Regulation of Biofilm Formation and Norspermidine Production by Iron in Vibrio Cholerae

Vibrio cholerae is a pathogenic bacterium and the causative agent of the diarrheal disease cholera. V. cholerae is thought to persist in the environment in the form of a biofilm. Biofilm formation is regulated by signals ranging from self produced signals to environmental signals. This work investigated whether iron availability and production of the polyamine, norspermidine, are linked to biofilm regulation. Through investigating mutants defective in vibriobactin synthesis (a siderophore) in regards to iron availability, I have shown that iron deficiency inhibits biofilm formation and that mutants defective in siderophore synthesis have increased biofilm formation compared to wild-type. Vibriobactin contains a norspermidine backbone and previous work has shown that norspermidine is a pro-biofilm signal. HPLC data does not show any increase in norspermidine levels in the cell or in the extracellular environment, but conditioned media experiments have shown that a pro-biofilm signal is present in the culture medium. Preliminary data suggests that a modified, potentially acetylated, form of norspermidine is the pro-biofilm signal in this system. Future work will be directed at acetylase mutants and media fractionation in order to conclusively determine what the pro-biofilm signal is in this syste

Method development for the determination of surface zeta potential of silver coated nylon substrates

Surface zeta potential (SZP) is an electro kinetic property of surfaces that is a result of the electrical double layer (EDL) that forms when a surface possessing a surface charge is dispersed in a bulk material.1 The EDL is made up of the stern layer containing tightly packed ions of the opposite charge of the surface, that extends from the surface to the diffuse layer, and the diffuse layer which contains ions of mixed charge that extends from the end of the stern layer to the slipping plane.The slipping plane is the interface between the particle or surface and the dispersant, the potential at this interface is the zeta potential (ZP).1 The goal of this project is to develop a method for measuring the surface zeta potential of silver coated nylon substrates. The effects of the measurement process on the surfaces were investigated and the SZP was measured at pH 5, 7 and 9.2 to see how varying pH affects SZP measurements. The measurement process was found to cause a rearrangement of the silver surface, although the mechanism of this rearrangement was not investigated. The method using in this project in combination with the dip cell arrangement purposed by Corbett, et al., resulted in quantifiable data for the determination of the SZP of silver coated nylon substrates under standard conditions using the tracer suspension provided by Malvern and at pH 5, 7 and 9.2 using a silica tracer suspension. There are still more ways in which this method can be expanded upon, but this project has set the foundation in place to move forward with the measurement of the SZP of sliver coated nylon substrates. Hopefully this foundation will lead to better understanding of SZP of silver coated nylon substrates and with it a better understanding of how things interact with the surface. This understanding would allow for the optimization of surface chemistry interactions, such as the interaction of human bodily fluid with the silver coated nylon evidence swabs being developed by the Evanoff research group for the one-step, non-destructive Surface-enhanced Raman spectroscopy (SERS) analysis of human bodily fluids found in sexual assault cases

Timeliness of Clinic Attendance is a good predictor of Virological Response and Resistance to Antiretroviral drugs in HIV-infected patients

Ensuring long-term adherence to therapy is essential for the success of HIV treatment. As access to viral load monitoring and genotyping is poor in resource-limited settings, a simple tool to monitor adherence is needed. We assessed the relationship between an indicator based on timeliness of clinic attendance and virological response and HIV drug resistance

Does household access to improved water and sanitation in infancy and childhood predict better vocabulary test performance in Ethiopian, Indian, Peruvian and Vietnamese cohort studies?

Abstract Objective Test associations between household water and sanitation (W&S) and children's concurrent and subsequent Peabody Picture Vocabulary Test (PPVT) scores. Design Prospective cohort study. Setting Ethiopia, India, Peru, Vietnam. Participants 7269 children. Primary outcome measures PPVT scores at 5 and 8 years. Key exposure variables were related to W&S, and collected at 1, 5 and 8 years, including ‘improved’ water (eg, piped, public tap or standpipe) and ‘improved’ toilets (eg, collection, storage, treatment and recycling of human excreta). Results Access to improved water at 1 year was associated with higher language scores at 5 years (3/4 unadjusted associations) and 8 years (4/4 unadjusted associations). Ethiopian children with access to improved water at 1 year had test scores that were 0.26 SD (95% CI 0.17 to 0.36) higher at 5 years than children without access. Access to improved water at 5 years was associated with higher concurrent PPVT scores (in 3/4 unadjusted associations), but not later scores (in 1/4 unadjusted associations). 5-year-old Peruvian children with access to improved water had better concurrent performance on the PPVT (0.44 SD, 95% CI 0.30 to 0.59) than children without access to improved water. Toilet access at 1 year was also associated with better PPVT scores at 5 years (3/4 unadjusted associations) and sometimes associated with test results at 8 years (2/4 unadjusted associations). Toilet access at 5 years was associated with concurrent PPVT scores (3/4 unadjusted associations). More than half of all associations in unadjusted models (water and toilets) persisted in adjusted models, particularly for toilets in India, Peru and Vietnam. Conclusions Access to ‘improved’ water and toilets had independent associations with children's PPVT scores that often persisted with adjustment for covariates. Our findings suggest that effects of W&S may go beyond subacute and acute infections and physical growth to include children's language performance, a critical component of cognitive development

Is there more to Wnt signalling in breast cancer than stabilisation of β-catenin?

Increased Wnt signalling has been implicated in the aetiology of many different human cancers, including breast cancers. In most cases, Wnt signalling is thought to drive tumourigenesis through the stabilisation of cytosolic β-catenin and the subsequent changes in the expression of T-cell factor (TCF)-dependent genes. However, this is not necessarily the only mechanism, as Wnt proteins can signal through a number of different intracellular signalling pathways. The ongoing work from Nancy Hynes' laboratory continues to highlight this latter possibility

Redox proteomics of the inflammatory secretome identifies a common set of redoxins and other glutathionylated proteins released in inflammation, influenza virus infection and oxidative stress

Protein cysteines can form transient disulfides with glutathione (GSH), resulting in the production of glutathionylated proteins, and this process is regarded as a mechanism by which the redox state of the cell can regulate protein function. Most studies on redox regulation of immunity have focused on intracellular proteins. In this study we have used redox proteomics to identify those proteins released in glutathionylated form by macrophages stimulated with lipopolysaccharide (LPS) after pre-loading the cells with biotinylated GSH. Of the several proteins identified in the redox secretome, we have selected a number for validation. Proteomic analysis indicated that LPS stimulated the release of peroxiredoxin (PRDX) 1, PRDX2, vimentin (VIM), profilin1 (PFN1) and thioredoxin 1 (TXN1). For PRDX1 and TXN1, we were able to confirm that the released protein is glutathionylated. PRDX1, PRDX2 and TXN1 were also released by the human pulmonary epithelial cell line, A549, infected with influenza virus. The release of the proteins identified was inhibited by the anti-inflammatory glucocorticoid, dexamethasone (DEX), which also inhibited tumor necrosis factor (TNF)-α release, and by thiol antioxidants (N-butanoyl GSH derivative, GSH-C4, and N-acetylcysteine (NAC), which did not affect TNF-α production. The proteins identified could be useful as biomarkers of oxidative stress associated with inflammation, and further studies will be required to investigate if the extracellular forms of these proteins has immunoregulatory functions

A multi-stage genome-wide association study of bladder cancer identifies multiple susceptibility loci.

We conducted a multi-stage, genome-wide association study of bladder cancer with a primary scan of 591,637 SNPs in 3,532 affected individuals (cases) and 5,120 controls of European descent from five studies followed by a replication strategy, which included 8,382 cases and 48,275 controls from 16 studies. In a combined analysis, we identified three new regions associated with bladder cancer on chromosomes 22q13.1, 19q12 and 2q37.1: rs1014971, (P = 8 × 10⁻¹²) maps to a non-genic region of chromosome 22q13.1, rs8102137 (P = 2 × 10⁻¹¹) on 19q12 maps to CCNE1 and rs11892031 (P = 1 × 10⁻⁷) maps to the UGT1A cluster on 2q37.1. We confirmed four previously identified genome-wide associations on chromosomes 3q28, 4p16.3, 8q24.21 and 8q24.3, validated previous candidate associations for the GSTM1 deletion (P = 4 × 10⁻¹¹) and a tag SNP for NAT2 acetylation status (P = 4 × 10⁻¹¹), and found interactions with smoking in both regions. Our findings on common variants associated with bladder cancer risk should provide new insights into the mechanisms of carcinogenesis

A New Vaccine for Tuberculosis: The Challenges of Development and Deployment

Tuberculosis (TB) is one of the world’s leading causes of death due to infection and efforts to control TB would be substantially aided by the availability of an improved TB vaccine. There are currently nine new TB vaccines in clinical development, and the first efficacy trials are due to commence in 2009. There are many complex ethical issues which arise at all stages of TB vaccine development, from the need to conduct trials in developing countries to informed consent and the process of ethical review. While it is important that these issues are discussed, it may also be timely to consider the challenges which may arise if a vaccine in clinical development proves to be highly effective. We examine a number of scenarios where decisions on the deployment of a new TB vaccine may impact on the rights and liberty of the individual

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty