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Articles 1 - 9 of 9
Full-Text Articles in Medicine and Health Sciences
Mechanism Of Toxt-Dependent Transcriptional Activation At The Vibrio Cholerae Tcpa Promoter, Robin R. Hulbert, Ronald K. Taylor
Mechanism Of Toxt-Dependent Transcriptional Activation At The Vibrio Cholerae Tcpa Promoter, Robin R. Hulbert, Ronald K. Taylor
Dartmouth Scholarship
The AraC homolog ToxT coordinately regulates virulence gene expression in Vibrio cholerae. ToxT is required for transcriptional activation of the genes encoding cholera toxin and the toxin coregulated pilus, among others. In this work we focused on the interaction of ToxT with the tcpA promoter and investigated the mechanism of ToxT-dependent transcriptional activation at tcpA. Deletion analysis showed that a region from −95 to +2 was sufficient for ToxT binding and activation, both of which were simultaneously lost when the deletion was extended to −63. A collection of point mutations generated by error-prone PCR revealed two small regions required …
Clinical And Epidemiological Correlates Of Genotypes Within The Mycobacterium Avium Complex Defined By Restriction And Sequence Analysis Of Hsp65, Sandra C. Smole, Fionnuala Mcaleese, Jutamas Ngampasutadol, C. Fordham Von Reyn, Robert D. Arbeit
Clinical And Epidemiological Correlates Of Genotypes Within The Mycobacterium Avium Complex Defined By Restriction And Sequence Analysis Of Hsp65, Sandra C. Smole, Fionnuala Mcaleese, Jutamas Ngampasutadol, C. Fordham Von Reyn, Robert D. Arbeit
Dartmouth Scholarship
Species identification of isolates of the Mycobacterium avium complex (MAC) remains a difficult task. Although M. avium and Mycobacterium intracellulare can be identified with expensive, commercially available probes, many MAC isolates remain unresolved, including those representing Mycobacterium lentiflavum as well as other potentially undefined species. PCR restriction analysis (PRA) of the hsp65 gene has been proposed as a rapid and inexpensive approach. We applied PRA to 278 MAC isolates, including 126 from blood of human immunodeficiency virus (HIV)-infected patients, 59 from sputum of HIV-negative patients with chronic obstructive pulmonary disease, 88 from environmental sources, and 5 pulmonary isolates from …
Identification Of The Vibrio Cholerae Enterobactin Receptors Vcta And Irga: Irga Is Not Required For Virulence, Alexandra R. Mey, Elizabeth E. Wyckoff, Amanda G. Oglesby, Eva Rab, Ronald K. Taylor, Shelley M. Payne
Identification Of The Vibrio Cholerae Enterobactin Receptors Vcta And Irga: Irga Is Not Required For Virulence, Alexandra R. Mey, Elizabeth E. Wyckoff, Amanda G. Oglesby, Eva Rab, Ronald K. Taylor, Shelley M. Payne
Dartmouth Scholarship
The gram-negative enteric pathogen Vibrio cholerae requires iron for growth. V. cholerae has multiple iron acquisition systems, including utilization of heme and hemoglobin, synthesis and transport of the catechol siderophore vibriobactin, and transport of several siderophores that it does not itself make. One siderophore that V. cholerae transports, but does not make, is enterobactin. Enterobactin transport requires TonB and is independent of the vibriobactin receptor ViuA. In this study, two candidate enterobactin receptor genes, irgA (VC0475) and vctA (VCA0232), were identified by analysis of the V. cholerae genomic sequence. A single mutation in either of these genes did not significantly …
Complement Resistance, As Determined By Viable Count And Flow Cytometric Methods, And Its Association With The Presence Of Iss And The Virulence Of Avian Escherichia Coli, Lisa K. Nolan, Catherine W. Giddings, Shelley M. Horne, Curt Doetkott, Penelope S. Gibbs, Richard E. Wooley, Steven L. Foley
Complement Resistance, As Determined By Viable Count And Flow Cytometric Methods, And Its Association With The Presence Of Iss And The Virulence Of Avian Escherichia Coli, Lisa K. Nolan, Catherine W. Giddings, Shelley M. Horne, Curt Doetkott, Penelope S. Gibbs, Richard E. Wooley, Steven L. Foley
Lisa K. Nolan
Previous work in our labs has shown that avian Escherichia coli virulence is correlated with resistance to complement. Also, our studies have revealed that the presence of the increased serum survival gene (iss), known to contribute to the complement resistance and virulence of mammalian E. coli, may predict the virulent nature of an avian E. coli isolate. This relationship warrants further research, but further clarification of the relationship among virulence, complement resistance, and iss sequences requires use of complement susceptibility assays. Such assays, unfortunately, are labor-intensive, expensive, and difficult to perform. In the present study, the results of two complement …
Location Of Increased Serum Survival Gene And Selected Virulence Traits On A Conjugative R Plasmid In An Avian Escherichia Coli Isolate, Timothy J. Johnson, Catherine W. Giddings, Shelley M. Horne, Penelope S. Gibbs, Richard E. Wooley, Jerod Skyberg, Pam Olah, Ronda Kercher, Julie S. Sherwood, Steven L. Foley, Lisa K. Nolan
Location Of Increased Serum Survival Gene And Selected Virulence Traits On A Conjugative R Plasmid In An Avian Escherichia Coli Isolate, Timothy J. Johnson, Catherine W. Giddings, Shelley M. Horne, Penelope S. Gibbs, Richard E. Wooley, Jerod Skyberg, Pam Olah, Ronda Kercher, Julie S. Sherwood, Steven L. Foley, Lisa K. Nolan
Lisa K. Nolan
Avian colibacillosis is a costly disease for the poultry industry. The mechanisms of virulence employed by the etiologic agent of this disease remain ill defined. However, accumulated evidence suggests that complement resistance and the presence of the increased serum survival gene (iss) in an avian Escherichia coli isolate may be indicative of its ability to cause disease. This association of iss with the E. coli implicated in avian disease may mean that iss and/or, perhaps, the genes associated with it are important contributors to avian E. coli virulence. For this reason, we have begun a search for iss's location in …
Virulence Factors Of Escherichia Coli From Cellulitis Or Colisepticemia Lesions In Chickens, J. S. Jeffrey, Lisa K. Nolan, K. H. Tonooka, S. Wolfe, C. W. Giddings, S. M. Horne, S. L. Foley, A. M. Lynne, J. O. Ebert, L. M. Elijah, G. Bjorklund, S. J. Pfaff-Mcdonough, R. S. Singer, C. Doetkott
Virulence Factors Of Escherichia Coli From Cellulitis Or Colisepticemia Lesions In Chickens, J. S. Jeffrey, Lisa K. Nolan, K. H. Tonooka, S. Wolfe, C. W. Giddings, S. M. Horne, S. L. Foley, A. M. Lynne, J. O. Ebert, L. M. Elijah, G. Bjorklund, S. J. Pfaff-Mcdonough, R. S. Singer, C. Doetkott
Lisa K. Nolan
This study was designed to compare virulence factors of cellulitis-derived Escherichia coli to colisepticemic E. coli in order to clarify whether E. coli associated with cellulitis comprise a unique subset of pathogenic E. coli. Isolates were tested for serotype, capsule, aerobactin production, colicin production, the presence of the iss gene, and serum resistance. Untypable isolates made up the greatest percentage of each group. Serotypes O2 and O78 were the most commonly identified among both groups of isolates. No statistical differences in the distribution of aerobactin or colicin production, capsule, or iss gene were observed between groups. Cluster analysis showed that …
Staphylococcus Aureus Agr And Sara Functions Are Required For Invasive Infection But Not Inflammatory Responses In The Lung, Geoffrey Heyer, Shahryar Saba, Robert Adamo, William Rush, Grace Soong, Ambrose Cheung, Alice Prince
Staphylococcus Aureus Agr And Sara Functions Are Required For Invasive Infection But Not Inflammatory Responses In The Lung, Geoffrey Heyer, Shahryar Saba, Robert Adamo, William Rush, Grace Soong, Ambrose Cheung, Alice Prince
Dartmouth Scholarship
Staphylococcus aureus strains lacking agr- and sarA-dependent gene products or specific MSCRAMM (microbial surface components recognizing adhesive matrix molecules) adhesins were compared for the ability to activate inflammatory responses in the lung. The mutants were evaluated for virulence in a mouse model of pneumonia and by quantifying their ability to stimulate interleukin-8 (IL-8) and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in respiratory epithelial cells. In a neonatal mouse, only strains with intact agr and sarA loci were consistently associated with invasive, fatal pulmonary infection (P < 0.001) and sarA was specifically required to cause bacteremia (P < 0.001). The agr and/or sarA mutants were, nonetheless, fully capable of producing pneumonia and were as proficient as the wild-type strain in stimulating epithelial IL-8 expression, a polymorphonuclear leukocyte chemokine, in airway cells. In contrast, agr and especially sarA mutants induced less epithelial GM-CSF expression, and MSCRAMM mutants lacking fibronectin binding proteins or clumping factor A, a ligand for fibrinogen, were unable to stimulate epithelial GM-CSF production. The ability to induce IL-8 expression was independent of the adherence properties of intact bacteria, indicating that shed and/or secreted bacterial components activate epithelial responses. While conserved staphylococcal components such as peptidoglycan are sufficient to evoke inflammation and cause pneumonia, the agr and sarA loci of S. aureus are critical for the coordination of invasive infection of the lungs.
Pathogenic Mechanisms Of Photobacterium Damselae Subspecies Piscicida In Hybrid Striped Bass, Ahmad A. Elkamel
Pathogenic Mechanisms Of Photobacterium Damselae Subspecies Piscicida In Hybrid Striped Bass, Ahmad A. Elkamel
LSU Doctoral Dissertations
Photobacterium damselae subspecies piscicida, previously known as Pasteurella piscicida, is an important pathogen of hybrid striped bass and many fish species cultured in brackish water in the United States, Japan, Europe, and the Mediterranean. The purpose of this study is to investigate virulence mechanisms that contribute to the pathogenesis of this organism. The ability of P. damselae to survive/replicate within hybrid striped bass macrophages was evaluated with an in vitro killing assay. Results indicated that the numbers of bacteria recovered from macrophages at 3, 6, 12, and 18 hours of incubation increased significantly over time. In contrast, the numbers of …
Studies On Early Diagnosis Of Rhodococcus Equi Infection By Elisa In Foals From Racehorse Breeding Studfarms In The Marmara Region, N. Yakut Özgür, Serkan İki̇z, Arzu Funda Bağcigi̇l, Babür Cari̇oğlu, Ömer Akay, Ati̇lla Ilgaz, Shinji Takai
Studies On Early Diagnosis Of Rhodococcus Equi Infection By Elisa In Foals From Racehorse Breeding Studfarms In The Marmara Region, N. Yakut Özgür, Serkan İki̇z, Arzu Funda Bağcigi̇l, Babür Cari̇oğlu, Ömer Akay, Ati̇lla Ilgaz, Shinji Takai
Turkish Journal of Veterinary & Animal Sciences
Due to the recent increasing mortality rates in 1- to 4-month-old Thoroughbred foals with Rhodococcus equi infection in Turkey, serum samples from 454 foals between 30 and 60 days on studfarms of the Marmara Region, where the Thoroughbred foal population is concentrated, were investigated by ELISA for early diagnosis of the infection. The Tween 20-extracted antigen of the R. equi ATCC 6939 strain was used in the ELISA. Two hundred and nine (46%) of the 454 foals were found to be ELISA-positive. Optical density (OD) values of 0.3 (positive limit) or higher were detected in 43% of foals aged 30-40 …