The effect of preferential sampling on sampling variance

We examine some variations of standard probability designs that preferentially sample sites based on how easy they are to access. Preferential sampling designs deliver unbiased estimates of mean and sampling variance and will ease the burden of data collection but at what cost to our design efficiency? Preferential sampling has the potential to either increase or decrease sampling variance depending on the application. We carry out a simulation study to gauge what effect it will have when sampling Soil Organic Carbon (SOC) values in a large agricultural region in south-eastern Australia. Preferential sampling in this region can reduce the distance to travel by up to 16%. Our study is based on a dataset of predicted SOC values produced from a datamining exercise. We consider three designs and two ways to determine ease of access. The overall conclusion is that sampling performance deteriorates as the strength of preferential sampling increases, due to the fact the regions of high SOC are harder to access. So our designs are inadvertently targeting regions of low SOC value. The good news, however, is that Generalised Random Tessellation Stratification (GRTS) sampling designs are not as badly affected as others and GRTS remains an efficient design compared to competitors.

B-Raf mutation : a key player in molecular biology of cancer

B-Raf is one of the more commonly mutated proto-oncogenes implicated in the development of cancers. In this review, we consider the mechanisms and clinical impacts of B-Raf mutations in cancer and discuss the implications for the patient in melanoma, thyroid cancer and colorectal cancer, where B-Raf mutations are particularly common.

Strategic targeting of the PI3K–NFκB axis in cisplatin-resistant NSCLC

Chemoresistance is a major therapeutic challenge to overcome in NSCLC, in order to improve the current survival rates of <15% at 5 years. We and others have shown increased PI3K signaling in NSCLC to be associated with a more aggressive disease, and a poorer prognosis. In this study, targeted inhibition of three strategic points of the PI3K–NFκB axis was performed with the aim of exploiting vulnerabilities in cisplatin-resistant NSCLC cells. Cisplatin-resistant cell lines were previously generated through prolonged exposure to the drug. Expression of PI3K and NFκB pathway-related genes were compared between cisplatin-resistant cells and their matched parent cells using a gene expression array, qRT-PCR, DNA sequencing, western blot, and immunofluorescence. Targeted inhibition was performed using GDC-0980, a dual PI3K–mTOR inhibitor currently in Phase II clinical trials in NSCLC, and DHMEQ, an inhibitor of NFκB translocation which has been used extensively both in vitro and in vivo. Effects of the two inhibitors were assessed by BrdU proliferation assay and multiparameter viability assay. NFKBIA was shown to be 12-fold overexpressed in cisplatin-resistant cells, with no mutations present in exons 3, 4, or 5 of the gene. Corresponding overexpression of IκBα was also observed. Treatment with DHMEQ (but not GDC-0980) led to significantly enhanced effects on viability and proliferation in cisplatin-resistant cells compared with parent cells. We conclude that NFκB inhibition represents a more promising strategy than PI3K–mTOR inhibition for treatment in the chemoresistance setting in NSCLC.

A high mobility P-type DPP-thieno[3,2-b]thiophene copolymer for organic thin-film transistors

A copolymer comprising 1,4-diketopyrrolo[3,4-c]pyrrole (DPP) and thieno[3,2-b]thiophene moieties, PDBT-co-TT, shows high hole mobility of up to 0.94 cm2 V-1 s-1 in organic thin-film transistors. The strong intermolecular interactions originated from π-π stacking and donor-acceptor interaction lead to the formation of interconnected polymer networks having an ordered lamellar structure, which have established highly efficient pathways for charge carrier transport.

Poly(2,5-bis(2-octyldodecyl)-3,6-di(furan-2-yl)-2,5-dihydro-pyrrolo[3,4-c] pyrrole-1,4-dione-co-thieno[3,2-b]thiophene): A high performance polymer semiconductor for both organic thin film transistors and organic photovoltaics

A new diketopyrrolopyrrole (DPP)-containing donor-acceptor polymer, poly(2,5-bis(2-octyldodecyl)-3,6-di(furan-2-yl)-2,5-dihydro-pyrrolo[3,4-c] pyrrole-1,4-dione-co-thieno[3,2-b]thiophene) (PDBF-co-TT), is synthesized and studied as a semiconductor in organic thin film transistors (OTFTs) and organic photovoltaics (OPVs). High hole mobility of up to 0.53 cm 2 V -1 s -1 in bottom-gate, top-contact OTFT devices is achieved owing to the ordered polymer chain packing and favoured chain orientation, strong intermolecular interactions, as well as uniform film morphology of PDBF-co-TT. The optimum band gap of 1.39 eV and high hole mobility make this polymer a promising donor semiconductor for the solar cell application. When paired with a fullerene acceptor, PC 71BM, the resulting OPV devices show a high power conversion efficiency of up to 4.38% under simulated standard AM1.5 solar illumination.

4-hexylbithieno[3,2-b:2′3′-e]pyridine: An efficient electron-accepting unit in fluorene and indenofluorene copolymers for light-emitting devices

4-Hexylbithienopyridine has been prepared as a novel electron-accepting monomer for conjugated polymers. To test its electronic properties, alternating copolymers with fluorene and indenofluorene polymers have been prepared. The copolymers displayed reduction potentials about 0.5 V lower than for the corresponding fluorene and indenofluorene homopolymers, indicating much improved electron-accepting properties. Analysis of the microscopic morphology of thin films of the copolymers by AFM shows that they lack the extensive supramolecular order seen with the homopolymers, which is attributed to the bithienopyridine units disrupting the π-stacking. LEDs using these polymers as the emitting layer produce blue-green emission with low turn-on voltages with aluminum electrodes confirming their improved electron affinity. The indenofluorene copolymer displayed an irreversible red shift in emission at high voltages, which is attributed to oxidation of the indenofluorene units. This red shift occurred at higher potentials than for indenofluorene homopolymers in LEDs, suggesting that the heterocyclic moieties offer some protection against electrically promoted oxidation.

Addressing alcohol related harms within maxillofacial trauma practice

Background A brief intervention, conducted in the acute setting care setting after an alcohol-related injury, has been reported to be highly beneficial in reducing the risk of re-injury and in reducing subsequent level of alcohol consumption. This project aimed to understand Australasian Oral and Maxillofacial Surgeons' attitudes, knowledge and skills in terms of alcohol screening and brief intervention within acute settings for patients admitted with facial trauma. Materials and Methods A web-based survey was made available to all members (n=200-250) of the Australian and New Zealand Association of Oral and Maxillofacial Surgeons (ANZAOMS), promoted through a number of email bulletins sent by the Association to all members. Implied consent is assumed for participants who complete the online survey. The survey explored their current level of involvement in treating patients with alcohol-relatd facial trauma, as well as their knowledge of and attitudes towards alcohol screening and brief intervention. The survey also explored their willingness for further training and involvement in implementing a SBI program. Parts of the survey were based on a hypothetical case with facial injury and drinking history which was presented to the participants and the participants were asked to give their response to this scenario. Results A total of 58 surgeons completed the on-line survey. 91% of surgeons surveyed were males and 88% were consultant surgeons. 71% would take alcohol history; 29% would deliver a brief alcohol intervention and 14% would refer the patients to an alcohol treatment service or clinician. 40% agreed to have adequate training in managing patients with alcohol-related injuries, while 17% and 19% felt they had adequate time and resources. 76% of surgeons reported the need for more information on where to refer patients for appropriate alcohol treatment. Conclusion The study findings confirm the challenges and barriers to implementing brief alcohol intervention in current practice. There are service gaps that exist, as well as opportunities for training.

Ecionines A and B, two new cytotoxic pyridoacridine alkaloids from the Australian marine sponge, Ecionemia geodides

Chemical investigations of the Australian marine sponge Ecionemia geodides resulted in the isolation of two new pyridoacridine alkaloids, ecionines A (1) and B (2), along with the previously isolated marine natural products, biemnadin (3) and meridine (4). Compounds 1 and 2 both contain an imine moiety, which is rare for the pyridoacridine structure class. The chemical structures of 1 and 2 were determined by extensive 1D and 2D NMR and MS data analyses. All compounds were tested against a panel of human bladder cancer cell lines, the increasingly metastatic TSU-Pr1 series (TSU-Pr1, TSU-Pr1-B1 and TSU-Pr1- B2) and the superficial bladder cancer cell line 5637. Ecionine A (1) displayed cytotoxicity against all cell lines, with IC50 values ranging from 3 to 7 mM. This is the first report of chemistry from the sponge genus Ecionemia.

B-lactamase-mediated resistance to antimicrobials : the relationship between genotype and phenotype

This thesis examined the ability to predict the emergence of bacteria resistant to antibiotics using genetic markers in the bacteria. Bacteria containing the genetic markers were able to become resistant to antibiotics, whereas bacteria that did not have the genetic markers remained susceptible. Existing techniques can identify the presence of resistance by looking at the characteristics of the bacteria during growth. However, having the ability to predict antibiotic resistance before it emerges could improve the preservation of currently available antibiotics and minimise treatment failure.

Identification of eusynstyelamide B as a potent cell cycle inhibitor following the generation and screening of an ascidian-derived extract library using a real time cell analyzer

Ascidians are marine invertebrates that have been a source of numerous cytotoxic compounds. Of the first six marine-derived drugs that made anticancer clinical trials, three originated from ascidian specimens. In order to identify new anti-neoplastic compounds, an ascidian extract library (143 samples) was generated and screened in MDA-MB-231 breast cancer cells using a real-time cell analyzer (RTCA). This resulted in 143 time-dependent cell response profiles (TCRP), which are read-outs of changes to the growth rate, morphology, and adhesive characteristics of the cell culture. Twenty-one extracts affected the TCRP of MDA-MB-231 cells and were further investigated regarding toxicity and specificity, as well as their effects on cell morphology and cell cycle. The results of these studies were used to prioritize extracts for bioassay-guided fractionation, which led to the isolation of the previously identified marine natural product, eusynstyelamide B (1). This bis-indole alkaloid was shown to display an IC50 of 5 μM in MDA-MB-231 cells. Moreover, 1 caused a strong cell cycle arrest in G2/M and induced apoptosis after 72 h treatment, making this molecule an attractive candidate for further mechanism of action studies.

Circulating fragments of N-Terminal Pro-B-Type Natriuretic Peptides in plasma of heart failure patients

BACKGROUND: The use of nonstandardized N-terminal pro-B-type natriuretic peptide (NT-proBNP) assays can contribute to the misdiagnosis of heart failure (HF). Moreover, there is yet to be established a common consensus regarding the circulating forms of NT-proBNP being used in current assays. We aimed to characterize and quantify the various forms of NT-proBNP in the circulation of HF patients. METHODS: Plasma samples were collected from HF patients (n = 20) at rest and stored at -80 degrees C. NT-proBNP was enriched from HF patient plasma by use of immunoprecipitation followed by mass spectrometric analysis. Customized homogeneous sandwich AlphaLISA (R) immunoassays were developed and validated to quantify 6 fragments of NT-proBNP. RESULTS: Mass spectrometry identified the presence of several N- and C-terminally processed forms of circulating NT-proBNP, with physiological proteolysis between Pro2-Leu3, Leu3-Gly4, Pro6-Gly7, and Pro75-Arg76. Consistent with this result, AlphaLISA immunoassays demonstrated that antibodies targeting the extreme N or C termini measured a low apparent concentration of circulating NT-proBNP. The apparent circulating NT-proBNP concentration was increased with antibodies targeting nonglycosylated and nonterminal epitopes (P < 0.05). CONCLUSIONS: In plasma collected from HF patients, immunoreactive NT-proBNP was present as multiple N- and C-terminally truncated fragments of the full length NT-proBNP molecule. Immunodetection of NT-proBNP was significantly improved with the use of antibodies that did not target these terminal regions. These findings support the development of a next generation NT-proBNP assay targeting nonterminal epitopes as well as avoiding the central glycosylated region of this molecule. (c) 2013 American Association for Clinical Chemistry

In vitro investigations on the effect of dermal fibroblasts on keratinocyte responses to ultraviolet B radiation

Exposure to ultraviolet radiation is closely linked to the development of skin cancers in humans. The ultraviolet B (UVB) radiation wavelength (280-320 nm), in particular, causes DNA damage in epidermal keratinocytes, which are linked to the generation of signature premalignant mutations. Interactions between dermal fibroblasts and keratinocytes play a role in epidermal repair and regeneration after UVB-induced damage. To investigate these processes, established two and three-dimensional culture models were utilized to study the impact of fibroblast-keratinocyte crosstalk during the acute UVB response. Using a coculture system it was observed that fibroblasts enhanced keratinocyte survival and the repair of cyclobutane pyrimidine dimers (CPDs) after UVB radiation exposure. These findings were also mirrored in irradiated human skin coculture models employed in this study. Fibroblast coculture was shown to play a role in the expression and activation of members of the apoptotic cascade, including caspase-3 and Bad. Interestingly, the expression and phosphorylation of p53, a key player in the regulation of keratinocyte cell fate postirradiation, was also shown to be influenced by fibroblast-produced factors. This study highlights the importance of synergistic interactions between fibroblasts and keratinocytes in maintaining a functional epidermis while promoting repair and regeneration following UVB radiation-induced damage.

What is plan B? Using Foucault's archaeology to enhance policy analysis

Many governments in western democracies conduct the work of leading their societies forward through policy generation and implementation. Despite government attempts at extensive negotiation, collaboration and debate, the general populace in these same countries frequently express feelings of disempowerment and undue pressure to be compliant, often leading to disengagement. Here we outline Plan B: a process for examining how policies that emerge from good intentions are frequently interpreted as burdensome or irrelevant by those on whom they have an impact. Using a case study of professional standards for teachers in Australia, we describe how we distilled Foucault’s notions of archaeology into a research approach centring on the creation of ‘polyhedrons of intelligibility’ as an alternative approach by which both policy makers and those affected by their policies may understand how their respective causes are supported and adversely affected.