13,050 results for Doctoral

  • The Ubiquitous Decline or Paradox of Aging: Young and Older Adults' Differences in Emotion Reactivity, Recognition and Regulation

    Lim, Bee Teng (2011)

    Doctoral thesis
    University of Otago

    The aging literature indicates that physical, cognitive and affective functions follow different trajectories across the lifespan. Physical and cognitive capabilities are shown to decline with advancing age, whereas affective functioning is suggested to remain stable or may even be enhanced in older adults. The main aim of the present thesis is to examine age differences in emotion reactivity, recognition and regulation. The inter-relationships among emotion reactivity, recognition and regulation were also assessed to provide a more complete picture of potentially different age trajectories of emotion processes. In addition, the effects of potential moderators, namely emotion intelligence and loneliness, on age differences in emotion reactivity were examined. In Study I, a standardised set of film stimuli was developed and validated. Forty-eight participants (24 young and 24 older adults) participated in the stimulus validation study. The chosen film stimuli were shown to be effective in eliciting target emotions in a laboratory setting. No significant age and sex differences were observed, and prior viewing of the film was shown to have no significant impact on participants’ self-reported emotion experience. In Study II, young-old differences in emotion reactivity, recognition and regulation as well as the inter-relationships among these affective functions were of interest. In addition, age-related decline in heart rates and skin conductance levels in response to affective film stimuli were observed. Older adults were significantly worse at recognising facial expressions of sadness and anger, and marginally worse at recognising facial expressions of fear. Older adults reported more habitual use of expressive suppression than their younger counterparts, while no age difference was found for cognitive reappraisal use. Emotion intelligence did not buffer against age-related decline in emotion reactivity. Finally, in Study III, I aimed to replicate the findings of Study II, as well as extend Study II by including facial electromyography as another index of emotion reactivity. I also employed emotion recognition tasks that are more complex and tap into other sensory modalities. Again, age-related decline in heart rates and skin conductance was observed. Young adults displayed significantly greater corrugator activity in response to fear-provoking film clips, but no significant age difference was found for corrugator activity in response to the anger and sadness-provoking film clips. Young and older adults also displayed comparable level of zygomatic facial activity when presented with the amusing film clip. Older adults were worse at recognising angry and fearful facial affect. As for the face-voice and body-voice matching tasks, older adults were worse at recognising all emotions except for surprise. Older adults also reported more habitual use of expressive suppression, and that was shown to affect emotion recognition performance. Taken together, these studies indicate that different components of affective functions are differentially affected by normal adult aging. Implications for competing perspectives of socioemotional functioning in older adults as well as suggestions for positive aging are provided.

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  • Carbon Monoxide and Hypothermic Pulsatile Perfusion in Renal Transplantation

    Winburn, Ian (2011)

    Doctoral thesis
    University of Otago

    Chronic kidney disease is a highly prevalent condition and renal transplantation is the definitive treatment for those with end stage renal failure. This life saving treatment is unfortunately hindered by a shortage of donor organs. In an attempt to boost the donor pool, the use of kidneys from Non Heart Beating Donors has become increasingly common, with Hypothermic Pulsatile Perfusion (HPP) of the donor kidney being employed in an attempt to improve outcomes from these extended criteria donor kidneys. HPP provides a theoretical opportunity for the pharmaco-modulation of donor kidneys ex vivo providing a “therapeutic window” whereby bioactives may be added to perfusates with the goal of maximising post transplantation outcomes. A candidate molecule is carbon monoxide (CO) that has been demonstrated to be vasodilatory and anti-apoptotic. However, little is known about the vascular function of kidneys during hypothermia and accordingly no data exist as to the effect that the administration of CO during HPP to donor kidneys has upon post transplant outcomes. Using an ex vivo isolated perfused rat kidney model this thesis provides robust data regarding renal vascular function during hypothermia; demonstrating that vasomotor responses to constrictors and dilators are preserved in addition to providing confirmation that autoregulation is present during HPP. In addition, the potential toxicity of CO to renal tubule cells (administered as carbon monoxide releasing molecule-2 (CORM-2) or CO gas) is investigated. Results demonstrate that despite protecting against apoptosis, CORM-2 is toxic to renal tubule cells independent of its solvent and most likely secondary to its ruthenium based parent molecule. As a consequence of these novel findings, CO gas was used in subsequent experiments that investigated the impact that CO administration during HPP has on outcomes following transplant Ischemia-Reperfusion Injury (IRI). Using a clinically applicable rat model of transplant IRI, it is demonstrated that persuflation of HPP solution with 0.001% CO gas provided protection against transplant IRI secondary to the anti-apoptotic and vaso-active properties of CO. Renal tubule damage and parenchymal oedema were diminished following CO treatment. Autoregulation was found to be absent in kidneys that had been subjected to the IRI protocol and CO administration did not improve this. The absence of any significant impact on mitochondrial energetics following CO administration in conjunction with an absence of increased ROS generation suggests CO is not toxic at the level of the cellular respiratory chain. Furthermore the impact that CO administration has appears to be independent of endogenous heme oxygenase-1 activity. In summary the results of the experiments detailed in this thesis support the hypothesis that the ex vivo application of CO gas during HPP provides protection against transplant IRI. These data provides the first step in a “bench to bedside” approach supporting the use of CO gas during HPP to minimise the deleterious impact of IRI. The current study offers a “proof of concept” providing a sound scientific basis for further research designed to investigate the impact CO administration (during HPP) has on clinical transplant outcomes in an in vivo large animal model.

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  • Messenger RNA Data Mining

    Pollock, Robert (2011)

    Doctoral thesis
    University of Otago

    Messenger RNA (mRNA) is the molecular intermediary carrying genetic information from the nucleus to the cytoplasm. All the information about cellular localisation, efficiency of translation and message stability must be found within the sequence of the mRNA molecule. Very little is known about the sequence elements that must direct many of these processes. De novo computational methods have been extremely useful in characterising the molecular determinants of function at the protein level. Similarly much has been learned about the functional elements at or near transcription start sites (TSSs). Computational methods have not yet been as successful in finding elements within the messenger RNA sequence. There is much evidence to suggest such elements exist. Conservation in genomic sequence corresponding to the mRNA 30 untranslated region (3'UTR) is greater than it is in the intergenic region. In addition there are a large number of proteins in the eukaryotic cell that contain RNA binding domains. In this study, predicted 3'UTR regions for all genes from the budding yeast Saccharomyces cerevisiae were extracted from the downstream region of each gene. Yeast makes a powerful platform for this purpose because of the vast repository of functional data available for cross checking results, and thereby validating methodology. In this work, the 3'UTR sequences of yeast were interrogated using computational methodology to find statistically significant patterns within the sequences. Such patterns (or sequence motifs) can be over-represented words—either contiguous words or regular expressions—or collections of locally aligned sequences (typically expressed as matrices of positional letter counts). Two methods were chosen here: the first, MEME, searches for statistically significant local alignments. The second, TEIRESIAS, enumerates words (allowing for wildcard letters) present in the sequence database, subject to certain constraints. The goal of this project was to find significant words using as naïve and unsupervised an approach as is possible, utilising little or no functional data upstream of the analysis. Through doing this, it was possible to illustrate the power of computational methodology to decipher the molecular details of cellular control, with little or no additional information. This approach represents a significant challenge for computational biology tools. The sequence dataset was searched for elements under two scenarios: the first, completely unsupervised (using all of the sequence data), and the second partly supervised. The partly supervised approach utilised mRNA halflife values were obtained from a genome-wide study of mRNA stability to bin the sequences before conducting the search. This study examines the performance of both MEME and TEIRESIAS when applied to these difficult problems, and considers ways of improving the sensitivity of the analysis (to find the maximum number of motifs). The effect of repetitive and duplicated sequences, and appropriate parameters for searching, on the output of TEIRESIAS is examined. Secondly a methodology for converting text-pattern motifs (from TEIRESIAS) into alignments that can be compared with MEME results, is developed. The partially supervised approach was conducted using MEME. MEME was not able to find many motifs when executed with default parameters, typically finding only low complexity elements, duplicated sequences, and alignments of only 2-3 sequences. After a concerted effort was made to optimize MEME, which is documented here, some 18,000 statistically significant alignments were found. After filtering and testing of the motifs, 3311 motifs comprising 1324 motif clusters were found to be associated with stability. Using the fully unsupervised approach, MEME was also able to find a large number of motifs, though (notably) slightly fewer than were found using the partially supervised approach. TEIRESIAS was also able to find many statistically significant patterns using the unsupervised method. The large number of motifs found during this analysis were tested for likely biological validity in several ways: by testing whether or not motif-containing sequences were biased towards stable or unstable sequences; by testing whether or not motif-containing sequences were enriched in functional and localisation classes of genes (Gene Ontology) and by testing for motif enrichment in the target mRNAs associated with known RNA binding proteins. These approaches confirmed that the motifs found were likely to have biological significance and leads to their consideration as candidates for likely components of functional elements.

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  • Brain and Behaviour in an Animal Model of Schizophrenia

    Wolff, Amy R (2011)

    Doctoral thesis
    University of Otago

    Schizophrenia is a chronic neurological disorder that causes significant impairment for ~1% of the population. Epidemiological studies have suggested that there is a link between prenatal exposure to infection and the development of schizophrenia in the progeny. In particular, maternal immune activation (MIA) in response to infection is thought to alter neurodevelopment so as to increase the risk of schizophrenia. The MIA animal model provides a useful platform to examine this link, as it separates the effects of infectious factors from immune activation. Here, the effects of MIA in the rat are characterized, with a particular focus on memory function and contextual processing, as these have been proposed to be core features of the cognitive symptoms of the disease. The contributions of the hippocampus to cognitive impairment in schizophrenia are also explored. MIA was induced in pregnant rat dams on gestational day 15 with a single injection of the synthetic cytokine inducer poly I:C. Open-field exploration and pre-pulse inhibition (PPI) were assessed in juvenile (35 day) and adult (> 3 month) offspring. Discrimination and reversal learning, memory function and contextual processing were assessed in adult animals. A separate group of adult animals were implanted with electrodes in the dorsal hippocampus for an in vivo examination of hippocampal place cell activity. MIA offspring were shown to display impaired PPI during testing conducted in adolescence and in adulthood. The MIA animals were also found to display abnormally rapid reversal learning of a position discrimination. MIA also resulted in memory impairment, with MIA animals displaying significantly reduced preferences for the novel object during recognition testing, and an increased memory for the reversed platform position in the Morris water maze task. MIA offspring also displayed evidence of impaired contextual processing, showing a reduced and less persistent reinstatement of rearing after a change in environmental context. The in vivo examination of hippocampal place cell activity indicated that cells in MIA offspring display a more spatially selective representation of 'place' than control cells. MIA animals were also less likely to shut down or turn on their spatial firing in one of the environmental contexts, indicative of reduced context specificity. Here it is demonstrated that MIA in the rat produces behaviours that are similar to the positive and cognitive symptoms seen in patients with schizophrenia. We have demonstrated for the first time that MIA results in a similar disruption of sensorimotor-gating and non-spatial memory in the adult rat, as has previously been reported for mice. Interestingly, we found that PPI impairments in the rat do not display the same post-pubertal pattern of emergence that is seen after MIA in the mouse. We have also shown for the first time that MIA is associated with impaired contextual processing, a disruption that is thought to be a core underlying deficit in schizophrenia. The examination of hippocampal place cell activity also suggested a reduced sensitivity to contextual information in the MIA animals. These results suggest reduced context-specificity of hippocampal representations may be a factor underlying contextual processing impairments in schizophrenia.

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  • Representing Romance at the Movies: Passionate Love and Film Genre

    Todd, Erica Roanna Morag Hawthorne (2011)

    Doctoral thesis
    University of Otago

    This thesis analyses the way love is presented as the central storyline in cinema drawing upon genre studies and informed by sociology. It ultimately finds that there are two dominant Hollywood love stories: the first is the romantic comedy, which film scholars have explored extensively; the second stands in opposition and focuses on passion. No scholarly investigation currently exists of the latter type of love story as a group, as having generic consistencies, a gap this thesis seeks to remedy. Though this project primarily explores the passionate love story as a cinematic form, it also contributes, through comparison, to the research on romantic comedy, which foregrounds another type of love: companionate love. These two love stories offer different alternatives to their audiences. As such, this project has implications beyond cinema studies and seeks to add to our understanding of intimate partnerships as one of the primary mechanisms of socialisation. The research comprises seven chapters. Chapter one explores cultural assumptions, definitions and depictions of love. Through this analysis, two notable, distinct types of intimate relationships between men and women emerge: companionate love and passionate love. Chapter two takes the approach of genre studies, which seeks to find recurrent patterns in stories, in order to understand how these two definitions of love inflect cinematic stories about love. This examination finds that the majority of existing scholarship focuses on a single dominant genre dealing with love: the romantic comedy, which centres on the problems of representing companionate love. As no study has concentrated on films that foreground passionate love, this research isolates the possible traits that would allow these films to be classified as part of a film genre. The following chapters look closely at three Hollywood and one non-Hollywood passionate love stories to ascertain their features: chapter three at Casablanca (Michael Curtiz: 1942); chapter four at Titanic (James Cameron: 1997) and The Notebook (Nick Cassavetes: 2004); and chapter five at Pépé le Moko (Julien Duvivier: 1937). Chapter six takes the conclusions of these textual analyses and finds that there is a group of films that share similar traits, which make up a genre that could be called “romantic drama”. Though love is central to both genres, the romantic drama can be defined against the romantic comedy. Genres are considered to be audience driven, thus chapter seven looks at responses from two small groups of filmgoers. Participants in an online survey were able to recognise cinematic love stories and distinguish between romantic comedies and romantic dramas. In conclusion, this research argues that many cinematic representations of passionate love can be grouped as a genre. It speculates that in a period where there has been a renaissance of research on romantic comedies, passionate love stories have been neglected because they do not make up an immediately clear genre and are often hybrids. Furthermore, the companionate love model offers a portrayal of courtship that speaks to contemporary society in contrast with the idealistic passionate love model, which is associated with adolescence and irrationality

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  • Understanding Conversion Disorder: Electrophysiological and behavioural evidence for impaired neuromotor preparation and movement execution

    Scott, Rebekah Laura (2011)

    Doctoral thesis
    University of Otago

    Conversion Disorder, originally hysteria, affects the voluntary motor system by disrupting the production of normal volitional movement and is characterised by unexplained neurological symptoms without an organic cause; unlike Malingering, where symptoms are intentionally produced or feigned (American Psychiatric Association, 1994). This thesis contains two studies. Study 1 examined two competing hypotheses, that disruption of either motor preparation or execution underlies the movement deficits associated with Conversion Disorder. The effect of movement-related uncertainty on motor preparation and execution was also determined using a precued reaction time (RT) paradigm in which participants made rapid finger flexions to an imperative visual stimulus. A precue provided complete (simple RT) or partial (2-choice RT) information about the response hand (left or right) and/or finger (index or middle). Electroencephalographic, electromyographic and kinematic measures were recorded during motor preparation and execution. In Study 1, movement performance of six individuals with upper limb unilateral conversion paresis was compared to twelve neurologically normal participants. Results indicated that Conversion Disorder patients initiated and executed movement more slowly and generated less force with their affected hand, and were slower overall than controls. Contingent negative variation (CNV) amplitudes were considerably smaller for affected hand responses, indicating impaired preparatory processes, particularly when patients knew in advance they had to prepare to move with their affected hand. Study 2 examined whether feigned paresis demonstrated behavioural and brain activity outcomes similar to conversion paresis. Two groups of twelve neurologically normal individuals were instructed to imagine they had difficulty moving their left upper limb under one of two instruction methods: “Imaginary resistance” or “diminished effort”. The effect of these instructions on motor preparation and execution were investigated using the same methods as in Study 1. The results of Study 2 indicated that participants instructed to feign paresis also initiated and executed movement more slowly and generated less force with their affected hand. CNV amplitudes were not affected by feigning. The nature of the feigning instruction had no effect on motor preparation or execution. Consistent with an integrated model of Conversion Disorder, both the preparation and execution phases of voluntary movement were significantly impaired in conversion and feigned paresis. Conversion paresis appears difficult to dissociate from feigned paresis when examining the behavioural and muscle activity data from the affected hand. However, differences in CNV amplitude between patients and feigning participants demonstrated changes in brain function during movement preparation that is specific to Conversion Disorder. This novel finding supports the use of motor event-related potentials as an additional approach to examine unexplained neurological motor symptoms. The experiments reported in this thesis provide new knowledge about the temporal organisation of brain function, muscle activity and behaviour underlying conversion and feigned symptoms. Future studies could build on these efforts by explaining in greater detail the functional mechanisms acting within motor areas of the brain that disrupt normal motor preparation and execution in Conversion Disorder. Whether the deficits in neuromotor preparation in Conversion Disorder are due to a prefrontal inhibitory mechanism or deficits in volition remain to be determined.

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  • Thinking across the Bible: Consonance and Dissonance in Early Modern English Biblical Verse

    Cop, Michael Andrew (2011)

    Doctoral thesis
    University of Otago

    Early modern English biblical verse at times seems clumsy or repetitious. This thesis argues that some of this poetic and narrative dissonance originates in the biblical events that poets and versifiers turned into verse. The Bible often reports events differently across its books. Such differing narrative strands are often dissonant: they do not report one unified, harmonious story. Early modern readers habitually thought across differing biblical narrative strands because biblical commentary, gospel harmonies, and the margins of the Bible itself encouraged their readers to do so; those same readers also believed that the differing narrative strands tell a harmonious story because they believed that the words of the Bible are consistent. Modern readers often do not share that same habit or belief. If we are to have informed readings of early modern biblical verse, we need to recapture the habit of thinking across the Bible and the belief that beneath the apparent biblical dissonance was an underlying consonance. My research indicates that when the Bible has conflicting details for an event, poets and versifiers sometimes include that conflict in their verse and thereby inherit biblical dissonance. The introduction exhibits the habit of thinking across the Bible in prose through the examples of biblical marginalia and commentaries as well as through the fullest textual representation of this habit, gospel harmonies. The subsequent chapters examine biblical verse, each exploring a story for which the relationship between biblical narrative strands becomes increasingly complex. Chapter 1 establishes what it means to versify the Bible by taking some metrical psalms and then versions of the Samson story as examples of poets and versifiers working on parts of the Bible for which there is only a single narrative strand but which still contain inconsistencies. Chapter 2 addresses versions of the Creation, a story for which there are two differing biblical narrative strands. The chapter classifies four methods of engaging biblical difference in verse through the examples of William Hunnis’s A Hyve Fvll of Hunnye, Joshua Sylvester’s translation of Guillaume de Saluste Du Bartas’s The Divine Weeks, John Milton’s Paradise Lost, and John Dryden’s The State of Innocence. Chapter 3 looks at the temptations of Jesus, a story for which there are three differing biblical narrative strands; it demonstrates specific rhetorical strategies for including biblical differences in verse through the examples of John Bale’s, Giles Fletcher’s, Henry Vaughan’s, John Milton’s, and Samuel Wesley’s versions of the temptation story. Chapter 4 explores the story of the anointing of Jesus, a story for which the relationship amongst the four differing narrative strands is ambiguous, and demonstrates that the more complex the relationship is amongst differing strands, the less likely versions are to incorporate the all of the differences from amongst those strands. The thesis concludes with a new reading of George Herbert’s “The Sacrifice,” a poem whose conclusion only reaches full potency when its readers think across the four differing narrative strands for the Passion.

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  • Paleomagnetic records of the last two million years of climate and oceanographic change in the New Zealand sector of the South Pacific

    Nelson, Faye Elizabeth (2011)

    Doctoral thesis
    University of Otago

    A high standing oceanic island in the mid-latitudes of the South Pacific, New Zealand is well situated to record far-field effects of global climate change. A 1.8 Ma paleomagnetic and environmental magnetic record from the Challenger Plateau, Tasman Sea, is presented here. Continuous sub-samples (u-channels) were collected from three long (up to ~40 m) giant piston cores (MD06-2987, -2988 and -2989), as well as shorter cores (TAN0712-14, -15, -17, -23, -27), within the global westerly system in front of New Zealand's Southern Alps. Magnetic grain size in the cores was determined from anhysteretic remanent magnetism (κARM) and volume magnetic susceptibility measured on u-channel samples using a pass-through cryogenic magnetometer with an in-line Bartington MS2C susceptibility bridge and solenoid in a shielded room (150 nT). Magnetic mineralogy was investigated using temperature-dependent susceptibility, hysteresis parameters and elemental analysis. Age control was achieved through radiocarbon ages, and correlation of the paleomagnetic inclination and relative paleointensity records (derived from NRM/saturationARM; RPIarm) to radiometrically dated geomagnetic excursions. An inclination anomaly and RPI minima in TAN0712-14 at 29.92 cal ka BP (2σ age range: 29.36 : 30.5 cal ka BP) is inferred to record the Mono Lake excursion and falls within the error range of the published radiometric age, supporting a relatively rapid lock-in of the paleomagnetic signal. MD06-2987, -2988 and -2989 make up a relative paleointensity (RPIarm) stack---West Coast South Island 1800-ka or WCSI-1800---and contain fifteen Brunhes and Matuyama excursions. Correlation with other stacks and the presence of coeval paleointensity minima support it as a South Pacific representation of Earth's geomagnetic field. Influxes of fine magnetic minerals in cores MD06-2988 and -2989 are inferred to be a clay content (ice cap glaciation) proxy and correlate with cold stadials (MIS 58, 52, 38, 36, 20 and 6). The magnetic grain-size record of MD06-2989 has spectral power at both obliquity and precession frequencies. Magnetic grain-size fining in MD06-2987 corresponds to Antarctic warm events (A6-A1) and implies circum-Antarctic waxing and waning in bottom water production on millennial timescales during the last interglacial. Higher frequency fining events correlate to millennial-scale warm Antarctic Isotopic Maxima events (AIM) 7-3. Termination I between 12.5 and 11.75 cal ka BP is defined by a monotonic increase in κARM, through the Younger Dryas (YD) chronozone and mirroring the EPICA ice core δ18O transition out of the Antarctic Cold Reversal. A simple phenomenological model is derived from the positive linear relationship (r = 0.86; n = 21; p = 1 x 10-6) of κARM and water depth on the continental shelf. Hydrodynamic sorting is inferred to be the primary process. Rock magnetic paleobathymetry has potential to provide quantitative constraints on estimates of water depth changes in, for example, shallow glacimarine settings. Together, the cores record most of the past two million years of oceanographic and climatic change at these sites, including tight connections between cooling/warming in New Zealand and Antarctica on timescales as short as 1000 years. This implies climate signals are rapidly communicated through both the ocean and atmosphere.

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  • Genetics and ecology of host specificity in the trematode parasite Maritrema novaezealandensis

    Koehler, Anson Van Arsdale (2011)

    Doctoral thesis
    University of Otago

    The specialisation of organisms for their primary resources is a fundamental concept in evolutionary ecology. For parasites, resource specialisation is essentially equivalent to host specificity. Generalist parasites exploit a wide range of host species, while specialists concentrate on a few. Elucidation of host specificity constraints is needed for a greater understanding of both evolutionary and ecological aspects of parasite transmission. In this thesis, I investigate how phenotypic and genetic variables constrain host specificity in the trematode Maritrema novaezealandensis. Using a field survey and several experimental studies, I explore environmental, immunological, morphological, behavioural, physiological, and genetic aspects of host specificity. A field survey was used to quantify patterns of host use by parasites throughout a community of intermediate hosts, in a locality known for its high prevalence of M. novaezealandensis, and to reveal the flow of parasites throughout the major crustacean species. The patterns observed depended on several biological and ecological factors, including the physiology, morphology, immunology, and behaviour of the various host species. Certain decapods were compatible hosts for M. novaezealandensis, while other crustaceans demonstrated lower host suitability as shown by high levels of melanised cysts and parasite stages not completing their development. In a mesocosm study multiple clones of M. novaezealandensis, ranging from low to high heterozygosity, were exposed simultaneously to the amphipods Paracalliope novizealandiae and Heterophoxus stephenseni to examine intraspecific genetic variation in host preferences. All clones preferred H. stephenseni to varying degrees, and no clear association was found with heterozygosity. Cercariae were exposed to the amphipods in the presence and absence of sand (refugium for H. stephenseni). Without sand, infection levels were significantly higher in H. stephenseni than in P. novizealandiae. With sand, H. stephenseni was able to hide, offsetting the parasite’s intrinsic preferences for this host, a finding illustrating the importance of habitat features as determinants of host usage. The immune response elicited by M. novaezealandensis in the crab Macrophthalmus hirtipes was investigated to see if significant differences exist in the immune responses generated by ten distinct clones on the basis that these clones could potentially differ in host specificity. Interclonal differences in immune response elicited were indeed detected, however, additional predictor variables (heterozygosity and the presence in the host of pre- existing parasites) did not influence this response. To investigate the degree of phenotypic variation within and among 42 clonal parasite lines of M. novaezealandensis, morphological traits, photoreactivity, and survivorship were measured and their variability was also quantified. Furthermore, the hypothesis that homozygotes are more variable than heterozygotes was tested. Substantial differences among clones in morphology, photoreactivity and survivorship were found, yet no significant differences among clones in levels of intra-clonal phenotypic variability were seen. In addition, no correlation was found between heterozygosity and phenotypic variation among clones, such that the prediction of highly variable homozygotes was unsupported. A subset of these clones was used in four infection experiments involving two crab and two amphipod species. Infection success and post-infection measures of fitness were quantified and related to phenotypic and genetic traits measured previously. Infection success varied among clones, dependent on which host was considered. Some clones acted as specialists, performing well in only some hosts, whereas others acted as generalists, performing equally well in all hosts. None of the genetic or phenotypic traits considered had consistent effects on infection success of clones across all host species. Overall, the clone- level host specificity of M. novaezealandensis for its second intermediate hosts was shown to depend on a wide range of factors, all combining to maintain a population-level generalist strategy in this trematode.

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  • Shaping Motherhood: Representations of Pregnancy in Popular Media

    Hine, Gabrielle Joanna (2011)

    Doctoral thesis
    University of Otago

    Until two decades ago, pregnant bodies were absent from mainstream media types or presented primarily in a maternal context. Today, the pregnant body is ubiquitous across a broad spectrum of media forms, including Internet websites, print media and screen narratives. This thesis explores the meanings and ramifications of this recently visible ideal, examining how contemporary media treat pregnant embodiment. This project focuses on the themes, tropes and discourses which characterise representations of pregnancy across four traditional media formats (magazines, novels, television and film fiction features); its goal is to elucidate the “story” about the pregnant body that contemporary media presents to the New Zealand woman as a consumer of both local and global culture. To answer this question, I look at the treatment of pregnancy in a set of examples drawn from a range of media genres (or formats) that are available to a New Zealand woman in the first decade of the twenty-first century. These include: thirteen mainstream women’s magazines published in New Zealand (1970-2008) and the Australian lifestyle magazine, Cosmopolitan Pregnancy (2005-2008); three “mummy lit” novels by Sophie Kinsella, Emily Giffin and Adele Parks; the television films Gone Up North for a While (1972) and Piece of My Heart (2009) which both follow the experiences of a young unmarried mother in post-war New Zealand; and the New Zealand television series Outrageous Fortune (2005-2010) and the American film Juno (2007), which each follow the unwanted pregnancy of a teenage girl in the twenty-first century. Current feminist media scholarship suggests the significance of maternity and domesticity to representations of women, but largely (with a few notable exceptions) fails to consider the pregnant body as representative of these ideals. This thesis responds to this oversight by examining how the treatment of pregnancy in contemporary media establishes a set of ideas about the nature of women’s lives. It argues that stories of pregnant embodiment are part of a wider narrative about a woman’s life more generally, what iconic second wave feminist Betty Friedan termed a “life plan.” I conclude that representations of pregnant embodiment mobilise a number of conflicting discourses that variously support and contradict each other. Women’s magazines offer a homogeneous vision of a feminine life plan, while mummy lit novels and screen narratives both acknowledge and contest this ideal; at the same time, each media type posits pregnancy as a significant milestone in the current life plan. Yet, all share a common agenda: encouraging the feminine subject to engage in a narcissistic relationship with her own body/self as a “mark” of her femininity. The disciplined pregnant body expresses the contradictions at the heart of femininity in a world in which a woman is expected to achieve success in the public realm as an individual, while finding personal fulfilment through motherhood (without which she is incomplete), which paradoxically only seems to intensify her narcissistic involvement with herself.

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  • Movements, migration, and ocean habits of six Pacific seabird species

    Adams, Josh (2011)

    Doctoral thesis
    University of Otago

    This thesis centres on methods and studies designed to increase knowledge surrounding the at sea distribution of seabirds during various periods in their annual cycle (i.e., breeding, migration, over-wintering). Following a brief introduction in Chapter 1, in Chapter 2, “Effects of archival tags on Sooty Shearwater (Puffinus griseus)”, I report the effects of global location sensing (GLS) tags applied to provisioning adult Sooty Shearwaters captured on Whenua Hou (Codfish Island, New Zealand). Specifically, I assessed effects on chick size, chick mass, and estimated post-fledging recruitment by comparing two groups: chicks reared by parents where one or both members of each breeding pair were outfitted with GLS tags versus chicks reared by non-handled and non-tagged adult pairs. Deployment of tags on adults resulted in 35% reduction in chick body mass and significantly reduced chick skeletal size preceding fledging. Chick mass was negatively related to the duration that adults carried tags. In this study, none of the chicks reared by pairs where both parents were tagged, 54% of chicks reared by pairs where one parent was tagged, and 83% of chicks reared by non-handled and non-tagged parents achieved a pre-fledging mass threshold of 564 g related to successful recruitment at age >1 yrs. Body mass of adults carrying tags and returning from transequatorial migration the following year were 4% lighter on average than non-tagged birds, but this difference was not statistically significant. I suggest that the ethics and potential risks of deployment of tags must be balanced against risks of not deploying them and thereby missing crucial information for understanding biological adaptations and informing conservation efforts. The designs and attachment methods for such devices continues to be modified to minimise disruption and effects to individuals. The placement and streamlining of tags in future studies on shearwaters and other seabirds should be considered to minimize efficiency penalties incurred by the reduction in hydrodynamic drag or displacement of mass. Caution is required especially when deploying tags on threatened species. The Sooty Shearwater exists in a perpetual summer and completes one of the lengthiest annual avian migrations (>28,000 km roundtrip). Previously, knowledge of shearwater movements came from opportunistic ship-based observations of the flight direction of individual birds along their vast migration route, and from serendipitous recoveries from beaches and fishery by-catch of individuals banded at colonies in New Zealand. In Chapter 3, “Wings over waves: the extraordinary trans-Pacific migration of the Sooty Shearwater”, I describe the first continuous satellite-tracking of the fall (boreal) trans-Pacific migration of the Sooty Shearwater from foraging areas off central California back to the South Pacific. Individual tracks were very consistent, with all birds closely following the shortest possible great circle route toward New Zealand. From departure to the first location south of the Tropic of Capricorn, individual shearwater paths were 10.1 ± 4.6% greater than respective great circle routes. Shearwaters traveled at 25 ± 6 km hr-1, slower than the instantaneous flight speeds recorded from ships. Traveling at 25 km hr-1 along the most direct possible route, a shearwater could leave San Luis Bay (California), traverse the Pacific, and reach the colony at Taiaroa Head (New Zealand) in 16.5 days. In the absence of information regarding the actual distribution, abundance, and hence, availability of zooplankton prey for seabirds, environmental factors can serve as proxies to help understand seabird habitats. In Chapter 4, “Oceanographic factors influencing the at sea distribution of Cassin’s Auklets that breed in the Channel Islands, California”, I used radio-telemetry data collected in 1999-2001 to evaluate at-sea habitat use among Cassin’s Auklets Ptychoramphus aleuticus breeding at Prince Island off southern California. I examined logistic regression between paired radio-telemetry (presence) versus random (pseudo-absence) location-associated habitat variables derived from satellite remote-sensing of sea surface temperature and chlorophyll a concentration, and digital bathymetry. In this chapter, I used a Baysian model-ranking approach to examine the predictive capacity of these oceanographic variables. Compared with random locations within their foraging area and after controlling for distance to colony, odds ratios indicated that auklets provisioning chicks occurred in relatively shallower, warmer, chlorophyll-rich water characterized by chlorophyll fronts near the insular shelf break. In Chapter 5, “Summer-time use of West Coast U. S. National Marine Sanctuaries by migrating Sooty Shearwaters (Puffinus griseus)”, I used a similar model-ranking approach that I developed in Chapter 4, to evaluate oceanographic factors that could potentially help predict the annual distribution of over-wintering Sooty Shearwaters in the California Current Large Marine Ecosystem (CCLME). During 2008 and 2009, I used satellite telemetry to evaluate shearwater ranging patterns among birds captured at three locations: Columbia River Plume, WA; Monterey Bay, CA; and Santa Barbara Channel, CA. Within the U. S. Exclusive Economic Zone (EEZ) during 2008 and 2009, shearwaters spent 68% and 46% of time over the shelf (1000 m), respectively. In 2008 and 2009, shearwaters spent 22% and 25% of their time in the EEZ within the five west coast National Marine Sanctuaries; high utilization occurred in non-Sanctuary waters of the EEZ. Individual birds from three discrete capture locations overlapped substantially in space and we identified several regional “hotspot” areas, including the Columbia River Plume, Cape Blanco, Monterey Bay, Estero/San Luis Obispo Bays, and the Santa Barbara Channel. After accounting for bathymetry, shearwater utilization in both years was positively associated with long-term mean chlorophyll a (range in estimated R2 = 0.13–0.20). Wind strength and direction are important factors related to the overall movements that delineate the distribution of petrels at sea. Consistent with the theme of exploring oceanographic habitat associations among tracked seabirds in Chapters 4 and 5, in Chapter 6, “Correlating seabird movements with ocean winds: linking satellite telemetry with ocean scatterometry”, I present a new method for quantifying the movements of far-ranging seabirds in relation to remotely-sensed ocean winds measured by the SeaWinds scatterometer onboard the QuikSCAT satellite. Individual seabirds (Sooty Shearwater, Pink-footed Shearwater, Hawaiian Petrel, Grey-faced Petrel, and Black-footed Albatross) all traveled predominantly with oblique, isotropic crossing to quartering tail-winds (i.e., 105° to 165° in relation to birds’ trajectory). For all five seabirds, entire track line trajectories were significantly correlated with co-located winds. I suggest that vector correlation can be used to quantify movements for any marine vertebrate when tracking and environmental data (winds or currents) are of sufficient quality and sample size. Vector correlation coefficients can then be used to assess population- or species-specific variability and used to test specific hypotheses related to how animal movements are associated with fluid environments.

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  • Response inhibition and properties of its underlying processes : evidence from behavioral and electrophysiological measurements

    Ko, Yao-Ting (2011)

    Doctoral thesis
    University of Otago

    I attempted to further our understanding of response inhibition by examining three questions concerning how it works. The first question that I examined was what determines the success of response inhibition. This question was examined with the stop-signal paradigm, a prominent experimental setting for the study of response inhibition. I hypothesized that the relative strength of activation and inhibitory processes is a determinant, which led to an examination of graded action of response inhibition. To examine graded response inhibition, several continuous measurements including response force, electromyography (EMG) and the lateralized readiness potential (LRP) derived from electroencephalography (EEG) were employed; and new methods of comparing conditions and of controlling for contributions from response activation were introduced. Results in the present study indicated that response inhibition works in a graded manner. The second question that I examined was how specifically targeted response inhibition is. In line with previous studies, results in the present study indicated that response inhibition works globally to some extent, at least when speeded responses were required. New information about global response inhibition in the present study was that global response inhibition was considered with two distinct lines of research – one line concerns selective response inhibition, where global response inhibition was indicated previously, and the other line concerns the psychological refractory period (PRP) paradigm, which has been a prominent experimental setting for the study of divided attention. The third question that I examined was on what level(s) of processing selective response inhibition and global response inhibition produce their effects. Results in the present study with measurements of response force, EMG and the LRP indicated that global effects of selective response inhibition within the stop-signal paradigm are produced at the motor stage of processing, and that global effects of response inhibition within the PRP paradigm are produced at the response-selection stage of processing.

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  • Regulation of E-cadherin by Human Papillomavirus type 16 E6

    D'Costa, Zarina (2011)

    Doctoral thesis
    University of Otago

    The primary risk factor for the development of cervical cancer is a persistent infection with certain high-risk human papillomavirus (HPV) types such as 16 and 18. The ability of these viruses to cause such persistent infections within the host can be attributed to several immune evasion mechanisms. One such mechanism involves adversely affecting the amount of viral antigen presented to the host immune system. It was previously shown that the E6 oncoprotein of HPV16 is capable of actively down-regulating expression of epithelial (E)-cadherin expression which directly correlates with depletion in the number of immune Langerhans cells (LCs) in the infected tissue. In this manner, HPV16 E6 is able to contribute to viral survival and protection. The aims of this study were firstly, to investigate the mechanism of E6 regulation of E-cadherin; secondly, to identify a region of E6 responsible for regulation of E-cadherin; thirdly, to investigate the roles of the other HPV16 oncoproteins in E-cadherin regulation and fourthly, to identify potential therapeutic interventions for early HPV16 infections. The E6 oncoprotein from HPV16 was expressed in HCT116 cells and its ability to regulate E-cadherin promoter, transcript and surface protein was investigated. E6 was found to regulate E-cadherin at a transcriptional level. The E-cadherin promoter was found to be repressed in HCT116 E6 cells through a methylation dependent mechanism that is independent of direct methylation of the E-cadherin promoter. In order to identify the region of E6 oncoprotein important for E-cadherin regulation, a range of HPV16 E6 mutants were tested for their abilities to decrease transcription of E-cadherin. Mutational analysis of HPV16 E6 led to the identification of residues 118-122 and the nearby R124 residue, located within the C-terminal zinc-finger binding domain to be important for transcriptional regulation of E-cadherin by E6. In addition, the other major oncoproteins of HPV16, namely E5 and E7 were co-expressed with E6 and their abilities to regulate surface E-cadherin were assessed. E7 was also found to be effective in decreasing surface E-cadherin levels, and this effect was enhanced when the two oncoproteins were co-expressed in HCT116 cells. Furthermore, regulation of E-cadherin by HPV16 oncoproteins was assessed under conditions of differentiation using a simple monolayer model of differentiation and a three-dimensional organotypic raft culture system. Lastly, in order to identify potential therapeutic interventions for early HPV16 infections, rational design was used to design peptide antagonists of E6 that could potentially interfere with E6 regulation of E-cadherin. Despite efficient delivery of peptide inhibitors of E6 into target E6 expressing cells, no restoration of E-cadherin levels were detected. However, another potential therapeutic compound, Indole-3-carbinol, was identified. This research gives insight into the mechanism of transcriptional regulation of E-cadherin by HPV16 E6. The data presented here suggest that a specific regulatory region of the protein can directly affect regulation of E-cadherin. These data may provide the foundation for an effective HPV16 inhibitor, which would help decrease the burden of HPV-related disease that affects millions of people each year.

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  • Re-conceptualising Sense of Place: Implications for place branding

    Santana, Adriana Campelo (2011)

    Doctoral thesis
    University of Otago

    This thesis is concerned with understanding what constitutes a sense of place and how such an understanding can help in the development of a place brand. Branding theory and techniques have been applied to places in order to promote economic development and to enhance the cultural differentiation of places. The development of a brand for places requires not just an understanding of the elements that create a communal sense of place, but also an understanding of how the place is part of the community it represents. What constitutes a sense of place can help in the development of a place brand. In this endeavour, the research problem is to understand what constructs determine a sense of place. In order to achieve the aims of this research, an investigation was conducted on the Chatham Islands of New Zealand, an archipelago with ten islands with an area of 966 km2 and a population of 609 inhabitants, located 800 km east of New Zealand. In this relatively isolated community that has a distinct cultural history, interactions with the environment are pronounced and relationships between people are critical. The thesis adopts a qualitative philosophical position, positioning research paradigms as interpretivist, postmodernist and constructivist. Accepting the existence of multiple realities, the ontology of this study is relativist leading to a transactional and subjectivist epistemology. The epistemology that guided the entire journey is based on the belief that a collaborative approach is necessary to create knowledge, via a phenomenological hermeneutic methodology. Multi-sited ethnography (Marcus 1995) through participant observation, phenomenological interviews, and videography was used as a strategy for inquiry. The constructs of time, ancestry, landscape, and community, were revealed to be determinants for the Chatham Islanders’ sense of place and they recognised them as elements of major significance in their lifestyle, and in their personal and communal identity. These constructs stand for a set of meanings that influence the habitus, the ways of doing things on the islands, and the significance of doing things in particular ways. In addition, the findings and discussion demonstrated how these constructs bestow meanings on the symbolic representations of the community, which are also reinforced through the sensory perceptions of the place. This thesis suggests a creational place branding approach that adopts a co-creation strategy to identify the constructs that determine the sense of place. A sense of place model is presented as a guide to investigate the set of meanings within each of these four constructs (time, ancestry, landscape, and community), and their importance in other places. The recognition and representation of these constructs are vitally important to brand imagery and brand communication. Equally important, is an understanding of how these constructs should be represented in order to properly express and preserve their meanings. Place imagery encompasses symbolic representations and sensory perceptions of the place. Therefore, this study develops and presents imagery representation criteria to provide procedures to enhance the ethos of the place in portraying a place brand. The creational ethically-driven place branding approach proposed in this thesis embraces the co-creation and recognises the cultural dependency of brand meanings. It requires that the ethos of the place and the people of the place should be positioned at the core of the brand to establish ownership, achieve authenticity and promote brand sustainability.

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  • A multiphase analysis of the personal benefits derived from cultural educational tour experiences.

    Grahn, åsa (2011)

    Doctoral thesis
    University of Otago

    In recent years, educational tourism has been established as an alternative to conventional mainstream tourism with a focus on learning through travelling. Cultural educational tourism is a type of tourism engaged in by travellers whose primary motivation is to learn about and to experience a host culture through in-depth encounters. This niche has had research attention, most commonly with a focus on educational tourism where the primary motivation is studying or learning (Go & van Fenema, 2006; Kalinowski & Weiler, 1992; Lück, 2003). This research explores the nature of Swedish tourists’ experiences on cultural educational tours to Tanzania. The principal objectives of the research were to gain an enhanced understanding of the cultural educational tour experience and to understand the nature of personal benefits derived from the experience. For purposes of the research, a phenomenological approach was adopted and pure qualitative research techniques with a temporal framework were implemented. The applied methods were semi-structured interviews, participant observation and personal travel diaries, which were implemented throughout cultural educational tour experiences that took place in Tanzania during three different tours. The empirical research was conducted during the anticipation, actual, reflection and recollection phases in order to gain an in-depth insight into the dynamic and complex experience of the participants. Twenty-seven Swedish tourists were included in the sample and in a total, 72 semi-structured interviews were conducted and divided throughout the following phases: 18 during the anticipation phase, 27 in the reflection phase and 27 in the recollection phase. As well, 20 personal travel diaries were completed by the tourists during their tour experience. Researching cultural educational tour participants’ subjective experiences through a longitudinal process and with the same participants throughout the various stages of the tour experience is rare, if not unprecedented, in the tourism literature. The qualitative materials employed in this study were generated in association with three extended tours to Tanzania in February, June and October of 2006, each lasting three weeks. The researcher was present on two tours for a total of 6 weeks. The interpretation and analysis of qualitative materials indicates that participation had a profound effect on all participants in the study. Participants reported on a benefit that related to a personalised cultural awareness and appreciation of the culture being visited, as a result of close cultural interactions with the hosts, and which intensified in the months following the tour experiences. The study also presents evidence of personal growth, which in turn gives rise to a sense of enhanced tolerance and understanding of one’s own actions during and after the tour. As well, critical interrogations of attitudes towards non-sustainable and ethical tourism development built up during the actual tour. This seemed to be most prominent among participants travelling for the first time with the specific tour operator. The findings highlight the strength of recollection which builds, with reflection, over the six months immediately following the actual tour experience. By generating insight into the complex and dynamic phases of the cultural educational tour experiences, the study has demonstrated the usefulness of a phenomenological approach to understanding participants’ tour experiences. The thesis concludes with a number of reflections in terms of theory and methods, as well as recommendations for future research that may further inform the study of a unique contemporary tourism phenomenon.

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  • Restorative effect of estrogen on basal forebrain cholinergic neurons

    Kőszegi, Zsombor (2011)

    Doctoral thesis
    University of Otago

    The basal forebrain cholinergic (BFC) system is one of the most important neurotransmitter systems in the brain. It has received much attention in the past two decades, primarily for its role in learning, memory, attention and behavior. The BFC system has also been reported to be particularly vulnerable in neurodegenerative diseases, such as in Alzheimer’s disease (AD). The gonadal steroid, estrogen, is an essential contributor in controlling the vulnerability of the BFC system. Besides its classical or genomic mechanism, estrogen is known to have non-classical actions on intracellular signaling pathways. In this study, we investigated the ameliorative effects of estrogen treatment and the role of non-classical estrogen actions on BFC neurons in a neurodegenerative mouse model, in vivo. N-methyl-D-aspartate (NMDA) was injected unilaterally into the substantia innominata - nucleus basalis magnocellularis (SI-NBM) complex of the basal forebrain to elicit cholinergic cell death in the injected area and thus fiber loss in the ipsilateral cortex. An acute treatment of 17β-estradiol (E2) after the NMDA-induced lesion restored the ipsilateral cholinergic fiber density in the cortex in a time- and dose-dependent manner. Conversely, it did not have any effect on the cholinergic cell loss in the SI-NBM. The ameliorative action of E2 on cholinergic fiber loss was detected in both intact and gonadectomized young male and female mice, but not in aged animals. The E2-induced cholinergic fiber density restoration was also absent in neuron-specific estrogen receptor α (ERα) knockout mice. Selective blockade of the mitogen activated protein kinase (MAPK) and protein kinase A (PKA) pathways prevented E2’s ability to restore the cholinergic fiber density. Furthermore, activation of non-classical estrogen signaling by a non-classical pathway activator (estren) induced E2-like fiber restoration. Our findings demonstrate that estrogen restores the cholinergic fiber density in the cortex through a non-classical signaling mechanism after the loss of subcortical cholinergic input. Similar restorative effects were observed in young animals, irrespective of sex or endogenous estrogen levels. These observations reveal a critical role for non-classical estrogen signaling via ERα and MAPK-PKA pathways in BFC neurons, in vivo. Taken together, our study discloses important aspects relating to the vulnerability of the BFC system in neurodegenerative processes, such as AD or traumatic brain injury and might shed light on future medical treatments through the use of non-classical estrogen pathway activators.

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  • The effect of exercise mode and muscle mass on plasma glucose oxidation during exercise in the fasted state

    Harvey, Christopher Ross (2011)

    Doctoral thesis
    University of Otago

    The purpose of this study was to investigate what effect the size and location of skeletal muscle mass have on the source of glucose oxidised with a specific emphasis on plasma glucose, and to find out how pre-exercise diet might influence these results. Indirect calorimetry and stable isotope methodology using orally ingested [13C]glucose were used to examine the effect of muscle mass and exercise mode on plasma glucose and muscle glycogen oxidation (PGO and MGO, resp.). Muscle mass: On separate occasions, eight healthy male cyclists (35–55 y) completed 75 min of arm cranking (Arms), one-legged cycling (1-leg) and two-legged cycling (2-leg) at 50% mean maximal power output (VO2peak, 33 ± 5, 41 ± 4 and 56 ± 5 mL/kg/min, resp.) and one-legged cycling at the same absolute intensity as 2-leg (2-legA; 94 ± 10 W). PGO in 2-leg was similar to that in Arms and greater than in 1-leg (p = 0.13, p = 0.002, resp.), while PGO in 1-leg was greater than in 2-legA (p = 0.03), (0.67 ± 0.17, 0.49 ± 0.16, 0.39 ± 0.10, and 0.27 ± 0.09 g/min, resp.). The percentage energy utilisation [%En] from plasma glucose in 2-leg was similar to that in 1-leg but less than in Arms (p = 0.26, p = 0.03, resp.), [13 ± 3, 15 ± 3 and 21 ± 5%En, resp.]. MGO was similar between 2-leg and 1-leg while both were greater than in Arms (p = 0.14, p ≤ 0.05, resp.) (1.15 ± 0.39, 0.89 ± 0.34, and 0.55 ± 0.23 g/min, resp.). Breakfast: Eight healthy male runners (18–22 y; VO2max, 67 ± 5 mL/kg/min) completed 75 min of treadmill running (59% VO2max) in both an overnight fasted state and 150 min after consuming a liquid CHO-rich breakfast. Greater CHO oxidation in the fed state was attributed to greater MGO (1.21 ± 0.63 vs. 0.79 ± 0.25 g/min [33 ± 15 vs. 23 ± 8%En], resp.) (p = 0.01) and while fat oxidation was enhanced in the fasted state (~35%), PGO was unaffected by dietary status (0.73 ± 0.16 vs. 0.71 ± 0.17 g/min [20 ± 4 vs. 20 ± 3%En], resp.) (p ≥ 0.23). PGO was related to the mode of exercise and both the size and location of the active muscle mass. As the lower limbs are generally better trained than the arms, specific training adaptations that reduce the reliance on CHO as an energy yielding substrate also reduce the reliance on plasma glucose during lower limb exercise. Muscle mass differentials and %En utilisation from plasma glucose indicate that PGO per kg is greater in arm than in lower limb muscle, i.e., PGO is inversely related to muscle mass, however, in lower limb muscle, PGO is proportional to the muscle mass. Breakfast feeding increases plasma insulin and glucose above fasting concentrations and during the early stages of exercise these conditions enhance PGO, and when combined with an increase in MGO, a transient decline in plasma glucose concentration is observed.

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  • Metaphor in Psychotherapy: Description and Applications

    Tay, Dennis (2011)

    Doctoral thesis
    University of Otago

    The relationship between metaphor, language, and thought, as hypothesised by cognitive linguists, requires detailed investigation of actual metaphor use in different situations and contexts. Researchers have examined metaphors in contexts as diverse as economics, politics, art, science, and advertising, both for the inherent interest in how metaphors function therein, and to interrogate cognitivist claims about the nature of metaphor. There has recently been an interest in furthering this descriptive imperative by considering the prescriptive aspects, or applicability, of metaphor. The main question is how advancements in metaphor theory can contribute to the judicious use of metaphors in the performance of language constituted “real world” activities. This thesis undertakes a discourse analysis of metaphors in the verbally enacted mental health resource of psychotherapy. My primary linguistic objective is to show how metaphors used in psychotherapy are shaped by its nature, and inform aspects of metaphor theory in significant ways. On the other hand, although many therapists profess an interest in metaphors, therapeutic research has been perceptibly indifferent towards relevant advancements in metaphor theory in the language sciences. The secondary therapeutic objective of this thesis is therefore to show how a discourse analytic approach to psychotherapeutic metaphors can potentially enhance their clinical use and management. Aspects of metaphor theory to be discussed are 1) the ideational resources of metaphor, which concerns whether therapeutic metaphors are ultimately constructed out of embodied, cultural, or individual-specific knowledge; 2) the rhetorical development of extended metaphors, which describes how source-target associations are elaborated in strategic and patterned ways in therapeutic talk; 3) the variability and variation of metaphor, which refer to how therapists and patients flexibly switch between different sources and targets, or innovate from conventional conceptual metaphors; and 4) the co-text of metaphors, which poses the question of how metaphors interact with co-textual elements (e.g. discourse markers) in their mutual constitution of psychotherapeutic talk. Therapeutic implications stemming from the above analyses include 1) how embodied, cultural, and individual-specific knowledge can be harnessed in complementary fashion for therapeutic purposes, 2) how rhetorical strategies can help therapists guide their patients towards more useful elaborations of their own metaphoric conceptualisations, 3) how variability of metaphor use can be associated with certain discourse objectives in psychotherapeutic interaction, 4) how varying instantiations of conceptual metaphors used to talk about psychotherapy contributes a channel of feedback to therapeutic theorisation, and 5) how the naturalistic distribution of discourse markers in extended metaphors implies more effective ways of communicating them to patients. I conclude the thesis by offering a synthesised summary of the discussion, highlighting emergent themes about the nature of metaphor in psychotherapy, and suggesting future directions both for metaphor research and psychotherapeutic practice.

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  • Biomarkers in early diagnosis of acute kidney injury

    Nejat, Maryam (2011)

    Doctoral thesis
    University of Otago

    Acute Kidney injury (AKI) is common and frequently fatal. Delay in plasma creatinine based diagnosis of AKI has compromised clinical trials of experimentally promising therapies of kidney injury. Therefore, a number of potential early urinary and plasma biomarkers of renal cell injury have been evaluated in several clinical and experimental studies. However, many uncertainties remain in the diagnostic and predictive capability of these biomarkers in various forms of AKI, especially in heterogeneous population. The overall aim in this project was to analyse the diagnostic and predictive performance of some novel AKI biomarkers in a heterogeneous high-risk population. This project focused on the performance of plasma and urinary cystatin C (CysC) as markers of kidney function and injury respectively and both as predictors of mortality. This involved separate analysis of plasma and urinary CysC clinical data, and an experimental study investigating the performance of urinary CysC in the presence of albuminuria. Finally, the ability of fractional urinary biomarkers (fractional excretion of sodium (FENa) and urea (FEurea) to distinguish between so-called pre-renal AKI and established AKI was assessed. Clinical data came from the EARLYARF study, which was initiated by Professor Zoltan Endre prior to commencement of my PhD project. I participated in data collection and data entry for the large part of this study and I was provided access to the database to address the objectives of my thesis. The hypotheses were explored by analysing data arising from this study. The experimental study of the effect of proteinuria and albuminuria on urinary CysC arose from the observation of cystatinuria in children with proteinuria. This was explored in an animal model of transient albuminuria, which I developed. Plasma CysC has been proposed as an alternative to plasma creatinine as a measure of renal function. In Chapter 3, relative changes of plasma CysC and plasma creatinine were compared in critically ill patients. I was able to demonstrate that plasma CysC generally increased prior to plasma creatinine. Plasma CysC and creatinine were similarly moderately predictive of death or the need for dialysis. Plasma CysC was a more effective and earlier surrogate marker of decreased renal function than plasma creatinine in a general intensive care unit population. In Chapter 4, the utility of urinary CysC as a diagnostic marker of AKI, and predictor of mortality in critically ill patients was evaluated. Urinary CysC was diagnostic of and predictive of death. Unexpectedly, it was also found to be diagnostic of sepsis. Concentrations of urinary CysC were significantly higher in the presence of sepsis (p<35 respectively. All urinary biomarkers increased with increasing duration and severity of AKI. CysC, NGAL and interleukin -18 (IL-18) concentrations were greater in both pre-renal AKI-FENa and pre-renal AKI-FEurea compared with controls. The result suggests that prerenal AKI represents the milder end of a continuum of renal cellular injury.

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  • Effects of Tetraplegia and Passive Heat Stress on Systemic and Cerebral Vascular Function at Rest and during Orthostasis.

    Wilson, Luke Charles (2011)

    Doctoral thesis
    University of Otago

    Spinal cord injury (SCI) is a debilitating disorder, causing cardiovascular dysfunction at rest and during orthostasis [as simulated by lower-body negative pressure (LBNP)], which differs with the level, completeness, and time since injury. However, the effect of SCI on cerebrovascular function remains unclear. In addition, the effects of passive heat stress (PHS) on integrative cerebrovascular and cardiorespiratory function at rest and during orthostasis following SCI are unknown. In able-bodied individuals, although PHS markedly increases the susceptibility to syncope, the mechanisms by which this occurs are poorly understood but are ultimately reflected in critical reductions in cerebral blood flow (CBF) during orthostatic stress. Therefore, the central aim of this thesis was to investigate the effects of chronic tetraplegic SCI on modulation of cardiovascular and cerebrovascular function at rest and during orthostasis with and without PHS. A secondary aim was to investigate the role of the potential mediator(s) of reduced CBF and orthostatic tolerance during PHS using multiple increments in body core temperature [Tc; +0.5°C, +1.0°C, and heat tolerance (+1.5°C or +2.0°C)]. This was undertaken in able-bodied individuals only, using mean middle cerebral artery blood flow velocity (MCAvmean) as an index of CBF. The purpose of Chapter 3 (first data Chapter) was to assess whether chronic tetraplegic SCI alters cerebrovascular function, in particular the brain’s capability to buffer changes in arterial blood pressure (termed dynamic cerebral autoregulation [CA]) and its responsiveness to changes in carbon dioxide (CO2; termed cerebrovascular reactivity). Dynamic CA gain and phase [as an index of the relative amplitude and latency of the relationship between arterial blood pressure and MCAv] were unaltered in all frequency ranges; however, the very-low frequency coherence (similar to correlation coefficient) of dynamic CA was reduced by ~21% in tetraplegia. Full MCAvmean reactivity was unchanged in tetraplegia, however its modulation was affected by tetraplegia in the hypercapnic range. Changes that were evident in dynamic CA coherence and during hypercapnia following chronic tetraplegia, may be indicative of cerebrovascular adaptation. The purpose of Chapter 4 was to examine the roles of potential mediators of reductions in MCAvmean and orthostatic tolerance with increasing severity of thermal strain (elevations in Tc). The reduction in partial pressure of end-tidal CO2 (PETCO2) was able to account for all of the progressive reduction in MCAvmean with increasing Tc, whereas during superimposed orthostatic stress (LBNP-induced) the reduction in PETCO2 accounted for only one third of the reduction in MCAvmean at terminal MCAvmean. Of note, Tc did not influence the reductions in MCAvmean during asymptomatic-LBNP (i.e., no signs of syncope), indicating that the baseline reductions in MCAvmean with elevations in Tc are the major risk factor for orthostatic intolerance. The purpose of Chapter 5 was to investigate whether the control of cardiorespiratory and cerebrovascular function is altered during PHS in chronic tetraplegic SCI. At matched elevations in Tc, reductions in PETCO2 were similar between tetraplegic and able-bodied individuals. However the majority of the tetraplegics’ cerebrovascular and cardiovascular variables were unresponsive to PHS to +1.0°C. Independent of group, dynamic CA and hypercapnic MCAvmean and cerebrovascular conductance reactivities were reduced. These findings indicate that PHS-induced elevations in sympathetic nervous activity (occurs in able-bodied individuals only) was not responsible for the reductions in dynamic CA and hypercapnic cerebrovascular reactivity. The purpose of Chapter 6 was to assess whether the control of cardiorespiratory and cerebrovascular function during orthostasis is altered in chronic tetraplegic SCI at normothermia or due to PHS. During asymptomatic-LBNP, reductions in mean arterial blood pressure (MAP) were larger in tetraplegia than in able-bodied individuals. Despite this, reductions in MCAvmean were similar, indicative of maintained or improved static CA in tetraplegic SCI. The preliminary findings of the cerebrovascular and cardiorespiratory responses leading to pre-syncope indicate that with similar reductions in MAP, MCAvmean was higher in tetraplegic than in able-bodied individuals. Although the mechanisms are unclear, such a response may be viewed as an adaptation in static CA following chronic tetraplegia. In conclusion, despite marked cardiovascular dysfunction with tetraplegia, it appears that cerebrovascular function during normothermic baseline and asymptomatic-LBNP may be compensated. Further research is required to confirm these findings and identify the mechanisms by which such changes may occur. During PHS, tetraplegics’ cerebrovascular and cardiorespiratory variables were largely unresponsive, and orthostatic tolerance was unaltered. Passive heat stress caused reductions in dynamic CA and hypercapnic MCAvmean and cerebrovascular conductance reactivities independently of group, indicating that such changes are not largely influenced by heat-induced increases in sympathetic nervous activity. In able-bodied individuals, heat-induced hypocapnia seems able to account for all of the reduced CBF with rising Tc, whereas the early and marked reduction in MAP may have a more prominent role in orthostatically-induced reductions in CBF.

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