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Search Results: 1 - 10 of 190327 matches for " Jeffery G. Leid "
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Tobacco Smoke Mediated Induction of Sinonasal Microbial Biofilms
Natalia Goldstein-Daruech,Emily K. Cope,Ke-Qing Zhao,Katarina Vukovic,Jennifer M. Kofonow,Laurel Doghramji,Bernardo González,Alexander G. Chiu,David W. Kennedy,James N. Palmer,Jeffery G. Leid,James L. Kreindler,Noam A. Cohen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015700
Abstract: Cigarette smokers and those exposed to second hand smoke are more susceptible to life threatening infection than non-smokers. While much is known about the devastating effect tobacco exposure has on the human body, less is known about the effect of tobacco smoke on the commensal and commonly found pathogenic bacteria of the human respiratory tract, or human respiratory tract microbiome. Chronic rhinosinusitis (CRS) is a common medical complaint, affecting 16% of the US population with an estimated aggregated cost of $6 billion annually. Epidemiologic studies demonstrate a correlation between tobacco smoke exposure and rhinosinusitis. Although a common cause of CRS has not been defined, bacterial presence within the nasal and paranasal sinuses is assumed to be contributory. Here we demonstrate that repetitive tobacco smoke exposure induces biofilm formation in a diverse set of bacteria isolated from the sinonasal cavities of patients with CRS. Additionally, bacteria isolated from patients with tobacco smoke exposure demonstrate robust in vitro biofilm formation when challenged with tobacco smoke compared to those isolated from smoke na?ve patients. Lastly, bacteria from smoke exposed patients can revert to a non-biofilm phenotype when grown in the absence of tobacco smoke. These observations support the hypothesis that tobacco exposure induces sinonasal biofilm formation, thereby contributing to the conversion of a transient and medically treatable infection to a persistent and therapeutically recalcitrant condition.
Andrew Lenard: A Mystery Unraveled
Jeffery Praught,Roman G. Smirnov
Symmetry, Integrability and Geometry : Methods and Applications , 2005,
Abstract: The theory of bi-Hamiltonian systems has its roots in what is commonly referred to as the ``Lenard recursion formula''. The story about the discovery of the formula told by Andrew Lenard is the subject of this article.
Andrew Lenard: A Mystery Unraveled
Jeffery Praught,Roman G. Smirnov
Mathematics , 2005, DOI: 10.3842/SIGMA.2005.005
Abstract: The theory of bi-Hamiltonian systems has its roots in what is commonly referred to as the "Lenard recursion formula". The story about the discovery of the formula told by Andrew Lenard is the subject of this article.
Diversity-Multiplexing Tradeoff of Network Coding with Bidirectional Random Relaying
Chun-Hung Liu,Jeffery G. Andrews
Mathematics , 2008,
Abstract: This paper develops a diversity-multiplexing tradeoff (DMT) over a bidirectional random relay set in a wireless network where the distribution of all nodes is a stationary Poisson point process. This is a nontrivial extension of the DMT because it requires consideration of the cooperation (or lack thereof) of relay nodes, the traffic pattern and the time allocation between the forward and reverse traffic directions. We then use this tradeoff to compare the DMTs of traditional time-division multihop (TDMH) and network coding (NC). Our main results are the derivations of the DMT for both TDMH and NC. This shows, surprisingly, that if relay nodes collaborate NC does not always have a better DMT than TDMH since it is difficult to simultaneously achieve bidirectional transmit diversity for both source nodes. In fact, for certain traffic patterns NC can have a worse DMT due to suboptimal time allocation between the forward and reverse transmission directions.
On the Accuracy of the Wyner Model in Cellular Networks
Jiaming Xu,Jun Zhang,Jeffery G. Andrews
Mathematics , 2010,
Abstract: The Wyner model has been widely used to model and analyze cellular networks due to its simplicity and analytical tractability. Its key aspects include fixed user locations and the deterministic and homogeneous interference intensity. While clearly a significant simplification of a real cellular system, which has random user locations and interference levels that vary by several orders of magnitude over a cell, a common presumption by theorists is that the Wyner model nevertheless captures the essential aspects of cellular interactions. But is this true? To answer this question, we consider both uplink and downlink transmissions, and both outage-based and average-based metrics. For the uplink, for both metrics, we conclude that the Wyner model is in fact quite accurate for systems with a sufficient number of simultaneous users, e.g. CDMA. Conversely, it is broadly inaccurate otherwise. With multicell processing, intracell TDMA is shown to be suboptimal in terms of average throughput, in sharp contrast to predictions using the Wyner model. Turning to the downlink, the Wyner model is highly inaccurate for outage since it depends largely on the user locations. However, for average or sum throughput, the Wyner model serves as an acceptable simplification in certain special cases if the interference parameter is set appropriately.
Amelioration of type 1 diabetes following treatment of non-obese diabetic mice with INGAP and lisofylline  [PDF]
Sarah A. Tersey, Jeffery D. Carter, Lawrence Rosenberg, David A. Taylor-Fishwick, Raghavendra G. Mirmira, Jerry L. Nadler
Journal of Diabetes Mellitus (JDM) , 2012, DOI: 10.4236/jdm.2012.22040
Abstract: Type 1 diabetes mellitus results from the autoimmune and inflammatory destruction of insulin-producing islet β cells, rendering individuals devoid of insulin production. Recent studies suggest that combination therapies consisting of anti-inflammatory agents and islet growth-promoting factors have the potential to cause sustained recovery of β cell mass, leading to amelioration or reversal of type 1 diabetes in mouse models. In this study, we hypothesized that the combination of the anti-inflammatory agent lisofylline (LSF) with an active peptide fragment of islet neogenesis associated protein (INGAP peptide) would lead to remission of type 1 diabetes in the non-obese diabetic (NOD) mouse. We treated groups of spontaneously diabetic NOD mice with combinations of LSF, INGAP peptide, or control saline parenterally for up to 6 weeks. Our results demonstrate that the mice receiving combined treatment with LSF and INGAP peptide exhibited partial remission of diabetes with increased plasma insulin levels. Histologic assessment of pancreata in mice receiving combined therapy revealed the presence of islet insulin staining, increased β cell replication, and evidence of Pdx1-positivity in ductal cells. By contrast, diabetic animals showed severe insulitis with no detectible insulin or Pdx1 staining. We conclude that the novel combination treatment with LSF and INGAP peptide has the potential to ameliorate hyperglycemia in the setting of established type 1 diabetes via the recovery of endogenous β cells and warrant further studies.
Cyclophosphamide induces an early wave of acrolein-independent apoptosis in the urothelium  [PDF]
Francis M. Hughes, Alexa G. Corn, Andrew R. Nimmich, Jeffery D. Pratt-Thomas, J. Todd Purves
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.48A2002
Abstract:

Hemorrhagic cystitis (HC) affects a significant number of patients undergoing cyclophosphamide (CP) chemotherapy despite treatment with 2-mercaptoethane sulfonate (Mesna) to inactivate the metabolite acrolein. While the mechanism is unknown, there is clearly acrolein-independent damage to the urothelium. In this study we have explored the induction of apoptosis in the urothelium as a marker of damage and the mechanism underlying the acrolein-independent apoptosis. Two waves of apoptosis (measured as caspase-3/7 activity and Poly (ADP-ribosyl) polymerase (PARP) cleavage) were detected following CP administration, one peaking at 2 h and a second at 48 h. The first wave was not blocked by Mesna, indicating it was independent of acrolein. Caspase-1 was also active at 2 h and activation of caspase-3/7 was blocked by a caspase-1 inhibitor, but not an IL-1 receptor antagonist, suggesting the direct activation of caspase-3/7 by caspase-1 without the need for IL-1 as an intermediate. Our results indicate that CP initiates an early, acrolein-independent wave of apoptosis that results from direct cleavage of caspase-3/7 by caspase-1.

Comparison and evaluation of methods for generating differentially expressed gene lists from microarray data
Ian B Jeffery, Desmond G Higgins, Aedín C Culhane
BMC Bioinformatics , 2006, DOI: 10.1186/1471-2105-7-359
Abstract: In this study, we compared the efficiency of the feature selection methods; significance analysis of microarrays (SAM), analysis of variance (ANOVA), empirical bayes t-statistic, template matching, maxT, between group analysis (BGA), Area under the receiver operating characteristic (ROC) curve, the Welch t-statistic, fold change, rank products, and sets of randomly selected genes. In each case these methods were applied to 9 different binary (two class) microarray datasets. Firstly we found little agreement in gene lists produced by the different methods. Only 8 to 21% of genes were in common across all 10 feature selection methods. Secondly, we evaluated the class prediction efficiency of each gene list in training and test cross-validation using four supervised classifiers.We report that the choice of feature selection method, the number of genes in the genelist, the number of cases (samples) and the noise in the dataset, substantially influence classification success. Recommendations are made for choice of feature selection. Area under a ROC curve performed well with datasets that had low levels of noise and large sample size. Rank products performs well when datasets had low numbers of samples or high levels of noise. The Empirical bayes t-statistic performed well across a range of sample sizes.Microarrays enable the simultaneous measurement of the expression levels of tens of thousands of genes and have found widespread application in biological and biomedical research. The use of microarrays to discover genes, which are differentially expressed between two or more groups of patients has many applications. These include the identification of disease biomarkers that may be important in the diagnoses of the different types and subtypes of diseases [1]. Although increasing numbers of multi-class microarray studies are performed, the vast majority continue to be two class (binary) studies, for example where a control and a treatment are examined. In this case, the
An anatomy ontology to represent biological knowledge in Dictyostelium discoideum
Pascale Gaudet, Jeffery G Williams, Petra Fey, Rex L Chisholm
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-130
Abstract: We present here an anatomy ontology for Dictyostelium based upon the life cycle of the organism.Anatomy ontologies are necessary to annotate species-specific events such as phenotypes, and the Dictyostelium anatomy ontology provides an essential tool for curation of the Dictyostelium genome.Dictyostelium discoideum is a facultative multicellular organism with a life cycle consisting of two mutually exclusive states, vegetative growth and development. During the vegetative cycle, Dictyostelium amoebae live as single cells that feed on bacteria and divide by binary fission. When environmental conditions are harsh, single-celled Dictyostelium amoebae enter a simple developmental pathway leading to the formation of a multicellular fruiting body composed of two main cell types: stalk cells supporting a spore-containing sorus [1,2]. Spores are protected by a tough cell wall that maximizes survival in adverse conditions. The stalk raises the spore head high enough for the spores to be scattered away to maximize the possibility of germination in a more favorable environment. The dispersion of spores in an environment favorable for successful germination and survival is granted by the ability of the slug to migrate towards light and heat. Other soil micro-organisms such as nematodes could also contribute to the dispersal of spores [3]. The size of the multicellular organism is quite variable, usually ranging from 10,000 to 100,000 cells [4], or up to 2,000,000 [5]; however, slugs composed of as few as 100 cells have been reported [6]. The proportion of spore to stalk cells is usually around 4:1, although the fraction of stalk cells decreases to as low as 10% in larger organisms [7-9]. Formation of the multicellular stages of the Dictyostelids is remarkable in that it is accomplished through the aggregation of neighboring cells rather than by division of a single cell (zygote), as is the case in most multicellular organisms. Its simple life cycle and the mutually exclusive gr
Tegnieke vir die bestudering van DNS metilering: ‘n Epigenetiese merk vir biodiversiteit
Vanessa O’Neill,Charlene Andraos,Tamsyn Jeffery,G. Koorsen
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie , 2012, DOI: 10.4102/satnt.v31i1.316
Abstract:
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