Medicine and Health Sciences Commons^™

Characterization Of Two Outer Membrane Proteins, Flgo And Flgp, That Influence Vibrio Cholerae Motility, Raquel M. Martinez, Madushini N. Dharmasena, Thomas J. Kirn, Ronald K. Taylor

Dartmouth Scholarship

Vibrio cholerae is highly motile by the action of a single polar flagellum. The loss of motility reduces the infectivity of V. cholerae, demonstrating that motility is an important virulence factor. FlrC is the sigma-54-dependent positive regulator of flagellar genes. Recently, the genes VC2206 (flgP) and VC2207 (flgO) were identified as being regulated by FlrC via a microarray analysis of an flrC mutant (D. C. Morris, F. Peng, J. R. Barker, and K. E. Klose, J. Bacteriol. 190:231-239, 2008). FlgP is reported to be an outer membrane lipoprotein required for motility that functions as a colonization factor. The study reported …

Aging And Environmental Exposures Alter Tissue-Specific Dna Methylation Dependent Upon Cpg Island Context, Brock C. Christensen, E Andres Houseman, Carmen J. Marsit, Shichun Zheng, Margaret R. Wrensch, Joseph L. Wiemels, Heather H. Nelson, Margaret R. Karagas

Dartmouth Scholarship

Epigenetic control of gene transcription is critical for normal human development and cellular differentiation. While alterations of epigenetic marks such as DNA methylation have been linked to cancers and many other human diseases, interindividual epigenetic variations in normal tissues due to aging, environmental factors, or innate susceptibility are poorly characterized. The plasticity, tissue-specific nature, and variability of gene expression are related to epigenomic states that vary across individuals. Thus, population-based investigations are needed to further our understanding of the fundamental dynamics of normal individual epigenomes. We analyzed 217 non-pathologic human tissues from 10 anatomic sites at 1,413 autosomal CpG loci …

A Truncation Mutation In Tbc1d4 In A Family With Acanthosis Nigricans And Postprandial Hyperinsulinemia, Satya Dash, Hiroyuki Sano, Justin J. Rochford, Robert K. Semple

Dartmouth Scholarship

Tre-2, BUB2, CDC16, 1 domain family member 4 (TBC1D4) (AS160) is a Rab-GTPase activating protein implicated in insulin-stimulated glucose transporter 4 (GLUT4) translocation in adipocytes and myotubes. To determine whether loss-of-function mutations in TBC1D4 might impair GLUT4 translocation and cause insulin resistance in humans, we screened the coding regions of this gene in 156 severely insulin-resistant patients. A female presenting at age 11 years with acanthosis nigricans and extreme postprandial hyperinsulinemia was heterozygous for a premature stop mutation (R363X) in TBC1D4. After demonstrating reduced expression of wild-type TBC1D4 protein and expression of the truncated protein in lymphocytes from the proband, …

U2os Cells Lacking Chk1 Undergo Aberrant Mitosis And Fail To Activate The Spindle Checkpoint, Laura Carrassa, Yolanda Sanchez, Eugenio Erba, Giovanna Damia

Dartmouth Scholarship

Chk1 is a conserved protein kinase originally identified in fission yeast, required to delay entry of cells with damaged or unreplicated DNA into mitosis. The requirement of Chk1 for both S and G2/M checkpoints has been elucidated while only few studies have connected Chk1 to the mitotic spindle checkpoint. We used a small interference RNA strategy to investigate the role of Chk1 in unstressed conditions. Chk1 depletion in U2OS human osteosarcoma cells inhibited cell proliferation and raised the percentage of cells with a 4N DNA content, which correlated with accumulation of giant polynucleated cells morphologically distinct from apoptotic cells, while …

Long-Distance Delivery Of Bacterial Virulence Factors By Pseudomonas Aeruginosa Outer Membrane Vesicles, Jennifer M. Bomberger, Daniel P. Maceachran, Bonita A. Coutermarsh, Siying Ye, George A. O'Toole, Bruce A. Stanton, Frederick M. Ausubel

Dartmouth Scholarship

Bacteria use a variety of secreted virulence factors to manipulate host cells, thereby causing significant morbidity and mortality. We report a mechanism for the long-distance delivery of multiple bacterial virulence factors, simultaneously and directly into the host cell cytoplasm, thus obviating the need for direct interaction of the pathogen with the host cell to cause cytotoxicity. We show that outer membrane–derived vesicles (OMV) secreted by the opportunistic human pathogen Pseudomonas aeruginosa deliver multiple virulence factors, including β-lactamase, alkaline phosphatase, hemolytic phospholipase C, and Cif, directly into the host cytoplasm via fusion of OMV with lipid rafts in the host plasma …

Paracrine Sonic Hedgehog Signalling By Prostate Cancer Cells Induces Osteoblast Differentiation, Samantha M Zunich, Taneka Douglas, Maria Valdovinos, Tiffany Chang

Dartmouth Scholarship

Sonic hedgehog (Shh) and components of its signalling pathway have been identified in human prostate carcinoma and increased levels of their expression appear to correlate with disease progression and metastasis. The mechanism through which Shh signalling could promote metastasis in bone, the most common site for prostate carcinoma metastasis, has not yet been investigated. The present study determined the effect of Shh signalling between prostate cancer cells and pre-osteoblasts on osteoblast differentiation, a requisite process for new bone formation that characterizes prostate carcinoma metastasis.

Lymphocyte Proliferation To Mycobacterial Antigens Is Detectable Across A Spectrum Of Hiv-Associated Tuberculosis, Timothy Lahey, Mecky Matee, Lillian Mtei, Muhammad Bakari, Kisali Pallangyo, C Fordham Von Reyn

Dartmouth Scholarship

Background:

Identifying novel TB diagnostics is a major public health priority. We explored the diagnostic characteristics of antimycobacterial lymphocyte proliferation assays (LPA) in HIV-infected subjects with latent or active TB.

Methods:

HIV-infected subjects with bacille Calmette Guérin (BCG) scars and CD4 counts ≥ 200 cells/mm³ entering a TB booster vaccine trial in Tanzania had baseline in vivo and in vitro immune tests performed: tuberculin skin tests (TST), LPA and five day assays of interferon gamma (IFN-γ) release. Assay antigens were early secreted antigenic target 6 (ESAT-6), antigen 85 (Ag85), and Mycobacterium tuberculosis whole cell lysate (WCL). Subjects were screened …

Interconnections Between Sigma B, Agr, And Proteolytic Activity In Staphylococcus Aureus Biofilm Maturation, Katherine J. Lauderdale, Blaise R. Boles, Ambrose L. Cheung, Alexander R. Horswill

Dartmouth Scholarship

Staphylococcus aureus is a proficient biofilm former on host tissues and medical implants. We mutagenized S. aureus strain SH1000 to identify loci essential for ica-independent mechanisms of biofilm maturation and identified multiple insertions in the rsbUVW-sigB operon. Following construction and characterization of a sigB deletion, we determined that the biofilm phenotype was due to a lack of sigma factor B (SigB) activity. The phenotype was conserved in a sigB mutant of USA300 strain LAC, a well-studied community-associated methicillin-resistant S. aureus isolate. We determined that agr RNAIII levels were elevated in the sigB mutants, and high levels of RNAIII expression are …

Corr4a And Vrt325 Do Not Reduce The Inflammatory Response To P. Aeruginosa In Human Cystic Fibrosis Airway Epithelial Cells, Laleh Talebian, Bonita Coutermarsh, Jacqueline Y. Channon, Bruce A. Stanton

Dartmouth Scholarship

P. aeruginosa chronically colonizes the lung in CF patients and elicits a proinflammatory response. Excessive secretion of IL-6 and IL-8 by CF airway cells in response to P. aeruginosa infection in the CF airway is though to contribute to lung injury. Accordingly, the goal of this study was to test the hypothesis that Corr4a and VRT325, investigational compounds that increase ΔF508-CFTR mediated Cl⁻ secretion in human CF airway cells, reduce the pro-inflammatory response to P. aeruginosa.