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Search Results: 1 - 10 of 146290 matches for " Brian K. Erickson "
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Effects of Diet on Resource Utilization by a Model Human Gut Microbiota Containing Bacteroides cellulosilyticus WH2, a Symbiont with an Extensive Glycobiome
Nathan P. McNulty,Meng Wu,Alison R. Erickson,Chongle Pan,Brian K. Erickson,Eric C. Martens,Nicholas A. Pudlo,Brian D. Muegge,Bernard Henrissat,Robert L. Hettich,Jeffrey I. Gordon
PLOS Biology , 2013, DOI: 10.1371/journal.pbio.1001637
Abstract: The human gut microbiota is an important metabolic organ, yet little is known about how its individual species interact, establish dominant positions, and respond to changes in environmental factors such as diet. In this study, gnotobiotic mice were colonized with an artificial microbiota comprising 12 sequenced human gut bacterial species and fed oscillating diets of disparate composition. Rapid, reproducible, and reversible changes in the structure of this assemblage were observed. Time-series microbial RNA-Seq analyses revealed staggered functional responses to diet shifts throughout the assemblage that were heavily focused on carbohydrate and amino acid metabolism. High-resolution shotgun metaproteomics confirmed many of these responses at a protein level. One member, Bacteroides cellulosilyticus WH2, proved exceptionally fit regardless of diet. Its genome encoded more carbohydrate active enzymes than any previously sequenced member of the Bacteroidetes. Transcriptional profiling indicated that B. cellulosilyticus WH2 is an adaptive forager that tailors its versatile carbohydrate utilization strategy to available dietary polysaccharides, with a strong emphasis on plant-derived xylans abundant in dietary staples like cereal grains. Two highly expressed, diet-specific polysaccharide utilization loci (PULs) in B. cellulosilyticus WH2 were identified, one with characteristics of xylan utilization systems. Introduction of a B. cellulosilyticus WH2 library comprising >90,000 isogenic transposon mutants into gnotobiotic mice, along with the other artificial community members, confirmed that these loci represent critical diet-specific fitness determinants. Carbohydrates that trigger dramatic increases in expression of these two loci and many of the organism's 111 other predicted PULs were identified by RNA-Seq during in vitro growth on 31 distinct carbohydrate substrates, allowing us to better interpret in vivo RNA-Seq and proteomics data. These results offer insight into how gut microbes adapt to dietary perturbations at both a community level and from the perspective of a well-adapted symbiont with exceptional saccharolytic capabilities, and illustrate the value of artificial communities.
Strategies for Metagenomic-Guided Whole-Community Proteomics of Complex Microbial Environments
Brandi L. Cantarel, Alison R. Erickson, Nathan C. VerBerkmoes, Brian K. Erickson, Patricia A. Carey, Chongle Pan, Manesh Shah, Emmanuel F. Mongodin, Janet K. Jansson, Claire M. Fraser-Liggett, Robert L. Hettich
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027173
Abstract: Accurate protein identification in large-scale proteomics experiments relies upon a detailed, accurate protein catalogue, which is derived from predictions of open reading frames based on genome sequence data. Integration of mass spectrometry-based proteomics data with computational proteome predictions from environmental metagenomic sequences has been challenging because of the variable overlap between proteomic datasets and corresponding short-read nucleotide sequence data. In this study, we have benchmarked several strategies for increasing microbial peptide spectral matching in metaproteomic datasets using protein predictions generated from matched metagenomic sequences from the same human fecal samples. Additionally, we investigated the impact of mass spectrometry-based filters (high mass accuracy, delta correlation), and de novo peptide sequencing on the number and robustness of peptide-spectrum assignments in these complex datasets. In summary, we find that high mass accuracy peptide measurements searched against non-assembled reads from DNA sequencing of the same samples significantly increased identifiable proteins without sacrificing accuracy.
Air Quality, Health and Community Action  [PDF]
Larry E. Erickson, Wendy Griswold, Ronaldo G. Maghirang, Brian P. Urbaszewski
Journal of Environmental Protection (JEP) , 2017, DOI: 10.4236/jep.2017.810067
Abstract: Air quality is impacting health in many cities in most countries because of particulate pollution, sulfur dioxide, nitrogen dioxide, and ozone. Very small particulates from engine emissions and coal fired electric power plants enter the lungs and pollute the blood of urban residents leading to a burden of disease with more than 3 million premature deaths per year attributed to outdoor air pollution. Welfare losses including premature deaths associated with air pollution were about $5 trillion in 2013. A global transition to electric vehicles, and the generation of electricity without combustion emissions would improve air quality significantly and reduce greenhouse gas emissions. This transition is in progress in many parts of the world with more than 2 million electric vehicles in service in 2017. Electric bus and electric taxi sales are increasing, and many large cities have multiple programs to improve air quality. When health costs are considered, it is very appropriate for communities to take action to improve air quality and health. This work reviews and reports many positive actions that are in progress in larger cities.
Severe Hemorrhagic Fever in Strain 13/N Guinea Pigs Infected with Lujo Virus
Brian H. Bird ,Kimberly A. Dodd,Bobbie R. Erickson,César G. Albari?o,Ayan K. Chakrabarti,Laura K. McMullan,Eric Bergeron,Ute Str?eher,Deborah Cannon,Brock Martin,JoAnn D. Coleman-McCray,Stuart T. Nichol,Christina F. Spiropoulou
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001801
Abstract: Lujo virus (LUJV) is a novel member of the Arenaviridae family that was first identified in 2008 after an outbreak of severe hemorrhagic fever (HF). In what was a small but rapidly progressing outbreak, this previously unknown virus was transmitted from the critically ill index patient to 4 attending healthcare workers. Four persons died during this outbreak, for a total case fatality of 80% (4/5). The suspected rodent source of the initial exposure to LUJV remains a mystery. Because of the ease of transmission, high case fatality, and novel nature of LUJV, we sought to establish an animal model of LUJV HF. Initial attempts in mice failed, but infection of inbred strain 13/N guinea pigs resulted in lethal disease. A total of 41 adult strain 13/N guinea pigs were infected with either wild-type LUJV or a full-length recombinant LUJV. Results demonstrated that strain 13/N guinea pigs provide an excellent model of severe and lethal LUJV HF that closely resembles what is known of the human disease. All infected animals experienced consistent weight loss (3–5% per day) and clinical illness characterized by ocular discharge, ruffled fur, hunched posture, and lethargy. Uniform lethality occurred by 11–16 days post-infection. All animals developed disseminated LUJV infection in various organs (liver, spleen, lung, and kidney), and leukopenia, lymphopenia, thrombocytopenia, coagulopathy, and elevated transaminase levels. Serial euthanasia studies revealed a temporal pattern of virus dissemination and increasing severity of disease, primarily targeting the liver, spleen, lungs, and lower gastrointestinal tract. Establishing an animal LUJV model is an important first step towards understanding the high pathogenicity of LUJV and developing vaccines and antiviral therapeutic drugs for this highly transmissible and lethal emerging pathogen.
Differentiation of Material Temperature through the Application of Increased Localized Dissolution via Heat Transfer  [PDF]
Brian K. Chen
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2015, DOI: 10.4236/jasmi.2015.53005
Abstract: Increased temperature of a solution increases its solubility, allowing for a greater level of dissolution of the solute. A greater level of dissolution will result in a change in the density of the solution. When a localized area of the solution is of a different temperature, this will affect the localized density. Density is one of the factors affecting rate of sinking and the difference in temperature will lead to a change in the rate of sinking. Thus, when an object is at different temperatures, it will transfer heat to or from the solution in different manners and the rate of sinking will be different. This study tested whether sinking rate in a solution with excess solute could be used to judge the temperature of an object and the effect was confirmed with impure Graphite blocks in a Potassium Iodide solution.
The role of selective cyclooxygenase isoforms in human intestinal smooth muscle cell stimulated prostanoid formation and proliferation
Walter E. Longo,Brian Erickson,Ninder Panesar,John E. Mazuski
Mediators of Inflammation , 1998, DOI: 10.1080/09629359890749
Abstract:
A High Temperature Calcium Vapor Cell for Spectroscopy on the 4s^2 1S0 to 4s4p 3P1 Intercombination Line
Christopher J. Erickson,Brian Neyenhuis,Dallin S. Durfee
Physics , 2005, DOI: 10.1063/1.2148992
Abstract: We have demonstrated a high temperature vapor cell for absorption spectroscopy on the Ca intercombination line. The cell uses a dual chamber design to achieve the high temperatures necessary for an optically dense vapor while avoiding the necessity of high temperature vacuum valves and glass-to-metal seals. We have observed over 50 percent absorption in a single pass through the cell. Although pressure broadening in the cell prevented us from performing saturated-absorption spectroscopy, the broadening resulted in higher signal-to-noise ratios by allowing us to probe the atoms with intensities much greater than the 0.2 uW/cm^2 saturation intensity of the unbroadened transition.
Structure of the Electric Flux in N=4 Supersymmetric Yang-Mills Theory
J. Erickson,G. W. Semenoff,K. Zarembo
Physics , 1999, DOI: 10.1016/S0370-2693(99)01131-4
Abstract: Correlators of Wilson loop operators with O_4=Tr(F_{\mu\nu}^2+...) are computed in N=4 super-Yang-Mills theory using the AdS/CFT correspondence. The results are compared with the leading order perturbative computations. As a consequence of conformal invariance, these correlators have identical forms in the weak and strong coupling limits for circular loops. They are essentially different for contours not protected by conformal symmetry.
Wilson Loops in N=4 Supersymmetric Yang--Mills Theory
J. K. Erickson,G. W. Semenoff,K. Zarembo
Physics , 2000, DOI: 10.1016/S0550-3213(00)00300-X
Abstract: Perturbative computations of the expectation value of the Wilson loop in N=4 supersymmetric Yang-Mills theory are reported. For the two special cases of a circular loop and a pair of anti-parallel lines, it is shown that the sum of an infinite class of ladder-like planar diagrams, when extrapolated to strong coupling, produces an expectation value characteristic of the results of the AdS/CFT correspondence, $\sim\exp((constant)\sqrt{g^2N})$. For the case of the circular loop, the sum is obtained analytically for all values of the coupling. In this case, the constant factor in front of $\sqrt{g^2N}$ also agrees with the supergravity results. We speculate that the sum of diagrams without internal vertices is exact and support this conjecture by showing that the leading corrections to the ladder diagrams cancel identically in four dimensions. We also show that, for arbitrary smooth loops, the ultraviolet divergences cancel to order $g^4N^2$.
IL-10 Inhibits LPS-Induced Expression of miR-147 in Murine Macrophages  [PDF]
Leah N. Cardwell, Brian K. Weaver
Advances in Biological Chemistry (ABC) , 2014, DOI: 10.4236/abc.2014.44032
Abstract: Interleukin-10 (IL-10) mediates an anti-inflammatory response that constrains immune responses and limits inflammation-associated pathology. IL-10 does so, in part, by selectively inhibiting pro-inflammatory cytokine and chemokine expression induced in macrophages in response to Toll-like receptor (TLR) signaling. The IL-10-mediated anti-inflammatory response is executed through the activation of STAT3 leading to induction of target genes referred to as IL-10-induced genes. As miRNAs have emerged as important negative regulators of gene expression in various systems, we sought to address whether the IL-10-mediated anti-inflammatory response acts through regulated expression of miRNA genes. Using quantitative PCR-based arrays, we examined 140 miRNA genes with putative roles in inflammation for changes in expression in response to IL-10 and lipopoly-saccharide (LPS) in primary mouse macrophages. IL-10 stimulation resulted in the inhibition of miR-147 expression induced in response to LPS, while having a potentiating effect on the induction of miR-455. miR-147 is the second TLR-induced miRNA, in addition to miR-155, identified to be counter-regulated by IL-10. Its suppression by IL-10 suggests that miR-147 may have an unknown pro-inflammatory function in TLR-triggered macrophages. The results extend the notion that IL-10 selectively regulates expression of miRNA genes, and that miRNA-mediated pathways are a component of the IL-10-mediated anti-inflammatory response.
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