83,178 results

  • Studies on the Antibacterial Activity of Venison

    Jamaludin, Mohd Hafiz (2014)

    Doctoral thesis
    University of Otago

    Meat stored under aerobic conditions and chilled temperatures has a very limited shelf life. Its deterioration is further influenced by the level of hygiene during slaughtering, processing and handling, where contamination by microorganisms such as bacteria, yeast and moulds will affect its shelf life. Several scientific reports have suggested venison has better bacterial stability than other commercial meats such as beef and lamb. However, there have yet to be in-depth investigations on the antibacterial properties and the mechanism of action in venison. The current study investigated the antibacterial activity of venison and the changes in bacterial numbers during aerobic storage of fresh venison. The microbiological (total bacterial count, Pseudomonads, Enterobacteriaceae, and lactic acid bacteria) and biochemical changes (pH, TBARS, glucose, glycogen, myoglobin derivatives) of 24 hour post-mortem venison and beef minced loins were compared during aerobic storage at 4 °C. The length of the bacterial lag phase (BLP) was used as an indicator of the bacterial inhibitory activity. Fresh venison had a significantly (P < 0.05) longer bacterial shelf life (time to 6 log CFU g-1) than beef (14 and 5 days respectively). The lower pH value (P < 0.05), and higher glucose and glycogen concentrations (P < 0.05), higher TBARS (P < 0.05), and higher iron concentration (P < 0.05) in venison than beef suggested a potential involvement of reactive oxygen species (ROS) in the observed phenomena. An evaluation of various ROS generation systems on bacterial growth indicated antibacterial activity arising from H2O2 rather than superoxide and hydroxyl radicals. Further evaluation of a glucose-glucose oxidase H2O2 generating system indicated that the extension of the bacterial lag phase was dependent on the concentration and maintenance of H2O2 during storage. An increase in glucose concentration increased the antibacterial activity (P < 0.05). Due to technical limitations to observe and quantify H2O2 directly in fresh venison during storage, a series of cause and effect experiments were used to evaluate the association of H2O2 in fresh meat with bacterial numbers. Altering the concentration of H2O2 via manipulation of catalase and SOD activities had no effect (P > 0.05) on bacterial growth. The use of tyrosine, tryptophan, SDS and EDTA to inhibit either SOD or Catalase, showed that only tyrosine had an effect on bacterial growth. A low tyrosine concentration (5 mg/g) treatment of both venison and beef resulted in a longer bacterial lag phase (P < 0.05). Since the generation of H2O2 in situ is largely dependent on the activity of several enzymatic systems involved in superoxide generation (a precursor for H2O2), various inhibitors (DPI, Antimycin, Oxypurinol, Rotenone, and L-name) associated with the superoxide production pathway were used to identify the possible relationship of superoxide with the length of the bacterial growth lag phase. A decrease (P < 0.05) in the bacterial lag phase in venison was observed in Oxypurinol treated samples, while an increase (P < 0.05) in the bacterial lag phase was observed with Rotenone, Antimycin and L-name treated samples. The effect of these inhibitors on ROS associated pathways indicated the potential relationship of oxidative activities with the bacterial growth lag phase and suggested that ROS may play a role in exerting antibacterial activities. Overall, circumstantial evidence suggests a potential role of ROS in increasing the shelf life of venison associated with the increased length of the bacterial lag phase.

    View record details
  • Microbial analysis of bite marks by sequence comparison of streptococcal DNA

    Kennedy, Darnell Maria (2014)

    Doctoral thesis
    University of Otago

    Human bite mark analysis can be a vital component in the investigation of violent offenses, providing crucial physical and biological evidence in criminal prosecutions. Variability in mechanical properties related to anatomical location, ageing and ethnicity of the skin undermine morphometric bite mark analysis. While the recovery of human DNA from bite marks may provide extremely compelling evidence, the presence of enzymes, especially deoxyribonuclease I, in saliva compromise the recovery of exposed DNA. The scientific rigor applied to the establishment of nuclear DNA analysis has highlighted the deficiencies in evidence underpinning other forensic disciplines, including bite mark analysis. Such inconsistencies now challenge the value and objectivity of morphometric bite mark evidence. Consequently, investigation in our laboratory persued an alternative method of analysis, based on bacterial genotyping. More than 700 bacterial taxa have been detected in the human oral cavity. The predominating species are of the genus Streptococcus and comprise the principal bacteria colonising the surface of the teeth. Streptococci exhibit extensive genetic diversity, which provides the premise for research aimed at exploring the forensic value of matching teeth to bite marks by bacterial genotyping. Streptococcal profiles may be distinctive among individuals to the degree that genotypic comparisons of isolates from bite marks and teeth can provide a correct match with a high level of confidence. The current research extends this approach by applying high-throughput sequencing to obtain streptococcal DNA sequences amplified directly from bite marks and teeth. Comparison of the sequences from the two sample types was used to establish the probability of matching a bite mark to the teeth responsible. Bite mark and teeth swabs were collected from 16 participants. Bacterial DNA was extracted to provide the template for PCR using streptococcal-specific primers for three different regions of genomic DNA: 16S ribosomal RNA (16S rRNA), 16S-23S intergenic spacer (ITS) and RNA polymerase beta subunit (rpoB). The PCR products were elucidated using high throughput sequencing technology (GS FLX, Roche) and the sequence reads from each bite mark were compared to those generated from all teeth samples. For all three regions, the greatest overlaps of identical reads were between bite mark samples and the corresponding teeth samples. The average proportions of shared reads between bite mark and corresponding teeth samples were 0.31, 0.41 and 0.31 and for non-corresponding samples were 0.11, 0.20 and 0.016, for 16S rRNA, ITS and rpoB, respectively. The probabilities of correctly distinguishing matching and non-matching teeth samples were 0.9 for ITS, 1.0 for 16S rRNA and 1.0 for rpoB. These findings strongly support the tenet that bacterial DNA amplified from bite marks and teeth can provide corroborating information in the identification of assailants in situations where the perpetrator’s DNA cannot be recovered.

    View record details
  • Ethnic Flames of the Burning Bush: An exploration of ethnic relations in congregations of the Presbyterian Church of Aotearoa New Zealand

    Joseph, Tokerau (2014)

    Doctoral thesis
    University of Otago

    This thesis is a work in practical theology that examines the tension between two realities. On the one hand, there are the stated policies of the Presbyterian Church of Aotearoa New Zealand (PCANZ) that encourage its members to live out a diverse life together. On the other hand, there is the reality confirmed in my data that PCANZ congregations reflect ethnic homogeneity rather than diversity. Although increasing sociological research about ethnic relations within religious and non-religious contexts overseas has contributed to a growing interest in this area, within the New Zealand context there has been very little study that includes a theological framework for considering such relations. At heart, my study observes the extent to which the ethnic composition of congregations is influenced by people’s theological understanding of the church and of their Christian identity, as opposed to tendencies affirming their ethnic/cultural identity. My research explores the challenges and the richness of the relations of parishioners and ministers to reveal how their theological and ethnic aspirations characterise the communities to which they belong. To understand the context and experiences of those in PCANZ congregations, I adopt a qualitative methodological approach that incorporates a combination of strategies. It requires analysing details from congregations about ethnic representation of members, ministers, attendees at worship services and leadership groups as well as of surveys and interviews of adult parishioners and ministers. My findings reveal that people’s own ethnic assumptions and preferences have been more influential than any theological aspirations they may hold for themselves and the church, resulting in the homogeneous reality of their communities. I offer reasons why this is theologically inadequate, and what might be done to change it. The unconsumed burning bush, the emblem of the PCANZ, is a sign of the mystery of God that speaks of hope to God’s people. My thesis title, ‘Ethnic Flames of the Burning Bush’, conveys the complexities and richness of ethnic relations in the PCANZ that do not seek to consume it; rather to enhance its hopeful witness of unity in diversity.

    View record details
  • Sovereign State Power and the Refugee: A Theological Engagement with Issues of State Sovereignty and its Implications for Refugee Policy Reform in New Zealand

    Fleming, Rebecca Jane (2014)

    Masters thesis
    University of Otago

    The current statistics from the United Nations High Commissioner for Refugees indicate the existence of an urgent global refugee crisis. In response to this crisis the New Zealand Government has proposed immigration policy reform, primarily through the Immigration Amendment Bill 2012. In this thesis I place the domestic debate regarding these policy reforms within the context of the international, deontological debate regarding the justification and legitimacy of nation-states and their obligations toward refugees and asylum seekers, and provide a theological perspective on it. I am concerned specifically with the questions “does a theological engagement with the deontological debate regarding the justification and legitimacy of nation-states, and the nature of their power, support the assumption that the New Zealand Government possesses the right to determine unilaterally its immigration policies regarding refugees and asylum seekers as it sees fit? If it does not, what limitations should be applied to the power able to be exercised by the New Zealand government when forming or reviewing these policies?” In order to engage theologically with the deontological debate I apply the reasoning of ethicists Christopher Wellman and Philip Cole to a biblical-theology of nations and their use of power to determine their theological justifiability. With a focus on the work of Oliver O’Donovan, this investigation reveals that secular authority in the post-Christ era is responsible for maintaining law and order subject to various limitations, including the requirement to act in accordance with the principles of justice. In the treatment of refugees and asylum seekers, justice requires that a state upholds a duty of care derived from scriptural principles. Therefore, on the basis of this research, it can be concluded that a theological perspective supports the New Zealand Government’s right to develop and enforce its border policies if it acts within the stipulated theological limitations. This is because the nation can be understood as possessing a qualified sovereignty. However, when applying the duty of care owed by states to refugees, the current proposed policy reforms are inconsistent with this duty and need revision.

    View record details
  • Teaching Teachers: The Influences on the Primary Science Pedagogy of First Year Pre-Service Teachers at Two New Zealand Universities

    Rosin, Victoria Kay (2014)

    Doctoral thesis
    University of Otago

    This study investigated the influences of teacher educators and university coursework on the primary science pedagogy of first year pre-service teachers at two New Zealand universities. The mixed methods study employed a constructivist and an interprevist lens and evaluated data collected from the Preferred and Actual (pre/post) course Constructivist Learning Environment Survey (CLES), syllabi analyses, and semi-structured interviews. These tools investigated if the primary science learning environments teacher educators created informed the pedagogical approaches of pre-service teachers and worked towards the effective pedagogy practices stated in The New Zealand Curriculum. Descriptive statistics for both universities indicated that pre-service teachers preferred to learn in a critical constructivist environment. Actual CLES results indicated where perceived constructivist principles were weak or strong in the course. Paired-samples t-tests had significant findings (p < .05) for both universities with modest to large effect sizes. Completion of analyses on gender, age, ethnicity and science qualifications indicated if these groupings had any significant differences. ANOVA results had significant differences (p < .05) between two ethnic groups and independent-samples t-tests were significant (p < .05) for age at one university. Syllabi analyses indicated a difference in the number of pedagogies used in the courses (3 versus 1). Interviews revealed the pre-service teachers’ science attitudes improved, however, science teaching time while on practicum was limited. Pre-service teachers indicated they were confident to teach science and that their teacher educators influenced their potential teaching practices. The findings supported 4 of the 7 effective pedagogy approaches listed in the curriculum. The research results indicated the complexity of the learning environment and ways to monitor it should be an important part of reviewing teacher education.

    View record details
  • Development and Application of Analytical Methods for Marine Toxins

    McNabb, Paul Simon (2014)

    Doctoral thesis
    University of Otago

    Shellfish accumulate marine toxins from their microalgal diet. The marine toxin tetrodotoxin (TTX) also accumulates in seafood, but via unknown mechanisms. Toxin determinations have traditionally been performed using live mouse bioassay. Due to ethical concerns and the poor analytical performance of these assays, alternatives are needed. During the present study, an LC-MS method for determining six brevetoxins was validated. The recovery ranged from 73% to 112% for most analytes and was 61% for one (PbTx-2). The within lab reproducibility ranged from 14% to 18% for most analytes except PbTx-2, which gave a value of 27%. The sum of the concentrations for all six brevetoxins, when compared to the mouse bioassay, appears to be a conservative measure of toxicity. A receptor binding assay (RBA) was also investigated as a replacement of the paralytic shellfish poisoning mouse bioassay. The assay was subjected to inter-laboratory testing and three spiked samples gave a recovery of 84% to 93% with reproducibility of 29%. Compared to HPLC alternatives, the RBA assay has the advantage of presenting results in a total toxicity format without the need for quantitation of each toxin and the application of toxin equivalence factors. Positive mouse bioassay results were commonly reported for Crassostrea gigas samples from Rangaunu Harbour, Northland, NZ prior to 2000 and have been attributed to the presence of Rangaunu Harbour Toxin (RHT). The nature of this toxin was further investigated using an LC-MS assay in light of the discovery of pinnatoxins (PnTxs) in C gigas from Australia. An LC-MS method was validated, and PnTx recovery ranged from 79% to 81% with reproducibility from 5.8% to 9.8%. Nine samples of C gigas collected between 1993 and 1995 and two samples collected in 2008 were tested for PnTxs using this new LC-MS assay method. All samples were found to contain PnTxs but no other toxins and so it was concluded that RHT is PnTx. A survey of the health of locals consuming shellfish from the area over many years suggested that PnTxs are of no concern for human health. Two LC-MS methods were developed and validated for the detection and quantification of TTX. One relied on direct quantitation of TTX after HILIC chromatography and the other method determined TTX after reaction with NaOH to form the C9 base. The recovery for the direct method at 1 mg TTX/kg was 94% to 120% and RSDR ranged from 9% to 27%. The C9 method demonstrated a recovery of 105% to 109% and RSDR ranged from 17% to 19%. TTX was found in four species during a year-long monitoring programme: Pleurobranchaea. maculata , Astrostole scabra, Crassostrea gigas and Paphies australis. Studies into the source of TTX revealed that TTX concentrations in P. maculata decrease at approximately the same rate in the wild and in aquarium. Feeding studies suggested that TTX could be acquired by P. maculata from their diet.

    View record details
  • An Experimental Analysis of the Effects of Past Choices on Present Choice: The Sunk Cost Effect

    Soares de Magalhães da Silva Correia, Paula Cristina (2014)

    Doctoral thesis
    University of Otago

    The present thesis examined the role of past choices on present choice, specifically, the sunk cost effect. The sunk cost effect is the tendency to persist in a losing course of action due to past investments in that particular option, when the optimal alternative would be to abandon that endeavor. These past investments can be either in terms of money, effort or time spent. This problem is of importance in the context of choice and decision-making because both economic and behavioral theories of choice predict that optimal choice is determined only by future benefits and not by past investments. The sunk cost effect is therefore seen as suboptimal choice. In this thesis, investments in time and effort were examined, and the underlying theme was whether a lack of discrimination between the outcomes of a choice could account for the influence of the past choices on current choice. Experiments in Chapters 2 and 3 concerned the sunk time effect, i.e., investments of time into a course of action. In these experiments, pigeons (Columba livia) chose between two concurrent alternatives, one producing food according to two Fixed-Interval schedules whereas the other allowed pigeons to escape from the trial by terminating it and starting a new, randomly chosen one. Escaping from the long Fixed-Interval schedule was the optimal choice because the short schedule had a higher probability of being selected (Chapter 2) or equal probability (Chapter 3), which would guarantee a sooner reward. The sunk time effect was observed in various conditions, such as: in the absence of cues signaling the type of trial or in the absence of reward in the long interval; at different fixed-interval durations and intertrial interval durations. Importantly, a Signal Detection analysis confirmed that lack of discrimination between scheduled contingencies was not the source of the preference for persisting. Experiments in Chapters 4 and 5 examined the sunk cost effect, i.e., investments in effort into a course of action. In modified versions of a standard concurrent-chains procedure, pigeons chose between two options, each ending in reward. In some trials (Chapter 4) or conditions (Chapter 5), the concurrent choice was preceded by a prior investment in one of the options, in the form of a fixed number of responses. In both chapters, the outcomes of the choice were independent of the prior investment, in that the prior investment in one of the options did not bind the subject to that option, nor did the prior investment change the amount of effort in either option in the outcome phase. Because of this, subjects were expected to show a preference in the choice phase, for the outcome that represented less effort to reward, regardless of being associated with prior investment. The sunk cost effect was observed with pigeons showing a preference for the option associated with prior investment, and this effect was stronger when more effort was spent in the prior investment phase (Chapter 5). Additionally, this preference could be so strong that pigeons were willing to expend twice as much effort in the alternative associated with the prior investment, when they could freely choose the other alternative (Chapter 4). Importantly, Matching Law analysis confirmed that this result was not due to an inability to discriminate between outcomes of the choice, and that it was indeed a bias created by the prior investment. The overall conclusion of the present thesis is that the sunk cost and sunk time effects do not result from an inability to discriminate between conditions of reward or between the outcomes of choice. Additionally, the sunk cost and sunk time effects seem to be learned effects rather than the result of a momentum to continue responding. Several possible accounts for this effect were discussed, including within-trial contrast, and delay-reduction, among others. At the present stage, within-trial contrast seems the best able to explain this preference for continuing an endeavor once time or effort has been invested.

    View record details
  • The Lived Experience of Older Adults' Adjustment to Lower Limb Amputation From the Perspective of Wheelchair Users.

    Lopez (nee Mulrooney), Lauren Claire (2014)

    Masters thesis
    University of Otago

    Aim: To present an in-depth description of the lived experience of psychosocial adjustment in older adults who use a wheelchair following lower limb amputation (LLA) due to vascular disease. In particular, to report on the experiences of positive psychosocial adjustment of individuals which may be useful to clinicians who want to facilitate positive psychosocial adjustment in their patients. Background: Amputation is a significant consequence of vascular and diabetic disease affecting elderly adults. Elderly adults undergoing LLA face challenging experiences of impaired mobility in addition to chronic co-morbidities. Rehabilitation for older adults includes optimising mobility with prostheses or wheelchairs. Using a prosthesis has been linked with positive psychosocial adjustment outcomes such as quality of life. Prosthetic training has been well documented in literature however the reported rates of prosthesis use by elderly adults is low due to the energy demands of moving a prosthesis. In comparison, there is little research available on wheelchair training or use for older adults. The effect of wheelchair use on the psychosocial adjustment of older adults with vascular disease is also less understood. A number of studies have examined the experience of adjustment in individuals using a prosthesis however limited research has defined or explored adjustment in individuals who use a wheelchair rather than a prosthesis as their primary means of mobility. Literature regarding adjustment to amputation has traditionally focused on quantitative and negative adjustment outcomes such as depression and anxiety. Positive adjustment outcomes are increasingly being explored particularly using qualitative methods which give voice to those who are experiencing amputation. Qualitative studies have explored adjustment with prosthesis users but the little personal experience of wheelchair users has been explored. It is not clear what the personal experience of adjustment to LLA by older adults who use a wheelchair is like. Method: This study used Interpretative Phenomenological Analysis (IPA) to explore the lived experience of adjustment to LLA by wheelchair users. This study interviewed four elderly men identified through hospital records. All four men used a wheelchair on a daily basis. Two men also used a prosthesis. One man used a powered wheelchair and the fourth man could not move himself independently in his wheelchair, relying on others to move him. Three men lived in their own homes and one lived in a care facility. Data were collected from one recorded semi-structured interview with each participant. Interview transcripts were analysed to identify themes in the participants’ narratives regarding their psychosocial adjustment to LLA in the context of their wheelchair use. Where possible, analysis was returned to participants to check for a “phenomenological nod”. Results: The participants did not directly refer to their wheelchairs when reflecting on their adjustment to LLA. Their adjustment did not appear to be directly influenced by what mobility aid they used but rather the mobility aid provided opportunities for adjustment to occur. Participants’ experiences of adjustment to LLA were described by two themes. The two themes were “Being an Active Agent” and “Psychosocial Adjustment as an Iterative Process”. The first theme of ‘Being an Active Agent’ described three elements of self-efficacy. The elements participants described were: cognitive processing as a coping strategy, self-beliefs and decision-making. Three participants spoke of making decisions with a sense of control, particularly the decision to choose leg amputation. The fourth participant’s narrative of choosing amputation contrasted with the other three participants in that he did not convey a sense of feeling control. Rather, he gave a sense that he felt disempowered both in the decision for amputation and in his daily life subsequent to amputation. The second theme ‘Psychosocial Adjustment as an Iterative Process’ described the iterative and ongoing nature of the participants’ narratives of adjustment to LLA. The second theme also described how the each of the participant’s experiences of adjustment to LLA were not isolated events but firmly linked to previous events of the participant’s greater life story. Conclusion: Rather than what mobility aid is used, the older adult’s adjustment to LLA appears to be influenced by the their sense of being an active agent in the adjustment process particularly in decision-making around LLA. This finding is consistent with similar studies of prosthesis users. Adjustment also appears to be an iterative and ongoing process which older adults continue to engage in after the amputation event. Further qualitative research is needed with a wider demographic to confirm the themes found here, particularly the contrasting experience of one participant. The findings of this study suggest practical frameworks that clinicians can use with older adults undergoing amputation, for example: Acceptance and Commitment Theory, Shared Treatment Decision Making and Structured Problem Solving.

    View record details
  • Do we have what it takes? An investigation into New Zealand occupational therapists' readiness to be self-directed learners

    Penman, Merrolee (2014)

    Doctoral thesis
    University of Otago

    In 2005, the Occupational Therapy Board of New Zealand (OTBNZ) introduced the Continuing Competence Framework for Recertification (CCFR) which included the mandated requirement for occupational therapists to regularly maintain an online professional development portfolio as part of the evidence required to demonstrate ongoing competence to practice. In designing the process, the assumption made was that all occupational therapists would have the attributes for, and skills of, self-directed learning, however, the degree to which this assumption holds true is not known for this population, nor is it known whether readiness to be a self-directed learner influences occupational therapists’ use of the CCFR as a professional development tool. The aims of this study were to determine the extent to which occupational therapists are ready to be self-directed learners, the factors which influence readiness to be a self-directed learner, and whether or not there is a connection between occupational therapists’ readiness to be a self-directed learner and their use of the CCFR as a professional development tool. Using a convergent parallel mixed methods design, data was collected from 173 participants via an online questionnaire, consisting of demographic and occupational questions and the Self-directed Learning Readiness Scale (Fisher, King, & Tague, 2001) adjusted for this study, and an in-depth interview with 16 participants based on their CCFR, analysed using Garrison’s (1997) Self-directed Learning model. Through triangulation of the qualitative and quantitative data analysed, the research question was answered in the affirmative, in that for the majority of participants, there did appear to be a connection between occupational therapists’ use of the CCFR as a professional development tool and self-directed learning readiness. Whereas the results of this study indicated that the majority of participants in this study were ready to be self-directed learners, factors influencing the use of the CCFR included beliefs or attitudes to learning, the degree of metacognitive awareness of themselves as learners, and personal definitions of competence to practice, with experience in supervision of allied health students and occupational therapists, and years employed, influencing self-directed learning readiness. The findings of this study have implications for occupational therapists, the Occupational Therapy Board of New Zealand, and academic institutions delivering occupational therapy programmes.

    View record details
  • Epigenetics and Expression of SFRP1 and PPARG and Epigenetic Effects of Glucocorticoids in B-cell Acute Lymphoblastic Leukaemia

    Foster, Timothy John (2014)

    Undergraduate thesis
    University of Otago

    B-cell Acute Lymphoblastic Leukaemia (B-ALL), a cancer of immature B-lymphocytes, is the most common cancer in childhood. This cancer is characterised by widespread abnormalities of DNA methylation, when compared with non-cancerous blood cells. DNA methylation is a chemical modification of the cytosine residues of DNA, and only cytosine residues immediately followed by guanine residues (so called CpG sequences or sites) undergo methylation. Methylation of CpG sites in gene promoter regions leads to non-expression of the methylated gene. DNA methylation abnormalities in cancers (such as B-ALL) have received significant attention over recent years, and have been shown to have significant biological effects in tumour cells, due to abnormal expression of the aberrantly methylated genes. This project aimed to show that the putative tumour suppressor genes, SFRP1 and PPARG, showed increased DNA methylation in B-ALL cells, when compared with normal blood cells and that this was associated with reduced expression of these genes in B-ALL. The methylation of the gene promoters was determined by bisulphite sequencing and gene expression by qRT-PCR. The results showed that PPARG and SFRP1 both show increased methylation in the gene promoter regions of B-ALL cells, when compared with normal blood cells. SFRP1 has previously been shown to show reduced expression in B-ALL and the qRT-PCR results showed that the PPARγ-1 transcript from the PPARG gene showed reduced expression in B-ALL cells, when compared with B-cells from normal blood as well as normal whole blood. Overall, it was concluded, on the basis of these results and others’, that SFRP1 and PPARG show reduced expression compared with normal blood cells, due to promoter methylation in B-ALL. It has also been suggested in the literature that glucocorticoid drugs (analogues to the steroid hormone cortisol) can alter the methylation of CpG sites in individual genes (in non B-ALL cells). This is of interest in the context of B-ALL, as glucocorticoids are well known to be strong anti-leukaemia agents and are used in B-ALL treatment. Glucocorticoids are also known to affect the expression of many genes, an effect that is compatible with changing the DNA methylation of cells. Therefore, this project also aimed to show that the glucocorticoid dexamethasone could induce changes in DNA methylation in many genes within the genomes of B-ALL cells. Multi-gene methylation was measured using the, relatively new, RRBS technique with the NALM-6 human B-ALL cell-line with or without exposure to dexamethasone acting as my model of B-ALL. The results showed a number of methylation changes throughout the genome, with some particularly strong methylation changes observed in the promoter regions of the genes SPINT2, GATA3, IRX5, SOX13, GATM, PDGFA and DOCK10; genes implicated in cancer or in steroid-sensitive metabolism (such as energy metabolism). These results suggest that steroids do indeed alter the DNA methylation of B-ALL cells, which, if these results are replicated, is a novel mode of action of glucocorticoids in B-ALL treatment.

    View record details
  • Pre-European Māori textiles from South Island New Zealand

    Smith, Catherine Ann (2014)

    Doctoral thesis
    University of Otago

    Hard copy available through interlibrary loan

    View record details
  • Delayed post-treatment of neonatal hypoxic-ischemic striatal injury with bone marrow-derived mesenchymal stem cells: An immunohistochemical/stereological and behavioural study

    Cameron, Stella Hope (2014)

    Masters thesis
    University of Otago

    Hypoxia/ischemia encephalopathy is a major contributor to the development of acute neonatal neurodevelopmental deficits, such as cerebral palsy (CP). One of the major sites afflicted by neonatal H/I injury is the striatum of the basal ganglia. Medium- spiny neurons (MSNs) comprise >97% of striatal neurons and play an important role in voluntary motor control. Damage to the striatum following neonatal H/I injury results in selective death of MSNs, and is correlated with the motor dysfunction that afflicts CP children. It is therefore clinically relevant to target the neuroprotection or neurorestoration of MSNs. Moderate hypothermia, a neuroprotective treatment that is currently used clinically, must be administered within 6 hours post-injury to be effective. A neurorestorative treatment that extends this window for therapeutic intervention would be highly beneficial. The neurorestorative potential of delayed treatment with bone marrow-derived mesenchymal stem cells (MSCs) was investigated in this thesis. Experimental procedures involved the exposure of postnatal day (PN) 7 male rats to H/I injury. Animals were then treated with a delayed subcutaneous high dose (HD, 7.70 x 105-1.43 x 106) of MSCs or diluent on PN14. Immunohistochemical/stereological and long-term behavioural studies were performed to determine if any effect was observed. This study first aimed to histologically confirm the findings of Alwakeel (2011) that demonstrated the restoration of the absolute number of striatal MSNs following a delayed HD MSC- treatment. A specific marker of MSNs, DARPP-32, was used. Secondly, this study investigated the neurogenic subventricular zone (SVZ) as the source of progenitor cells from which newly generated MSNs are derived. This involved double-immunolabelling with bromodeoxyuridine (BrdU), a progenitor cell marker, and DARPP-32. The Cavalieri and unfolding methods were used to stereologically quantify the absolute number of DARPP-32 and BrdU/DARPP-32-positive neurons within the striatum. MSC-treatment significantly increased the absolute number of DARPP-32-positive and BrdU/DARPP-32- positive striatal neurons. These results confirm the neurorestorative potential of MSCs. This study is the first to provide evidence of the SVZ as the neurogenic source of replacement striatal MSNs following delayed MSC-treatment of neonatal H/I injury. Behavioural testing investigated whether MSC-treatment was capable of long- term attenuation of motor function deficits resulting from neonatal hypoxia/ischemia. Repeated cylinder testing was performed on PN21, PN35, PN88-90, and PN162-164. Staircase testing and foot-fault testing were performed between PN61-86, and on PN103-105, respectively. Cylinder testing on PN35 and PN90, as well as staircase testing, demonstrated significant motor deficits of H/I diluent-treated animals compared to the uninjured control cohort. Significant motor deficits were not demonstrated between H/I MSC-treated and uninjured control cohorts. These results may be suggestive of motor improvement of MSC-treated animals. The foot-fault test did not demonstrate significant differences in motor performance between cohorts. The therapeutic potential of bone-marrow derived MSCs for the delayed treatment of neonatal hypoxia/ischemia is therefore supported by the findings of this study. The endogenous regenerative processes of the neonatal brain, through trophic enrichment provided by MSC-treatment, may be harnessed to drive the neurorestoration of MSNs. Further investigation should be actively pursued to ready MSCs for clinical use for the treatment of children with CP.

    View record details
  • The role of stargazin deficits in brain disorders

    Shevtsova, Olga (2014)

    Doctoral thesis
    University of Otago

    Glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are the major mediators of fast excitatory transmission in the mammalian central nervous system (CNS). Regulation of AMPAR trafficking into and out of synapses is important for synaptic transmission and synaptic plasticity. AMPARs are trafficked to the synapse by transmembrane AMPAR regulatory proteins (TARPs). TARPs are auxiliary AMPAR subunits, which play a crucial role in AMPAR synaptic trafficking, channel desensitisation and controlling agonist-binding activity. TARP γ2 (stargazin) is ablated in the brain of the stargazer mouse. Emerging evidence implicates abnormal expression of stargazin in numerous neurological disorders, including ataxia and absence epilepsy. This thesis investigates how a mutation in the CACNG2 gene, encoding the protein stargazin, affects normal brain function. In particular, this study explores how the loss of stargazin leads to ataxia and absence epilepsy. This study uses the spontaneous mutant mouse stargazer to investigate how stargazin deficits cause a loss of AMPARs at synapses. It had been previously shown in vitro that stargazin mutation leads to the loss of functional AMPARs in the cerebellum and thalamus of stargazer mouse. However, the mechanisms of AMPAR and TARP interplay at synapses in different brain regions are still unclear. The aim of this study was to investigate in situ at the ultrastructural level how the loss of stargazin affects the expression levels of synaptic proteins involved in signalling at synapses in the cerebellum and thalamus and therefore leads to the brain disorders of ataxia and absence epilepsy respectively in the stargazer mouse. The levels of AMPAR subunits GluA2/3 and GluA4 were evaluated by measuring the relative density of immunogold at the postsynaptic density in ultrathin sections in the cerebellum and thalamus from ataxic and epileptic stargazers compared to matched control littermates. It was found that there was a selective loss in the expression of GluA2/3 and GluA4 at parallel fibre (PF)-Purkinje cell (PC), climbing fibre-PC and PF-interneuron synapses in the cerebellar molecular layer (ML) of ataxic stargazers. In the thalamus of epileptic stargazers, the loss of stargazin leads to region and synapse specific changes in AMPAR expression. The levels of GluA2/3 and GluA4 were selectively decreased at corticothalamic (CT) synapses in the reticular thalamic nucleus (RTN) but not at CT synapses in the ventral posterior thalamic region in epileptic stargazers. Although, there was a loss of AMPAR expression at CT synapses in the RTN of stargazers, no significant changes were observed at thalamocortical synapses in the RTN region. In conclusion, the findings obtained in the present study demonstrated the selective loss of AMPARs at the ML cerebellar synapses, which could affect the cerebellar output to the deep cerebellar nuclei. This could contribute to the ataxic phenotype in stargazers. The selective regional and synapse specific loss of AMPARs in the thalamus of epileptic stargazers leads to disturbances within the cortico-thalamo-cortical circuit and generates spike-wave discharges within this circuit and the absence epilepsy phenotype. Understanding the cellular and molecular mechanisms underlying the impact of stargazin deficits on these brain disorders could contribute to future development of therapeutic strategies.  

    View record details
  • Vitellogenesis in the New Zealand cushion sea star Patiriella regularis

    Alqaisi, Khalid (2014)

    Doctoral thesis
    University of Otago

    Yolk protein is crucial in oviparous animals because it provides most of the nutrients for developing embryos. The yolk protein precursor in the majority of oviparous animals is vitellogenin (Vtg) which belongs to the large lipid transfer protein (LLTP) superfamily. In the phylum Echinodermata, a transferrin-like protein was identified as the yolk protein precursor in the classes Echinoidea and Holothuroidea and termed major yolk protein (MYP). In the class Asteroidea, a functional Vtg has been recently reported in Parvulastra exigua. However, it is still unknown whether Vtg is the major yolk protein in asteroids or if they have different forms of Vtg. Moreover, is it possible that asteroids synthesise MYP? Do sea stars synthesise vertebrate-like sex steroid hormones (VLSHs), such as estrogen, to control vitellogenesis? To answer these questions, the present study aimed mainly to determine yolk protein precursor transcript abundance and steroidogenic enzyme activity in the New Zealand cushion sea star Patiriella regularis. Furthermore, the present study aimed: i) to describe oocyte formation in P. regularis and categorise the stages of the reproductive cycle (Chapter 2); ii) to identify the yolk protein precursors (Chapter 3); iii) to examine yolk protein precursor mRNA levels and sites of synthesis during oogenesis and iv) to examine steroidogenic enzyme activity throughout the reproductive cycle. The reproductive cycle of female P. regularis was studied in Chapter 2 using histological analysis and organ index analysis of samples collected on a monthly basis. The annual reproductive cycle of P. regularis was divided into five stages: I) recovery stage, II) growing stage, III) mature stage, IV) partly spawned stage and V) spent stage. P. regularis spawned in the austral summer and oocyte growth occurred mainly between autumn and spring. Two distinct Vtgs (termed PrVtg1 and PrVtg2) that belong to the LLTP superfamily have been identified and sequenced in Chapter 3. In addition, a partial cDNA encoding MYP (termed PrMYP) was cloned and sequenced. Amino acid sequencing for the prominent proteins in ovulated eggs matched the deduced amino acid sequences of PrVtgs. These results provided the first evidence that at least two Vtgs correspond to yolk proteins in echinoderms. In addition, it is the first report for the expression of MYP in a sea star. Chapter 4 showed that the expression levels of PrVtg1 differed significantly during the reproductive cycle in both the pyloric caeca and ovary. PrVtg2 mRNA levels changed significantly in the pyloric caeca during the reproductive cycle while it was stable in the ovary. In situ hybridisation analysis showed that PrVtg transcripts were present in the digestive epithelium of the pyloric caeca. In the ovary, PrVtg1 transcripts were localised in the somatic cells rather than follicle cells, while PrVtg2 transcripts were identified in the follicle cells. These results provide evidence that somatic cells in sea star ovaries function in Vtg synthesis and that both the pyloric caeca and the ovary are the main vitellogenic organs in sea stars. Interestingly, PrMYP transcripts were identified in the growing oocyte, which contrasts with findings from other echinoderm species, such as sea urchins. In Chapter 5, pyloric caeca and ovary were incubated with pregnenolone (P5) and androstenedione (AD). Subsequently, the concentrations of pregnenolone (P4), androstenedione (AD), testosterone (T) and estradiol-17β were measured using liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry. Both organs converted P5 and AD into P4 and T respectively, but the concentration of P4 and T did not change significantly during the reproductive cycle. Analysis of transcriptome data from P. regularis ovary indicated that the transcripts encoding crucial steroidogenic proteins were absent. Thus, it is suggested that VLSHs do not control asteroid reproduction nor are they are synthesised for a particular physiological function. The present study provided novel results that advance the understanding of vitellogenesis in asteroids. In addition, the present study provided valuable knowledge that will advance the understanding of Vtg evolution in the phylum Echinodermata and the relationship between asteroid Vtgs with Vtgs from other animals.

    View record details
  • Functional analysis of the Orf virus ORF116 gene: a potential modulator of the interferon response

    AlDaif, Basheer (2014)

    Masters thesis
    University of Otago

    Orf virus (OV) is the type species of the Parapoxvirus genus. Like other poxviruses, genetic and functional studies have revealed that it has immunomodulatory genes that manipulate the innate immune response, often during the early stage of infection. The main focus of this study was to find the possible function of a novel gene in OV, ORF116, in strain NZ2 using a microarray approach. The ORF116 gene is 696 nts encoding a predicted polypeptide of 231 aa. Northern blotting analysis and reverse transcription-PCR have shown that ORF116 was expressed early. Northern blotting revealed a transcript of 2.1 kb detected in OV-NZ2 infected cells which could be detected as early as 2 h.p.i. by RT-PCR. The deletion of the ORF116 gene, showed that the virus replicated in primary lamb testis (LT) cells and HeLa cells, indicating that this gene is non-essential in cell culture, although viral growth was reduced in both cell types. Moreover, the deletion mutant produced smaller plaques on LT cells and induced a slower cytopathic effect in HeLa cells. Microarray expression profiling in HeLa-infected cells was conducted to identify genes whose expression altered with the presence of ORF116 and also to analyze the global change in gene expression induced by OV-NZ2 or OV-NZ2Δ116 at early times post-infection. Major findings showed that 3000 and 2200 transcripts were altered in their expression in OV-NZ2- and OV-NZ2Δ116-infected HeLa cells at 6 h.p.i. compared with the mock infection control. Furthermore, two genes IL-6 and IFI16 showed a similar expression pattern of up-regulation and down-regulation respectively relative to mock infection. The analysis of differential cellular gene expression has shown 68 genes differentially expressed at either 4 or 6 h.p.i. Of all of the genes that were analyzed by microarray, IFI44 showed the greatest differential expression between wild type and knockout virus. IFI44 expression was 4.17-fold higher in the knockout compared with the wild type at 4 h.p.i. It was also found that other interferon-stimulated genes were up-regulated to higher levels in the knockout which included RIG-I, MDA5, IFIT2, IFIT1, OAS1, OASL and ISG20. The differential expression of these genes was validated by qRT-PCR which suggests that ORF116 has a role in subverting the interferon (IFN) effector response. This study represents the first functional analysis of ORF116 gene encoded by a parapoxvirus.

    View record details
  • A web-based dietary assessment method for exploring iron bioavailability: developing a food list and pretesting

    Hussein, Areege Hassan (2014)

    Masters thesis
    University of Otago

    Iron deficiency is the most common nutrient disorder worldwide. To assess intake in a population, food frequency questionnaires (FFQs) are commonly used as a low-burden, cost-effective method of dietary assessment. However, most FFQs measure intake by day, and do not account for nutrient or food component interactions when eaten as a meal. This is important for non-haem iron which has absorption modifiers (e.g., vitamin C and phytate) that affect its bioavailability. The Web-Meal-Based Intake Assessment Tool (Web-MBIAT) assesses iron intake by meal, potentially allowing for these interactions to be taken into account. The first aim of this study was to generate a food list for the Web-MBIAT program that estimates the intake of iron and its absorption modifiers in premenopausal adult women (aged 19-50y) living in New Zealand. The second aim was to assess the usability of the Web-MBIAT program from the perspective of the interviewer. FOODfiles 2010 version 2.0 and literature on the phytate content of foods were used to generate two food lists. Cut-offs were set using the literature or observing a natural break in the nutrient content of foods in FOODfiles. Cut-offs for the ‘main’ food list were: iron (≥2mg/100g); vitamin C (≥7mg /100g, except ≥10mg/100g for non-alcoholic beverages); meat, fish and poultry (≥30g/100g); and phytate (≥50mg/100g). The Adult Nutrition Survey 2008/09 was used to identify food groups that contributed ≥4% to iron and ≥10% to vitamin C intake in the target population. Reasons for exclusion such as ‘similar item already in food list’, were developed to limit the food list length. Cut-offs for the ‘short’ food list were: iron (≥8mg/100g), vitamin C (≥80mg /100g) and phytate (≥750mg /100g). Staff (who were Dietitians or Nutritionists) and graduate students were recruited by email from the Department of Human Nutrition, University of Otago, as interviewers to pretest the Web-MBIAT and user’s manual. Interviewers conducted the FFQ with a standardized diet and were timed. Interviewers’ characteristics and audio recordings of their feedback were gathered, and a list of issues and suggestions were categorized for analysis. The main iron food list contained 420 items, (16% of the total number of foods in FOODfiles). The most common reason for inclusion and was meeting a specific food component cut-off (97% of inclusions). The most common reason for exclusion was a ‘similar food item already in food list’ (47% of exclusions). The short food list contained 24 items. A total of 10 interviewers were recruited. In pretesting, most interviewers were positive about the Web-MBIAT program and user’s manual. However, the main issues identified by both groups concerned the Web-MBIAT’s ‘logic and navigation’ — particularly searching food items — and the lack of colour in the user’s manual. Proposed modifications include removing case-sensitive searching of food items, assessing supplement use, and having more prompts to guide the interviewer. The next step is to modify and validate the Web-MBIAT (against weighed diet records), before future use.

    View record details
  • Cultural Competence Training for Health Researchers

    Dawson, Anna Margaret (2013)

    Masters thesis
    University of Otago

    The purpose of this thesis is to investigate, within an Aotearoa/New Zealand context, the need for, approach to and effectiveness of cultural competence training for health researchers. Although there have been programmes in cultural competence training for New Zealand health professionals, often with a focus on cultural competence when working with Māori, there has been less focus on cultural competence training for health researchers. In recent times cultural competency has been implemented mainly in health settings and associated with provider-patient interaction. However, there is a growing appreciation that health researchers should also demonstrate cultural competency. In New Zealand particular emphasis is placed on responsiveness to Māori in research and cultural competence in relation to Māori is fore-grounded in this thesis. This thesis has three aims: (i) To review recognised cultural competency frameworks (ii) Develop a cultural competence training intervention within a health research group setting (iii) To implement a cultural competence training intervention for a health research group and evaluate the process and effectiveness of this cultural competence training intervention including determining key concepts and content required for researchers to become cultural competent. Using an action research methodology and informed by theoretical frameworks in this field, an intervention was developed with the Cancer Society Social and Behavioural Research Unit, SBRU (University of Otago, Dunedin, New Zealand). The intervention consisted of three wānaka, held at Te Kura Kaupapa Māori o Ōtepoti. Each wānaka focused on a particular element of cultural competency; (i) Cultural Awareness or Identity, (ii) Cultural Knowledge and (iii) Cultural Action. Prior to each wānaka participants attended three one hour workshops and were further supported by an electronic newsletter, supported readings, cultural teachings, group discussions and opportunities to practise mihi mihi (introduction) and waiata (songs). Prior to the intervention, participants provided information about their experience working with Māori and other cultures, experience of different aspects of te ao Māori (e.g. pōwhiri, noho) and their expectations and desires about what could be included in the intervention. After the intervention participants completed a questionnaire (and a follow-up interview if desired) which inquired as to whether the intervention had improved their ability to further the SBRU strategic objectives in relation to Māori research and suggestions for future initiatives, included generalisability, barriers and key concepts. There were eight participants in this study. Findings suggest that progress was made on each of three strategic goals identified by the SBRU, these included increased understanding of the Treaty of Waitangi and its relevance to research and society, practical experience in te reo Māori, pōwhiri and mihi and insights into meaningful Māori consultation, partnerships and relationships. In conclusion, if research is to contribute to reducing health inequities there is a need for cultural competence to ensure research practices are responsive to Māori. This study shows that a tailored intervention can be successful in cultural competence among health researchers and identifies key elements which would be useful for future initiatives.

    View record details
  • Is Baby-led Weaning a feasible method for introducing complementary foods to infants in New Zealand?

    Cameron, Sonya Lynne (2014)

    Doctoral thesis
    University of Otago

    Baby-led Weaning (BLW) is an alternative method for introducing complementary foods to infants in which the infant feeds themselves hand-held foods instead of being spoon-fed by an adult. Anecdotal evidence suggests that many parents in New Zealand and elsewhere are choosing this method instead of conventional spoon-feeding. The aim of this thesis was to determine the feasibility of BLW as an alternative approach to introducing complementary food. To address this overall aim, five Aspects of Feasibility are investigated in this thesis, namely 1) What is the likelihood of parents meeting the prerequisites of BLW (i.e., exclusive breastfeeding to 6 months and introducing complementary food at 6 months)? 2) How acceptable is BLW to parents and healthcare professionals? 3) What are the current practices of those following a ‘BLW approach’? 4) What are the potential risks and benefits of BLW? 5) If there are risks, can these be addressed or minimised in a satisfactory way? The first two Chapters of this thesis examine whether support from a lactation consultant increased the number of women who were able to exclusively breastfeed until 180 days (the WHO recommendation) and subsequently delay the introduction of complementary food. Of the 803 mothers from the Prevention of Overweight in Infancy (POI) randomised controlled trial, 8.1% exclusively breastfed to 6 months and 12.6% introduced complementary foods at 6 months. There were no differences in the rates of exclusive breastfeeding or complementary feeding between the intervention and control groups at 180 days (6 months), but more women in the intervention groups delayed the introduction of complementary food until after 5 months. Mothers who smoked or had a higher BMI were less likely to exclusively breastfeed to 6 months, whereas there was a positive association with maternal infant feeding attitude. Being older and having a supportive partner both increased the odds of delaying solids until 6 months whereas there was a negative association with alcohol consumption during pregnancy. Phase two of this thesis focused on BLW in New Zealand. Interviews with 31 healthcare professionals showed that they had major concerns about BLW, principally to do with potential choking, iron deficiency, and inadequate energy intake. By contrast, 20 mothers who had used BLW successfully considered it to be a healthier and more convenient way to introduce complementary foods. However, choking was reported by six of these mothers – most commonly with raw apple. A nationwide survey was used to describe complementary feeding practices in New Zealand. Although 29% of parents consider themselves to be following BLW, very few (8%) were doing so strictly. However, the extent to which BLW was followed impacted on its potential benefits (e.g., sharing family meals) and risks (e.g. low-iron first foods). A modified version of BLW (Baby-Led Introduction to SolidS (BLISS)) was developed to address concerns around choking, and low energy and iron intakes. A 12-week pilot study in 23 participants showed that, compared to BLW, BLISS reduced offering of high-risk choking foods, and increased high-iron foods. Collectively these results suggest that although BLW may be advantageous for certain families, it may not be feasible for a large proportion of the population. Many questions regarding BLW still need to be addressed, specifically its safety and nutrient sufficiency, along with proposed benefits as reported by parents.

    View record details
  • 'With Friends Like These…': The Social Contagion of Non-Suicidal Self-Injury Amongst Adolescent Females

    Hermansson-Webb, Eve Bridget (2014)

    Doctoral thesis
    University of Otago

    Research on the psychology of adolescent self-injury is relatively nascent. For some time, self-injury has predominantly been considered a behaviour pathognomonic of borderline personality disorder and, to a somewhat lesser extent, of psychosis or intellectual disability (Hayward, 2007). However, recent empirical research has suggested that self-injury – particularly that of a superficial nature, or causing “mild to moderate tissue damage” (Skegg, 2005, p. 2) – is a behaviour present to a significant degree in nonclinical populations, most notably amongst adolescents (e.g., Muehlenkamp, Williams, Gutierrez, & Claes, 2009). Indeed, amongst this demographic, the behaviour has been described as occurring at a rate of ‘epidemic’ proportions (Miller & Smith, 2008), with females being the most likely to self-injure (e.g., 64% of adolescents who self-injure; Ross & Heath, 2002). Understandably, many parents, teachers, school counsellors, and other health professionals have expressed deep concerns over the trend of non-suicidal self-injury (NSSI). The reasons for the “swift proliferation” (D'Onofrio, 2007, p. 6) of NSSI are, as yet, undetermined; however, one prominent theory is that of social contagion, which states that emotions, attitudes and behaviours are communicable across members of a social network. The overall aim of the studies presented in this thesis was the investigation of social contagion theory as it pertained to the NSSI attitudes and behaviours of NZ adolescent females. There were two primary objectives. The first objective was to establish an independent but informed perspective, using reports obtained from school counsellors, on the prevalence of female adolescent NSSI behaviour in NZ secondary schools, its evident pattern amongst friendship groups, and beliefs held by counsellors about the reasons for and likely communicability of such behaviours. The second objective was to investigate whether a social contagion effect was discernible in the NSSI attitudes and NSSI behaviours of NZ adolescent female students, based on direct empirical evidence. Attitude-related variables investigated included positive endorsement of NSSI and beliefs about reasons for engaging in the behaviour. Sub-elements of this second objective were as follows: i) to investigate whether a social contagion effect was discernible in the depressive symptomatology present amongst the same population, given that such pathology is commonly co-morbid with NSSI and is also considered to be transmissible via social contagion; and, in an effort to transcend the confound between peer selection and socialisation effects (a limitation present in much of the extant research on the social contagion of various behaviours), ii) to trial a longitudinal social network methodological design, towards identifying its potential value in differentiating said effects in NSSI research. The research involved three distinct studies. In Study 1, an online self-report questionnaire was administered to NZ secondary school guidance counsellors to ascertain the estimated prevalence rate of NSSI by adolescent females, the nature of NSSI encountered, its pattern amongst friendship groups, and counsellors’ beliefs about NSSI. Results indicated that NSSI is indeed a pervasive problem within NZ secondary schools, similar to schools internationally, and that there was sufficient report of NSSI occurring within friendship cliques to warrant further, more direct research into the phenomenon of peer contagion. In Study 2, adolescent girls from two NZ secondary schools were asked about their NSSI attitudes, behaviours, depressive symptoms, and friendship constellations. Friendship cliques and dyads were identified by way of social network analyses. Comparisons within identified friendship cliques showed that girls’ depressive symptoms and NSSI attitudes significantly corresponded with those of their clique and dyad friends, and that being in a clique seemed to be a protective factor for depression and for pathological attitudes towards NSSI. Hierarchical regression analyses showed a significant effect of peer-related variables when predicting individual depression and NSSI attitude scores after personal variables had been taken into account, offering preliminary support for contagion theory. However, the selection versus socialisation confound remained. With a view to potentially addressing this confound, Study 3 involved a longitudinal approach whereby the original questionnaire was re-administered six months later to a subset of girls from one of the schools who had completed the questionnaire in Study 2. This constituted a trial-run of a methodological design involving both longitudinal and social network analyses for the purpose of identifying the potential strengths and weaknesses of using such an approach to differentiate selection from socialisation effects. Results showed no evidence for socialisation effects in the depression scores or NSSI attitudes of adolescent females; however, this may have been due to certain extraneous factors. On the whole, the methodological design has clear potential for differentiating selection from socialisation effects in NSSI research. The overall finding of the thesis, and the distinct contribution to knowledge, was that NSSI attitudes and depressive symptomatology are homophilous within friendship cliques and dyads, and that the use of a longitudinal social network design has potential for differentiating selection from socialisation effects in future research investigating the social contagion of depression and NSSI attitudes and behaviour. It is hoped that further empirical research might combine similar methodology with greater longitudinal time separation and a broader sample group to provide incontrovertible empirical evidence to support a contagion theory of NSSI.

    View record details
  • Modeled Insulin Sensitivity and Interstitial Insulin Action from a Pilot Study of Dynamic Insulin Sensitivity Tests

    Lin, J.; Jamaludin, U.; Docherty, P.D.; Razak, N.N.; Le Compte, A.J.; Pretty, C.G.; Hann, C.E.; Shaw, G.M.; Chase, J.G. (2010)


    University of Canterbury Library

    An accurate test for insulin resistance can delay or prevent the development of Type 2 diabetes and its complications. The current gold standard test, CLAMP, is too labor intensive to be used in general practice. A recently developed dynamic insulin sensitivity test, DIST, uses a glucose-insulin-C-peptide model to calculate model-based insulin sensitivity, SI. Preliminary results show good correlation to CLAMP. However both CLAMP and DIST ignore saturation in insulin-mediated glucose removal. This study uses the data from 17 patients who underwent multiple DISTs to investigate interstitial insulin action and its influence on modeled insulin sensitivity. The critical parameters influencing interstitial insulin action are saturation in insulin receptor binding, αG, and plasma-interstitial difiusion rate, nI . Very low values of αG and very low values of nI produced the most intra-patient variability in SI. Repeatability in SI is enhanced with modeled insulin receptor saturation. Future parameter study on subjects with varying degree of insulin resistance may provide a better understanding of different contributing factors of insulin resistance.

    View record details