Oligopolyphenylenevinylene-Conjugated Oligoelectrolyte Membrane Insertion Molecules Selectively Disrupt Cell Envelopes of Gram-Positive Bacteria

The modification of microbial membranes to achieve biotechnological strain improvement with exogenous small molecules, such as oligopolyphenylenevinylene-conjugated oligoelectrolyte (OPV-COE) membrane insertion molecules (MIMs), is an emerging biotechnological field. Little is known about the interactions of OPV-COEs with their target, the bacterial envelope. We studied the toxicity of three previously reported OPV-COEs with a selection of Gram-negative and Gram-positive organisms and demonstrated that Gram-positive bacteria are more sensitive to OPV-COEs than Gram-negative bacteria. Transmission electron microscopy demonstrated that these MIMs disrupt microbial membranes and that this occurred to a much greater degree in Gram-positive organisms. We used a number of mutants to probe the nature of MIM interactions with the microbial envelope but were unable to align the membrane perturbation effects of these compounds to previously reported membrane disruption mechanisms of, for example, cationic antimicrobial peptides. Instead, the data support the notion that OPV-COEs disrupt microbial membranes through a suspected interaction with diphosphatidylglycerol (DPG), a major component of Gram-positive membranes. The integrity of model membranes containing elevated amounts of DPG was disrupted to a greater extent by MIMs than those prepared from Escherichia coli total lipid extracts alone

Inhibition of the Quorum Sensing System, Elastase Production and Biofilm Formation in Pseudomonas aeruginosa by Psammaplin A and Bisaprasin

Natural products derived from marine sponges have exhibited bioactivity and, in some cases, serve as potent quorum sensing inhibitory agents that prevent biofilm formation and attenuate virulence factor expression by pathogenic microorganisms. In this study, the inhibitory activity of the psammaplin-type compounds, psammaplin A (1) and bisaprasin (2), isolated from the marine sponge, Aplysinellarhax, are evaluated in quorum sensing inhibitory assays based on the Pseudomonas aeruginosa PAO1 lasB-gfp(ASV) and rhlA-gfp(ASV) biosensor strains. The results indicate that psammaplin A (1) showed moderate inhibition on lasB-gfp expression, but significantly inhibited the QS-gene promoter, rhlA-gfp, with IC50 values at 14.02 μM and 4.99 μM, respectively. In contrast, bisaprasin (2) displayed significant florescence inhibition in both biosensors, PAO1 lasB-gfp and rhlA-gfp, with IC50 values at 3.53 μM and 2.41 μM, respectively. Preliminary analysis suggested the importance of the bromotyrosine and oxime functionalities for QSI activity in these molecules. In addition, psammaplin A and bisaprasin downregulated elastase expression as determined by the standard enzymatic elastase assay, although greater reduction in elastase production was observed with 1 at 50 μM and 100 μM. Furthermore, the study revealed that bisaprasin (2) reduced biofilm formation in P. aeruginosa

Large-scale evolutionary surveillance of the 2009 H1N1 influenza A virus using resequencing arrays

In April 2009, a new influenza A (H1N1 2009) virus emerged that rapidly spread around the world. While current variants of this virus have caused widespread disease, particularly in vulnerable groups, there remains the possibility that future variants may cause increased virulence, drug resistance or vaccine escape. Early detection of these virus variants may offer the chance for increased containment and potentially prevention of the virus spread. We have developed and field-tested a resequencing kit that is capable of interrogating all eight segments of the 2009 influenza A(H1N1) virus genome and its variants, with added focus on critical regions such as drug-binding sites, structural components and mutation hotspots. The accompanying base-calling software (EvolSTAR) introduces novel methods that utilize neighbourhood hybridization intensity profiles and substitution bias of probes on the microarray for mutation confirmation and recovery of ambiguous base queries. Our results demonstrate that EvolSTAR is highly accurate and has a much improved call rate. The high throughput and short turn-around time from sample to sequence and analysis results (30 h for 24 samples) makes this kit an efficient large-scale evolutionary biosurveillance tool

DDX3X loss is an adverse prognostic marker in diffuse large B-cell lymphoma and is associated with chemoresistance in aggressive non-Hodgkin lymphoma subtypes.

Funder: addenbrooke's charitable trust, cambridge university hospital

Integrated approach to the assessment of CO2e-mitigation measures for the road passenger transport sector in Bahrain

The transport sector is one of the fastest-growing energy-consuming sectors in the world and it contributes greatly to emissions of carbon dioxide equivalent (CO2e). In Bahrain, CO2e emissions from the transport sector grew by an average of 8% annually between 1994 and 2006. The aim of this research was to develop an integrated approach to assess the measures adopted to reduce CO2e emissions by the transport sector within the context of climate change mitigation. This approach used the multi-criteria analysis methodology of the Analytic Hierarchy Process (AHP) to embed conventional assessment methods and a participatory approach. Three extensions to the original AHP methodology were developed: multi-AHP models, scenario packaging, and the examination of the plausibility of the results. The AHP results showed that certain fuel economy standards achieved the highest scores against five qualitative and quantitative criteria. Using socially and politically acceptable options, an integrated approach to CO2e mitigation could achieve a reduction in emissions of around 22% by 2030 (compared with 2010), at a cost of USD 112 per metric tonne of avoided CO2e emissions. Results from surveys of policymakers, experts, and the general public indicated that the outcomes of scenario packaging were plausible. The contributions of this research are two-fold. First, for the first time in Bahrain, the preferences of the general public have been considered and integrated with both the preferences of policymakers and experts and the results obtained from conventional assessment methods. Second, a structured approach for the integration of different assessment methods, transferable to other contexts, was developed and examined. Furthermore, multi-AHP models were introduced that can reflect the preferences of different concerned groups. Applications of this approach include assessment of the implementation of mitigation measures that could affect a number of concerned groups, decision making in energy-consuming sectors, and development of mitigation policy packages

Recent Developments in Nitric Oxide Donors and Delivery for Antimicrobial and Anti-Biofilm Applications

The use of nitric oxide (NO) is emerging as a promising, novel approach for the treatment of antibiotic resistant bacteria and biofilm infections. Depending on the concentration, NO can induce biofilm dispersal, increase bacteria susceptibility to antibiotic treatment, and induce cell damage or cell death via the formation of reactive oxygen or reactive nitrogen species. The use of NO is, however, limited by its reactivity, which can affect NO delivery to its target site and result in off-target effects. To overcome these issues, and enable spatial or temporal control over NO release, various strategies for the design of NO-releasing materials, including the incorporation of photo-activable, charge-switchable, or bacteria-targeting groups, have been developed. Other strategies have focused on increased NO storage and delivery by encapsulation or conjugation of NO donors within a single polymeric framework. This review compiles recent developments in NO drugs and NO-releasing materials designed for applications in antimicrobial or anti-biofilm treatment and discusses limitations and variability in biological responses in response to the use of NO for bacterial eradiation

Novel nitric oxide donors for the dispersal and control of Pseudomonas aeruginosa biofilms

The use of nitric oxide (NO) represents a novel strategy for the control of biofilms by inducing biofilm dispersal and promoting the eradication of susceptible, dispersed cells by antibiotic treatment. NO, as a free radical, is highly reactive and its production and metabolism is tightly regulated under physiological conditions. In addition, due to the involvement of NO in various pathological processes, several classes of NO donors with varying pharmacological properties have been developed for different treatments. In the case of biofilm control, two main classes of NO donor are typically used to induce biofilm dispersal, sodium nitroprusside (SNP) and diazeniumdiolates (NONOates). The latter of which generally have short half-lives. In the first study, an alternative class of NO donors, furoxans, which can have an extended duration of NO-release, was evaluated as a biofilm dispersing agent using P. aeruginosa biofilms. It was shown that a furoxan with a shorter half-life, LL4254, could induce dispersal to a similar extent as a control NONOate. Furoxans with longer half-lives, LL4212 and LL4216, could also induce biofilm dispersal, but only when used at higher concentrations. As LL4212 and LL4216 were later found to affect the growth of P. aeruginosa, they were considered unsuitable for use as biofilm dispersing agents. Thus, the study indicated that secondary effects of NO donor compounds were important considerations for their development as biofilm control agents. In the second study, the application of cephalosporin-linked diazeniumdiolate NO donors, which are stable until activation by bacterial specific β-lactamases present within biofilms, were evaluated. The study laid the groundwork for the assessment of these compounds in vivo, as factors influencing NO release from these compounds were evaluated. While the compounds were effective in dispersing P. aeruginosa biofilms in vitro, their activity was limited in vivo, likely due to differences in experimental conditions in the two systems. Preliminary assessment of one lead compound, DEACP, in a mouse implant model of biofilm infection also suggested that dispersal may lead to poor prognosis, as higher bacterial counts were retrieved from spleen samples of mice in NO-treated groups as a consequence of dispersal. Further studies would be required for optimization of the use of these compounds in vivo. In addition, antibiotic treatment is recommended for clearance of dispersed bacteria to reduce incidences of sepsis due to dispersed cells. In the last study, genes and proteins that may be involved in NO sensing and NO induced dispersal were tested for their response to NO treatment. Two purified proteins, DipA and RbdA, were not found to act as sensors of NO, and are likely to be involved in the dispersal process through other mechanisms. Using a batch microplate system for biofilm dispersal, transposon mutants of several genes previously shown to be defective in dispersal in flow systems, were unexpectedly found to be unaffected in NO induced dispersal, indicating that there may be genetic redundancies and that the response to NO and that NO induced dispersal may be additionally regulated by the growth conditions.Doctor of Philosophy (IGS

Molecular wires : behaviour and uptake in cells.

Transmembrane electron transfer molecules (TETMs) are phenylenevinylene oligoelectrolytes that associate with and insert themselves into bacterial membranes and can facilitate electron transfer across the membrane. They can be used to improve the efficiency of microbial fuel cells (MFC) and other remediation technologies that rely on transmembrane electron transport, such as reductive dechlorination. In addition, toxicities of TETMs against bacteria have been observed. In this project, we demonstrate that TETMs display anti-microbial activities towards both gram positive and gram negative bacteria, with gram positive bacteria being more susceptible to TETMs than gram negative organisms. Uptake studies suggest that the differential toxicities of TETMs against these bacteria may be due to the faster rate of uptake or the preferential accumulation of TETMs in a gram positive bacterium, as compared to a gram negative bacterium. Furthermore, membrane integrity studies indicate that TETMs result in membrane perturbation, which may be a factor accounting for their anti-microbial activity. Results from these studies provide a minimum inhibitory concentration of TETMs, and hence a guideline for the dosage to be used for their application in MFC and remediation process. In addition to their use in biotechnology for electron transfer, the results also indicated that TETMs could be potentially used as antimicrobials.Bachelor of Science in Biological Science

The impact of task type, group size and proximity on group support system

148 p.As organizations flatten their hierarchy and globalize, there is an increasing possibility that members of a work team would be physically distributed. In an increasingly competitive business environment, there is a need to make decisions in real time and to allow the team to work together over a period of time. There is growing interest in the use of group support systems to support such spatially separated teams to meet synchronously and asynchronously. However, there is still apprehension about this use of GSS, as the body of research in DGSS still does not paint a very clear picture, especially about how DGSS can support different group tasks, group sizes, and promote team building and preserve decision quality at the same time.ACCOUNTANC