Bibliography: leaves 87-117. / vii, 117, [64] leaves, [8] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Indicates that PGE's and CsA may have similar modes of action. Findings suggest that therapies that selectively subpopulations of leucocytes, and manipulate the inflammatory mediators they produce, may be effective in the treatment of chronic immuno-inflammatory diseases similar to rheumatioid arthritis. / Thesis (Ph.D.)--University of Adelaide, Dept. of Pathology, 1994?

Along with an increasing understanding of the harmful effects on the environment of a wide range of pollutants has come the need for more sensitive, faster and less expensive detection methods of identification and quantitation. Many environmental pollutants occur in low levels and often in complex matrices thus analysis can be difficult, time consuming and costly. Because of the availability and easy cultivation of the microorganisms with potentially high specificity, there is considerable interest in the use of living microorganisms as the analytical component (the biocomponent) of sensors for pollutants. While a number of biosensors using bacteria have been developed, yeast has been comparatively rarely used as the biocomponent. Yeast are attractive because they are easy to culture and they are eukaryotes which means their biochemistry is in many respects closer to that of higher organisms. This thesis describes the development of whole cell bioassays that use yeast cells as a sensing element and redox mediators to probe the intracellular redox reactions to monitor the catabolic activity of the yeast resulting from the external substrate, steady-state voltammetry is utilised as the electrochemical detection technique. The isogenic differential enzyme analysis (IDEA) concept of Lincoln Ventures Limited, lead NERF funded research consortium uses bacteria that have been cultured using specific organic pollutants as the carbon source which are the biocomponent in sensors. The use of wild type yeast Arxula adeninivorans that has the ability to use a very wide variety of substrates as sources of carbon and nitrogen was used as an alternative to bacteria to validate the “IDEA” concept. Naphthalene and di-butyl phthalate were chosen as model target contaminant molecules. The performance, detection limits and the usefulness of yeast based biosensor applications for environmental analysis are discussed. This thesis also describes the development and optimisation of a simple, cost effective in vivo estrogens bioassay for the detection of estrogens using either genetically modified or a wild type yeast Saccharomyces cerevisiae. In this study, catabolic repression by glucose was exploited to achieve specificity to estrogens in complex environmental samples that eliminates the requirement for conventional sample preparation. This is the first time that the use of wild type yeast to quantify estrogens has been reported. The attractive features of the bioassay are its use of a non-GMO organism, its speed, its high specificity and sensitivity with a detection limit of 10-15 M. The similarity of binding affinities for major estrogens to those of human estrogens receptors makes this in vivo estrogen bioassay very useful for analytical/screening procedures. The electrochemical detection method also makes it easy to interface with a variety of electronic devices.

<p>The ability to physically interconnect many distributed, autonomous and heterogeneous software systems on a large scale presents new opportunities for sharing and reuse of existing, and for the creataion of new information and new computational services. However, finding and combining information in many such systems is a challenge even for the most advanced computer users. To address this challenge, mediator systems logically integrate many sources to hide their heterogeneity and distribution and give the users the illusion of a single coherent system.</p><p>Many new areas, such as scientific collaboration, require cooperation between many autonomous groups willing to share their knowledge. These areas require that the data integration process can be distributed among many autonomous parties, so that large integration solutions can be constructed from smaller ones. For this we propose a decentralized mediation architecture, peer mediator systems (PMS), based on the peer-to-peer (P2P) paradigm. In a PMS, reuse of human effort is achieved through logical composability of the mediators in terms of other mediators and sources by defining mediator views in terms of views in other mediators and sources.</p><p>Our thesis is that logical composability in a P2P mediation architecture is an important requirement and that composable mediators can be implemented efficiently through query processing techniques.</p><p>In order to compute answers of queries in a PMS, logical mediator compositions must be translated to query execution plans, where mediators and sources cooperate to compute query answers. The focus of this dissertation is on query processing methods to realize composability in a PMS architecture in an efficient way that scales over the number of mediators.</p><p>Our contributions consist of an investigation of the interfaces and capabilities for peer mediators, and the design, implementation and experimental study of several query processing techniques that realize composability in an efficient and scalable way.</p>

<p>Type 1 diabetes (T1D) is due to a selective loss of the insulin producing β-cells. However, the process responsible for this loss is still unknown. There is accumulating evidence that enteroviruses (EVs) are involved in T1D. In addition to direct virus-induced cytolysis, EVs could facilitate β-cell destruction by inducing inflammatory cytokines. Induction of such genes has previously been shown in EV-infected islets <i>in vitro</i>. Modulation of inflammatory mediators expressed in the islets could be a possible strategy to reduce β-cell destruction.</p><p>In the first paper we screened uninfected isolated human islets for genes with the potential to induce or modulate an immune response. We found that several of the genes expressed in the islets encode proteins with a powerful biological activity, such as IL-1β, IL-8, MIP-2α, MCP-1 and MIF. This indicates that the islets themselves can express several triggers of inflammation, and if expressed <i>in vivo</i> these mediators would probably contribute to β-cell destruction.</p><p>The vitamin B3 derivate, nicotinamide (NA), has been shown to modulate expression of factors important for coagulation and inflammatory responses. Addition of NA into isolated islet cultures resulted in a reduced expression of the pro-inflammatory chemokine MCP-1 and the coagulation activator tissue factor, suggesting that NA may have implications for both inflammatory responses and the pro-coagulant activity of islets.</p><p>We successfully isolated EVs from three newly diagnosed T1D patients. All isolates showed tropism for human islets and β-cells <i>in vitro</i> and clearly affected islet function. We also found that EV infection induced islet secretion of the chemokines IP-10 and MCP-1and that this induction could be blocked or reduced by addition of NA to the culture medium. Interestingly, NA also reduced viral replication and virus-induced islet destruction.</p><p>To conclude, this thesis provides new information about expression and modulation of inflammatory mediators in infected and uninfected human islets that could trigger inflammatory reactions leading to β-cell destruction. Moreover, it further strengthens the causal relationship between EV and T1D.</p>

Type 1 diabetes (T1D) is due to a selective loss of the insulin producing β-cells. However, the process responsible for this loss is still unknown. There is accumulating evidence that enteroviruses (EVs) are involved in T1D. In addition to direct virus-induced cytolysis, EVs could facilitate β-cell destruction by inducing inflammatory cytokines. Induction of such genes has previously been shown in EV-infected islets in vitro. Modulation of inflammatory mediators expressed in the islets could be a possible strategy to reduce β-cell destruction. In the first paper we screened uninfected isolated human islets for genes with the potential to induce or modulate an immune response. We found that several of the genes expressed in the islets encode proteins with a powerful biological activity, such as IL-1β, IL-8, MIP-2α, MCP-1 and MIF. This indicates that the islets themselves can express several triggers of inflammation, and if expressed in vivo these mediators would probably contribute to β-cell destruction. The vitamin B3 derivate, nicotinamide (NA), has been shown to modulate expression of factors important for coagulation and inflammatory responses. Addition of NA into isolated islet cultures resulted in a reduced expression of the pro-inflammatory chemokine MCP-1 and the coagulation activator tissue factor, suggesting that NA may have implications for both inflammatory responses and the pro-coagulant activity of islets. We successfully isolated EVs from three newly diagnosed T1D patients. All isolates showed tropism for human islets and β-cells in vitro and clearly affected islet function. We also found that EV infection induced islet secretion of the chemokines IP-10 and MCP-1and that this induction could be blocked or reduced by addition of NA to the culture medium. Interestingly, NA also reduced viral replication and virus-induced islet destruction. To conclude, this thesis provides new information about expression and modulation of inflammatory mediators in infected and uninfected human islets that could trigger inflammatory reactions leading to β-cell destruction. Moreover, it further strengthens the causal relationship between EV and T1D.

No description available.

The ability to physically interconnect many distributed, autonomous and heterogeneous software systems on a large scale presents new opportunities for sharing and reuse of existing, and for the creataion of new information and new computational services. However, finding and combining information in many such systems is a challenge even for the most advanced computer users. To address this challenge, mediator systems logically integrate many sources to hide their heterogeneity and distribution and give the users the illusion of a single coherent system. Many new areas, such as scientific collaboration, require cooperation between many autonomous groups willing to share their knowledge. These areas require that the data integration process can be distributed among many autonomous parties, so that large integration solutions can be constructed from smaller ones. For this we propose a decentralized mediation architecture, peer mediator systems (PMS), based on the peer-to-peer (P2P) paradigm. In a PMS, reuse of human effort is achieved through logical composability of the mediators in terms of other mediators and sources by defining mediator views in terms of views in other mediators and sources. Our thesis is that logical composability in a P2P mediation architecture is an important requirement and that composable mediators can be implemented efficiently through query processing techniques. In order to compute answers of queries in a PMS, logical mediator compositions must be translated to query execution plans, where mediators and sources cooperate to compute query answers. The focus of this dissertation is on query processing methods to realize composability in a PMS architecture in an efficient way that scales over the number of mediators. Our contributions consist of an investigation of the interfaces and capabilities for peer mediators, and the design, implementation and experimental study of several query processing techniques that realize composability in an efficient and scalable way.

Researchers have failed to specify when crime and counter-normative actions, as opposed to other responses may occur as a consequence of relative deprivation. To clarify this issue, a mediational model was developed that specified the causal processes leading from the recognition of deprivation to crime and counter-normative actions. This model hypothesizes that the recognition of deprivation (cognitive relative deprivation) leads to feelings associated with this recognition (affective relative deprivation) which in turn leads to crime and counter-normative actions. This model applies to both personal and group deprivation. In both cases, the feelings associated with deprivation include anger, resentment, dissatisfaction, and discontent. Data from a sample of 950 males between the ages of 16 to 30 supported the mediational model. Moderator variables were hypothesized to influence the causal processes in the mediational model, and were thus employed to specify the conditions under which the recognition of deprivation became more likely to lead to intense emotional reactions, and the conditions under which these emotional reactions became more likely to lead to crime and counter-normative actions. Personal deprivation was found to lead to stronger emotional responses if persons were pessimistic about their deprivation being relieved in the future, while at the group level, higher levels of optimism were related to stronger emotional responses. Both types of deprivation also lead to stronger emotional responses when persons believe that financial success and wealth are important. The emotive responses for both personal and group deprivation, in turn, were more likely to lead to crime and counter-normative actions if deprived persons had criminal peers. It was also found that the recognition of personal deprivation was more likely to lead to depression and lower self-esteem if people blamed themselves for their deprivation than if they did not. Persons who were not optimistic that their deprivation would be relieved in the future were more depressed than persons who were optimistic. Persons whose in-group was deprived were more likely to have lower self-esteem if they blamed the in-group for its deprivation than if they did not.

A series of macrocyclic FeIII/II and CoIII/II transition metal complexes has been selected and tested to serve as artificial mediators in redox potentiometry of proteins and also in catalytic cyclic voltammetry of redox active enzymes. The potentials of these mediators ranges approximately from +200 mV to -600 mV vs the normal hydrogen electrode (NHE) at pH 7, which spans the range of most redox active proteins. These coordination complexes are mostly stable in both the oxidized and the reduced forms and show pH-independent electrochemistry within the range 6 < pH < 9. A significant advantage of these mediators is to exhibit very weak visible absorption maxima which enable proteins with low extinction coefficients to be studied by optical potentiometry without spectral interference from the mediators. These mediators have been applied to the catalytic electrochemistry of dimethyl sulfoxide (DMSO) reductase. DMSO reductase isolated from Rhodobacter capsulatus has been studied extensively in this work. It is an 82 kDa monomeric, soluble enzyme found in the periplasmic space of the organism where it is responsible for catalyzing the reduction of DMSO to dimethyl sulfide (DMS). DMSO is a rather inert and difficult to analyse compound, which appears in foods and beverages, such as wine, coffee, and tea. Enzyme based methods offer an effective way to detect DMSO in these samples. Rhodobacter capsulatus DMSO reductase contains only a single molybdenum cofactor which cycles between MoVI and MoIV during catalysis and provides a rare example of a Mo enzyme that has no other cofactors such as hemes, Fe-S clusters and flavins. Previous studies of direct (unmediated) electrocatalysis by DMSO reductase have shown only modest activity in comparison to that of other Mo enzymes. Mediated electrochemistry of DMSO reductase from Rhodobacter capsulatus using low-potential macrocyclic complexes such as [Co(trans-diammac)]3+, [Co(cis-diammac)]3+, or [Co(AMMEsar)]3+ as a mediator has been studied. The normal transient CoIII/II voltammetric response of the complex is converted into a sigmoidal (steady state) waveform in the presence of both DMSO and DMSO reductase. A single set of enzymatic rate and equilibrium constants has been determined through digital simulation (DigiSim) of the cyclic voltammetry performed under conditions where the scan rate, DMSO concentration, DMSO reductase concentration and mediator concentration were varied systematically. This information provides new insight to the kinetics of the DMSO reductase catalytic mechanism that has never before been obtained from steady state or stopped flow kinetics studies. Of note is that lowering the thermodynamic driving force by sequentially raising the redox potential of the mediator ([Co(trans-diammac)]3+ to [Co(cis-diammac)]3+ to [Co(AMMESar)]3+) slows the enzyme-mediator electron transfer reaction in accord with Marcus theory. Finally, preparation of enantiomerically pure sulfoxides by an electrochemical enzymatic system utilizing DMSO reductase from Rhodobacter capsulatus has also been investigated. This method has been performed using the coordination complex [Co(trans-diammac)]3+ as an electron donor during bulk electrocatalysis. The results indicate that DMSO reductase from R. capsulatus prefers to catalyze the reduction of both R-MPTSO (methyl p-tolyl sulfoxide) and R-MPSO (methyl phenyl sulfoxide) over their S-enantiomers. These results have been rationalized on the basis of the published crystal structure of DMSO reductase (R. capsulatus) with DMSO bound at the active site.

Amendments inserted inside front cover. / Bibliograpghy: leaves 111-139. / xvi, 139, [29] leaves, [10] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The in vivo adminstration of Tumour Necrosis Factor-alpha as an antineoplastic agent has been severely restricted by dose-limiting side effects. Human TNF mutants with selective binding to the Human TNF receptors were employed to examine the role of these receptors in the mediation of TNF's cytotoxic and proinflammatory activities. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1995?