10,447 results for The University of Auckland Library

  • Evaluation of utilisation of the Prevention of Mother-to-Child Transmission of HIV Programme in Central province, Kenya

    Ngugi, Catherine Njeri (2013)

    Masters thesis
    The University of Auckland Library

    Background: The PMTCT HIV programme has been one of the most successful HIV preventive interventions towards HIV-free future generations. However, even though the programme is virtually effective in developed countries, many developing countries are reporting child HIV infections due to the MTCT. The programme has existed in Kenya for more than a decade, yet in 2011, 12,894children were HIV infected due to MTCT Objective: To evaluate the PMTCT programme, especially the HIV testing from the antenatal period to the postnatal period among expectant parents attending Nyeri Provincial General Hospital in Central Province, Kenya. Design: Retrospective analysis of the hospital registers. Methods: Three hospital registers were analysed for the period from July 2009 to September 2012. The registers were for antenatal, intrapartum and postnatal care respectively. Each register documented the utilisation of PMTCT services by the expectant parents. Descriptive and inferential statistics were produced to analyse data from the registers. Results: The PMTCT services utilisation was sub-optimal. Of the 504 expectant mothers who attended the antenatal clinic, 59.9% came once, 80.4% had their first visit in the third trimester (between weeks 28 and 40) and only 6.9% were accompanied by their partners. All the women were HIV tested in their first visit but only 12.1% were rescreened after three months, and only 3.8% had been tested prior to the current pregnancy (p=0.000). No expectant mother was tested for HIV intrapartum or postpartum. The children of the 504 mothers who were HIV tested were those whose parent/s were known to be HIV positive or who had presented to a child welfare clinic with recurring symptoms suggestive of a failing immune system. Conclusion: Public health programs need to strengthen the PMTCT and HIV prevention programmes to ensure that HIV testing preconception and in pregnancy is fully implemented and strengthened, alongside continued education of the public through community programmes and the media. To avert further horizontal and vertical transmission of HIV, there is a need to address urgently the identified missed opportunities in the PMTCT program. These programmatic challenges require health system redesign and strengthening, resource allocation, addressing research gaps and reassessing the current PMTCT policies.

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  • Suicide Pavilions

    Esling, S; Chon, C (2013-12-05)

    Creative work
    The University of Auckland Library

    Artworks ‘Suicide Pavilions’ is a collaborative exhibition of new work between Auckland-based artists Simon Esling and Clara Chon comprising works on paper, a photograph, printed suicide notes and objects. The suicide pavilions themselves are delicate watercolour, ink, and pencil works on paper depicting contemplative spaces for those who harbour the thought of suicide. Central to these pieces is the idea spoken by the protagonist, Harry, in Herman Hesse’s 'Steppenwolf', ‘that to call suicides only those who actually destroy themselves is false’. Instead, it is the tension within the deliberation of suicide - the avoidance of suicide while holding the thought of it - that Esling and Chon have chosen to explore. The architectural atmosphere of Esling’s imagined illustrations plays on the contrasting aspects of the interior and exterior, and their accompanying structural connotations: lightness, darkness - the flow from one place to another (from one state of mind to the next), as well as their ability to elicit a general ambience or mood. In the drawings and suicide notes (which are both real and imagined) Esling captures those fleeting moments of relief, and inevitably, of falling shadow. The selected sculptural objects suggest something more visceral - they become the tangible points for the physical expression of the psychological friction of the suicide. With its requisite holes and straps, Chon’s crafted leather harness speaks to both the freedom and restraint inherent in the mind of the suicide, where a simultaneous desire exists to be freed from one world, yet remain in it. - Jamie Hanton, Director

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  • Studies on the roles of transition metals in diabetogenesis

    Chan, Yih-Kai (2008)

    Doctoral thesis
    The University of Auckland Library

    Diabetic cardiomyopathy is one of the causes of mortality and morbidity associated with diabetes. Diabetes is a disorder characterised by chronic hyperglycaemia and cardiovascular complications. The relationship between these integrally linked conditions has long been recognised, and for a significant portion of individuals the two conditions co-exist as part of metabolic syndrome. The presence of diabetes increases the risk of heart failure up to fivefold and three-fold in women and men, respectively, when compared to individuals without diabetes. While there has been a significant declining trend in cardiovascular mortality and morbidity in the general population over the past two decades, unfortunately such trends have not been seen among diabetic patients. As a result, this has persuaded many health professionals to re-evaluate their current treatment and pharmacological regimens. It is a well established fact that oxidative stress is a contributory mechanism in many agerelated disorders including T2DM, especially in those with poor glycaemic control. Thus far, clinical trials with antioxidant or carbonyl-trapping agents have produced mixed results, suggesting that the mechanisms underlying this disorder may be more complex than previously thought. Although altered systemic regulation of trace metals in diabetes has been previously investigated, it is still unclear whether changed trace metal metabolism would cause heart disease in common forms of diabetes and whether metal chelation can reverse this condition. Our hypothesis is that the accumulation of redox-active trace metals including Cu and Fe in cardiac muscle may, at least in part, result in cardiomyopathy through the generation of excess reactive oxygen species. We believed that the administration of a specific metal chelator should ameliorate this process by increasing the excretion of free systemic Cu and Fe, consequently limiting the production of superoxide oxygen free radicals and arresting the process of diabetic cardiomyopathy. Data from pre-clinical studies conducted in our laboratory using diabetic animal model with diabetes-induced abnormal Cu metabolism have been remarkably consistent in demonstrating that oral dosing with triethylenetetramine (TETA) can effectively remove systemic Cu via increased urinary Cu excretion, improve cardiomyocyte structure, reverse elevations in left ventricular collagen and ??1-integrin, and alleviate heart failure, all in the presence of a consistently high circulating blood glucose profile. Taken together, these findings support the beneficial role of TETA in diabetic animal model and lay the foundation for its potential therapeutic effect in humans with diabetes. This thesis describes a series of randomised, placebo-controlled clinical trials that have investigated the metabolism of Cu and Fe and seven other trace metals in patients with chronic T2DM compared with non-diabetic control subjects. This thesis also examines the mechanism of action of TETA and addresses the hypothesis that a decrease in body systemic Cu pool through chelation therapy may improve cardiac complication in diabetic subjects. Trial 1 is a randomised, double-blind, placebo- and diet-controlled study which measured the 6d balance of Cu and Fe and seven other essential trace metals, in twenty male T2DM and twenty age-matched control subjects in whom we later probed systemic metal balance with oral TETA. Basal urinary output and balance of Cu and Fe was significantly elevated in diabetes, and the two output values correlated strongly (p<0.05). TETA did not change the metabolism of Mg and six other essential trace metals monitored. Trial 3 examined the dose-response effect of TETA, at and below the dose given to patients with the Wilson???s disease over a 7d period, on Cu and eight other trace metals in a subgroup of seven T2DM and seven control subjects who had completed trial 1. The results of this i i trial showed that there was a linear dose-response relationship over the dose range 300~2400 mg/d on urinary Cu excretion in both T2DM and control subjects. However, there was no significant difference between the two subject groups at any of the four doses tested. In addition, 300mg/d of TETA was effective in mobilizing Cu in both T2DM and healthy control subjects. Trial 4 described the full work-up of a sensitive LC-MS methodology to identify and quantify TETA and its metabolite(s) in human urine. Using the LC-MS, TETA metabolism and excretion was investigated by analysing the urine of seven T2DM and seven control subjects who received escalating doses of TETA (samples obtained from trial 3). I have successfully identified and characterised two major metabolites of TETA in the urine of both T2DM and control subjects, N1-monoacetytriethylenetetramine (MAT) and diacetytriethylenetetramine (DAT), the latter which has not been previously reported. The results from urinary TETA excretion analyses also showed that T2DM may metabolise TETA more extensively than control subjects, which in turn is associated with its higher uptake or bioavailability. Urinary Zn excretion was mainly linked with urinary TETA and MAT in T2DM and healthy controls, respectively, whereas urinary Cu excretion was associated with urinary TETA excretion in healthy controls and urinary TETA+MAT excretion in T2DM subjects. These results suggest that MAT may also be involved in the mechanism by which TETA extracts systemic free Cu in diabetes. The identification of the two major metabolites of TETA and the development of a robust analytical LC-MS methodology reported in this study is an important step to further investigate the pharmacological actions of TETA in diabetic individuals. Collectively, the results presented in this thesis and in association with previous animal and clinical studies from our laboratory have provided consistent supporting evidences for the use of TETA clinically as a safe and effective therapy to prevent the genesis of some diabetic complications, in conjunction with conventional complication modifying therapies.

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  • Aroha mai: nurses, nursing and mental illness

    Kidd, Jacqueline Dianne (2008)

    Doctoral thesis
    The University of Auckland Library

    This research takes an autoethnographical approach to exploring the connections between being a nurse, doing nursing work, and experiencing a mental illness. Data is comprised of autoethnographical stories from 18 nurses. Drawing on Lyotard???s (1988) postmodern philosophy of ???regimes of phrases??? and ???genres of discourse,??? the nurses??? stories yielded three motifs: Nursing, Tangata Whaiora (people seeking wellness) and Bullying. Motifs are recurring topical, emotional and contextual patterns which have been created in this research by means of the formation of collective stories from the content of the nurses??? stories, artwork, fictional vignettes and poetry. Interpretation of the motifs was undertaken by identifying and exploring connected or dissenting aspects within and between the motifs. Using Fine???s (1994) notion of hyphenated lives, the spaces between these aspects were conceptualised as hyphens. The Nursing motif revealed a hyphen between the notion of the nurses as selfless and tireless carers, and the mastery requirements of professionalism. The nurses??? hope for caring, belonging, expertise and ???goodness??? were also features of the nursing motif. The Tangata Whaiora motif revealed the hyphen between being a compliant patient and a self-determined person seeking wellness, and also foreshadowed the notion that the nursing identity does not ???permit??? the dual identities of nurse and tangata whaiora. This research has found that nurses who have experienced, or are vulnerable to, mental illness negotiate a nexus of hyphens between societal, professional and personal expectations of the nurse. Ongoing unsuccessful negotiation of their identities is exhausting and leads to enduring distress. At times, negotiation is not possible and the nurse is immobilised in a differend of silence and injustice. At such times, the only resolution possible for the nurse is to leave the nursing profession. Bullying surfaced as a feature of the hyphen between the nursing and tangata whaiora identities, as well as being a part of each identity as colonising, silencing and/or discriminatory acts. Successful negotiation between and among the nursing and tangata whaiora hyphens requires a radical restructuring of the nursing image and culture across the education, workplace and personal/clinical areas. Three strategies are proposed for the discipline of nursing to achieve this change: transformatory education, a conscientisation programme, and mandatory emancipatory clinical supervision.

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  • Severe speech and language difficulties in school aged children from language unit and mainstream settings: A qualitative study of parental experiences

    Fraser, Kelly; Purdy, Suzanne (2008)

    Conference item
    The University of Auckland Library

    Conference details: Reflecting Connections 2008, the second conference jointly hosted by the New Zealand Speech-Language Therapists Association and Speech Pathology Australia. Held at the SKYCITY Convention Centre in Auckland, New Zealand, from the 25th to the 29th of May, 2008. http://www.reflectingconnections.co.nz/ Semi-structured interviews were conducted with sixteen parents to investigate their experiences of having a child with a severe speech and language disorder. Seven parents had children in primary mainstream education, seven had children in a language unit setting within a primary school, and two parents of older children completing their education took part. Content and thematic analyses were performed on the transcribed data. Nine key content areas were identified in the transcriptions of parents whose children were in both educational settings: early intervention, pathways, experience of language unit, experience of mainstream, other educational settings, support, parental involvement, impact on family, and optimising outcomes. A thematic analysis identified the following themes that describe the parents??? experiences and perceptions: (1) seeking support, (2) optimising solutions/finding a best fit, (3) concern for the future, (4) satisfaction/dissatisfaction with school, (5) access to support, (6) relationships, and (7) ???idealised??? solutions/finding a perfect world.

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  • The great dedicatory inscription of Ramesses II: A Solar-Osirian tractate at Abydos

    Spalinger, Anthony (2009)

    Book
    The University of Auckland Library

    This volume cover the interaction of a major historical event with the development of the Egyptian Solar-Osirian theology. Pharaoh Ramesses II visited the sacred area of Abydos soon after his recognition of power at Luxor in Thebes. With him were many high officials, one of whom would be soon appointed to be the high Priest of Amun at Thebes, Nebwenenef. During his visit, the king stressed his personal relationship with his father, Seti I as well as ordering the completion of his temple. By analyzing certain passages within Ramesses' official account, the "Dedicatory Inscription", with others of Seti, a more nuanced appreciation of the growing theological system of Osirus plus Re, the sun god, comes to the fore. This significance of this is heightened when we remember that the king's account was exhibited in the portico of Seti I's temple.

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  • Integrating Teachers' Conceptions: Assessment, Teaching, Learning, Curriculum and Efficacy

    Brown, Gavin (2008)

    Book item
    The University of Auckland Library

    How teachers' beliefs about assessment, teaching, learning, curriculum, and efficacy relate to each other is not well understood. The general stereotype proposes a dichotomy between a teacher transmission of surface content for accountability conception and a leaner-centered, deep learning assessed for formative purposes approach. ...

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  • Experimental analysis of the psychological effect of head injury

    Gronwall, D. M. A. (Dorothy M. A.) (1972)

    Doctoral thesis
    The University of Auckland Library

    Restricted Item. Print thesis available in the University of Auckland Library or may be available through Interlibrary Loan. The purpose of this study was to investigate the immediate consequences of concussion. Previous work had either concentrated on memory defects only, included cases of cerebral damage as well as concussion, or examined residual defects persisting after the period of impaired consciousness had ended. It was hoped to determine which function or functions might be affected in concussion by testing only young adult cases of 'pure' concussion in the immediate post-traumatic period. In the main experiment a paced serial addition task was administered to a mildly concussed (MC) and seriously concussed (SC) group at twenty-four-hourly intervals during the hospital period, and thirty to forty days after discharge. A normal control and hospital control group were given the task at similar time intervals. Recent concussion impaired performance and SC Ss needed almost five times as long as controls to process each correct response while MC Ss were about twenty per cent slower, However, responses were qualitatively similar in all groups, and concussed Ss differed only in producing many more late response errors. At retest the MC group had regained control level, but although SC Ss had significantly improved PASAT scores they were still poorer than the other three groups. Experiments II and III investigated stages in the information transmission process which may have produced restricted information processing shown by PASAT results. Reaction and movement times were not longer than normal, although central processing time was. MC Ss did not have significantly slower non-symbolic RTs, or symbolic two- and four-choice RTs, but they differed significantly from controls on eight- and ten-choice symbolic trials. Again this difference between groups was not found at retest four weeks later. Results suggested inefficient 'pigeon-holing' (Broadbent, 1971) as a possible factor in reduced information transmission following concussion. However, a message repetition task indicated no difference between concussed and non-concussed Ss in use of this mechanism. Message repetition also demonstrated that patients had no difficulty in auditory perception of verbal material. In the third stage, normal Ss were given message repetition with and without a concurrent distracting task. Performance during distraction was sufficiently similar to that of recently concussed Ss to suggest that the patient group may have been poorer than controls on the same task only because they also had reduced processing capacity. When given PASAT with a secondary paced task, performance of another group of normal Ss was almost identical to concussed Ss in the first experiment. Finally, to test the possibility that reduced processing capacity was the result of increased distractability, that is, processing task-irrelevant stimuli, an attention task (speech shadowing) was given to a small group of MC Ss and normal controls. There were no instances of intrusions or interference from an irrelevant message to indicate a defect in selective attention, although MC Ss had significantly lower shadowing scores. It was concluded that reduction in processing capacity produced by concussion was a function of patients' lower level of arousal, and that performance resembled that reported in the literature from sleep-deprived Ss and cases of brain-stem damage or dysfunction. A feature of results was the extremely competent performance exhibited by concussion patients, given a reduction in total capacity. Similar optimizing behaviour was evident during distraction tasks, and it was suggested that ability to monitor and control distribution of available processing space by instructions ('set') is a general characteristic of ordered behaviour. This ability was not disturbed by degrees of concussion sustained by experimental Ss in this study. Amnesic symptoms of the immediate post-traumatic period were considered in terms of lowered arousal level. It was proposed that these might be explained by a combination of two factors: (i) processing space insufficient to store items while responding to them, and (ii) tagging of items in storage with levels of concurrent background activity, and thus 'state-dependent' memory. Evidence for a processing deficit existing after termination of the period of PTA was reviewed, and the possibility of permanent effect in terms of increased disability following repeated concussions. Some aspects of results important in considering rehabilitation programmes for head-injured patients were noted.

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  • Teachers' self-reported assessment practices and conceptions: Using structural equation modelling to examine measurement and structural models.

    Brown, Gavin (2009)

    Book item
    The University of Auckland Library

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  • Interaction of fruit fibres and antioxidants in bread

    Satchithananthasivam, Anusooya; Perera, Conrad; Quek, Siew-Young; Sun-Waterhouse, D (2009)

    Conference item
    The University of Auckland Library

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  • Results from the Australian arm of an international RCT of a Brief Intervention for Illicit drug use linked to the scores on the Alcohol, SMoking abn Substance Involvement ScreeningTest (ASSIST)

    Dennington, V; Humeniuk, RE; Newcombe, David; Ali, R; Vial, R (2007)

    Report
    The University of Auckland Library

    This report presents the findings from the Australian component of the international World Health Organisation ASSIST (Alcohol, Smoking and Substance Involvement Screening Test) Phase III Screening and Brief Intervention study. Abbreviated

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  • New antifungal and antibacterial compounds: 1,3-oxazoline- and 1,3-oxazolidine-2-thiones

    Oliveira, Maria; Justino, J; Silva, S; Tatibouet, A; Rollin, P; Rauter, AP (2009-01-20)

    Conference poster
    The University of Auckland Library

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  • A Primer on Modular Mass-Action Modelling with CellML

    Cooling, Michael (2010)

    Book item
    The University of Auckland Library

    CellML is a model exchange format designed to greatly facilitate the communication of models. Here we provide a primer on modelling mass-action kinetics with CellML and discuss some of the language features for structuring models. We illustrate these with examples of simple reactions, from which we build a basic biochemical system. We explore some best practices for structuring the models to greatly aid model reusability, as well as communication, and provide information on interacting with the CellML research community. CellML source code for the models in this chapter can be found online at the CellML model Repository (Lloyd et al. 2008), at http://models.cellml.org/workspace/modularmassactionprimer.

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  • Effect of reinforcing steel bond on the seismic performance of lightly reinforced concrete walls

    Patel, VJ; Van, BC; Henry, Richard (2014-03-21)

    Conference item
    The University of Auckland Library

    During the Canterbury earthquake series, several reinforced concrete (RC) walls formed a limited number of cracks at the wall base as opposed to the expected distributed cracking in ductile plastic hinge regions. The ductility of a lightly reinforced concrete wall is dependent on the distribution of cracks, as well as the reinforcement bond and yield penetration at each crack. A series of experimental tests were conducted to investigate how the bond characteristics of reinforcing steel would influence the yield penetration and crack distribution in lightly reinforced concrete members. To vary the bond characteristics, reinforcement with three different deformation patterns were investigated, including a standard deformation pattern and two modified bars with either half the rib height or double the rib spacing of a standard bar. Pull out tests were conducted to quantify the bond strength of the reinforcement with different deformation patterns, followed by direct tension tests of prisms that represented the end region of an RC wall with minimum vertical reinforcement. The pull out tests indicated that halving the rib height and doubling the rib spacing had similar effects of reducing the reinforcement bond strength. The direct tension tests showed similar crack patterns for the two modified bar types, but increased secondary cracking for the standard bar due to the higher bond strength. However, only the half rib height bar displayed a higher ductility than the standard bar, with significantly greater yield penetration at each crack. Using half rib height bars as vertical reinforcement would potentially improve the ductility of lightly reinforced concrete walls.

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  • Bibliography. Cultural Diversity: Issues for Social Work in New Zealand 1990-2010

    Bingham, Patricia (2011)

    Report
    The University of Auckland Library

    This bibliography attempts to bring together research and literature relevant to multicultural and indigenous social work practice in New Zealand.

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  • Topics on Structural Transformation and Economic Development

    Bah, El-Hadj (2008)

    Doctoral thesis
    The University of Auckland Library

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  • Overview of outcomes, trends and issues from the EEPiSE project involving ten schools from Gisborne to Northland

    Walker, Joanne (2006)

    Conference item
    The University of Auckland Library

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  • Cytokinins and the division or expansion of plant cells

    Beuning, Lesley L. (1988)

    Doctoral thesis
    The University of Auckland Library

    The effect of cytokinins was studied in three systems: the alga Chlorella, callus cultures and etiolated cucumber cotyledons. In Chlorella cultures: 1) A range of concentrations of 6BA and IP had no effect on growth; 2) Low concentrations of an anticytokinin had no effect on growth, whereas higher concentrations appeared to be inhibitory. 3) Characterisation of the Chlorella species suggested that it was surrounded by an impermeable sporopollenin layer which hindered the uptake of cytokinin. 4) The uptake of radioactive adenine occurred readily, whereas the uptake of radioactive 6BA was very slow in both growing and saturated cultures of Chlorella. 5) Extracts isolated from Chlorella and the medium in which Chlorella was growing contained cytokinin-like activity in two bioassays. 6) HPLC analyses of these extracts showed that there were fractions which eluted at the positions of IP and IPA. In callus cultures: A.1) A carrot callus was grown from the secondary phloem of the storage root of carrot. 2) This callus, which was grown on 2,4-D and kinetin, produced roots and shoots when subcultured onto IAA and kinetin. 3) Growth on 2,4-D alone was independent of the presence of kinetin. 4) Growth was inhibited in the presence of an anticytokinin, suggesting that the callus produced a cytokinin. B.1) A tobacco callus was grown from a young leaf of tobacco. 2) This callus habituated to cytokinin independence following subculture onto lower concentrations of kinetin. 3) Subculture of the habituated callus onto a higher concentration of kinetin resulted in the production of roots and shoots. C.1) Cytokinin-dependent soybean and tobacco callus cultures were obtained from the Botany Department, University of Otago. 2) Analysis of the total proteins from suspension and callus cultures of soybean by 1-D polyacrylamide gel electrophoresis showed one small 6BA-induced change in the proteins from the suspension cultures. In etiolated cucumber cotyledons: 1) 6BA caused the expansion of excised etiolated cucumber cotyledons after a 24h-hour incubation in the dark in a solution containing 6BA, in comparison to cotyledons incubated in water only. 2) The cotyledons curved upwards and in the light microscope the cells of the vascular bundles and the lower epidermis exhibited greater expansion than the upper epidermis. 3) Electron microscopic examination showed that the central vacuole of palisade cells from cotyledons treated with 6BA had expanded and that the cytoplasm had probably lost water and was compressed by the vacuole against the cell wall. 4) In contrast to other research, there was no apparent increase in polysome formation in 6BA-treated cotyledons in comparison to untreated cotyledons examined in the electron microscope. 5) A number of protein extraction methods were tried before a method was found which produced a protein extract suitable for both 1-D and 2-D polyacrylamide gel electrophoresis analyses. 6) 1-D and 2-D polyacrylamide gel electrophoresis showed that a number of proteins either increased or decreased following the treatment of cotyledons with 6BA. 7) A number of RNA extraction methods were tried, to obtain RNA suitable for translation in vitro. Only one method produced RNA which appeared to be free of contaminating substances. Weak translation of this RNA was obtained in vitro and it might be possible to develop conditions for optimal translation of the RNA given an adequate supply of an in vitro translation system.

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  • Variation of head injuries by ethnic background

    Gilthorpe, MS; Bedi, R; Lay-Yee, R (1997)

    Conference item
    The University of Auckland Library

    The aim was to examine variations by ethnic background, or people who use government funded secondary services for emergency treatment of injuries to the head, during 1995 - the first year of mandatory ethnic monitoring within United Kingdom (UK) hospitals. Inpatient activity data from 6 contiguous UK District Health Authorities (approx. 2 million population), with large black and minority ethnic communities (approx. 360,000), were combined with demographic details of the 1991 national census. For the first six months of ethnic monitoring, hospital inpatient activity comprised some 65,524 emergency consultations, of which 1,927 (2.9%) were for injuries to the head. These injuries were generally over three times as common amongst males (chi-squared: p<0.001). Furthermore, it was observed that the incidence of these injuries remained high amongst older black males and were also more common amongst the Indian male community (aged 55 and over). In conclusion, clear differences in service utilisation for head injuries exist for different minority ethnic groups. In particular, black males aged between 25 and 34 years are more likely to present as emergencies with head injuries than any other ethnic group, and this feature is sustained by the older male black community.

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  • Studies on the Metabolism of Plant Cells in Tissue Culture

    Bellamy, A. R. (1965)

    Doctoral thesis
    The University of Auckland Library

    1. A tobacco cell-suspension tissue culture system derived from pith cells of Nicotiana tabacum L. var Wisconsin 38 was established. This system was used to study methods of purifying nucleic acids, phosphate ester and nucleic acid metabolism in cells subjected to nutritional shifts, and problems relating to the control of cell division in plant cells. 2. Cell cultures consisting of single cells, groups of cells and small aggregates were maintained in liquid medium on rotary shakers. Cultures exhibited an exponential growth period during which the cell generation time was 2, 3 days. 3. Cells removed from culture medium and resuspended in dilute inorganic salt solutions (step-down nutritional shift) exhibited marked changes in their phosphate and sulphate accumulation rates and in phosphate ester metabolism, but not in the type and rate of respiration. 4. Such metabolic responses to culture shifts were not related to cell damage or shock effects, but appeared to be a feature of changes in the nutritional environment of cells. The response of cells to a step-down nutritional shift was maximal at exponential- and late-stationary phases of culture growth. Step-up nutritional shifts (resuspending cells in enriched culture medium) produced some effects similar to those found for step-down cells. Actinomycin D did not prevent the phosphate accumulation response of cells to culture shifts, and was shown to inhibit only 50 per cent of the synthesis of rapidly-labelled ribonucleic acid. 5. RNA prepared from tobacco cells or rat liver by conventional phenol extraction was contaminated with other materials which composed as much as sixty per cent of the weight of the total preparation. RNA prepared from (32P) tobacco cells contained minor radioactivity in RNA but major radioactivity in a wide range of contaminating phosphate esters of high specific radioactivity. 6. Purification of RNA by the Kirby two-phase partition procedure removed most major contaminants but failed to remove (32P) phosphate esters. The procedure also resulted in degraded RNA. 7. A new method was developed for the purification of RNA prepared by the phenol procedure. It involved recovery of RNA from the upper phase of the two-phase Kirby extraction mixture by precipitation as the cetyltrimethylammonium (CETA) salt instead of by dialysis. This procedure reduced manipulation times and much more effectively removed RNAase and (32P) phosphate esters from the RNA. 8. TMV-RNA prepared by the new procedure was fully infectious. RNA prepared and purified from a mixture of whole rat liver and TMV was almost equally as infectious as RNA prepared from TMV alone. Infectivity of purified RNA, prepared from a mixture of tobacco cells and TMV, was stable in solution at 30??C for four hours. TMV-RNA prepared in this way and stored at -12??C in vacuo over P2O5 retained infectivity for at least 6 months. 9. Extraction of (32P) exponential-phase cells by aqueous phenol plus detergent released only RNA with the ribosomal type of base composition. Similar extractions in the presence of high salt concentrations released this RNA together with DNA and rapidly-labelled RNA. 10. During short treatments with (32P) orthophosphate, exponential-phase cells synthesised RNA with a base composition intermediate between that of ribosomal RNA and DNA. Cells subjected to a step-down nutritional shift prior to treatment with (32P) orthophosphate, synthesised RNA with a base composition close to that of tobacco DNA. 11. Following treatment times with (32P orthophosphate, or (32P) plus (3H) uridine, and following a step-down or steady-state nutritional shift to non-radioactive medium, tobacco cells exhibited the following changes in phosphate ester and RNA metabolism:- a. Changes in the levels of radioactivity present in the nucleoside triphosphate RNA precursors and other phosphate esters. b. A reduction in the rate of increase of specific radioactivity of RNA of step-down cells, followed by a subsequent recovery. c. Changes in the (32P) base composition of the RNA synthesised following the culture shift. d. Changes in the radioactive sedimentation profiles of RNA. 12. Extracts prepared from exponential-phase tobacco cells contained cytokinin (cell division stimulant) activity. Fractionation of cells, and bioassay of levels of cytokinins present in the various fractions, demonstrated the presence of soluble compounds with cytokinin activity in cell debris and cytoplasmic fractions, but not in the nuclear fraction. 13. Unhydrolysed (polymeric) tobacco nucleic acids (RNA plus DNA), prepared from exponential-phase tobacco cells, showed no cytokinin activity. A ribonucleotide mixture prepared by alkaline hydrolysis of these tobacco-cell nucleic acid preparations, mixtures of purified ribonucleotides, or a mixture of tobacco deoxyribo- and ribonucleosides resulting from snake-venom digestion, contained no activity. Deoxyribonucleotides were inhibitory. 14. A ribonucleotide mixture prepared by alkaline hydrolysis of RNA isolated from rat liver and sheep liver, contained cytokinin activity. Deoxyribo- and ribonucleoside mixtures resulting from snake-venom digestion of sheep-liver RNA and DNA contained similar levels of cytokinin activity to that found in extracts prepared by alkaline hydrolysis.

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