1,492 research outputs found

    Persistent anthrax as a major driver of wildlife mortality in a tropical rainforest

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    Anthrax is a globally important animal disease and zoonosis. Despite this, our current knowledge of anthrax ecology is largely limited to arid ecosystems, where outbreaks are most commonly reported. Here we show that the dynamics of an anthrax-causing agent, Bacillus cereus biovar anthracis, in a tropical rainforest have severe consequences for local wildlife communities. Using data and samples collected over three decades, we show that rainforest anthrax is a persistent and widespread cause of death for a broad range of mammalian hosts. We predict that this pathogen will accelerate the decline and possibly result in the extirpation of local chimpanzee (Pan troglodytes verus) populations. We present the epidemiology of a cryptic pathogen and show that its presence has important implications for conservation

    Tertiary hypothyroidism in a dog

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    <p/> <p>A nine-year-old male entire Labrador was diagnosed with pituitary dependent hyperadrenocorticism. Following seven months of successful mitotane therapy, the dog presented with marked weight gain, seborrhoea and alopecia. Routine clinicopathological analyses revealed marked hypercholesterolaemia. Serum total and free thyroxine (T4) concentrations were below their respective reference ranges. Serum thyroid stimulating hormone (cTSH) concentration was within reference range. TSH and thyrotropin releasing hormone (TRH) response tests revealed adequate stimulation of total T4 in both, and cTSH in the latter test. Magnetic resonance imaging revealed a mass arising from the pituitary fossa, with suprasellar extension. A diagnosis of tertiary hypothyroidism was made. Following four weeks of levothyroxine therapy, circulating cholesterol concentration had declined, weight loss had ensued and dermatological abnormalities had improved. Euthanasia was performed four months later due to the development of neurological signs. A highly infiltrative pituitary adenoma, with effacement of the overlying hypothalamus was identified on post mortem examination. Tertiary hypothyroidism has not been previously reported in dogs.</p

    Development and validation of a short version of the Partnership Self-Assessment Tool (PSAT) among professionals in Dutch disease-management partnerships

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    Background: The extent to which partnership synergy is created within quality improvement programmes in the Netherlands is unknown. In this article, we describe the psychometric testing of the Partnership Self-Assessment Tool (PSAT) among professionals in twenty-two disease-management partnerships participating in quality improvement projects focused on chronic care in the Netherlands. Our objectives are to validate the PSAT in the Netherlands and to reduce the number of items of the original PSAT while maintaining validity and reliability. Methods. The Dutch version of the PSAT was tested in twenty-two disease-management partnerships with 218 professionals. We tested the instrument by means of structural equation modelling, and examined its validity and reliability. Results: After eliminating 14 items, the confirmatory factor analyses revealed good indices of fit with the resulting 15-item PSAT-Short version (PSAT-S). Internal consistency as represented by Cronbach's alpha ranged from acceptable (0.75) for the 'efficiency' subscale to excellent for the 'leadership' subscale (0.87). Convergent validity was provided with high correlations of the partnership dimensions and partnership synergy (ranged from 0.512 to 0.609) and high correlations with chronic illness care (ranged from 0.447 to 0.329). Conclusion: The psychometric properties and convergent validity of the PSAT-S were satisfactory rendering it a valid and reliable instrument for assessing partnership syne

    Defining the molecular basis of interaction between R3 receptor-type protein tyrosine phosphatases and VE-cadherin

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    Receptor-type protein tyrosine phosphatases (RPTPs) of the R3 subgroup play key roles in the immune, vascular and nervous systems. They are characterised by a large ectodomain comprising multiple FNIII-like repeats, a transmembrane domain, and a single intracellular phosphatase domain. The functional role of the extracellular region has not been clearly defined and potential roles in ligand interaction, di-merization, and regulation of cell-cell contacts have been reported. Here bimolecular fluorescence complementation (BiFC) in live cells was used to examine the molecular basis for the interaction of VE-PTP with VE-cadherin, two proteins involved in endothelial cell contact and maintenance of vascu-lar integrity. The potential of other R3-PTPs to interact with VE-cadherin was also explored using this method. Quantitative BiFC analysis, using a VE-PTP construct expressing only the ectodomain and transmembrane domain, revealed a specific interaction with VE-cadherin, when compared with con-trols. Controls were sialophorin, an unrelated membrane protein with a large ectodomain, and a mem-brane anchored C-terminal Venus-YFP fragment, lacking both ectodomain and transmembrane do-mains. Truncation of the first 16 FNIII-like repeats from the ectodomain of VE-PTP indicated that re-moval of this region is not sufficient to disrupt the interaction with VE-cadherin, although it occurs predominantly in an intracellular location. A construct with a deletion of only the 17th domain of VE-PTP was, in contrast to previous studies, still able to interact with VE-cadherin, although this also was predominantly intracellular. Other members of the R3-PTP family (DEP-1, GLEPP1 and SAP-1) also exhibited the potential to interact with VE-cadherin. The direct interaction of DEP-1 with VE-cadherin is likely to be of physiological relevance since both proteins are expressed in endothelial cells. Together the data presented in the study suggest a role for both the ectodomain and transmembrane domain of R3-PTPs in interaction with VE-cadherin

    Neurodevelopmental risk factors in schizophrenia

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    The authors review environmental and neurodevelopmental risk factors for schizophrenic disorders, with emphasis on minor physical anomalies, particularly craniofacial anomalies and dermatoglyphic variations. The high prevalence of these anomalies among schizophrenic subjects supports the neurodevelopmental theory of the etiology of schizophrenia, since they suggest either genetically or epigenetically controlled faulty embryonic development of structures of ectodermal origin like brain and skin. This may disturb neurodevelopment that in turn may cause these subjects to be at increased risk for the development of schizophrenia and related disorders. The precise confirmation of this theory, at least in some cases, will provide further understanding of these illnesses, allowing easy and inexpensive identification of subjects at risk and providing guidelines for the development of new pharmacological interventions for early treatment and even for primary prevention of the illness

    Identifying Insects with Incomplete DNA Barcode Libraries, African Fruit Flies (Diptera: Tephritidae) as a Test Case

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    We propose a general working strategy to deal with incomplete reference libraries in the DNA barcoding identification of species. Considering that (1) queries with a large genetic distance with their best DNA barcode match are more likely to be misidentified and (2) imposing a distance threshold profitably reduces identification errors, we modelled relationships between identification performances and distance thresholds in four DNA barcode libraries of Diptera (n = 4270), Lepidoptera (n = 7577), Hymenoptera (n = 2067) and Tephritidae (n = 602 DNA barcodes). In all cases, more restrictive distance thresholds produced a gradual increase in the proportion of true negatives, a gradual decrease of false positives and more abrupt variations in the proportions of true positives and false negatives. More restrictive distance thresholds improved precision, yet negatively affected accuracy due to the higher proportions of queries discarded (viz. having a distance query-best match above the threshold). Using a simple linear regression we calculated an ad hoc distance threshold for the tephritid library producing an estimated relative identification error <0.05. According to the expectations, when we used this threshold for the identification of 188 independently collected tephritids, less than 5% of queries with a distance query-best match below the threshold were misidentified. Ad hoc thresholds can be calculated for each particular reference library of DNA barcodes and should be used as cut-off mark defining whether we can proceed identifying the query with a known estimated error probability (e.g. 5%) or whether we should discard the query and consider alternative/complementary identification methods

    Transverse propagation of action potentials between parallel chains of cardiac muscle and smooth muscle cells in PSpice simulations

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    BACKGROUND: We previously examined transverse propagation of action potentials between 2 and 3 parallel chain of cardiac muscle cells (CMC) simulated using the PSpice program. The present study was done to examine transverse propagation between 5 parallel chains in an expanded model of CMC and smooth muscle cells (SMC). METHODS: Excitation was transmitted from cell to cell along a strand of 5 cells not connected by low-resistance tunnels (gap-junction connexons). The entire surface membrane of each cell fired nearly simultaneously, and nearly all the propagation time was spent at the cell junctions, the junctional delay time being about 0.3 – 0.5 ms (CMC) or 0.8 – 1.6 ms (SMC). A negative cleft potential (V(jc)) develops in the narrow junctional clefts, whose magnitude depends on the radial cleft resistance (R(jc)), which depolarizes the postjunctional membrane (post-JM) to threshold. Propagation velocity (θ) increased with amplitude of V(jc). Therefore, one mechanism for the transfer of excitation from one cell to the next is by the electric field (EF) that is generated in the junctional cleft when the pre-JM fires. In the present study, 5 parallel stands of 5 cells each (5 × 5 model) were used. RESULTS: With electrical stimulation of the first cell of the first strand (cell A1), propagation rapidly spread down that chain and then jumped to the second strand (B chain), followed by jumping to the third, fourth, and fifth strands (C, D, E chains). The rapidity by which the parallel chains became activated depended on the longitudinal resistance of the narrow extracellular cleft between the parallel strands (R(ol2)); the higher the R(ol2 )resistance, the faster the θ. The transverse resistance of the cleft (R(or2)) had almost no effect. Increasing R(jc )decreases the total propagation time (TPT) over the 25-cell network. When the first cell of the third strand (cell C1) was stimulated, propagation spread down the C chain and jumped to the other two strands (B and D) nearly simultaneously. CONCLUSIONS: Transverse propagation of excitation occurred at multiple points along the chain as longitudinal propagation was occurring, causing the APs in the contiguous chains to become bunched up. Transverse propagation was more erratic and labile in SMC compared to CMC. Transverse transmission of excitation did not require low-resistance connections between the chains, but instead depended on the value of R(ol2). The tighter the packing of the chains facilitated transverse propagation

    Different SO(10) Paths to Fermion Masses and Mixings

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    Recently SO(10) models with type-II see-saw dominance have been proposed as a promising framework for obtaining Grand Unification theories with approximate Tri-bimaximal (TB) mixing in the neutrino sector. We make a general study of SO(10) models with type-II see-saw dominance and show that an excellent fit can be obtained for fermion masses and mixings, also including the neutrino sector. To make this statement more significant we compare the performance of type-II see-saw dominance models in fitting the fermion masses and mixings with more conventional models which have no built-in TB mixing in the neutrino sector. For a fair comparison the same input data and fitting procedure is adopted for all different theories. We find that the type-II dominance models lead to an excellent fit, comparable with the best among the available models, but the tight structure of this framework implies a significantly larger amount of fine tuning with respect to other approaches.Comment: 24 pages, References and minor wording changes adde
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