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Search Results: 1 - 10 of 198817 matches for " Scott D. Foster "
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Inhibited Production of iNOS by Murine J774 Macrophages Occurs via a phoP-Regulated Differential Expression of NFκB and AP-1
Scott D. Hulme,Paul A. Barrow,Neil Foster
Interdisciplinary Perspectives on Infectious Diseases , 2012, DOI: 10.1155/2012/483170
Abstract: Background. There are no reported data to explain how Salmonella suppress nitrite ion production in macrophages or whether this phenomenon is unique to typhoidal or non-typhoidal serovars. The aims of this study were, therefore, to investigate these phenomena. Methods. We measured survival of S. typhimurium 14028 and its phoP mutant in murine J774 macrophages, cultured with or without interferon gamma. We compared expression of inducible nitric oxide synthase (iNOS) mRNA and protein, and nitrite ion production and also examined binding of nuclear factor B (NF B) and activator protein 1 (AP-1) to macrophage DNA. Results. S. typhimurium 14028 inhibited binding of NF B and AP-1 to DNA in murine J774. A macrophages via an intact phoP regulon. This correlated with increased survival and reduced iNOS expression. Suppression of NF B activity was ameliorated in macrophages cultured with IFN-γ and this correlated with increased expression of iNOS mRNA and nitrite ion production, although IFN-γ had no effect on AP-1/DNA interaction. We show, that with one exception, suppression of iNOS is unique to typhoidal serovars. Conclusion. S. typhimurium inhibit NF B and AP-1 interaction with macrophage DNA via the PhoP regulon, this reduces nitrite ion production and is principally associated with typhoidal serovars. 1. Introduction S. typhimurium infection in mice is a standard laboratory model for human typhoid, and previous studies have shown that S. typhimurium mutants which are unable to survive in murine macrophages are avirulent [1]. Thus, survival of Salmonella in macrophages appears to be a critical step in the induction of typhoid. The Salmonella phoP/phoQ regulon regulates genes located on Salmonella Pathogenicity Island 2 (SPI-2) which encode proteins needed for survival of Salmonella inside of macrophages [2] and Salmonellae which have mutations in their phoP/phoQ regulon are avirulent in mice [3]. The affect of phoP on salmonella survival is multifaceted but studies by Svensson et al. [4] have shown that phoP mutation induces increased nitrite ion production by macrophages compared with nitrite ion production induced by the parent strain but this study did not investigate the mechanisms behind this phenomenon. Studies using and mice indicate that reactive nitrogen species (RNS) are important in controlling Salmonella later in the infection and this is preceded by a reactive oxygen species (ROS)-dependent control phase [5, 6] and it is also known that nitric oxide increases the sensitivity to cellular acid by phoP mutants [7]. Taken together these studies
Accounting for Location Error in Kalman Filters: Integrating Animal Borne Sensor Data into Assimilation Schemes
Aritra Sengupta, Scott D. Foster, Toby A. Patterson, Mark Bravington
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042093
Abstract: Data assimilation is a crucial aspect of modern oceanography. It allows the future forecasting and backward smoothing of ocean state from the noisy observations. Statistical methods are employed to perform these tasks and are often based on or related to the Kalman filter. Typically Kalman filters assumes that the locations associated with observations are known with certainty. This is reasonable for typical oceanographic measurement methods. Recently, however an alternative and abundant source of data comes from the deployment of ocean sensors on marine animals. This source of data has some attractive properties: unlike traditional oceanographic collection platforms, it is relatively cheap to collect, plentiful, has multiple scientific uses and users, and samples areas of the ocean that are often difficult of costly to sample. However, inherent uncertainty in the location of the observations is a barrier to full utilisation of animal-borne sensor data in data-assimilation schemes. In this article we examine this issue and suggest a simple approximation to explicitly incorporate the location uncertainty, while staying in the scope of Kalman-filter-like methods. The approximation stems from a Taylor-series approximation to elements of the updating equation.
Twenty Years of High-Resolution Sea Surface Temperature Imagery around Australia: Inter-Annual and Annual Variability
Scott D. Foster, David A. Griffin, Piers K. Dunstan
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100762
Abstract: The physical climate defines a significant portion of the habitats in which biological communities and species reside. It is important to quantify these environmental conditions, and how they have changed, as this will inform future efforts to study many natural systems. In this article, we present the results of a statistical summary of the variability in sea surface temperature (SST) time-series data for the waters surrounding Australia, from 1993 to 2013. We partition variation in the SST series into annual trends, inter-annual trends, and a number of components of random variation. We utilise satellite data and validate the statistical summary from these data to summaries of data from long-term monitoring stations and from the global drifter program. The spatially dense results, available as maps from the Australian Oceanographic Data Network's data portal (http://www.cmar.csiro.au/geonetwork/srv/?en/metadata.show?id=51805), show clear trends that associate with oceanographic features. Noteworthy oceanographic features include: average warming was greatest off southern West Australia and off eastern Tasmania, where the warming was around 0.6°C per decade for a twenty year study period, and insubstantial warming in areas dominated by the East Australian Current, but this area did exhibit high levels of inter-annual variability (long-term trend increases and decreases but does not increase on average). The results of the analyses can be directly incorporated into (biogeographic) models that explain variation in biological data where both biological and environmental data are on a fine scale.
Multi-species distribution modeling using penalized mixture of regressions
Francis K. C. Hui,David I. Warton,Scott D. Foster
Statistics , 2015, DOI: 10.1214/15-AOAS813
Abstract: Multi-species distribution modeling, which relates the occurrence of multiple species to environmental variables, is an important tool used by ecologists for both predicting the distribution of species in a community and identifying the important variables driving species co-occurrences. Recently, Dunstan, Foster and Darnell [Ecol. Model. 222 (2011) 955-963] proposed using finite mixture of regression (FMR) models for multi-species distribution modeling, where species are clustered based on their environmental response to form a small number of "archetypal responses." As an illustrative example, they applied their mixture model approach to a presence-absence data set of 200 marine organisms, collected along the Great Barrier Reef in Australia. Little attention, however, was given to the problem of model selection - since the archetypes (mixture components) may depend on different but likely overlapping sets of covariates, a method is needed for performing variable selection on all components simultaneously. In this article, we consider using penalized likelihood functions for variable selection in FMR models. We propose two penalties which exploit the grouped structure of the covariates, that is, each covariate is represented by a group of coefficients, one for each component. This leads to an attractive form of shrinkage that allows a covariate to be removed from all components simultaneously. Both penalties are shown to possess specific forms of variable selection consistency, with simulations indicating they outperform other methods which do not take into account the grouped structure. When applied to the Great Barrier Reef data set, penalized FMR models offer more insight into the important variables driving species co-occurrence in the marine community (compared to previous results where no model selection was conducted), while offering a computationally stable method of modeling complex species-environment relationships (through regularization).
Outcomes of 23-gauge pars plana vitrectomy in combined scleral buckling and vitrectomy for complex rhegmatogenous retinal detachments
Scott D. Schoenberger,Daniel M. Miller,Christopher D. Riemann,Robert E. Foster
Eye Reports , 2011, DOI: 10.4081/eye.2011.e3
Abstract: Rhegmatogenous retinal detachments associated with proliferative vitreoretinopathy, giant retinal tears, ocular trauma, proliferative diabetic retinopathy, or necrotizing retinitis are considered more complex than those without these factors. The aim of the current review is to address the surgical outcomes and complications of 23-gauge pars plana vitrectomy with scleral buckling (23GPPV/SB) for repair of these complex retinal detachments. This retrospective study involved 54 eyes of 53 patients who underwent 23GPPV/SB between July 2007 and September 2009. Preoperative diagnosis, surgical technique, preoperative and postoperative visual acuities, intraoperative and postoperative complications, and anatomic reattachment rates were examined. Fifty-four eyes of 53 patients were reviewed in this study and indications for surgery varied. Mean logarithm of the minimal angle of resolution (logMAR) pre- and post-operative visual acuities were 1.166 (20/293) and 0.780 (20/120), respectively, which led to a statistically significant improvement in logMAR (P=0.0165). Single operation and final reattachment rates were 87% (47 of 54 eyes) and 100%, respectively. Postoperative complications included choroidal effusion/hemorrhage (14.8%, 8 of 54 eyes) and vitreous hemorrhage (11.1%, 6 of 54 eyes). Other more infrequent complications included hyphema (9.3%, 5 of 54 eyes), hypotony (5.6%, 3 of 54 eyes) and ocular hypertension > 35 mmHg (3.7%, 2 of 54 eyes). A total of 31.5% (17 of 54 eyes) of patients had a complication in the postoperative time period, but 58.8% of these resolved spontaneously without requiring an intervention. 23GPPV/SB may be considered for complex retinal detachment repair with good anatomic reattachment rates, but with relatively high complication rates.
Efficacy of CMX001 as a Prophylactic and Presymptomatic Antiviral Agent in New Zealand White Rabbits Infected with Rabbitpox Virus, a Model for Orthopoxvirus Infections of Humans
Amanda D. Rice,Mathew M. Adams,Bernhard Lampert,Scott Foster,Randall Lanier,Alice Robertson,George Painter,Richard W. Moyer
Viruses , 2011, DOI: 10.3390/v3020063
Abstract: CMX001, a lipophilic nucleotide analog formed by covalently linking 3?(hexdecyloxy)propan-1-ol to cidofovir (CDV), is being developed as a treatment for smallpox. CMX001 has dramatically increased potency versus CDV against all dsDNA viruses and, in contrast to CDV, is orally available and has shown no evidence of nephrotoxicity in healthy volunteers or severely ill transplant patients to date. Although smallpox has been eliminated from the environment, treatments are urgently being sought due to the risk of smallpox being used as a bioterrorism agent and for monkeypox virus, a zoonotic disease of Africa, and adverse reactions to smallpox virus vaccinations. In the absence of human cases of smallpox, new treatments must be tested for efficacy in animal models. Here we first review and discuss the rabbitpox virus (RPV) infection of New Zealand White rabbits as a model for smallpox to test the efficacy of CMX001 as a prophylactic and early disease antiviral. Our results should also be applicable to monkeypox virus infections and for treatment of adverse reactions to smallpox vaccination.
Trilinear Hexahedra with Integral-Averaged Volumes for Nearly Incompressible Nonlinear Deformation  [PDF]
Craig D. Foster, Talisa Mohammad Nejad
Engineering (ENG) , 2015, DOI: 10.4236/eng.2015.711067
Abstract: Many materials such as biological tissues, polymers, and metals in plasticity can undergo large deformations with very little change in volume. Low-order finite elements are also preferred for certain applications, but are well known to behave poorly for such nearly incompressible materials. Of the several methods to relieve this volumetric locking, the \"\" method remains popular as no extra variables or nodes need to be added, making the implementation relatively straightforward and efficient. In the large deformation regime, the incompressibility is often treated by using a reduced order or averaged value of the volumetric part of the deformation gradient, and hence this technique is often termed an \"\" approach. However, there is little in the literature detailing the relationship between the choice of \"\" and the resulting \"\" and stiffness matrices. In this article, we develop a framework for relating the choice of \"\" to the resulting \"\" and stiffness matrices. We examine two volume-averaged choices for \"\" , one in the reference and one in the current configuration. Volume-averaged \"\" formulation has the advantage that no integration points are added. Therefore, there is a modest savings in memory and no integration point quantities needed to be interpolated between different sets of points. Numerical results show that the two formulations developed give similar results to existing methods.
Efficacy of CMX001 as a Post Exposure Antiviral in New?Zealand White Rabbits Infected with Rabbitpox Virus, a?Model for Orthopoxvirus Infections of Humans
Amanda D. Rice,Mathew M. Adams,Greg Wallace,Andrew M. Burrage,Scott F. Lindsey,Andrew J. Smith,Daniele Swetnam,Brandi R. Manning,Stacey A. Gray,Bernhard Lampert,Scott Foster,Randall Lanier,Alice Robertson,George Painter,Richard W. Moyer
Viruses , 2011, DOI: 10.3390/v3010047
Abstract: CMX001, a lipophilic nucleotide analog formed by covalently linking 3-(hexdecyloxy)propan-1-ol to cidofovir (CDV), is being developed as a treatment for smallpox. In the absence of human cases of smallpox, new treatments must be tested for efficacy in animal models. Previously, we demonstrated the efficacy of CMX001 in protecting New Zealand White rabbits from mortality following intradermal infection with rabbitpox virus as a model for smallpox, monkeypox and for treatment of adverse reactions to smallpox vaccination. Here we extend these studies by exploring different dosing regimens and performing randomized, blinded, placebo-controlled studies. In addition, because rabbitpox virus can be transmitted via naturally generated aerosols (animal to animal transmission), we report on studies to test the efficacy of CMX001 in protecting rabbits from lethal rabbitpox virus disease when infection occurs by animal to animal transmission. In all cases, CMX001 treatment was initiated at the onset of observable lesions in the ears to model the use of CMX001 as a treatment for symptomatic smallpox. The results demonstrate that CMX001 is an effective treatment for symptomatic rabbitpox virus infection. The rabbitpox model has key similarities to human smallpox including an incubation period, generalized systemic disease, the occurrence of lesions which may be used as a trigger for initiating therapy, and natural animal to animal spread, making it an appropriate model.
Foundation Myth as legal formant: The medieval Law Merchant and the new Lex Mercatoria
Nicholas H. D. Foster
Forum Historiae Iuris , 2005,
Abstract:
Universality of collapsing two-dimensional self-avoiding trails
D P Foster
Physics , 2009, DOI: 10.1088/1751-8113/42/37/372002
Abstract: Results of a numerically exact transfer matrix calculation for the model of Interacting Self-Avoiding Trails are presented. The results lead to the conclusion that, at the collapse transition, Self-Avoiding Trails are in the same universality class as the O(n=0) model of Blote and Nienhuis (or vertex-interacting self-avoiding walk), which has thermal exponent $\nu=12/23$, contrary to previous conjectures.
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