Chlamydia trachomatis: quantification, immunological investigation and co-infection with HIV-1

Three aspects of Chlamydia trachomatis translational research were explored in this thesis. Firstly, as over 75% of patients with LGV are also HIV-1 sero-positive, a cell-culture model was established to investigate whether HIV-1 altered the replication of C. trachomatis serovar L2 in vitro. Inclusion size was significantly increased in the presence of HIV-1, but there was no significant alteration in chlamydial growth kinetics, infectivity, morphology, or transcription of 16sRNA, ompA or euo, suggesting that viral co-infection did not induce chlamydial persistence. It is, therefore, unlikely that the association of HIV-1 and LGV in vivo is due to an impact of HIV-1 on chlamydial replication in co-infected cells. Secondly, as there is no information on the chlamydial load shed by individuals with a rectal C. trachomatis infection, a qPCR assay was developed and used to determine the number of C. trachomatis organisms per rectal swab in NAAT-positive patients. The geometric mean chlamydial load was 5.0 x 105 organisms per swab (Standard Deviation, 152) and load was associated with proctitis, but not symptoms or HIV-1 infection. Asymptomatic individuals shed as much C. trachomatis as patients with rectal symptoms and might maintain transmission in the community. Finally, an ex vivo IFN-γ ELISpot assay was developed to characterise human cellular immune responses to the C. trachomatis-specific protein, Pgp3. T-cell epitopes were found along the length of the protein, but the magnitude of the immune responses was low. The Pgp3- induced IFN-γ response correlated with C. trachomatis exposure and was dynamic, decreasing after effective treatment. These observations suggest that Pgp3- induced IFN-γ may be useful as a biomarker for current infection, although the sensitivity and specificity of the ELISpot assay need improvement

Feasibility Study of Laser-Fabricated Micro-Needles as an Electrospray Thruster

Capable of carrying small-scale instruments, micro-satellites, often called CubeSats for their shape, provide an excellent platform for a variety of educational and research missions. However, once placed in orbit satellites experience small amounts of drag that slow the craft down, and deteriorate its orbit over time. The addition of a propulsion system will allow a CubeSat to correct and maintain orbit, as well as perform other maneuvers. Due to their size and power requirements, CubeSats cannot accommodate conventional propulsion methods. Instead, these satellites rely on electric propulsion to provide a compact, low power thruster for making orbital adjustments. Of particular interest to this research are electrospray thrusters. Because of their size, electrospray thrusters can easily be clustered together to form large arrays to make up for the small amounts of thrust, making them ideal for CubeSats.Microfabrication techniques developed at UTSI allow preparation of arrays of emitters suitable for electrospray applications, and exhibiting critical dimensions that can potentially enable smaller, denser arrays requiring less space and power. In this work, these needles were modeled and simulated under an applied voltage to determine if they can be used as electric field enhancers in a thruster. Using procedures established from references, the optimal emitter spacing was also determined

Reserve Bank Operations in the Foreign Exchange Market: Effectiveness and Profitability

Since the float of the Australian dollar in December 1983, the Reserve Bank has intervened in the foreign exchange market in order to exert a stabilising influence. Whether this intervention has been stabilising cannot be directly observed since the behaviour of the exchange rate in its absence cannot be known. However, there are a number of ways of assessing it indirectly. The best known is the Friedman “profits test”. Friedman (1953) argued that a central bank which was stabilising the exchange rate would tend to buy foreign exchange when its price was low, and sell when its price is high, and hence its operations would be profitable. This paper applies the profits test to the Bank’s foreign exchange operations since the exchange rate was floated. The main conclusion is that over this period the Bank’s foreign exchange operations have produced total profits of around $A3.4 billion, suggesting that intervention has tended to be stabilising. Other statistical tests developed by Wonnacott (1982) and Mayer and Taguchi (1983), also presented in this paper, support this conclusion.

Defining the complementarities between antibodies and haptens to refine our understanding and aid the prediction of a successful binding interaction

Acknowledgments The authors would like to thank the Scottish Universities Life Sciences Alliance (SULSA) for their support.Peer reviewedPublisher PD

Quantitative Dynamic Contrast Enhanced Magnetic Resonance Imaging for Evaluation of the Myocardium in Ischaemic Heart Disease

Background: Use of contrast enhanced cardiac magnetic resonance imaging (MRI) for identification of focal pathology (perfusion deficit and scar) is widespread. Quantitative analysis of dynamic contrast enhanced (DCE) MRI data may allow objective assessment of focal and diffuse disease. However it is a complex process and not widely adopted outside the research domain. For accurate quantification temporal variation in relative contrast agent concentration in the myocardium and feeding blood supply must be measured. While MRI signal intensity can be used as a probe of contrast agent concentration its response is non-linear. Aims: In this thesis non-linearity correction methods for quantitative myocardial DCE-MRI are compared, the feasibility of a novel bookend T1 based correction is tested and the method is used in clinical studies to assess myocardial characteristics in health and ischaemic disease. Methods: Signal non-linearity correction methods were compared using simulation, phantom experiments and a volunteer study. Methods compared were independent sampling strategies (dual-bolus and dual-sequence), previously proposed model based correction (native T1 or proton density weighted image based) and bookend T1 based correction which is proposed as a method to account for imperfect magnetisation preparation. The feasibility of the bookend T1 method was tested and characteristics of heathy and diseased myocardium were assessed in clinical studies of ischaemia and infarction. Conclusions: Native T1 based correction has been found to be highly sensitive to imperfect magnetisation preparation, and is thus recommended against. Model based correction using proton density weighted images or bookend T1 data have been found to be more accurate and precise than dual-sampling methods. The clinical studies have demonstrated the feasibility of the bookend T1 based method and have yielded insights into myocardial characteristics in a range of conditions

The Air-temperature Response to Green/blue-infrastructure Evaluation Tool (TARGET v1.0) : an efficient and user-friendly model of city cooling

The adverse impacts of urban heat and global climate change are leading policymakers to consider green and blue infrastructure (GBI) for heat mitigation benefits. Though many models exist to evaluate the cooling impacts of GBI, their complexity and computational demand leaves most of them largely inaccessible to those without specialist expertise and computing facilities. Here a new model called The Air-temperature Response to Green/blue-infrastructure Evaluation Tool (TARGET) is presented. TARGET is designed to be efficient and easy to use, with fewer user-defined parameters and less model input data required than other urban climate models. TARGET can be used to model average street-level air temperature at canyon-to-block scales (e.g. 100 m resolution), meaning it can be used to assess temperature impacts of suburb-to-city-scale GBI proposals. The model aims to balance realistic representation of physical processes and computation efficiency. An evaluation against two different datasets shows that TARGET can reproduce the magnitude and patterns of both air temperature and surface temperature within suburban environments. To demonstrate the utility of the model for planners and policymakers, the results from two precinct-scale heat mitigation scenarios are presented. TARGET is available to the public, and ongoing development, including a graphical user interface, is planned for future work

Experimental Violation of Two-Party Leggett-Garg Inequalities with Semiweak Measurements

We generalize the derivation of Leggett-Garg inequalities to systematically treat a larger class of experimental situations by allowing multiparticle correlations, invasive detection, and ambiguous detector results. Furthermore, we show how many such inequalities may be tested simultaneously with a single setup. As a proof of principle, we violate several such two-particle inequalities with data obtained from a polarization-entangled biphoton state and a semiweak polarization measurement based on Fresnel reflection. We also point out a nontrivial connection between specific two-party Leggett-Garg inequality violations and convex sums of strange weak values

The Stronger Downregulation of in vitro and in vivo Innate Antiviral Responses by a Very Virulent Strain of Infectious Bursal Disease Virus (IBDV), Compared to a Classical Strain, Is Mediated, in Part, by the VP4 Protein

IBDV is economically important to the poultry industry. Very virulent (vv) strains cause higher mortality rates than other strains for reasons that remain poorly understood. In order to provide more information on IBDV disease outcome, groups of chickens (n = 18) were inoculated with the vv strain, UK661, or the classical strain, F52/70. Birds infected with UK661 had a lower survival rate (50%) compared to F52/70 (80%). There was no difference in peak viral replication in the bursa of Fabricius (BF), but the expression of chicken IFNα, IFNβ, MX1, and IL-8 was significantly lower in the BF of birds infected with UK661 compared to F52/70 (p < 0.05) as quantified by RTqPCR, and this trend was also observed in DT40 cells infected with UK661 or F52/70 (p < 0.05). The induction of expression of type I IFN in DF-1 cells stimulated with polyI:C (measured by an IFN-β luciferase reporter assay) was significantly reduced in cells expressing ectopic VP4 from UK661 (p < 0.05), but was higher in cells expressing ectopic VP4 from F52/70. Cells infected with a chimeric recombinant IBDV carrying the UK661-VP4 gene in the background of PBG98, an attenuated vaccine strain that induces high levels of innate responses (PBG98-VP4UK661) also showed a reduced level of IFNα and IL-8 compared to cells infected with a chimeric virus carrying the F52/70-VP4 gene (PBG98-VP4F52/70) (p < 0.01), and birds infected with PBG98-VP4UK661 also had a reduced expression of IFNα in the BF compared to birds infected with PBG98-VP4F52/70 (p < 0.05). Taken together, these data demonstrate that UK661 induced the expression of lower levels of anti-viral type I IFN and proinflammatory genes than the classical strain in vitro and in vivo and this was, in part, due to strain-dependent differences in the VP4 protein