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Interactions between a saprotroph and a mycorrhizal fungus of Sitka spruce in a model systemJones, L. R. January 1988 (has links)
In microcosms, <i>Picea sitchensis</i> seedlings were grown aseptically in perlite + vermiculite with NH<SUB>4</SUB>-N or NH<SUB>4</SUB>NO<SUB>3</SUB>-N, with an ectomycorrhizal fungus, <i>Lactarius rufus</i> and/or a saprotrophic fungus <i>Hygrophoropsis aurantiaca</i>. Total and fluorescein diacetate (FDA) active hyphal length, mycorrhizal infection and plant dry weight were measured (8 to 16 weeks). In perlite with NH<SUB>4</SUB>-N, total hyphal length of extramatrical mycelium (EMM) produced by <i>L. rufus</i> was 693 m gdwt perlite or 47 m per mycorrhizal root-tip. This was reduced to 141 m gdwt in the presence of <i>H. aurantiaca</i>. Nutrient solution pH and plant growth were also reduced. In liquid culture, acidification of the medium (H<SUP>+ </SUP> equivalent) per NH<SUB>4</SUB> ion uptake was ≤ 3.8 times greater for <i>H. aurantiaca</i> than <i>L. rufus</i>. Growth (dwt) of <i>H. aurantiaca</i> was inversely related to pH. Growth of <i>L. rufus</i> was unaffected by pH 2.7 to 5.0. In perlite + vermiculite with NH_4-N, <i>L. rufus</i> hyphal length was unaffected by the presence of <i>H. aurantiaca</i>. In this experiment, no mycorrhizas formed in treatments with NH_4NO_3-N and EMM production by <i>L. rufus</i> was greatly reduced compared to treatments with NH_4-N. In a different experiment with NH_4NO_3-N, total hyphal length of EMM for <i>L. rufus</i> grown alone was apparently greatly reduced, (compared with an experiment with NH_4-N) but was increased in the presence of <i>H. aurantiaca</i>. Plant dry weight was also increased in the presence of <i>H. aurantiaca</i> with perlite + vermiculite. Total hyphal length of <i>H. aurantiaca</i> was not affected by the presence of <i>L. rufus</i> in any experiment. FDA-active hyphal length of both fungi decreased or remained constant and was 1% to 3% of total hyphal length at a week 16. Percentage mycorrhizal root-tips was similar between treatments at week 16 but differences occurred at weeks 8, 10 and 12 which suggested an inverse relationship between % infection and pH.
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Regulation of chitin synthesis in Candida albicansSchofield, David Alexander January 1994 (has links)
The study of the regulation of chitin synthesis in the pathogen <i>Candida albicans</i> is a challenging field. It not only offers a possibility of a better understanding of the dimorphic transition but also may help in the development of an effective antifungal. The suggestion that the regulation of cell wall synthesis may be closely coupled to the turgor pressure of the fungus has been investigated. The synthesis of chitin by the enzyme chitin synthase was studied under conditions of osmotic stress. Mixed membrane fractions from protoplasts of <i>C.albicans</i> incubated in medium of low osmolality exhibited up to four-fold greater native enzyme activity as compared to protoplasts incubated at high osmolality. This was also the case for preparations from whole cells of <i>C.albicans</i>, <i>Coprinus cinereus</i> and <i>Saccharomyces cerevisiae</i> and also from protoplasts from <i>S.cerevisiae</i>. Trypsin-treated enzyme preparations did not show this regulation to the same degree. The addition of nikkomycin Z, a differential chitin synthase inhibitor, partially restored this regulation. The synthesis of chitin, assessed by following the incorporation of (<sup>14</sup>C)-GlcNAc into chitin in the cell wall, was also greater in <i>C.albicans</i> cells incubated in medium of low osmolality. However, the incorporation of (<sup>14</sup>C)-GlcNAc into the cell wall of regenerating protoplasts exhibited the opposite effect. This was substantiated further by measuring the fluorescence of regenerating protoplasts following the addition of Calcofluor white. Following the attempted cloning of the <i>C.albicans</i> <i>CHS3 (CSD2</i>) gene, a detailed northern analysis of three chitin synthase genes during growth and dimorphism of <i>C.albicans</i> was performed. <i>CHS1</i> was expressed during both the yeast and hyphal phases of growth while <i>CHS2</i> and <i>CHS3</i> were preferentially expressed in the hyphal form. There was no difference in expression of the chitin synthase genes in invasive and non-invasive clinical isolates of <i>C.albicans</i> and all three genes showed highest levels of mRNA when grown in medium of neutral pH.
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The immune response of the grey mullet, Chelon labrosus (Risso, 1826), to Cryptocotyle lingua (Creplin, 1825), (Digenea)Wood, Bradbury Patrick January 1990 (has links)
The ability of thick-lipped grey mullet to mount both humoral and cellular immune responses to Cryptocotyle lingua has been demonstrated here for the first time. Of the 3 procedures for immunisation investigated, namely exposure to live cercariae, intraperitoneal (ip) injection of whole killed cercariae and ip injection of a cercarial sonicate, the former gave the highest primary antibody titres with a peak response at 4 weeks post infection. Peak titres occurred at 5 and 7 weeks after immunisation by ip injection of sonicated cercariae and whole killed cercariae respectively. An enhanced secondary antibody response was observed following challenge by ip injection of sonicated cercariae. Cercariacidal activity, apparently involving complement, was detected in normal serum and enhanced in immune serum. However, the mechanism for complement activation remains uncertain. Parasite antigens were identified following separation by SOS-PAGE and immunoblotting using mullet and rabbit antisera. Mullet failed to respond to certain parasite proteins recognised by rabbit antiserum and in situ immunogold-silver staining demonstrated that mullet. immunised by exposure to live cercariae, were unable to recognise the metacercarial cyst wall. Migration and polarisation of pronephric leucocytes in vitro was enhanced following immunisation but cellular adherence to encysted and unencysted parasites was not observed. In vitro studies further demonstrated a possible role for fish serum in stimulating metacercarial encystment. The intensity of melanisation of the host capsule in metacercarial infections was increased in fish held in total darkness and with increased temperature. The rate of development of the metacercarial tegument and cyst wall and the associated host response was similarly affected by temperature and initial development was inhibited by prior immunisation via ip injection of sonicated cercariae. There was however, no evidence of protection against cercarial infection following such immunisation. These results are discussed in relation to mechanisms of immunity, metacercarial survival strategies and control of metazoan infections in fish.
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The diagnosis and management of bacteriuria in elderly subjectsFlanagan, Peter Gerald January 1989 (has links)
No description available.
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Activated macrophages: implications in HIV-associated disease pathogenesisKillebrew, Deirdre Anne January 2005 (has links)
Mode of access: World Wide Web. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 158-166). / Electronic reproduction. / Also available by subscription via World Wide Web / xiii, 166 leaves, bound col. ill. 29 cm. +
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Epidemiological studies of Yersinia enterocolitica in South Australia /Ormerod, Stephen. Unknown Date (has links)
Thesis (MAppSc)--University of South Australia, 1996
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Systematic reviews and economic evaluation of HIV behavioural interventions in China.Wang, Shuhong January 2007 (has links)
Title page, contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / This thesis focuses on behavioural interventions for preventing sexual transmission of HIV. The international literature on the evaluation of this type of intervention largely originates from developed countries and from Africa. China, where the AIDS epidemic is growing rapidly, lacks rigorous evaluation studies to determine the effectiveness of HIV prevention activities. This study develops a model to inform decision-making based on evidence generated in settings other than those for which policy is being developed. This model is illustrated through two case studies in China, the first on HIV/AIDS prevention strategies targeting young people, and the second on men who have sex with men. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1284184 / Thesis (Ph.D.) -- University of Adelaide, School of Population Health and Clinical Practice, 2007
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Evaluating monitoring strategies, short-term disease progression and rate of treatment change in HIV-infected patients commencing antiretroviral therapy in the Asia-Pacific regionSrasuebkul, Preeyaporn, Public Health & Community Medicine, Faculty of Medicine, UNSW January 2008 (has links)
This thesis assesses factors associated with a number of short and long-term outcomes in HIV-infected patients receiving antiretroviral treatment in Asia. Analyses in this thesis were based on two cohorts of HIV-infected patients; The Treat Asia HIV Observational Database (TAHOD), a multi-centre prospective observational cohort from countries in Asia-Pacific region, and the HIV Netherlands Australia Thailand (HIV-NAT) collaboration cohort, a cohort of patients treated with antiretroviral treatments at HIV-NAT in Bangkok, Thailand. We examined factors associated with time to immunological failure endpoints, such as CD4≤ 200 cells/??L, CD4≤ 100 cells/ ??L, and CD4 return to baseline, and with the virological failure endpoint, detectable viral load defined as a value greater than 500 copies/mL. Multivariate Cox proportional hazard models were used. Results showed that CD4 count at baseline and changes in CD4 strongly predicted immunological failure. For virological failure, detectable viral load at baseline was the strongest predictor. As a step to developing simplified monitoring strategies, in which patients with a low risk of failure could have their monitoring CD4 count and viral load tests deferred, we developed predictive models for each immunological and virological failure endpoint. Models were developed on the HIV-NAT cohort, and validated on the independent TAHOD cohort. For predictive models, the complementary log-log transformation for each endpoint was fitted appropriate to the interval censored nature of the data. To assess goodness-of-fit, cut-offs were defined for the predicted risks that separated patients from low risk to high risk. Overall, the observed versus expected failures from HIV-NAT data agreed quite well across all endpoints, probably reflecting that the HIV-NAT database was the data we built the models upon. Not only did these models fit the HIV-NAT database well, they also discriminated patients from low to high risk groups. When we validated models with TAHOD data, the observed and expected failures agreed well only in the model for CD4 count return to baseline. For most of the endpoints, the predictive models overestimated the number of failures, with predicted values larger than observed. However, the proportions of failures were lowest in the low risk group and highest in the high risk group, indicating that our models did discriminate between patients at high and low risk, and that the predictive models might still be of use for the purpose of simplified monitoring strategies. With CD4 count and viral load monitoring tests now comprising a large component of the cost of HIV treatment in resource limited settings, we developed and assessed a simplified monitoring strategy that aimed to reduce the numbers of monitoring tests performed. The predictive models developed earlier were used to calculate the probabilities of failure in TAHOD patients. We assumed that patients would have their CD4 and viral load assessments annually, at baseline and at one year, predicted risk of failure at ensuing clinical visits, week 12, 24 and 36. For patients at low predicted risk of failure at ensuing clinical visits, we assessed the effect of deferring monitoring tests, both in terms of blood tests avoided, and in terms of delaying detection of failure in some patients. A number of levels for the predicted risk of failure that lead to deferral of testing were evaluated. The results suggested that predicted probabilities of failure of 10% - 20% gave the best results across all failure endpoints. These cut-offs could save a median of 598 (51.6%) (range 37 (2.6%)_-1,218 (81.9%) ) blood tests over the first year of treatment, but would fail to detect 29 (18%) (range 10 (7.4%) - 128 (39.3%) ) failures. The median time from failure to detection in those patients who did fail and had deferred monitoring tests was 28 weeks. Rates of antiretroviral treatment change in TAHOD were examined. We identified patterns and factors associated with the rate of treatment change. Median time to the first treatment change was 3.2 years. Factors predicting rate of treatment change in TAHOD were treatment combination, being on second or third combination, number of drugs available in each site and being an injecting drug user. The overall rate of treatment change in TAHOD was 29 per 1OO-person-year. Around 30% of patients stopped their treatment due to adverse events. These rates of treatment change are lower than have been seen in patients in western countries. This may be due to patients in developing countries having access to fewer antiretroviral drugs than patients in developed countries.
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The Biosynthesis of pyrimidines by escherichis coli.Back, Kenneth John Campbell. Unknown Date (has links)
No description available.
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The Biosynthesis of pyrimidines by escherichis coli.Back, Kenneth John Campbell. Unknown Date (has links)
No description available.
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