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Biomedical subjects

Mary Meehan

Publications and source records attributed to Mary Meehan.

14 recordsLinked to original sources
PubMed2003

Hormonal contraceptive use and HIV-1 infection in a population-based cohort in Rakai, Uganda.

BACKGROUND: Hormonal contraceptives have been associated with increased risk of HIV acquisition. METHODS: The association between hormonal contraception use and HIV acquisition was assessed in a rural community-based cohort in Rakai District, Uganda. A group of 5117 sexually active HIV-negative women were surveyed at 10 month intervals between 1994 and 1999. Information on demographic and sociobehavioral characteristics, use of hormonal contraception (pill and injectable methods), condoms and the number of sexual partners was obtained by home-based interview. HIV incidence rate ratios (IRR) and 95% confidence intervals (CI) associated with hormonal contraception were estimated by multivariate Poisson regression after adjustment for age, condom use, number of sexual partners, marital status, education and history of genital ulcer disease. RESULTS: At one or more interviews, 16.6% of women reported use of hormonal contraceptives and 23.0% reported condom use. HIV incidence was 2.3/100 person-years in hormonal contraceptive users compared with 1.5/100 person-years in non-hormonal contraceptive users (unadjusted IRR, 1.56; 95% CI, 1.00-2.33). After multivariate adjustment, the IRR associated with hormonal contraceptives was reduced to 0.94 (95% CI, 0.53-1.64). The adjusted IRR was 1.12 (95% CI, 0.48-2.56) with oral contraceptive use and 0.84 (95%CI, 0.41-1.72) with injectable methods. CONCLUSION: Use of hormonal contraception is not associated with HIV acquisition after adjustment for behavioral confounding.

Adolescent↗
PubMed2003

The Staphylococcus aureus surface protein SasG and its homologues promote bacterial adherence to human desquamated nasal epithelial cells.

Staphylococcus aureus binds to human desquamated nasal epithelial cells, a phenomenon likely to be important in nasal colonization. ClfB was identified previously as one staphylococcal adhesin that promoted binding to nasal epithelia. In this study, it is shown that the S. aureus surface protein SasG, identified previously by in silico analysis of genome sequences, and two homologous proteins, Pls of S. aureus and AAP of Staphylococcus epidermidis, also promote bacterial adherence to nasal epithelial cells. Conditions for in vitro expression of SasG by S. aureus were not found. Adherence assays were therefore performed with S. aureus and Lactococcus lactis expressing SasG from an expression plasmid. These studies showed that SasG did not bind several ligands typically bound by S. aureus. Significantly, SasG and Pls did promote bacterial adherence to nasal epithelial cells. Furthermore, pre-incubation of epithelial cells with purified recombinant proteins revealed that the N-terminal A regions of SasG, Pls and AAP, but not the B repeats of SasG, inhibited adherence of L. lactis expressing SasG in a dose-dependent fashion. These results suggest that SasG, Pls and AAP bind to the same as-yet-unidentified receptor on the surface of nasal epithelial cells. In addition, expression of SasG, like Pls, reduced adherence of S. aureus to fibronectin and fibrinogen.

Bacterial Adhesion↗
PubMed2002

The C-terminal portion of the fibrinogen-binding protein of Streptococcus equi subsp. equi contains extensive alpha-helical coiled-coil structure and contributes to thermal stability.

The major cell wall-associated protein of the equine pathogen Streptococcus equi subsp. equi is a fibrinogen-binding protein (FgBP) which binds horse fibrinogen and equine IgG-Fc avidly through residues located in the N-terminal half and central regions of the molecule, respectively. The molecule is a major virulence factor for the organism and displays protective potential. In the present study, we use circular dichroism spectroscopy to investigate the secondary structure of the protein and show through the analysis of a panel of recombinant FgBP truncates that the C-terminal portion of FgBP contains an extensive alpha-helical coiled-coil structure that contributes to the thermal stability of the molecule.

Animals↗
PubMed2000

Localization and characterization of the ligand-binding domain of the fibrinogen-binding protein (FgBP) of Streptococcus equi subsp. equi.

The group C streptococcus Streptococcus equi subsp. equi possesses a 498-residue major cell-wall-associated protein (FgBP) which binds horse fibrinogen (Fg), reacts with convalescent horse serum and protects against lethal S. equi challenge in a small animal model. In the present study, analysis of a panel of 17 purified N- and C-terminal FgBP truncates by ligand affinity blotting and SDS-PAGE revealed that the region required for maximum binding of Fg extended over the first half of the mature protein. The C-terminal two-thirds of this domain is predicted to be alpha-helical coiled-coil and the N-terminal one-third to possess non-coiled-coil single strands. Residues at the extreme N-terminus and within the coiled-coil region are both required for ligand binding. A high incidence of alpha-helical coiled-coil structure also seems to be responsible in part for the aberrant mobility of FgBP on SDS gels. The efficiency with which FgBP binds Fg from different animal species decreases in the order horse > mouse, pig > rat > sheep, dog, bovine, human. Binding to horse Fg is inversely related to temperature over the range 45-4 degrees C and is independent of Ca2+ ions. MS analysis provided corroborative evidence that FgBP is covalently linked to the cell wall peptidoglycan.

Animals↗
PubMed1998

Affinity purification and characterization of a fibrinogen-binding protein complex which protects mice against lethal challenge with Streptococcus equi subsp. equi.

Cell-wall-associated proteins from Streptococcus equi subsp. equi, the causative agent of strangles, were analysed with a view to identifying a potential protective antigen. Preparations of these proteins, isolated from mutanolysin extracts of cell walls, were shown to contain one major high-M(r) protein species (apparent M(r) 220,000 and 550,000 when analysed by SDS-PAGE and gel-filtration chromatography, respectively). The high-M(r) protein bound horse fibrinogen and was purified under non-denaturing conditions using fibrinogen affinity chromatography. The fibrinogen-binding protein (FgBP) reacted with serum taken from horses recovering from strangles and protected mice against lethal challenge from S. equi subsp. equi. The sequence of the corresponding gene (fbp) was determined and shown to encode a mature protein (M(r) 54,597) with predicted coiled-coil structure. An FgBP truncate, lacking the C-terminal cell wall/membrane anchor domain, was overexpressed in and purified from Escherichia coli and was shown to behave in an analogous fashion to the wild-type product in terms of M(r) estimation, fibrinogen binding and seroreactivity.

Amino Acid Sequence↗