Phenytoin metabolism by human cytochrome P450 : involvement of P450 3A and 2C forms in secondary metabolism and drug-protein adduct formation

The anticonvulsant phenytoin (5,5-diphenylhydantoin) provokes a skin rash in 5 to 10% of patients, which heralds the start of an idiosyncratic reaction that may result from covalent modification of normal self proteins by reactive drug metabolites. Phenytoin is metabolized by cytochrome P450 (P450) enzymes primarily to 5-(p-hydroxyphenyl-),5-phenylhydantoin (HPPH), which may be further metabolized to a catechol that spontaneously oxidizes to semiquinone and quinone species that covalently modify proteins. The aim of this study was to determine which P450s catalyze HPPH metabolism to the catechol, proposed to be the final enzymatic step in phenytoin bioactivation. Recombinant human P450s were coexpressed with NADPH-cytochrome P450 reductase in Escherichia coli. Novel bicistronic expression vectors were constructed for P450 2C19 and the three major variants of P450 2C9, i.e., 2C9*1, 2C9*2, and 2C9*3. HPPH metabolism and covalent adduct formation were assessed in parallel. P450 2C19 was the most effective catalyst of HPPH oxidation to the catechol metabolite and was also associated with the highest levels of covalent adduct formation. P450 3A4, 3A5, 3A7, 2C9*1, and 2C9*2 also catalyzed bioactivation of HPPH, but to a lesser extent. Fluorographic analysis showed that the major targets of adduct formation in bacterial membranes were the catalytic P450 forms, as suggested from experiments with human liver microsomes. These results suggest that P450 2C19 and other forms from the 2C and 3A subfamilies may be targets as well as catalysts of drug-protein adduct formation from phenytoin.

Inhibition of homogenous formation of calcium carbonate by poly (acrylic acid). The effect of molar mass and end-group functionality

The ability of poly(acrylic acid) (PAA) with different end groups and molar masses prepared by Atom Transfer Radical Polymerization (ATRP) to inhibit the formation of calcium carbonate scale at low and elevated temperatures was investigated. Inhibition of CaCO3 deposition was affected by the hydrophobicity of the end groups of PAA, with the greatest inhibition seen for PAA with hydrophobic end groups of moderate size (6–10 carbons). The morphologies of CaCO3 crystals were significantly distorted in the presence of these PAAs. The smallest morphological change was in the presence of PAA with long hydrophobic end groups (16 carbons) and the relative inhibition observed for all species were in the same order at 30 °C and 100 °C. As well as distorting morphologies, the scale inhibitors appeared to stabilize the less thermodynamically favorable polymorph, vaterite, to a degree proportional to their ability to inhibit precipitation.

Bonding and bridging : transition to school and social capital formation among a community of Indigenous Australian children

This study reports on an intervention program designed to facilitate transition to school of a whole community of Indigenous Australian children who had previously not been attending. The children were from families displaced from their traditional lands and experienced on-going social marginalisation and transience. A social capital framework was employed to track change in the children’s social inclusion and family-school engagement for two years, from school entry. Sociometric measurement and interview techniques were applied to assess the children’s social connectedness and peer relationship quality. Using these data, analyses examined whether bonding within the group supported or inhibited formation of new social relationships. Although transience disrupted attendance, there was a group trend towards increased social inclusion with some evidence that group bonds supported bridging to new social relationships. Change in family-school engagement was tracked using multi-informant interviews. Limited engagement between school and families presented an on-going challenge to sustained educational engagement.

A school by any other name...is still a rock band?

How is your academic institution structured? If you work within a university, then no doubt you are familiar with the use of faculties or perhaps colleges. What about departments or schools? Whatever names or structures are employed, how would you describe the working relationship between academics and professional staff members? As a research scientist and academic over the last twenty years, my appointments have almost always been made through academic departments or schools. In each case, the academic unit has been led by a senior academic manager, such as a chair or head, supported by a dedicated team of professional staff. More recently, however, I have had the opportunity of leading an academic discipline and the experience has led me to reflect more broadly about leadership styles and academic structures within the Australian higher education sector. The written record of this reflection was published last year in the Australian Universities Review (Harkin and Healy, 2013), but I’m pleased to be able to provide a brief synopsis here for the readership of Insights.

Comparison of functionals for metal hexaboride band structure calculations

Density functional calculations of the electronic band structure for superconducting and semi-conducting metal hexaborides are compared using a consistent suite of assumptions and with emphasis on the physical implications of computed models. Spin polarization enhances mathematical accuracy of the functional approximations and adds significant physical meaning to model interpretation. For YB6 and LaB6, differences in alpha and beta projections occur near the Fermi energy. These differences are pronounced for superconducting hexaborides but do not occur for other metal hexaborides.

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

The reactions of distonic 4-(N, N, N-trimethylammonium)-2-methylphenyl and 5-(N, N, N-trimethylammonium)-2-methylphenyl radical cations (m/z 149) with O-2 are studied in the gas phase using ion-trap mass spectrometry. Photodissociation (PD) of halogenated precursors gives rise to the target distonic charge-tagged methylphenyl radical whereas collision-induced dissociation (CID) is found to produce unreactive radical ions. The PD generated distonic radicals, however, react rapidly with O-2 to form \[M + O2](center dot+) and \[M + O-2 - OH](center dot+) ions, detected at m/z 181 and m/z 164, respectively. Quantum chemical calculations using G3SX(MP3) and M06-2X theories are deployed to examine key decomposition pathways of the 5-(N, N, N-trimethylammonium)-2-methylphenylperoxyl radical and rationalise the observed product ions. The prevailing product mechanism involves a 1,5- H shift in the peroxyl radical forming a QOOH-type intermediate that subsequently eliminates (OH)-O-center dot to yield charge-tagged 2-quinone methide. Our study suggests that the analogous process should occur for the neutral methylphenyl + O-2 reaction, thus serving as a plausible source of (OH)-O-center dot radicals in combustion environments. Grants: ARC/DP0986738, ARC/DP130100862

Formation and Fragmentation of Unsaturated Fatty Acid M-2H+Na (-) Ions: Stabilized Carbanions for Charge-Directed Fragmentation

Fatty acids are long-chain carboxylic acids that readily produce \[M - H](-) ions upon negative ion electrospray ionization (ESI) and cationic complexes with alkali, alkaline earth, and transition metals in positive ion ESI. In contrast, only one anionic monomeric fatty acid-metal ion complex has been reported in the literature, namely \[M - 2H + (FeCl)-Cl-II](-). In this manuscript, we present two methods to form anionic unsaturated fatty acid-sodium ion complexes (i.e., \[M - 2H + Na](-)). We find that these ions may be generated efficiently by two distinct methods: (1) negative ion ESI of a methanolic solution containing the fatty acid and sodium fluoride forming an \[M - H + NaF](-) ion. Subsequent collision-induced dissociation (CID) results in the desired \[M - 2H + Na](-) ion via the neutral loss of HF. (2) Direct formation of the \[M - 2H + Na](-) ion by negative ion ESI of a methanolic solution containing the fatty acid and sodium hydroxide or bicarbonate. In addition to deprotonation of the carboxylic acid moiety, formation of \[M - 2H + Na](-) ions requires the removal of a proton from the fatty acid acyl chain. We propose that this deprotonation occurs at the bis-allylic position(s) of polyunsaturated fatty acids resulting in the formation of a resonance-stabilized carbanion. This proposal is supported by ab initio calculations, which reveal that removal of a proton from the bis-allylic position, followed by neutral loss of HX (where X = F- and -OH), is the lowest energy dissociation pathway.

Formation of the heterocumulene anion SCCCN- by a cyano migration from the radical anion of 1,2-dicyanoethylenedithiolate

The anionic heterocumulene SCCCN- was generated in the gas phase by collisional activation of the radical anion of 1,2-dicyanoethylenedithiolate. The mechanism of this reaction, as well as the structures of neutral and anionic products, was investigated by hybrid density functional theory (DFT) calculations. Dissociation to form SCCCN- and SCN is proposed to occur by a radical directed cyano migration reaction, with calculations suggesting this is the lowest energy fragmentation pathway available to the precursor anion. In contrast, the even-electron protonated 1,2-dicyanoethylenedithiolate anion fragmented by loss of HCN.

'What's on your mind?' Writing on Facebook as a tool for self-formation

In the context of modern western psychologised, techno-social hybrid realities, where individuals are incited constantly to work on themselves and perform their self-development in public, the use of online social networking sites (SNSs) can be conceptualised as what Foucault has described as a ‘technique of self’. This article explores examples of status updates on Facebook to reveal that writing on Facebook is a tool for self-formation with historical roots. Exploring examples of self-writing from the past, and considering some of the continuities and discontinuities between these age-old practices and their modern translations, provides a non-technologically deterministic and historically aware way of thinking about the use of new media technologies in modern societies that understands them to be more than mere tools for communication.

Characteristics of spatial variation, size distribution, formation and growth of particles in urban environments

This thesis is the first comprehensive study of important parameters relating to aerosols' impact on climate and human health, namely spatial variation, particle size distribution and new particle formation. We determined the importance of spatial variation of particle number concentration in microscale environments, developed a method for particle size parameterisation and provided knowledge about the chemistry of new particle formation. This is a significant contribution to our understanding of processes behind the transformation and dynamics of urban aerosols. This PhD project included extensive measurements of air quality parameters using state of the art instrumentation at each of the 25 sites within the Brisbane metropolitan area and advanced statistical analysis.

All the worldwide web's a stage : teenage girls' self-presentation and identities formation through status updates

This study investigates grade eight girls’ use of status updates on Facebook in order to create identities online. Using sociologist Erving Goffman’s theory of self-presentation as a framework, Jones and Pittman’s subsequent strategies of self-presentation are used to discover the ways in which teenage girls use status updates in order to create identities online and manage audience impressions. Using a mixed methods design, the results showed that, while existing self-presentation strategies persist, social networking has created new means of self-presentation. This study adds to a growing pool of research regarding teens’ engagement with social networking websites to form identities.

Ananyi (Going) by Tjupi Band

Research background: Ananyi (Going) is an intercultural music project with lyrics sung in Luritja and English, undertaken in collaboration with the Tjupi Band and producer Jeffrey McLaughlin. The project contributes to cultural maintenance for Australian First Nations peoples, and is informed by prior work in this area by scholars including Peter Dunbar-Hall, Chris Gibson and Karl Neuenfeldt. These existing studies have discussed the complexities of intercultural collaboration, and the types of cultural politics that are involved when Indigenous and non-Indigenous musicians and scholars work together on projects of cultural significance. Critical race theory has also informed the creative work, as a means of interpreting the implicit and explicit discourses of race that arise through intercultural creative practice. The project asked the research question, how can collaborative music making contribute to intercultural understanding and the maintenance of Australian First Nations languages and cultures? Research contribution: The project has identified that recorded popular music is important in the maintenance of Luritja language and culture, and that intercultural collaboration in the areas of digital sound production and distribution can assist with cultural maintenance in both local and national contexts. Research significance: The compact disc was released on the CAAMA Music label, and supported through competitive grants from the Australian Government’s Contemporary Music Touring Grant and the Arnhem Land Progress Association (ALPA). The research context of the work is detailed in Brydie-Leigh Bartleet and Gavin Carfoot 2013. "Desert harmony: Stories of collaboration between Indigenous musicians and university students." International Education Journal: Comparative Perspectives 12 (1): 180-196.

Becoming a pharmacist : the role of curriculum in professional identity formation

Objective To understand how the formal curriculum experience of an Australian undergraduate pharmacy program supports students’ professional identity formation. Methods A qualitative ethnographic study was conducted over four weeks using participant observation and examined the ‘typical’ student experience from the perspective of a pharmacist. A one-week period of observation was undertaken with each of the four year groups (that is, for years one to four) comprising the undergraduate curriculum. Data were collected through observation of the formal curriculum experience using field notes, a reflective journal and informal interviews with 38 pharmacy students. Data were analyzed thematically using an a priori analytical framework. Results Our findings showed that the observed curriculum was a conventional curricular experience which focused on the provision of technical knowledge and provided some opportunities for practical engagement. There were some opportunities for students to imagine themselves as pharmacists, for example, when the lecture content related to practice or teaching staff described their approach to practice problems. However, there were limited opportunities for students to observe pharmacist role models, experiment with being a pharmacist or evaluate their professional identities. While curricular learning activities were available for students to develop as pharmacists e.g. patient counseling, there was no contact with patients and pharmacist academic staff tended to role model as educators with little evidence of their pharmacist selves. Conclusion These findings suggest that the current conventional approach to the curriculum design may not be fully enabling learning experiences which support students in successfully negotiating their professional identities. Instead it appeared to reinforce their identities as students with a naïve understanding of professional practice, making their future transition to professional practice challenging.

Mechanical influences on endothelial cell network formation in vitro

While both the restoration of the blood supply and an appropriate local mechanical environment are critical for uneventful bone healing, their influence on each other remains unclear. Human bone fracture haematomas (<72h post-trauma) were cultivated for 3 days in fibrin matrices, with or without cyclic compression. Conditioned medium from these cultures enhanced the formation of vessel-like networks by HMEC-1 cells, and mechanical loading further elevated it, without affecting the cells’ metabolic activity. While haematomas released the angiogenesis-regulators, VEGF and TGF-β1, their concentrations were not affected by mechanical loading. However, direct cyclic stretching of the HMEC-1 cells decreased network formation. The appearance of the networks and a trend towards elevated VEGF under strain suggested physical disruption rather than biochemical modulation as the responsible mechanism. Thus, early fracture haematomas and their mechanical loading increase the paracrine stimulation of endothelial organisation in vitro, but direct periodic strains may disrupt or impair vessel assembly in otherwise favourable conditions.