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Search Results: 1 - 10 of 467306 matches for " Timothy A Justin "
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Targets for a Comparative Neurobiology of Language
Justin T. Kiggins,Jordan A. Comins,Timothy Q. Gentner
Frontiers in Evolutionary Neuroscience , 2012, DOI: 10.3389/fnevo.2012.00006
Abstract: One longstanding impediment to progress in understanding the neural basis of language is the development of model systems that retain language-relevant cognitive behaviors yet permit invasive cellular neuroscience methods. Recent experiments in songbirds suggest that this group may be developed into a powerful animal model, particularly for components of grammatical processing. It remains unknown, however, what a neuroscience of language perception may look like when instantiated at the cellular or network level. Here we deconstruct language perception into a minimal set of cognitive processes necessary to support grammatical processing. We then review the current state of our understanding about the neural mechanisms of these requisite cognitive processes in songbirds. We note where current knowledge is lacking, and suggest how these mechanisms may ultimately combine to support an emergent mechanism capable of processing grammatical structures of differing complexity.
Mineralization Content Alters Osteogenic Responses of Bone Marrow Stromal Cells on Hydroxyapatite/Polycaprolactone Composite Nanofiber Scaffolds
Timothy T. Ruckh,Derek A. Carroll,Justin R. Weaver,Ketul C. Popat
Journal of Functional Biomaterials , 2012, DOI: 10.3390/jfb3040776
Abstract: Synthetic tissue scaffolds have a high potential impact for patients experiencing osteogenesis imperfecta. Using electrospinning, tissue scaffolds composed of hydroxyapatite/polycaprolactone (HAp/PCL) composite nanofibers were fabricated with two different HAp concentrations—1% and 10% of the solid scaffold weight. After physico-chemical scaffold characterization, rat bone marrow stromal cells were cultured on the composite scaffolds in maintenance medium and then in osteogenic medium. Quantitative PCR, colorimetric assays, immunofluorescent labeling, and electron microscopy measured osteogenic cell responses to the HAp/PCL scaffolds. In maintenance conditions, both Hap/PCL scaffolds and control scaffolds supported cell colonization through seven days with minor differences. In osteogenic conditions, the 10% HAp scaffolds exhibited significantly increased ALP assay levels at week 3, consistent with previous reports. However, qPCR analysis demonstrated an overall decrease in bone matrix-associated genes on Hap/PCL scaffolds. Osteopontin and osteocalcin immunofluorescent microscopy revealed a trend that both mineralized scaffolds had greater amounts of both proteins, though qPCR results indicated the opposite trend for osteopontin. Additionally, type I collagen expression decreased on HAp scaffolds. These results indicate that cells are sensitive to minor changes in mineral content within nanofibers, even at just 1% w/w, and elucidating the sensing mechanism may lead to optimized osteogenic scaffold designs.
Atrial fibrillation and survival in colorectal cancer
Stewart R Walsh, Kelly M Gladwish, Nicholas J Ward, Timothy A Justin, Neil J Keeling
World Journal of Surgical Oncology , 2004, DOI: 10.1186/1477-7819-2-40
Abstract: A prospective colorectal cancer patient database was cross-referenced with the hospital clinical-coding database to identify patients who had underwent colorectal cancer surgery and were in atrial fibrillation pre- or postoperatively.A total of 175 patients underwent surgery for colorectal cancer over a two-year period. Of these, 13 patients had atrial fibrillation pre- or postoperatively. Atrial fibrillation correlated with worse two-year survival (p = 0.04; log-rank test). However, in a Cox regression analysis, atrial fibrillation was not significantly associated with survival.The presence or development of atrial fibrillation in patients undergoing surgery for colorectal cancer is associated with worse overall survival, however it was not found to be an independent factor in multivariate analysis.In general, colorectal cancer patients are three times more likely to be in atrial fibrillation preoperatively than matched controls undergoing non-colorectal cancer surgery [1,2]. It may also occur postoperatively. Recent data suggest that atrial fibrillation may be an inflammatory complication, resulting from the initiation of an inflammatory response to surgery or infection [3-6]. Colorectal cancer patients may have elevated C-reactive protein (CRP) levels [7] indicating a systemic inflammatory response. Elevated CRP levels may be associated with a worse prognosis in colorectal cancer patients [8]. Postoperative dysrhythmias may [9] or may not [10] be associated with worse survival following surgery for lung cancer. We hypothesised that atrial fibrillation (AF) is an adverse prognostic indicator in patients undergoing surgery for colorectal cancer.Patients who underwent a resection for colorectal cancer between 1st January 2000 and 31st December 2001 in a 600-bed district general hospital in the United Kingdom National Health Service were identified. The hospital serves a population of approximately 230,000. About 90 elective and emergency laparotomies are performed e
Friends of Hot Jupiters III: An Infrared Spectroscopic Search for Low-Mass Stellar Companions
Danielle Piskorz,Heather A. Knutson,Henry Ngo,Philip S. Muirhead,Konstantin Batygin,Justin R. Crepp,Sasha Hinkley,Timothy D. Morton
Physics , 2015, DOI: 10.1088/0004-637X/814/2/148
Abstract: Surveys of nearby field stars indicate that stellar binaries are common, yet little is known about the effects that these companions may have on planet formation and evolution. The Friends of Hot Jupiters project uses three complementary techniques to search for stellar companions to known planet-hosting stars: radial velocity monitoring, adaptive optics imaging, and near-infrared spectroscopy. In this paper, we examine high-resolution K band infrared spectra of fifty stars hosting gas giant planets on short-period orbits. We use spectral fitting to search for blended lines due to the presence of cool stellar companions in the spectra of our target stars, where we are sensitive to companions with temperatures between 3500-5000 K and projected separations less than 100 AU in most systems. We identify eight systems with candidate low-mass companions, including one companion that was independently detected in our AO imaging survey. For systems with radial velocity accelerations, a spectroscopic non-detection rules out scenarios involving a stellar companion in a high inclination orbit. We use these data to place an upper limit on the stellar binary fraction at small projected separations, and show that the observed population of candidate companions is consistent with that of field stars and also with the population of wide-separation companions detected in our previous AO survey. We find no evidence that spectroscopic stellar companions are preferentially located in systems with short-period gas giant planets on eccentric and/or misaligned orbits.
Friends of Hot Jupiters II: No Correspondence Between Hot-Jupiter Spin-Orbit Misalignment and the Incidence of Directly Imaged Stellar Companions
Henry Ngo,Heather A. Knutson,Sasha Hinkley,Justin R. Crepp,Eric B. Bechter,Konstantin Batygin,Andrew W. Howard,John A. Johnson,Timothy D. Morton,Philip S. Muirhead
Physics , 2014, DOI: 10.1088/0004-637X/800/2/138
Abstract: Multi-star systems are common, yet little is known about a stellar companion's influence on the formation and evolution of planetary systems. For instance, stellar companions may have facilitated the inward migration of hot Jupiters towards to their present day positions. Many observed short period gas giant planets also have orbits that are misaligned with respect to their star's spin axis, which has also been attributed to the presence of a massive outer companion on a non-coplanar orbit. We present the results of a multi-band direct imaging survey using Keck NIRC2 to measure the fraction of short period gas giant planets found in multi-star systems. Over three years, we completed a survey of 50 targets ("Friends of Hot Jupiters") with 27 targets showing some signature of multi-body interaction (misaligned or eccentric orbits) and 23 targets in a control sample (well-aligned and circular orbits). We report the masses, projected separations, and confirmed common proper motion for the 19 stellar companions found around 17 stars. Correcting for survey incompleteness, we report companion fractions of $48\%\pm9\%$, $47\%\pm12\%$, and $51\%\pm13\%$ in our total, misaligned/eccentric, and control samples, respectively. This total stellar companion fraction is $2.8\,\sigma$ larger than the fraction of field stars with companions approximately $50-2000\,$AU. We observe no correlation between misaligned/eccentric hot Jupiter systems and the incidence of stellar companions. Combining this result with our previous radial velocity survey, we determine that $72\% \pm 16\%$ of hot Jupiters are part of multi-planet and/or multi-star systems.
SELDI-TOF-MS Serum Profiling Reveals Predictors of Cardiac MRI Changes in Marathon Runners
George D. Wilson,Timothy J. Geddes,Barbara L. Pruetz,Bryan J. Thibodeau,Amy Murawka,James M. Colar,Peter A. McCullough,Justin E. Trivax
International Journal of Proteomics , 2012, DOI: 10.1155/2012/679301
Abstract: Purpose. To utilize proteomics to discover proteins associated with significant cardiac magnetic resonance imaging (MRI) changes in marathon runners. Methods. Serum from 25 runners was analyzed by surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS). Proteomic profiles were compared in serum samples obtained prior to the race, at the finish line and within 7 hours after race to identify dynamic proteins correlated with cardiac MRI changes. Results. 693 protein/peptide clusters were identified using two ProteinChip surface chemistries and, of these, 116 were significantly different between the three time points. We identified 7 different patterns of protein expression change within the runners and 5 prerace protein peaks, 16 finish-line protein levels, and 15 postrace proteins which were correlated with significant postrace cardiac MRI changes. Conclusions. This study has identified baseline levels of proteins which may be predictive of risk of significant cardiac damage following a marathon race. Preliminary identification of the significant proteins suggested the involvement of cytokines and other proteins involved in stress and inflammatory response. 1. Introduction A central paradox of physical activity is the association of moderate exercise with decreased cardiovascular morbidity and mortality [1, 2], whereas vigorous physical exertion increases the short-term risk of sudden cardiac death [3, 4]. Due to the rising participation in endurance sports, there is much current interest in postexercise changes in cardiac function [5]. Ever since the first marathon runner, Phidippides, collapsed and died at the finish of his famous run in ancient Greece, death due to heart-related stress has been an occasional occurrence in marathon events. Sudden unexpected death during marathons and other high impact activities is usually due to underlying and often unsuspected heart disease [6–8] and such catastrophes often attract substantial public attention [9]. Identification of marathon runners at risk is difficult, and the need for medical examinations remains controversial [2, 10, 11]. The risk of sudden cardiac death associated with marathon running has been suggested to be too low to recommend routine screening for coronary artery disease [12, 13]. An alternative approach to cardiac screening is to identify biomarkers which may predispose runners to increased risk of cardiac events. Many physical and biochemical changes have been described during endurance sports including transient changes in systolic and more persistent
Evolution of the HIV-1 nef gene in HLA-B*57 Positive Elite Suppressors
Maria Salgado, Timothy P Brennan, Karen A O'Connell, Justin R Bailey, Stuart C Ray, Robert F Siliciano, Joel N Blankson
Retrovirology , 2010, DOI: 10.1186/1742-4690-7-94
Abstract: The mechanisms responsible for the control of the HIV-1 replication in elite suppressors are not fully understood [1-3]. Replication competent virus has been isolated from some ES [4-6] and genotypic [4], phenotypic [4], and epidemiologic [7] analyses have suggested that these isolates are generally fully pathogenic. Thus it appears that in many cases, host factors rather than infection with defective virus are responsible for the elite control of viral replication. The HLA-B*57 allele is overrepresented in ES [8-14] which suggests an important role of CD8+ T cells. These cells have been shown to exert selective pressure on HLA-B*57 restricted epitopes in ES [15-17] and LTNPs [18], and we have previously documented evidence of evolution in the gag gene in plasma virus of HLA-B*57 positive ES over a 5 year period [19]. However, some studies have suggested that Gag is preferentially targeted by CD8+ T cells in patients who control viremia [12,20] and it is therefore possible that viral evolution in ES is limited to this gene. To test this hypothesis, we analyzed proviral and plasma nef sequences in ES over a 6 year period and compared the rate of evolution in these two compartments to the rate of evolution of observed for the gag gene.Four previously described HLA-B*57 ES patients were studied [16,21]. Viral RNA was isolated from plasma, and genomic DNA was purified from resting CD4+ T cells as described previously [16]. To limit PCR resampling, nef genes were amplified from provirus in genomic DNA and from plasma-derived RNA by limiting dilution "digital" nested PCR using previously described primers and conditions [21]. PCR products were directly sequenced using an ABI PRISM 3700 DNA analyzer (Applied Biosystems). Chromatograms were manually examined for the presence of double peaks indicative of two templates per sequencing reaction. Such sequences were discarded. Sequences were assembled using CodonCode Aligner, version 1.3.1, aligned using ClustalX, and the align
Sequence Analysis and Serological Responses against Borrelia turicatae BipA, a Putative Species-Specific Antigen
Job E. Lopez ,Hannah K. Wilder,William Boyle,L. Brock Drumheller,Justin A. Thornton,Bridget Willeford,Timothy W. Morgan,Andrea Varela-Stokes
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002454
Abstract: Background Relapsing fever spirochetes are global yet neglected pathogens causing recurrent febrile episodes, chills, nausea, vomiting, and pregnancy complications. Given these nonspecific clinical manifestations, improving diagnostic assays for relapsing fever spirochetes will allow for identification of endemic foci and expedite proper treatment. Previously, an antigen designated the Borrelia immunogenic protein A (BipA) was identified in the North American species Borrelia hermsii. Thus far, BipA appears unique to relapsing fever spirochetes. The antigen remains unidentified outside of these pathogens, while interspecies amino acid identity for BipA in relapsing fever spirochetes is only 24–36%. The current study investigated the immunogenicity of BipA in Borrelia turicatae, a species distributed in the southern United States and Latin America. Methodology/Principal Findings bipA was amplified from six isolates of Borrelia turicatae, and sequence analysis demonstrated that the gene is conserved among isolates. A tick transmission system was developed for B. turicatae in mice and a canine, two likely vertebrate hosts, which enabled the evaluation of serological responses against recombinant BipA (rBipA). These studies indicated that BipA is antigenic in both animal systems after infection by tick bite, yet serum antibodies failed to bind to B. hermsii rBipA at a detectable level. Moreover, mice continued to generate an antibody response against BipA one year after the initial infection, further demonstrating the protein's potential toward identifying endemic foci for B. turicatae. Conclusions/Significance These initial studies support the hypothesis that BipA is a spirochete antigen unique to a relapsing fever Borrelia species, and could be used to improve efforts for identifying B. turicatae endemic regions.
Objectively Measured Activity Patterns among Adults in Residential Aged Care
Natasha Reid,Elizabeth Eakin,Timothy Henwood,Justin W. L. Keogh,Hugh E. Senior,Paul A. Gardiner,Elisabeth Winkler,Genevieve N. Healy
International Journal of Environmental Research and Public Health , 2013, DOI: 10.3390/ijerph10126783
Abstract: Objectives: To determine the feasibility of using the activPAL3 TM activity monitor, and, to describe the activity patterns of residential aged care residents. Design: Cross-sectional. Setting: Randomly selected aged care facilities within 100 km of the Gold Coast, Queensland, Australia. Participants: Ambulatory, older (≥60 years) residential aged care adults without cognitive impairment. Measurements: Feasibility was assessed by consent rate, sleep/wear diary completion, and through interviews with staff/participants. Activity patterns (sitting/lying, standing, and stepping) were measured via activPAL3 TM monitors worn continuously for seven days. Times spent in each activity were described and then compared across days of the week and hours of the day using linear mixed models. Results: Consent rate was 48% (n = 41). Activity patterns are described for the 31 participants (mean age 84.2 years) who provided at least one day of valid monitor data. In total, 14 (45%) completed the sleep/wear diary. Participants spent a median (interquartile range) of 12.4 (1.7) h sitting/lying (with 73% of this accumulated in unbroken bouts of ≥30 min), 1.9 (1.3) h standing, and 21.4 (36.7) min stepping during their monitored waking hours per day. Activity did not vary significantly by day of the week ( p ≥ 0.05); stepping showed significant hourly variation ( p = 0.018). Conclusions: Older adults in residential aged care were consistently highly sedentary. Feasibility considerations for objective activity monitoring identified for this population include poor diary completion and lost monitors.
The Photoeccentric Effect and Proto-Hot Jupiters II. KOI-1474.01, a candidate eccentric planet perturbed by an unseen companion
Rebekah I. Dawson,John Asher Johnson,Timothy D. Morton,Justin R. Crepp,Daniel C. Fabrycky,Ruth A. Murray-Clay,Andrew W. Howard
Physics , 2012, DOI: 10.1088/0004-637X/761/2/163
Abstract: The exoplanets known as hot Jupiters---Jupiter-sized planets with periods less than 10 days---likely are relics of dynamical processes that shape all planetary system architectures. Socrates et al. (2012) argued that high eccentricity migration (HEM) mechanisms proposed for situating these close-in planets should produce an observable population of highly eccentric proto-hot Jupiters that have not yet tidally circularized. HEM should also create failed-hot Jupiters, with periapses just beyond the influence of fast circularization. Using the technique we previously presented for measuring eccentricities from photometry (the "photoeccentric effect"), we are distilling a collection of eccentric proto- and failed-hot Jupiters from the Kepler Objects of Interest (KOI). Here we present the first, KOI-1474.01, which has a long orbital period (69.7340 days) and a large eccentricity e = 0.81+0.10/-0.07, skirting the proto-hot Jupiter boundary. Combining Kepler photometry, ground-based spectroscopy, and stellar evolution models, we characterize host KOI-1474 as a rapidly-rotating F-star. Statistical arguments reveal that the transiting candidate has a low false-positive probability of 3.1%. KOI-1474.01 also exhibits transit timing variations of order an hour. We explore characteristics of the third-body perturber, which is possibly the "smoking-gun" cause of KOI-1474.01's large eccentricity. Using the host-star's rotation period, radius, and projected rotational velocity, we find KOI-1474.01's orbit is marginally consistent with aligned with the stellar spin axis, although a reanalysis is warranted with future additional data. Finally, we discuss how the number and existence of proto-hot Jupiters will not only demonstrate that hot Jupiters migrate via HEM, but also shed light on the typical timescale for the mechanism.
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