2,116 research outputs found

    The first polluted river? Repeated copper contamination of fluvial sediments associated with Late Neolithic human activity in southern Jordan

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    The roots of pyrometallurgy are obscure. This paper explores one possible precursor, in the Faynan Orefield in southern Jordan. There, at approximately 7000 cal. BP, banks of a near-perennial meandering stream (today represented by complex overbank wetland and anthropogenic deposits) were contaminated repeatedly by copper emitted by human activities. Variations in the distribution of copper in this sequence are not readily explained in other ways, although the precise mechanism of contamination remains unclear. The degree of copper enhancement was up to an order of magnitude greater than that measured in Pleistocene fluvial and paludal sediments, in contemporary or slightly older Holocene stream and pond deposits, and in the adjacent modern wadi braidplain. Lead is less enhanced, more variable, and appears to have been less influenced by contemporaneous human activities at this location. Pyrometallurgy in this region may have appeared as a byproduct of the activity practised on the stream-bank in the Wadi Faynan ~7000 years ago

    Heterotic Sigma Models with N=2 Space-Time Supersymmetry

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    We study the non-linear sigma model realization of a heterotic vacuum with N=2 space-time supersymmetry. We examine the requirements of (0,2) + (0,4) world-sheet supersymmetry and show that a geometric vacuum must be described by a principal two-torus bundle over a K3 manifold.Comment: 20 pages, uses xy-pic; v3: typos corrected, reference added, discussion of constraints on Hermitian form modifie

    The impact of cardiovascular co-morbidities and duration of diabetes on the association between microvascular function and glycaemic control

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    This is the final version of the article. Available from BioMed Central via the DOI in this record.BACKGROUND: Good glycaemic control in type 2 diabetes (T2DM) protects the microcirculation. Current guidelines suggest glycaemic targets be relaxed in advanced diabetes. We explored whether disease duration or pre-existing macrovascular complications attenuated the association between hyperglycaemia and microvascular function. METHODS: 743 participants with T2DM (n = 222), cardiovascular disease (CVD = 183), both (n = 177) or neither (controls = 161) from two centres in the UK, underwent standard clinical measures and endothelial dependent (ACh) and independent (SNP) microvascular function assessment using laser Doppler imaging. RESULTS: People with T2DM and CVD had attenuated ACh and SNP responses compared to controls. This was additive in those with both (ANOVA p < 0.001). In regression models, cardiovascular risk factors accounted for attenuated ACh and SNP responses in CVD, whereas HbA1c accounted for the effects of T2DM. HbA1c was associated with ACh and SNP response after adjustment for cardiovascular risk factors (adjusted standardised beta (β) -0.096, p = <0.008 and -0.135, p < 0.001, respectively). Pre-existing CVD did not modify this association (β -0.099; p = 0.006 and -0.138; p < 0.001, respectively). Duration of diabetes accounted for the association between HbA1c and ACh (β -0.043; p = 0.3), but not between HbA1c and SNP (β -0.105; p = 0.02). CONCLUSIONS: In those with T2DM and CVD, good glycaemic control is still associated with better microvascular function, whereas in those with prolonged disease this association is lost. This suggests duration of diabetes may be a better surrogate for "advanced disease" than concomitant CVD, although this requires prospective validation.This received support from the Innovative Medicines Initiative Joint Undertaking under the Grant Agreement No. 115006; http://www.imi-summit.eu

    Vitamin D Binding Protein and Monocyte Response to 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D: Analysis by Mathematical Modeling

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    Vitamin D binding protein (DBP) plays a key role in the bioavailability of active 1,25-dihydroxyvitamin D (1,25(OH)2D) and its precursor 25-hydroxyvitamin D (25OHD), but accurate analysis of DBP-bound and free 25OHD and 1,25(OH)2D is difficult. To address this, two new mathematical models were developed to estimate: 1) serum levels of free 25OHD/1,25(OH)2D based on DBP concentration and genotype; 2) the impact of DBP on the biological activity of 25OHD/1,25(OH)2D in vivo. The initial extracellular steady state (eSS) model predicted that 50 nM 25OHD and 100 pM 1,25(OH)2D), <0.1% 25OHD and <1.5% 1,25(OH)2D are ‘free’ in vivo. However, for any given concentration of total 25OHD, levels of free 25OHD are higher for low affinity versus high affinity forms of DBP. The eSS model was then combined with an intracellular (iSS) model that incorporated conversion of 25OHD to 1,25(OH)2D via the enzyme CYP27B1, as well as binding of 1,25(OH)2D to the vitamin D receptor (VDR). The iSS model was optimized to 25OHD/1,25(OH)2D-mediated in vitro dose-responsive induction of the vitamin D target gene cathelicidin (CAMP) in human monocytes. The iSS model was then used to predict vitamin D activity in vivo (100% serum). The predicted induction of CAMP in vivo was minimal at basal settings but increased with enhanced expression of VDR (5-fold) and CYP27B1 (10-fold). Consistent with the eSS model, the iSS model predicted stronger responses to 25OHD for low affinity forms of DBP. Finally, the iSS model was used to compare the efficiency of endogenously synthesized versus exogenously added 1,25(OH)2D. Data strongly support the endogenous model as the most viable mode for CAMP induction by vitamin D in vivo. These novel mathematical models underline the importance of DBP as a determinant of vitamin D ‘status’ in vivo, with future implications for clinical studies of vitamin D status and supplementation

    Treatment of an Intramammary Bacterial Infection with 25-Hydroxyvitamin D3

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    Deficiency of serum levels of 25-hydroxyvitamin D3 has been correlated with increased risk of infectious diseases such as tuberculosis and influenza. A plausible reason for this association is that expression of genes encoding important antimicrobial proteins depends on concentrations of 1,25-dihydroxyvitamin D3 produced by activated immune cells at sites of infection, and that synthesis of 1,25-dihydroxyvitamin D3 is dependent on the availability of 25-hydroxyvitamin D3. Thus, increasing the availability of 25(OH)D3 for immune cell synthesis of 1,25-dihydroxyvitamin D3 at sites of infection has been hypothesized to aid in clearance of the infection. This report details the treatment of an acute intramammary infection with infusion of 25-hydroxyvitamin D3 to the site of infection. Ten lactating cows were infected with in one quarter of their mammary glands. Half of the animals were treated intramammary with 25-hydroxyvitamin D3. The 25-hydroxyvitamin D3 treated animal showed significantly lower bacterial counts in milk and showed reduced symptomatic affects of the mastitis. It is significant that treatment with 25-hydroxyvitamin D3 reduced the severity of an acute bacterial infection. This finding suggested a significant non-antibiotic complimentary role for 25-hydroxyvitamin D3 in the treatment of infections in compartments naturally low in 25-hydroxyvitamin D3 such as the mammary gland and by extension, possibly upper respiratory tract infections

    A Systematic Review of Mosquito Coils and Passive Emanators: Defining Recommendations for Spatial Repellency Testing Methodologies.

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    Mosquito coils, vaporizer mats and emanators confer protection against mosquito bites through the spatial action of emanated vapor or airborne pyrethroid particles. These products dominate the pest control market; therefore, it is vital to characterize mosquito responses elicited by the chemical actives and their potential for disease prevention. The aim of this review was to determine effects of mosquito coils and emanators on mosquito responses that reduce human-vector contact and to propose scientific consensus on terminologies and methodologies used for evaluation of product formats that could contain spatial chemical actives, including indoor residual spraying (IRS), long lasting insecticide treated nets (LLINs) and insecticide treated materials (ITMs). PubMed, (National Centre for Biotechnology Information (NCBI), U.S. National Library of Medicine, NIH), MEDLINE, LILAC, Cochrane library, IBECS and Armed Forces Pest Management Board Literature Retrieval System search engines were used to identify studies of pyrethroid based coils and emanators with key-words "Mosquito coils" "Mosquito emanators" and "Spatial repellents". It was concluded that there is need to improve statistical reporting of studies, and reach consensus in the methodologies and terminologies used through standardized testing guidelines. Despite differing evaluation methodologies, data showed that coils and emanators induce mortality, deterrence, repellency as well as reduce the ability of mosquitoes to feed on humans. Available data on efficacy outdoors, dose-response relationships and effective distance of coils and emanators is inadequate for developing a target product profile (TPP), which will be required for such chemicals before optimized implementation can occur for maximum benefits in disease control

    Hyaluronic acid as a treatment for ankle osteoarthritis

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    Viscosupplementation refers to the concept of synovial fluid replacement with intra-articular injections of hyaluronic acid (HA) for the relief of pain associated with osteoarthritis (OA). Intra-articular viscosupplementation was approved by the Food and Drug Administration (FDA) in 1997. It is currently indicated only for the treatment of pain associated with knee OA. However, OA can occur in several of the weight-bearing joints of the foot and ankle. Ankle OA produces chronic disability that directly impacts the quality of life. There is only limited published literature relating to the use of HA in the ankle. This paper will review the authors’ experience, indications, clinical outcomes, and complications of viscosupplementation therapy in patients with ankle OA

    The Role of Citrullinated Proteins Suggests a Novel Mechanism in the Pathogenesis of Multiple Sclerosis

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    The pathogenesis of MS is unknown. In our studies, we have demonstrated an important role for citrullinated myelin basic protein (MBP). The accompanying loss of positive charge compromises the ability of MBP to interact with the lipid bilayer. The conversion of arginine to citrulline in brain is carried out by an enzyme peptidyl arginine deiminase (PAD) 2. The amount of PAD 2 in brain was increased in MS normal-appearing white matter. The mechanism responsible for this increase involved hypomethylation of the promoter region in the PAD 2 gene in MS, but no change (compared to normal) was found in thymus tissue DNA from the same MS patients. In addition, no change was observed in other neurological diseases, including Alzheimer’s, Parkinson’s, and Huntington’s. We propose that citrullinated MBP, resulting from elevated levels of PAD 2 represents an important biochemical pathway in the pathogenesis of MS

    Degenerate Rotating Black Holes, Chiral CFTs and Fermi Surfaces I - Analytic Results for Quasinormal Modes

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    In this work we discuss charged rotating black holes in AdS5×S5AdS_5 \times S^5 that degenerate to extremal black holes with zero entropy. These black holes have scaling properties between charge and angular momentum similar to those of Fermi surface operators in a subsector of N=4\mathcal{N}=4 SYM. We add a massless uncharged scalar to the five dimensional supergravity theory, such that it still forms a consistent truncation of the type IIB ten dimensional supergravity and analyze its quasinormal modes. Separating the equation of motion to a radial and angular part, we proceed to solve the radial equation using the asymptotic matching expansion method applied to a Heun equation with two nearby singularities. We use the continued fraction method for the angular Heun equation and obtain numerical results for the quasinormal modes. In the case of the supersymmetric black hole we present some analytic results for the decay rates of the scalar perturbations. The spectrum of quasinormal modes obtained is similar to that of a chiral 1+1 CFT, which is consistent with the conjectured field-theoretic dual. In addition, some of the modes can be found analytically.Comment: 41 pages, 1 figure, LaTeX; v2: typos corrected, references adde
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