The Influence of pH Variation on CooA Activity

CooA, a CO-sensing heme protein, acts as a transcriptional activator of CO-metabolizing proteins in bacteria such as Rhodospirillum rubrum and Carboxydothermus hydrogenoformans through sequence-specific DNA binding. Previous research indicated a reduced iron center and CO gas were necessary for CooA to achieve its active conformation and bind DNA. To determine if other reaction conditions facilitate CooA activation, the role of pH on CooA function was tested. Specifically, a fluorescence anisotropy assay was employed to measure possible Fe(III) CooA DNA binding from pH 3 - 12. Interestingly, CooA was observed to bind DNA without CO at acidic conditions, with optimal binding observed at pH ~3. These results are discussed in light of the normal CO-dependent activation mechanism of CooA proteins

Design of a Horizontal Axis Open-Centre Tidal Stream Turbine using Computational Fluid Dynamics

Tidal energy is one of the most promising emerging renewable energy sources which remains largely untapped, due primarily to the challenges of submerged operation within sensitive marine environments. Extracting kinetic energy from dense and energetic flow streams which vary in height, reverse flow direction roughly twice a day and carry sediment as well as marine life requires a unique application of engineering knowledge. A variety of tidal turbine technologies have been developed in response, although as yet the industry is far from mature and there remains great potential for improvement. The research presented in this study introduces a new type of turbine design which has been developed specifically to address the issue of balancing marine friendly technology with efficient energy harvest. This is accomplished through the use of an open-centre concept which houses the blades between the hub and shroud, thus minimizing the risk of blade tip impact and providing free passage through the central aperture. In this study several iterations of the design are tested using the methods of computational fluid dynamics (CFD), each one featuring a different helical blade geometry of varying length and twist angle. A numerical model of the new design is presented in which the energy generation potential is assessed by measuring the amount of torque produced by a stationary blade placed in a steady flow. The torque is calculated by determining the pressure force acting on each blade surface and the resulting moment generated about the rotation axis of the turbine. This method allows for a great number of geometries to be tested under simulated turbine operating conditions, without requiring a prohibitive amount of computational resources. The initial assessment of this new type of turbine is promising, indicating that certain blade geometries produce a greater amount of torque than a model of the conventional open-centre turbine developed by OpenHydro

The Interactions between Insulin and Androgens in Progression to Castrate-Resistant Prostate Cancer

An association between the metabolic syndrome and reduced testosterone levels has been identified, and a specific inverse relationship between insulin and testosterone levels suggests that an important metabolic crosstalk exists between these two hormonal axes; however, the mechanisms by which insulin and androgens may be reciprocally regulated are not well described. Androgen-dependant gene pathways regulate the growth and maintenance of both normal and malignant prostate tissue, and androgen-deprivation therapy (ADT) in patients exploits this dependence when used to treat recurrent and metastatic prostate cancer resulting in tumour regression. A major systemic side effect of ADT includes induction of key features of the metabolic syndrome and the consistent feature of hyperinsulinaemia. Recent studies have specifically identified a correlation between elevated insulin and high-grade PCa and more rapid progression to castrate resistant disease. This paper examines the relationship between insulin and androgens in the context of prostate cancer progression. Prostate cancer patients present a promising cohort for the exploration of insulin stabilising agents as adjunct treatments for hormone deprivation or enhancers of chemosensitivity for treatment of advanced prostate cancer

Numerical simulation and flow visualization using soap film of the self-organized vortex structure in the wake of an array of cylinders

With the aid of computational fluid dynamics (CFD) and simple flow visualization technique using flowing soap-film, we present here the wake structures behind an array of cylinders for Reynolds numbers corresponding to both laminar and turbulent flow regimes. The image results illustrate interesting vortex interactions past these equally spaced cylinders; for low Reynolds number flow, well-organized wake pattern persists and manifests unsteadily to different symmetry states. An increase of free stream flow velocity causes the wake transition, resulting in the formation of asymmetric flow wake with chaotic mixing at the far wake. Observations from both the numerical simulations and soap-film are in good agreement at least qualitatively

Evaluation at scale of microbiome-derived metabolites as biomarker of flavan-3-ol intake in epidemiological studies.

The accurate assessment of dietary intake is crucial to investigate the effect of diet on health. Currently used methods, relying on self-reporting and food composition data, are known to have limitations and might not be suitable to estimate the intake of many bioactive food components. An alternative are nutritional biomarkers, which can allow an unbiased assessment of intake. They require a careful evaluation of their suitability, including: (a) the availability of a precise, accurate and robust analytical method, (b) their specificity (c) a consistent relationship with actual intake. We have evaluated human metabolites of a microbiome-derived flavan-3-ol catabolite, 5-(3',4'-dihydroxyphenyl)-[gamma]-valerolactone (gVL), as biomarker of flavan-3-ol intake in large epidemiological studies. Flavan-3-ols are widely consumed plant bioactives, which have received considerable interest due to their potential ability to reduce CVD risk. The availability of authentic standards allowed the development of a validated high-throughput method suitable for large-scale studies. In dietary intervention studies, we could show that gVL metabolites are specific for flavan-3-ols present in tea, fruits, wine and cocoa-derived products, with a strong correlation between intake and biomarker (Spearman's r = 0.90). This biomarker will allow for the first time to estimate flavan-3-ol intake and further investigation of associations between intake and disease risk