2,235 research outputs found

    Kinetic study of the thermal denaturation of a hyperthermostable extracellular α-amylase from <i>Pyrococcus furiosus</i>

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    AbstractHyperthermophilic enzymes are of industrial importance and interest, especially due to their denaturation kinetics at commercial sterilisation temperatures inside safety indicating time–temperature integrators (TTIs). The thermal stability and irreversible thermal inactivation of native extracellular Pyrococcus furiosus α-amylase were investigated using differential scanning calorimetry, circular dichroism and Fourier transform infrared spectroscopy. Denaturation of the amylase was irreversible above a Tm of approximately 106°C and could be described by a one-step irreversible model. The activation energy at 121°C was found to be 316kJ/mol. Using CD and FT-IR spectroscopy it was shown that folding and stability greatly increase with temperature. Under an isothermal holding temperature of 121°C, the structure of the PFA changes during denaturation from an α-helical structure, through a β-sheet structure to an aggregated protein. Such data reinforces the use of P. furiosus α-amylase as a labile species in TTIs

    Staphylococcus aureus protein A binding to von Willebrand factor A1 domain is mediated by conserved IgG binding regions.

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    Protein A (Spa) is a surface-associated protein of Staphylococcus aureus best known for its ability to bind to the Fc region of IgG. Spa also binds strongly to the Fab region of the immunoglobulins bearing V(H)3 heavy chains and to von Willebrand factor (vWF). Previous studies have suggested that the protein A-vWF interaction is important in S. aureus adherence to platelets under conditions of shear stress. We demonstrate that Spa expression is sufficient for adherence of bacteria to immobilized vWF under low fluid shear. The full length recombinant Ig-binding region of protein A, Spa-EDABC, fused to glutathione-S-transferase (GST), bound recombinant vWF in a dose-dependent and saturable fashion with half maximal binding of about 30 nm in immunosorbent assays. Full length-Spa did not bind recombinant vWF A3 domain but displayed binding to recombinant vWF domains A1 and D\u27-D3 (half maximal binding at 100 nm and 250 nm, respectively). Each recombinant protein A Ig-binding domain bound to the A1 domain in a similar manner to the full length-Spa molecule (half maximal binding 100 nm). Amino acid substitutions were introduced in the GST-SpaD protein at sites known to be involved in IgG Fc or in V(H)3 Fab binding. Mutants altered in residues that recognized IgG Fc but not those that recognized V(H)3 Fab had reduced binding to vWF A1 and D\u27-D3. This indicated that both vWF regions recognized a region on helices I and II that overlapped the IgG Fc binding site

    Drug-Resistant Tuberculosis--Current Dilemmas, Unanswered Questions, Challenges and Priority Needs

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    Tuberculosis was declared a global emergency by the World Health Organization (WHO) in 1993. Following the declaration and the promotion in 1995 of directly observed treatment short course (DOTS), a cost-effective strategy to contain the tuberculosis epidemic, nearly 7 million lives have been saved compared with the pre-DOTS era, high cure rates have been achieved in most countries worldwide, and the global incidence of tuberculosis has been in a slow decline since the early 2000s. However, the emergence and spread of multidrug-resistant (MDR) tuberculosis, extensively drug-resistant (XDR) tuberculosis, and more recently, totally drug-resistant tuberculosis pose a threat to global tuberculosis control. Multidrug-resistant tuberculosis is a man-made problem. Laboratory facilities for drug susceptibility testing are inadequate in most tuberculosis-endemic countries, especially in Africa; thus diagnosis is missed, routine surveillance is not implemented, and the actual numbers of global drug-resistant tuberculosis cases have yet to be estimated. This exposes an ominous situation and reveals an urgent need for commitment by national programs to health system improvement because the response to MDR tuberculosis requires strong health services in general. Multidrug-resistant tuberculosis and XDR tuberculosis greatly complicate patient management within resource-poor national tuberculosis programs, reducing treatment efficacy and increasing the cost of treatment to the extent that it could bankrupt healthcare financing in tuberculosis-endemic areas. Why, despite nearly 20 years of WHO-promoted activity and >12 years of MDR tuberculosis–specific activity, has the country response to the drug-resistant tuberculosis epidemic been so ineffectual? The current dilemmas, unanswered questions, operational issues, challenges, and priority needs for global drug resistance screening and surveillance, improved treatment regimens, and management of outcomes and prevention of DR tuberculosis are discussed

    A Novel Glycoproteomics Workflow Reveals Dynamic O-GlcNAcylation of COPÎł1 as a Candidate Regulator of Protein Trafficking

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    O-linked β-N-acetylglucosamine (O-GlcNAc) is an abundant and essential intracellular form of protein glycosylation in animals and plants. In humans, dysregulation of O-GlcNAcylation occurs in a wide range of diseases, including cancer, diabetes, and neurodegeneration. Since its discovery more than 30 years ago, great strides have been made in understanding central aspects of O-GlcNAc signaling, including identifying thousands of its substrates and characterizing the enzymes that govern it. However, while many O-GlcNAcylated proteins have been reported, only a small subset of these change their glycosylation status in response to a typical stimulus or stress. Identifying the functionally important O-GlcNAcylation changes in any given signaling context remains a significant challenge in the field. To address this need, we leveraged chemical biology and quantitative mass spectrometry methods to create a new glycoproteomics workflow for profiling stimulus-dependent changes in O-GlcNAcylated proteins. In proof-of-principle experiments, we used this new workflow to interrogate changes in O-GlcNAc substrates in mammalian protein trafficking pathways. Interestingly, our results revealed dynamic O-GlcNAcylation of COPγ1, an essential component of the coat protein I (COPI) complex that mediates Golgi protein trafficking. Moreover, we detected 11 O-GlcNAc moieties on COPγ1 and found that this modification is reduced by a model secretory stress that halts COPI trafficking. Our results suggest that O-GlcNAcylation may regulate the mammalian COPI system, analogous to its previously reported roles in other protein trafficking pathways. More broadly, our glycoproteomics workflow is applicable to myriad systems and stimuli, empowering future studies of O-GlcNAc in a host of biological contexts

    Joint Statement on Pediatric Education at Schools of Pharmacy

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    Providing health care for children is a unique specialty, and pediatric patients represent approximately 25% of the population. Education of pharmacy students on patients across the lifespan is required by current Accreditation Council for Pharmacy Education standards and outcomes; thus, it is essential that pharmacy students gain a proficiency in caring for children. A collaborative panel of pediatric faculty members from schools and colleges of pharmacy was established to review the current literature regarding pediatric education in Doctor of Pharmacy curricula and establish updated recommendations for the provision of pediatric pharmacy education. This statement outlines five recommendations supporting inclusion of pediatric content and skills in Doctor of Pharmacy curricula

    Consumer\u27s Guide to Regulatory Impact Analysis: Ten Tips for Being an Informed Policymaker

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    Regulatory impact analyses (RIAs) weigh the benefits of regulations against the burdens they impose and are invaluable tools for informing decision makers.We offer 10 tips for nonspecialist policymakers and interested stakeholders who will be reading RIAs as consumers. Core problem: Determine whether the RIA identifies the core problem (compelling public need) the regulation is intended to address. Alternatives: Look for an objective, policy-neutral evaluation of the relative merits of reasonable alternatives. Baseline: Check whether the RIA presents a reasonable “counterfactual” against which benefits and costs are measured. Increments: Evaluate whether totals and averages obscure relevant distinctions and trade-offs. Uncertainty: Recognize that all estimates involve uncertainty, and ask what effect key assumptions, data, and models have on those estimates. Transparency: Look for transparency and objectivity of analytical inputs. Benefits: Examine how projected benefits relate to stated objectives. Costs: Understand what costs are included. Distribution: Consider how benefits and costs are distributed. Symmetrical treatment: Ensure that benefits and costs are presented symmetrically

    Consumer\u27s Guide to Regulatory Impact Analysis: Ten Tips for Being an Informed Policymaker

    Get PDF
    Regulatory impact analyses (RIAs) weigh the benefits of regulations against the burdens they impose and are invaluable tools for informing decision makers.We offer 10 tips for nonspecialist policymakers and interested stakeholders who will be reading RIAs as consumers. Core problem: Determine whether the RIA identifies the core problem (compelling public need) the regulation is intended to address. Alternatives: Look for an objective, policy-neutral evaluation of the relative merits of reasonable alternatives. Baseline: Check whether the RIA presents a reasonable “counterfactual” against which benefits and costs are measured. Increments: Evaluate whether totals and averages obscure relevant distinctions and trade-offs. Uncertainty: Recognize that all estimates involve uncertainty, and ask what effect key assumptions, data, and models have on those estimates. Transparency: Look for transparency and objectivity of analytical inputs. Benefits: Examine how projected benefits relate to stated objectives. Costs: Understand what costs are included. Distribution: Consider how benefits and costs are distributed. Symmetrical treatment: Ensure that benefits and costs are presented symmetrically

    Early warning signals of simulated Amazon rainforest dieback

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    Copyright © The Author(s) 2013. This article is published with open access at Springerlink.comWe test proposed generic tipping point early warning signals in a complex climate model (HadCM3) which simulates future dieback of the Amazon rainforest. The equation governing tree cover in the model suggests that zero and non-zero stable states of tree cover co-exist, and a transcritical bifurcation is approached as productivity declines. Forest dieback is a non-linear change in the non-zero tree cover state, as productivity declines, which should exhibit critical slowing down. We use an ensemble of versions of HadCM3 to test for the corresponding early warning signals. However, on approaching simulated Amazon dieback, expected early warning signals of critical slowing down are not seen in tree cover, vegetation carbon or net primary productivity. The lack of a convincing trend in autocorrelation appears to be a result of the system being forced rapidly and non-linearly. There is a robust rise in variance with time, but this can be explained by increases in inter-annual temperature and precipitation variability that force the forest. This failure of generic early warning indicators led us to seek more system-specific, observable indicators of changing forest stability in the model. The sensitivity of net ecosystem productivity to temperature anomalies (a negative correlation) generally increases as dieback approaches, which is attributable to a non-linear sensitivity of ecosystem respiration to temperature. As a result, the sensitivity of atmospheric CO2 anomalies to temperature anomalies (a positive correlation) increases as dieback approaches. This stability indicator has the benefit of being readily observable in the real world.NERCJoint DECC/Defra Met Office Hadley Centre Climate ProgrammeUniversity of Exete
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