions of the reciprocal relationship of man and nature from which fertility flowed. Chapter Four, Inside the Confederacy: the pursuit of legitimacy, concentrates on internal Bauan politics, the difficulties encountered by any leadership to maintain a consensus and the need to engineer and survive the most complex political manoeuvres. Chapter Five, Legitimacy attained, further pursues Cakobau' s rise to power within the confederacy and his attainment of the title Vunivalu. He had become 'legitimate’ leader by ruthless methods and now had a position to secure. Chapters Six and Seven are confined to Bau's relations with the confederacies of Cakaudrove, Rewa and Verata, and the patterns of marriage and war evident to 1854. Chapter Eight, The Tongans: Bau’s mercenaries and Cakobau's nemesis, traces the careers of the Tongan brothers, Lasike and Tupou Toutai, loyal mercenaries of the Vunivalu. Their stance is compared with the more ambiguous role of their natural enemies, the Tongan King Taufa’ahau, and his supporters. Chapter Nine, The Foreigners: the observation and pursuit of Technology contrasts the activities of the traders with those of the British and American navies, and the Bauan reaction to them. Cakobau's exposure to foreign naval technology created a desire for these same tools and techniques in an attempt to consolidate and increase his power. Chapter Ten, The Lotu: new answers to old questions, focuses on the eventual decision of Cakobau to embrace Christianity, a decision which, after years of deliberation, constituted a major religious, social and political event. As duly installed Vunivalu he was in a position to redefine the moral order, a redefinition with ramifications that touched all aspects of Bauan culture. Chapter Eleven, 1855, draws together the themes developed in the preceding chapters. With Cakaudrove and Rewa neutralised as threats and with Cakobau's influence within the Bauan domain more extensive than it had ever been, his new authority apparently sanctioned by King George Taufa'ahau of Tonga and by Britain in the person of a naval captain, the Christian Vunivalu and Bau had, by September 1855, never seemed in a more powerful position. Ironically, the Americans accepted this position and in so doing posed a mortal threat to the Vunivalu and to the confederacy he represented.

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  • Creating a Modified Monopoly game for promoting students’ higher-order thinking skills and knowledge retention

    Tan Ming Kuang (2018)

    Doctoral thesis
    University of Otago

    While a deep understanding of basic accounting concepts is fundamental for students to fully comprehend the discipline, research has consistently found that students struggle with understanding accounting concepts and tend to achieve lower-order learning outcomes. New approaches are therefore needed to provide educational interventions that help students achieve learning outcomes that reflect a deep understanding of concepts and retention of them for a long period of time. Simulation games have been proven as an effective approach for promoting higher-order thinking and knowledge retention. To date, however, there has been no reliable evidence that the game approaches are effective at enhancing students’ higher-order thinking skills and knowledge retention in the accounting learning domain. The aim of this study is to modify a popular business simulation game, Monopoly™, to facilitate the acquisition of concept application skills and to investigate its effectiveness in the accounting domain. The ability to apply conceptual knowledge is classified as higher-order thinking in the revised Bloom’s taxonomy. This study uses situated learning theory, whereby a cognitive apprenticeship approach is utilised to develop a Modified Monopoly game that emphasizes 1) the use of accounting concepts in an authentic context, 2) the use of a variety of business contexts, and 3) the clarity of the game tasks. Additionally, the teacher’s role is to provide coaching, scaffolding, and fading support to students. These modifications and the active nature of the game’s activities are expected to facilitate the acquisition of concept application skills and the retention of the skills for a long period of time. To examine the effectiveness of the Modified Monopoly game developed by the author, this study involved a total of 200 accounting students from eight high schools in one of the largest cities in New Zealand. A quasi-experimental non-equivalent group design was employed, with a random assignment based on school/class and two control groups. These control groups, in which students learned the same accounting concepts, were defined as ‘the Extended Problem’ and ‘computer assisted instruction’ (CAI) groups. The Extended Problem group used a traditional paper-based approach in solving accounting scenarios, while the CAI group used computers for the given accounting scenarios. This study therefore employed three approaches: Modified Monopoly game, Extended Problem, and CAI. All the students were assessed for their cognitive ability to apply the accounting concepts at three stages. For the purposes of the assessment of conceptual knowledge, two assessment sets were developed. Each of the sets included 28 items with the same difficulty level. Prior to the application of the Modified Monopoly game, the Extended Problem, or the CAI, each student in each group was subjected to an assessment pre-test. Then a second set of assessment questions, a post-test, was given to the students in each group after they experienced learning through the three approaches. To capture the learning retention, all the students in each group were subjected to the second set of assessment questions again after a three- to six-month period (delayed post-test). The improvement scores (post-test – pre-test) and the deterioration scores (delayed post-test – post-test) were used to analyse the data of 144 students completing all the tests. The former assessed higher-order thinking skills, while the latter assessed knowledge retention. Additionally, a self-reported questionnaire asking students’ perception of the assigned approach was collected. Results showed that both the Modified Monopoly and the Extended Problem group, but not the CAI group, demonstrated significant improvement in higher-order thinking skills. The improvement scores of the Modified Monopoly group were significantly higher than the CAI group but lower than the Extended Problem group. However, students from the Modified Monopoly group did not demonstrate the level of knowledge deterioration compared with those from the Extended Problem group, suggesting that the game resulted in better knowledge retention than the Extended Problem approach. Additionally, the game groups demonstrated a significantly higher level of enjoyment and enthusiasm to continue the use of the Modified Monopoly approach than those using the Extended Problem. This study concludes that the Modified Monopoly approach is more effective for promoting higher-order thinking skills than the CAI approach and more effective than the Extended Problem for students’ knowledge retention.

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  • Antiplatelet and anticoagulant therapy in patients with acute coronary syndromes and atrial fibrillation

    Fake, Aimee Louise (2018)

    Doctoral thesis
    University of Otago

    Dual antiplatelet therapy (DAPT), consisting of aspirin and a P2Y12 receptor antagonist, is the standard of care following an acute coronary syndrome (ACS) presentation, and oral anticoagulation (OAC) is standard of care for stroke prevention in atrial fibrillation (AF) patients. In patients with AF who present with an ACS, it is not clear whether the combination of DAPT and OAC, known as triple therapy (TT), should be the preferred treatment strategy, or whether DAPT alone is optimal. The first two studies in this thesis examined contemporary antiplatelet/anticoagulant management in New Zealand. The first study examined management of 93 ACS patients with AF from a single-centre. We found DAPT was the preferred treatment regimen, and no TT use was observed. Decisions regarding therapy did not appear to be based on assessments of stroke or bleeding risk. In the second study, we utilised the national ANZACS-QI registry, and examined pharmacy prescription data for 610 ACS patients who underwent percutaneous coronary intervention (PCI) with a history of AF. In this cohort DAPT was again the most common discharge regimen followed by TT, and their use was not driven by stroke risk (CHA2DS2VASc scores). Rates of DAPT and TT declined markedly over the 12 months following the ACS event. On the basis of these two studies we concluded that no consistent treatment strategy was evident for the management of ACS patients with AF. A systematic literature review was then undertaken to identify optimal therapy. We selected papers describing treatment regimens and one-year outcomes for patients with AF and either ACS or PCI. The inclusion of stable PCI patients was necessary as the majority of literature featured mixed cohorts of ACS or stable coronary disease undergoing PCI. The identified literature was entirely observational in nature and the overall quality was poor. The largest studies reported that TT offered significant reductions in stroke over DAPT, and a consistent increase in bleeding associated with TT was reported. On the basis that the available literature did not offer clear guidance on when the benefits associated with stroke reduction with TT would be greater than the harm associated with excess bleeding, we constructed a decision analysis model. This model addressed likely thresholds at which TT stroke reduction may exceed harm from bleeding. Under most modelled scenarios TT was not preferred above DAPT at CHA2DS2VASc 2, and only outperformed DAPT when stroke risk was high in the CHA2DS2VASc 3-5 range. Given the importance of bleeding in determining the net clinical benefit of DAPT versus TT we examined how accurately bleeding events could be predicted in a cohort of 1000 acute myocardial infarction patients. We examined the ACS bleeding scores CRUSADE and ACTION as well as low platelet reactivity (LPR) to predict one-year TIMI major and minor bleeding. We found that neither score nor LPR accurately predicted one-year bleeding events. The clinical problem of optimal antiplatelet/anticoagulant therapy in ACS patients with AF remains significant. Our data suggests that at low stroke risks DAPT is probably the treatment of choice, with TT becoming more acceptable at higher stroke risk. Accurate classification of bleeding risk in this population is needed to minimise potential harms associated with TT.

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