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Articles 1 - 10 of 10
Full-Text Articles in Life Sciences
Dead Zones In Porous Catalysts: Concentration Profiles And Efficiency Factors, Roger L. York, Kaitlin M. Bratlie, Lloyd R. Hile, Larry K. Jang
Dead Zones In Porous Catalysts: Concentration Profiles And Efficiency Factors, Roger L. York, Kaitlin M. Bratlie, Lloyd R. Hile, Larry K. Jang
Kaitlin M. Bratlie
This paper examines the conditions under which a dead zone, or a portion of the catalyst devoid of reactant, can form in a porous catalyst in which simultaneous reaction and diffusion are occurring. The condition that allows for the existence of a dead zone is defined by a critical Thiele modulus. When the Thiele modulus - the ratio of chemical reaction to diffusion - is greater than the critical Thiele modulus, a dead zone exists. This dead zone can be mathematically defined by a change of boundary conditions. We examine nth order reactions in isothermal infinite slabs, infinite cylinders, and …
Rapid Biocompatibility Analysis Of Materials Via In Vivo Fluorescence Imaging Of Mouse Models, Kaitlin M. Bratlie, Tram T. Dang, Stephen Lyle, Matthias Nahrendorf, Ralph Weissleder, Robert Langer, Daniel G. Anderson
Rapid Biocompatibility Analysis Of Materials Via In Vivo Fluorescence Imaging Of Mouse Models, Kaitlin M. Bratlie, Tram T. Dang, Stephen Lyle, Matthias Nahrendorf, Ralph Weissleder, Robert Langer, Daniel G. Anderson
Kaitlin M. Bratlie
Background: Many materials are unsuitable for medical use because of poor biocompatibility. Recently, advances in the high throughput synthesis of biomaterials has significantly increased the number of potential biomaterials, however current biocompatibility analysis methods are slow and require histological analysis. Methodology/Principal Findings: Here we develop rapid, non-invasive methods for in vivo quantification of the inflammatory response to implanted biomaterials. Materials were placed subcutaneously in an array format and monitored for host responses as per ISO 10993-6: 2001. Host cell activity in response to these materials was imaged kinetically, in vivo using fluorescent whole animal imaging. Data captured using whole animal …
Furfural Inhibits Growth By Limiting Sulfur Assimilation In Ethanologenic Escherichia Coli Strain Ly180, Elliot N. Miller, Laura R. Jarboe, Peter C. Turner, Prita Pharkya, Lorraine P. Yomano, Sean W. York, David Nunn, K. T. Shanmugan, Lonnie O. Ingram
Furfural Inhibits Growth By Limiting Sulfur Assimilation In Ethanologenic Escherichia Coli Strain Ly180, Elliot N. Miller, Laura R. Jarboe, Peter C. Turner, Prita Pharkya, Lorraine P. Yomano, Sean W. York, David Nunn, K. T. Shanmugan, Lonnie O. Ingram
Laura R. Jarboe
A wide variety of commercial products can be potentially made from monomeric sugars produced by the dilute acid hydrolysis of lignocellulosic biomass. However, this process is accompanied by side products such as furfural that hinder microbial growth and fermentation. To investigate the mechanism of furfural inhibition, mRNA microarrays of an ethanologenic strain of Escherichia coli (LY180) were compared immediately prior to and 15 min after a moderate furfural challenge. Expression of genes and regulators associated with the biosynthesis of cysteine and methionine was increased by furfural, consistent with a limitation of these critical metabolites. This was in contrast to a …
Silencing Of Nadph-Dependent Oxidoreductase Genes (Yqhd And Dkga) In Furfural-Resistant Ethanologenic Escherichia Coli, Elliot N. Miller, Laura R. Jarboe, L. P. Yomano, S. W. York, K. T. Shanmugam, L. O. Ingram
Silencing Of Nadph-Dependent Oxidoreductase Genes (Yqhd And Dkga) In Furfural-Resistant Ethanologenic Escherichia Coli, Elliot N. Miller, Laura R. Jarboe, L. P. Yomano, S. W. York, K. T. Shanmugam, L. O. Ingram
Laura R. Jarboe
Low concentrations of furfural are formed as a side product during the dilute acid hydrolysis of hemicellulose. Growth is inhibited by exposure to furfural but resumes after the complete reduction of furfural to the less toxic furfuryl alcohol. Growth-based selection was used to isolate a furfural-resistant mutant of ethanologenic Escherichia coli LY180, designated strain EMFR9. Based on mRNA expression levels in the parent and mutant in response to furfural challenge, genes encoding 12 oxidoreductases were found to vary by more than twofold (eight were higher in EMFR9; four were higher in the parent). All 12 genes were cloned. When expressed …
Applications Of Transposable Elements In Fish For Transgenesis And Functional Genomics, Perry B. Hackett, Karl J. Clark, Stephen C. Ekker, Jeffrey J. Essner
Applications Of Transposable Elements In Fish For Transgenesis And Functional Genomics, Perry B. Hackett, Karl J. Clark, Stephen C. Ekker, Jeffrey J. Essner
Jeffrey J. Essner
Transgenic fish were first made more than 30 years ago. Since then a variety of methods and const ructs have been tested for introducing genetic sequences into fish for scientitlc investigations as well as commercial purposes. Here we review transposable clements and t heir applications in fish. Transposons can be used to deliver genes to chromosomes to confer new traits or as insertional agents and traps to uncover the functions and expression patterns of natural genes in chromosomes. Two DNA transposons have been characterized for transposon-based gene transfer and insertional mutagenesis. The t1rst is d1e Sleeping Beauty transposon system that …
Jun Dimerization Protein 2 Functions As A Progesterone Receptor N-Terminal Domain Coactivator, James S. Adelman, Suzanne E. Wardell, Viroj Boonyaratanakornkit, Ami Aronheim
Jun Dimerization Protein 2 Functions As A Progesterone Receptor N-Terminal Domain Coactivator, James S. Adelman, Suzanne E. Wardell, Viroj Boonyaratanakornkit, Ami Aronheim
James S. Adelman
The progesterone receptor (PR) contains two transcription activation function (AF) domains, constitutive AF-1 in the N terminus and AF-2 in the C terminus. AF-2 activity is mediated by a hormone-dependent interaction with a family of steroid receptor coactivators (SRCs). SRC-1 can also stimulate AF-1 activity through a secondary domain that interacts simultaneously with the primary AF-2 interaction site. Other protein interactions and mechanisms that mediate AF-1 activity are not well defined. By interaction cloning, we identified an AP-1 family member, Jun dimerization protein 2 (JDP-2), as a novel PR-interacting protein. JDP-2 was first defined as a c-Jun interacting protein that …
Predicting The Growth Of Salmonella Typhimurium On Beef By Using The Temperature Function Integration Technique, James S. Dickson, G. R. Siragusa, J. E. Wray Jr.
Predicting The Growth Of Salmonella Typhimurium On Beef By Using The Temperature Function Integration Technique, James S. Dickson, G. R. Siragusa, J. E. Wray Jr.
James S. Dickson
Lag and generation times for the growth of Salmonella typhimurium on sterile lean beef were modeled as functions of cooling time under various carcass-chilling scenarios. Gompertz growth models were fit to the log10 colony counts over time at each of six temperatures in the range of 15 to 40 degrees C. Lag and generation times were defined as the points at which the second and first derivatives, respectively, of each growth curve attained a maximum. Generation time and lag time parameters were modeled as functions of temperature by use of exponential-decay models. The models were applied to typical beef carcass-cooling …
Use Of A Bacteriocin Produced By Pediococcus Acidilactici To Inhibit Listeria Monocytogenes Associated With Fresh Meat, J. W. Nielsen, James S. Dickson, J. D. Crouse
Use Of A Bacteriocin Produced By Pediococcus Acidilactici To Inhibit Listeria Monocytogenes Associated With Fresh Meat, J. W. Nielsen, James S. Dickson, J. D. Crouse
James S. Dickson
A bacteriocin produced by Pediococcus acidilactici had an inhibitory and bactericidal effect on Listeria monocytogenes associated with fresh meat. MICs were significantly lower than minimum killing concentrations. When meat was inoculated with L. monocytogenes, the bacteriocin reduced the number of attached bacteria in 2 min by 0.5 to 2.2 log cycles depending upon bacteriocin concentration. Meat treated initially with the bacteriocin resulted in attachment of 1.0 to 2.5 log cycles fewer bacteria than that attained with the control. The bacteriocin, after 28 days of refrigerated storage on meat surfaces, was stable and exhibited an inhibitory effect on L. monocytogenes.
An Electrochemical Method Of Measuring The Oxidation Rate Of Ferrous To Ferric Iron With Oxygen In The Presence Of Thiobacillus Ferrooxidans, David J. Oliver, B. Pesic, P. Wichlacz
An Electrochemical Method Of Measuring The Oxidation Rate Of Ferrous To Ferric Iron With Oxygen In The Presence Of Thiobacillus Ferrooxidans, David J. Oliver, B. Pesic, P. Wichlacz
David J. Oliver
The oxidation of Fe2+ with oxygen in sulfate solutions was studied in the presence of T. ferrooxidans. To measure the chemical activity of bacteria, and the oxidation rate of iron, the redox potentials of solutions were continuously monitored during the experiments. The redox potentials were simultaneously monitored on the platinum and pyrite indicator electrodes. The redox potential versus time curves were further used to calculate the basic kinetic parameters, such as the reaction orders, the activation energy, and the frequency factor. It was found that under atmospheric conditions, and at Fe2+ < 0.001M, T < 25°C, and at pH above 2.2, the oxidation of iron is governed by the following rate expression: [equation image] Below pH = 2.2, the oxidation rate is independent of H+ Concentration.
Cell Surface Charge Characteristics And Their Relationship To Bacterial Attachment To Meat Surfaces, James S. Dickson, M. Koohmaraie
Cell Surface Charge Characteristics And Their Relationship To Bacterial Attachment To Meat Surfaces, James S. Dickson, M. Koohmaraie
James S. Dickson
Cell surface charge and hydrophobicity of Bacillus subtilis, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis were determined by hydrocarbon adherence, hydrophobic interaction, and electrostatic interaction chromatography. Surface charge and hydrophobicity were compared with the initial attachment values and rates of attachment of the bacteria to meat surfaces. There was a linear correlation between the relative negative charge on the bacterial cell surface and initial attachment to lean beef muscle (r2 = 0.885) and fat tissue (r2 = 0.777). Hydrophobicity correlated well with attachment to fat tissue only. The relative hydrophobicity of each bacterium …