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Search Results: 1 - 10 of 131313 matches for " Spencer V. Nyholm "
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Characterizing the Host and Symbiont Proteomes in the Association between the Bobtail Squid, Euprymna scolopes, and the Bacterium, Vibrio fischeri
Tyler R. Schleicher, Spencer V. Nyholm
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0025649
Abstract: The beneficial symbiosis between the Hawaiian bobtail squid, Euprymna scolopes, and the bioluminescent bacterium, Vibrio fischeri, provides a unique opportunity to study host/microbe interactions within a natural microenvironment. Colonization of the squid light organ by V. fischeri begins a lifelong association with a regulated daily rhythm. Each morning the host expels an exudate from the light organ consisting of 95% of the symbiont population in addition to host hemocytes and shed epithelial cells. We analyzed the host and symbiont proteomes of adult squid exudate and surrounding light organ epithelial tissue using 1D- and 2D-polyacrylamide gel electrophoresis and multidimensional protein identification technology (MudPIT) in an effort to understand the contribution of both partners to the maintenance of this association. These proteomic analyses putatively identified 1581 unique proteins, 870 proteins originating from the symbiont and 711 from the host. Identified host proteins indicate a role of the innate immune system and reactive oxygen species (ROS) in regulating the symbiosis. Symbiont proteins detected enhance our understanding of the role of quorum sensing, two-component signaling, motility, and detoxification of ROS and reactive nitrogen species (RNS) inside the light organ. This study offers the first proteomic analysis of the symbiotic microenvironment of the adult light organ and provides the identification of proteins important to the regulation of this beneficial association.
Expression and Putative Function of Innate Immunity Genes under in situ Conditions in the Symbiotic Hydrothermal Vent Tubeworm Ridgeia piscesae
Spencer V. Nyholm, Pengfei Song, Jeanne Dang, Corey Bunce, Peter R. Girguis
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038267
Abstract: The relationships between hydrothermal vent tubeworms and sulfide-oxidizing bacteria have served as model associations for understanding chemoautotrophy and endosymbiosis. Numerous studies have focused on the physiological and biochemical adaptations that enable these symbioses to sustain some of the highest recorded carbon fixation rates ever measured. However, far fewer studies have explored the molecular mechanisms underlying the regulation of host and symbiont interactions, specifically those mediated by the innate immune system of the host. To that end, we conducted a series of studies where we maintained the tubeworm, Ridgeia piscesae, in high-pressure aquaria and examined global and quantitative changes in gene expression via high-throughput transcriptomics and quantitative real-time PCR (qPCR). We analyzed over 32,000 full-length expressed sequence tags as well as 26 Mb of transcript sequences from the trophosome (the organ that houses the endosymbiotic bacteria) and the plume (the gas exchange organ in contact with the free-living microbial community). R. piscesae maintained under conditions that promote chemoautotrophy expressed a number of putative cell signaling and innate immunity genes, including pattern recognition receptors (PRRs), often associated with recognizing microbe-associated molecular patterns (MAMPs). Eighteen genes involved with innate immunity, cell signaling, cell stress and metabolite exchange were further analyzed using qPCR. PRRs, including five peptidoglycan recognition proteins and a Toll-like receptor, were expressed significantly higher in the trophosome compared to the plume. Although PRRs are often associated with mediating host responses to infection by pathogens, the differences in expression between the plume and trophosome also implicate similar mechanisms of microbial recognition in interactions between the host and symbiont. We posit that regulation of this association involves a molecular “dialogue” between the partners that includes interactions between the host’s innate immune system and the symbiont.
Insurance and Banking Interconnectedness in Europe: The Opinion of Equity Markets
Ken Nyholm
Economics Research International , 2012, DOI: 10.1155/2012/525089
Abstract: Conditional expected shortfalls calculated for European insurance companies and banks under stressed market conditions are shown to be of similar magnitudes. Measured at 95% and 99% stress levels, on data covering the period from 1995 to 2011, the equity-return tail losses of insurance undertakings and banks are indistinguishable. Granger causality analysis, on all pairs of banks and insurance companies included in the sample, shows that banks and insurance companies have equal propensity to cause each others price movements. Even though the business model of insurance undertakings is different from the business model typically applied by banks, and even though insurance companies are not depending to a similar degree on short term funding as banks, the empirical results indicate that the financial equity markets in Europe do not differentiate their trading of banks and insurance companies in periods of stress.
Insurance and Banking Interconnectedness in Europe: The Opinion of Equity Markets
Ken Nyholm
Economics Research International , 2012, DOI: 10.1155/2012/525089
Abstract: Conditional expected shortfalls calculated for European insurance companies and banks under stressed market conditions are shown to be of similar magnitudes. Measured at 95% and 99% stress levels, on data covering the period from 1995 to 2011, the equity-return tail losses of insurance undertakings and banks are indistinguishable. Granger causality analysis, on all pairs of banks and insurance companies included in the sample, shows that banks and insurance companies have equal propensity to cause each others price movements. Even though the business model of insurance undertakings is different from the business model typically applied by banks, and even though insurance companies are not depending to a similar degree on short term funding as banks, the empirical results indicate that the financial equity markets in Europe do not differentiate their trading of banks and insurance companies in periods of stress. 1. Introduction Insurance companies perform an important task in the economy by ensuring that economic agents can buy protection against risks that otherwise cannot be hedged. In this way they complement financial markets by making risk-hedging instruments available. A traditional insurance company will build its business model around the collection of premiums over time, from households and firms, and by the implementation of an appropriate asset allocation as a storage of wealth, whereby premiums and investment returns are accumulated and grown with the help of financial market instruments. The aim of such investment activities is to build an asset base that will enable the company to cover future insurance claims, that are uncertain in amount and timing. A traditional bank also serves a central role in the economy by providing credit intermediation for agents with lending and borrowing needs. Traditional banking operations reduce the search costs, and potentially creates better prised and organised markets for credit intermediation, to the benefit of agents with surplus and deficit cash positions. Economic agents can thus turn to a bank to deposit funds and obtain loans, respectively, rather than searching for bilateral agreements in the markets. These different roles played by insurance companies and banks in the economy naturally lead to differences in their balance sheet compositions and to differences in their risk profiles and potential business-cycle vulnerabilities. An insurance company can relatively freely determine its asset composition and will inherently strive to minimise the shortfall risk stemming from states of the world where
A Review of Microbiology Experiments & Lab Techniques with CD-ROM
Deborah V. Harbour,Juliet V. Spencer
Journal of Microbiology & Biology Education , 2010, DOI: 10.1128/jmbe.v11i2.209
Abstract: n/a
On Hemostasis of Cold Atmospheric Air Plasma  [PDF]
Spencer Kuo
Open Journal of Emergency Medicine (OJEM) , 2018, DOI: 10.4236/ojem.2018.64012
Abstract: The efficacy and mechanism of a cold atmospheric-pressure air plasma (CAAP), which carries abundant atomic oxygen (OI), on blood coagulation are studied. The tests on sodium citrate mixed blood-droplet samples show that 1) The heat delivered by the CAAP has no impact on the observed clot formation, 2) Plasma effluent activates platelets to promote coagulation state and cascade, and 3) The degree of clotting increases with the OI flux delivered by the CAAP. The full clotting time is shortened from about 25 minutes of the natural clotting time to about 16 s of the CAAP treatment time. The tests on smeared blood samples show that the reduction of the platelet count and the increase of RBC count are proportional to the applied OI flux. In vivo tests, using swine as nimal model, swift hemostasis of large and deep cut wounds on the back by the CAAP treatment was demonstrated. A cut artery was sealed completely with 25 s treatment. The pressure applied by a finger on the cut artery could be removed immediately after the treatment and there was no re-bleed. Based on the in vitro test results and the animal model trials, CAAP coagulation mechanism is presented.
Methods for Detection of Matrix Metalloproteinases as Biomarkers in Cardiovascular Disease
Viorica Lopez-Avila,Juliet V. Spencer
Clinical Medicine : Cardiology , 2008,
Abstract: Matrix metalloproteinases (MMPs) are a family of zinc-dependent proteolytic enzymes that degrade extracellular matrix (ECM) components like collagen, fibronectin, and laminin. While this activity is important for normal development, morphogenesis, and wound healing, deregulation of MMP activity has been implicated in a number of cardiovascular diseases, including congenital heart defects, atherosclerosis, myocardial infarction, and congestive heart failure. MMPs are good potential diagnostic indicators of cardiovascular disease, but current detection methods are time consuming and quite laborious. This review will discuss MMP biology, current methods for detection of MMPs from patient samples, and potential new developments in multiplexed analysis of MMPs.
cmvIL-10 Stimulates the Invasive Potential of MDA-MB-231 Breast Cancer Cells
Cendy A. Valle Oseguera, Juliet V. Spencer
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0088708
Abstract: Cancer is the result of unregulated cell growth that leads to tumor formation, and in many cases, metastases. Although there are several risk factors associated with cancer, one area that remains poorly understood is the impact of infectious disease. Human cytomegalovirus (HCMV) is a member of the herpesvirus family that is highly prevalent in the population. HCMV usually causes clinical disease only in immune compromised individuals, but recent evidence suggests that HCMV may be strongly associated with some forms of cancer, particularly glioblastoma and breast cancer. We investigated the possibility that cmvIL-10, a viral cytokine with homology to human IL-10 that is secreted from infected cells, could act in a paracrine manner to alter the tumor microenvironment, induce cell signaling, and increase the invasive potential of cancer cells. We found that human MDA-MB-231 breast cancer cells express the IL-10 receptor and that exposure to cmvIL-10 results in activation of Stat3, a transcription factor strongly associated with enhanced metastatic potential and chemo-resistance. In addition, cmvIL-10 stimulated an increase in DNA synthesis and cell proliferation, protected MDA-MB-231 cells from etoposide-induced apoptosis, and also greatly enhanced chemotaxis toward epidermal growth factor (EGF). These results suggest a significant and wide-ranging role for cmvIL-10 in the progression of breast cancer and could have broad implications for the diagnosis and treatment of cancer in HCMV-positive patients.
Diophantine inequalities and quasi-algebraically closed fields
Craig V. Spencer,Trevor D. Wooley
Mathematics , 2010,
Abstract: Consider a form $g(x_1,...,x_s)$ of degree $d$, having coefficients in the completion $F_q((1/t))$ of the field of fractions $F_q(t)$ associated to the finite field $F_q$. We establish that whenever $s>d^2$, then the form $g$ takes arbitrarily small values for non-zero arguments $x\in F_q[t]^s$. We provide related results for problems involving distribution modulo $F_q[t]$, and analogous conclusions for quasi-algebraically closed fields in general.
Intersective polynomials and Diophantine approximation, II
Thai Hoang Le,Craig V. Spencer
Mathematics , 2013,
Abstract: By applying Schmidt's lattice method, we prove results on simultaneous Diophantine approximation modulo 1 for systems of polynomials in a single prime variable provided that certain local conditions are met.
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