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Search Results: 1 - 10 of 465324 matches for " Stuart A. Morgan "
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Regulation of Lipogenesis by Glucocorticoids and Insulin in Human Adipose Tissue
Laura L. Gathercole, Stuart A. Morgan, Iwona J. Bujalska, David Hauton, Paul M. Stewart, Jeremy W. Tomlinson
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0026223
Abstract: Patients with glucocorticoid (GC) excess, Cushing's syndrome, develop a classic phenotype characterized by central obesity and insulin resistance. GCs are known to increase the release of fatty acids from adipose, by stimulating lipolysis, however, the impact of GCs on the processes that regulate lipid accumulation has not been explored. Intracellular levels of active GC are dependent upon the activity of 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) and we have hypothesized that 11β-HSD1 activity can regulate lipid homeostasis in human adipose tissue (Chub-S7 cell line and primary cultures of human subcutaneous (sc) and omental (om) adipocytes. Across adipocyte differentiation, lipogenesis increased whilst β-oxidation decreased. GC treatment decreased lipogenesis but did not alter rates of β-oxidation in Chub-S7 cells, whilst insulin increased lipogenesis in all adipocyte cell models. Low dose Dexamethasone pre-treatment (5 nM) of Chub-S7 cells augmented the ability of insulin to stimulate lipogenesis and there was no evidence of adipose tissue insulin resistance in primary sc cells. Both cortisol and cortisone decreased lipogenesis; selective 11β-HSD1 inhibition completely abolished cortisone-mediated repression of lipogenesis. GCs have potent actions upon lipid homeostasis and these effects are dependent upon interactions with insulin. These in vitro data suggest that manipulation of GC availability through selective 11β-HSD1 inhibition modifies lipid homeostasis in human adipocytes.
Effects of the neurological wake-up test on clinical examination, intracranial pressure, brain metabolism and brain tissue oxygenation in severely brain-injured patients
Raimund Helbok, Pedro Kurtz, Michael J Schmidt, Morgan R Stuart, Luis Fernandez, Sander E Connolly, Kiwon Lee, Erich Schmutzhard, Stephan A Mayer, Jan Claassen, Neeraj Badjatia
Critical Care , 2012, DOI: 10.1186/cc11880
Abstract: This prospective observational study was performed in a neuroscience intensive care unit in a tertiary-care academic center. Twenty consecutive severely brain-injured patients with multimodal neuromonitoring were analyzed for levels of brain lactate, pyruvate and glucose, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and brain tissue oxygen tension (PbtO2) during IS trials.Of the 82 trial days, 54 IS-trials were performed as interruption of sedation and analgesics were not considered safe on 28 days (34%). An increase in the FOUR Score (Full Outline of UnResponsiveness score) was observed in 50% of IS-trials by a median of three (two to four) points. Detection of a new neurologic deficit occurred in one trial (2%), and in one-third of IS-trials the trial had to be stopped due to an ICP-crisis (> 20 mmHg), agitation or systemic desaturation. In IS-trials that had to be aborted, a significant increase in ICP and decrease in PbtO2 (P < 0.05), including 67% with critical values of PbtO2 < 20 mmHg, a tendency to brain metabolic distress (P < 0.07) was observed.Interruption of sedation revealed new relevant clinical information in only one trial and a large number of trials could not be performed or had to be stopped due to safety issues. Weighing pros and cons of IS-trials in patients with acute brain injury seems important as related side effects may overcome the clinical benefit.Titrating sedatives and analgesics to achieve the right balance between deep sedation and wakefulness and to ameliorate patients' comfort in the intensive care unit (ICU) is an integral part of critical care [1]. Over-sedation can lead to prolonged duration of mechanical ventilation and ICU stay and increase the incidence of secondary complications, including nosocomial infections and delirium.Daily interruption of sedation trials (IS-trials) have been implemented in many surgical and medical ICUs after randomized controlled trials demonstrated that IS decreased the duration of
Impact of Sequence Non-Identities on Recombination within the pil System of Neisseria gonorrhoeae  [PDF]
Stuart A. Hill, Jenny Wachter
Open Journal of Genetics (OJGen) , 2014, DOI: 10.4236/ojgen.2014.43023
Abstract:

Neisseria gonorrhoeae engages in extensive intra-cellular gene conversion between the PilE-expression locus (pilE) and the transcriptionally-silent pil gene copies (pilS). In silico analyses were applied to investigate the extent of sequence heterogeneity between the various pilS gene copies. Analysis of synonymous and non-synonymous substitutions between the different pilS genes indicated that relatively few amino acid changes would occur due to nucleotide polymorphisms towards the 5’ end of the pilS genes whereas more frequent amino acid substitutions would be incorporated within the “hypervariable” region. The lack of non-synonymous substitutions at the 5’ end of the genes was found to be under selective pressure as indicated by a positive DT score utilizing the Tajima test. The presence or absence of mismatch repair appeared to only impact recombination when non-identical DNAs recombined via the DNA transformation route, where small pil sequence heterogeneities were sufficient to terminate recombination tracts, with these sequence constraints being relieved in cells carrying a mutS mutation. Therefore, the data indicate that the effect of sequence heterogeneity on recombination within the pil

Adjuvant Chemotherapy for Brain Tumors Delivered via a Novel Intra-Cavity Moldable Polymer Matrix
Cheryl V. Rahman, Stuart J. Smith, Paul S. Morgan, Keith A. Langmack, Phil A. Clarke, Alison A. Ritchie, Donald C. Macarthur, Felicity R. Rose, Kevin M. Shakesheff, Richard G. Grundy, Ruman Rahman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0077435
Abstract: Introduction Polymer-based delivery systems offer innovative intra-cavity administration of drugs, with the potential to better target micro-deposits of cancer cells in brain parenchyma beyond the resected cavity. Here we evaluate clinical utility, toxicity and sustained drug release capability of a novel formulation of poly(lactic-co-glycolic acid) (PLGA)/poly(ethylene glycol) (PEG) microparticles. Methods PLGA/PEG microparticle-based matrices were molded around an ex vivo brain pseudo-resection cavity and analyzed using magnetic resonance imaging and computerized tomography. In vitro toxicity of the polymer was assessed using tumor and endothelial cells and drug release from trichostatin A-, etoposide- and methotrexate-loaded matrices was determined. To verify activity of released agents, tumor cells were seeded onto drug-loaded matrices and viability assessed. Results PLGA/PEG matrices can be molded around a pseudo-resection cavity wall with no polymer-related artifact on clinical scans. The polymer withstands fractionated radiotherapy, with no disruption of microparticle structure. No toxicity was evident when tumor or endothelial cells were grown on control matrices in vitro. Trichostatin A, etoposide and methotrexate were released from the matrices over a 3-4 week period in vitro and etoposide released over 3 days in vivo, with released agents retaining cytotoxic capabilities. PLGA/PEG microparticle-based matrices molded around a resection cavity wall are distinguishable in clinical scanning modalities. Matrices are non-toxic in vitro suggesting good biocompatibility in vivo. Active trichostatin A, etoposide and methotrexate can be incorporated and released gradually from matrices, with radiotherapy unlikely to interfere with release. Conclusion The PLGA/PEG delivery system offers an innovative intra-cavity approach to administer chemotherapeutics for improved local control of malignant brain tumors.
Planejando para a diferencia o: a experiência de professores de escolas primárias da Irlanda do Norte
Brian McGarvey,Stuart Marriott,Valerie Morgan,Lesley Abbott
Práxis Educativa , 2009,
Abstract: This paper describes how a group of primary schools in Northern Ireland planned a differentiated curriculum, and the extent to which subject co-ordinators offer guidance to teacher colleagues in planning for English, mathematics and science. The views of headteachers, subject co-ordinators and teachers on the ways in which plans are translated into classroom practice for higher and lower attaining pupils in both classwork and homework were obtained. The curriculum support staff described how far they consider teachers are applying the principles of differentiation, including progression and continuity. The results showed that, although most teachers were said to understand the meaning of differentiation moderately well, help was needed in drawing up schemes of work and providing for the extremes of pupil attainment.
Some general properties of the renormalized stress-energy tensor for static quantum states on (n+1)-dimensional spherically symmetric black holes
Dean Morgan,Stuart Thom,Elizabeth Winstanley,Phil M. Young
Physics , 2007, DOI: 10.1007/s10714-007-0486-3
Abstract: We study the renormalized stress-energy tensor (RSET) for static quantum states on (n+1)-dimensional, static, spherically symmetric black holes. By solving the conservation equations, we are able to write the stress-energy tensor in terms of a single unknown function of the radial co-ordinate, plus two arbitrary constants. Conditions for the stress-energy tensor to be regular at event horizons (including the extremal and ``ultra-extremal'' cases) are then derived using generalized Kruskal-like co-ordinates. These results should be useful for future calculations of the RSET for static quantum states on spherically symmetric black hole geometries in any number of space-time dimensions.
Merger of white dwarf-neutron star binaries: Prelude to hydrodynamic simulations in general relativity
Vasileios Paschalidis,Morgan MacLeod,Thomas W. Baumgarte,Stuart L. Shapiro
Physics , 2009, DOI: 10.1103/PhysRevD.80.024006
Abstract: White dwarf-neutron star binaries generate detectable gravitational radiation. We construct Newtonian equilibrium models of corotational white dwarf-neutron star (WDNS) binaries in circular orbit and find that these models terminate at the Roche limit. At this point the binary will undergo either stable mass transfer (SMT) and evolve on a secular time scale, or unstable mass transfer (UMT), which results in the tidal disruption of the WD. The path a given binary will follow depends primarily on its mass ratio. We analyze the fate of known WDNS binaries and use population synthesis results to estimate the number of LISA-resolved galactic binaries that will undergo either SMT or UMT. We model the quasistationary SMT epoch by solving a set of simple ordinary differential equations and compute the corresponding gravitational waveforms. Finally, we discuss in general terms the possible fate of binaries that undergo UMT and construct approximate Newtonian equilibrium configurations of merged WDNS remnants. We use these configurations to assess plausible outcomes of our future, fully relativistic simulations of these systems. If sufficient WD debris lands on the NS, the remnant may collapse, whereby the gravitational waves from the inspiral, merger, and collapse phases will sweep from LISA through LIGO frequency bands. If the debris forms a disk about the NS, it may fragment and form planets.
Accuracy of Stream Habitat Interpolations Across Spatial Scales  [PDF]
Kenneth R. Sheehan, Stuart A. Welsh
Journal of Geographic Information System (JGIS) , 2013, DOI: 10.4236/jgis.2013.56057
Abstract:

Stream habitat data are often collected across spatial scales because relationships among habitat, species occurrence, and management plans are linked at multiple spatial scales. Unfortunately, scale is often a factor limiting insight gained from spatial analysis of stream habitat data. Considerable cost is often expended to collect data at several spatial scales to provide accurate evaluation of spatial relationships in streams. To address utility of single scale set of stream habitat data used at varying scales, we examined the influence that data scaling had on accuracy of natural neighbor predictions of depth, flow, and benthic substrate. To achieve this goal, we measured two streams at gridded resolution of 0.33 × 0.33 meter cell size over a combined area of 934 m2 to create a baseline for natural neighbor interpolated maps at 12 incremental scales ranging from a raster cell size of 0.11 m2 to 16 m2. Analysis of predictive maps showed a logarithmic linear decay pattern in RMSE values in interpolation accuracy for variables as resolution of data used to interpolate study areas became coarser. Proportional accuracy of interpolated models (r2) decreased, but it was maintained up to 78% as interpolation scale moved from 0.11 m2 to 16 m2. Results indicated that accuracy retention was suitable for assessment and management purposes at various scales different from the data collection scale. Our study is relevant to spatial modeling, fish habitat assessment, and stream habitat management because it highlights the potential of using a single dataset to fulfill analysis needs rather than investing considerable cost to develop several scaled datasets

The Suh Muscle Hook: A New Muscle Hook for Tight Extraocular Muscles during Strabismus Surgery  [PDF]
Lin Luo, Linda A. Morgan, Donny W. Suh, Elise K. Morgan
Open Journal of Ophthalmology (OJOph) , 2017, DOI: 10.4236/ojoph.2017.71008
Abstract: Purpose: To introduce an advanced muscle hook to decrease risks and create more feasible extraocular muscle surgeries for physicians. Case Report: Tight extraocular muscles during strabismus surgery could be extremely challenging even in experienced hands due to restricted globe rotation, limited view, and lack of muscle elasticity. Although a variety of surgical instruments have been introduced through the years, traditional muscle hooks such as the Jameson hook are largely unchanged and are bulky and cumbersome. Using the traditional muscle hook under situations such as pediatric strabismus surgery with smaller eyes and extraocular muscles may increase the risk of perforating the globe or even rupturing the muscles. We developed the “Suh muscle hook”, which has a 0.55 mm wide grooved track in a 1.1 mm wide horizontal bar, a semi-sharp dissecting tip, and a 30-degree bending near the handle accommodating for nasal bridge to better facilitate surgeons dealing with tight extraocular muscles and minimize risks during strabismus surgery.
Electromagnetic Holography on Cylindrical Surfaces Using K-Space Transformations
M. A. Morgan
PIER , 2003, DOI: 10.2528/PIER03020302
Abstract: Spectral decomposition in 2-D space is used to develop transfer functions that relate modal electromagnetic fields on concentric cylindrical surfaces. It is shown that all time-average radiated power is generated by superluminal modes (phase velocity ) which are confined to the baseband . Subluminal modes, with outside of the radiated band, are radially evanescent but permit recovery of imaging resolution that exceeds the usual diffraction limit provided by the radiated fields. Outward translation between cylinder surfaces is found to have a stable low-pass 2-D transfer characteristic in space, where spatial resolution decreases with increased radius. The inverse transfer functions for inward translation of field components (termed backpropagation) employ a high-pass process that amplifies subluminal evanescent modes, thus potentially enhancing resolution while also amplifying measurement noise. A 2-D filter with flat elliptical passband and Gaussian roll-off is used to mitigate noise amplification with backpropagation. Outward translation and backpropagation are tested using sampled data on finite-length cylinders for various noise levels.
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