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Dietetics, Nutrition and Biological Sciences

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Author: search.filters.author.Fyfe, LornaEnd date: 1999

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    Phenotypic changes in the lipopolysaccaride of Pseudomonas aeruginosa and E.coli grown in milk-based enteral nutrient solutions
    (Elsevier, 1999-01) Hodgson, Ian; Stewart, John; Fyfe, Lorna
    Previous studies have shown enteral nutritional solutions (ENS) contaminated with large numbers of microorganisms from the environment or gastrointestinal (GI) tract of patients have caused respiratory infections, acute and chronic enteritis, and septicemia. The introduction of closed- enteral feeding systems has been used to prevent contaminating organisms from entering enteral feeding systems in large numbers. However, there is some discussion as to whether this has been an effective measure in reducing ENS-related infections because there is anecdotal evidence to suggest that disease processes resulting from enteral feeding are still commonplace in the hospital and home. This is because there is very little information about the growth of microorganisms in ENS and whether growth in ENS may affect the virulence and pathogenicity of microorganisms. This study shows that Escherichia coli and Pseudomonas aeruginosa may grow at 25C from either high or low initial numbers to up to 9.2 log colony-forming units per mL in a range of milk-based ENS. However, these organisms did not grow in the fruit-based ENS. The effect on the lipopolysaccharide (LPS) of culturing E. coli and P. aeruginosa in milk-based ENS as opposed to standard laboratory media was examined using polyacrylamide gel electrophoresis. We found that there were significant qualitative changes in the phenotype of O-polysaccharide side chains of the LPS from these organisms. O-polysaccharide is known to mediate in the complement, antibiotic and bile resistance, and affect adherence. Therefore, changes in the virulence and pathogenicity of these microorganisms when cultured in ENS may be indicated. Thus, the study provides further evidence for reevaluating the microbiologic and immunologic effects of enteral feeding, especially on the microbial flora of the GI tract.
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    Inhibition of Listeria monocytogenes and Salmonella enteriditis by combinations of plant oils and derivatives of benzoic acid: the development of synergistic antimicrobial combinations.
    (International Society of Chemotherapy, 1998) Fyfe, Lorna; Armstrong, Fiona; Stewart, John
    This study describes inhibitory properties of combinations of oil of fennel, oil of anise or oil of basil with either benzoic acid or methyl-paraben against Listeria monocytogenes and Salmonella enteriditis. Micro-organisms were cultured at 37 degrees C in broth and viable counts measured over a 48-h period. S. enteriditis was particularly sensitive to inhibition by a combination of oil of anise, fennel or basil with methyl-paraben where there was < 10 CFU/ml after 1 h. L. monocytogenes was less sensitive to inhibition by each combination however there was a significant reduction in growth of 4-8 log by combinations of all oils and methyl-paraben at 8, 24 and 48 h. Synergistic inhibition by one or more combinations was evident against each micro-organism.
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    Murine immune response to recombinant HIV1 p24 core protein following subcutaneous, intraperitoneal and intravenous immunisation
    (Wiley-Blackwell, 1991-11) Fyfe, Lorna; Maingay, J.; Robinson, A. C.; Howie, S. E.
    The murine immune response to baculovirus-produced human immunodeficiency virus type-1 (HIV-1)p24 was examined after injection by three different routes: subcutaneously (s.c.), intraperitoneally (i.p.) and intravenously (i.v.). Both antigen-specific T-cell proliferation and serum antibody were induced by i.p. injection. In contrast, s.c. and i.v. injection of antigen resulted in specific antibody generation alone. Lympho-proliferative responses seen after i.p. injection were confined to splenocytes, and were greater after a low dose of antigen than after a high dose. p24-specific proliferation was not detected in lymph node cells. CD4:CD8 ratios were normal in lymph nodes and spleen at all times, irrespective of the dose or route of administration. p24-specific serum IgG antibodies were detected in all animals after the second injection of antigen. After s.c. and i.v. administration of high doses of antigen, the median antibody titres continued to rise after a third injection, but plateaued in animals injected by the i.p. route. In contrast, low doses of antigen given i.p. increased the median titre during and after the course of four injections. A low antigen dose given s.c. resulted in a plateau of median titre between the third and fourth injections. In i.v.-injected animals the median titre decreased between the third and fourth injections. IgG1 p24-specific antibodies were detected in all immunized mice, whereas IgM antibodies were detectable only following i.p. injection of antigen.
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    Identification of major common extracellular proteins secreted by Aeromonas salmonicida strains isolated from diseased fish
    (1987-04-01) Fyfe, Lorna; Coleman, G.; Munro, A. L.
    Ten different strains of Aeromonas salmonicida that were isolated from diseased fish were grown under identical conditions (24 h at 25 degree C) in 3% (wt/vol) tryptone soya broth medium supplemented with vitamins and inorganic ions. In each case the extracellular proteins that were formed were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it was found that there were two significant common components, one with a molecular weight of 70,000 and the other with a weight of 56,000. Application of enzyme purification techniques to the supernatant fraction proteins of a culture of one of the strains resulted in the isolation of a 70-kilodalton (kDa) component, which was found to be a serine protease, and a 56-kDa component, which was hemolytic to trout erythrocytes. Rocket immunoelectrophoresis with rabbit antibodies to the isolated protease and hemolysin showed the same antigenic components in the supernatant fractions of all the cultures. These activities were assayed, and protease activity was found to vary by a factor of three, from 59 to 195 U/ml, while the range of hemolytic activity was over a narrow band, from 28 to 43 U/ml. There was an inconsistency between the immunoelectrophoretic and direct assay data in only one case. This indicated the presence of additional hemolytic activity, in addition to the 56-kDa component. The detection of large amounts of the same protease and hemolysin, two potent degradative activities, in a random series of strains of A. salmonicida suggests that they may be obligatory virulence factors in the development of furunculosis.
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    A study of the pathological effect of isolated Aeromonas salmonicida extracellular protease on Atlantic salmon, Salmo salar
    (Wiley, 1986-09) Fyfe, Lorna; Finley, A.; Coleman, G.; Munro, A. L. S.
    A comparison was made between the effects of Aeromonas salmonidda extracellular protease and total extracellular products (ECP) following intramuscular injection into juvenile Atlantic salmon, Salmo salar L. Thus, 20, 10, 5, 2.5 and 1.5 units of salt-free protease in 0.2 ml water were compared with ECP preparations with the same levels of proteolytic activity. The highest concentration of ECP produced a gross pathology with a large furuncular lesion 36 h after injection. The corresponding protease preparation had a lesser effect, although a furuncle was formed and tissue liquefaction was produced. These effects were less marked with reduced concentrations. At the lowest level studied, no significant effect was observed with protease alone but ECP (0.8 _g of protein) produced a small, characteristic lesion similar to that achieved with 5 units of isolated protease.
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    A comparative study of the formation of extracellular proteins by Aeromonas salmonicida at two different temperatures
    (Wiley, 1987-04) Fyfe, Lorna; Coleman, G.; Munro, A. L.
    Aeromonas salmonicida was grown in a supplemented 3% (w/v) tryptone soya broth medium at 10 degrees C, a temperature at the lower end of the range over which furunculosis has been observed to occur in the field, and 25 degrees C, the optimum temperature for growth. Similar bacterial densities in the range 2.35 +/- 0.05 mg dry wt/ml were achieved in the two cultures at the beginning of the stationary phase of the growth cycle, after 125 h at 10 degrees C and 18 h at 25 degrees C. At this point, at the higher temperature 1.5 times more exoprotein was formed, 80 +/- 2.8 micrograms/ml compared with 54 +/- 1.7 micrograms/ml. Exoprotein contained the same proportion of haemolysin at both temperatures and twice as much protease at the higher temperature. The most marked difference was in an unidentified 100 kD protein which was formed in a 10-fold greater amount at 10 degrees C.
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    A comparison of the distribution of extracellular proteins produced by the protease-secreting organism Aeromonas salmonicida during aerobic and anaerobic growth
    (1986) Fyfe, Lorna; Coleman, G.; Munro, A. L.
    Aeromonas salmonicida was grown aerobically and anaerobically in supplemented 3% (w/v) tryptone soya broth medium for 24 h at 25 degrees C. Although the bacterial density achieved was 4.9 times higher in the aerobic culture, the exoprotein produced per unit of bacterial dry weight was only 1.9 times higher than in the anaerobic culture. However, the protease activity of the exoprotein showed a marked reduction anaerobically, being only one-tenth of that of the exoprotein produced aerobically. This finding was consistent with the differing SDS-PAGE patterns of the extracellular proteins from the two cultures, which also showed marked loss and reinforcement of other, as yet unidentified extracellular products.
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    Inhibition of bacteria and yeast by oil of fennel and paraben: Development of synergistic antimicrobial combinations
    (Taylor & Francis, 1998) Hodgson, Ian; Stewart, John; Fyfe, Lorna
    This study describes inhibitory properties of combinations of oil of fennel and paraben (methyl, ethyl or propyl) against C. albicans, E. coli and S. aureus. Bacteria or yeast were cultured in broth at 25C and viable counts were measured over a period of 24 h. E. coli was particularly sensitive to inhibition by each combination where there was <10 of units/mL at all times of culture. C. albicans and S. aureus were less susceptible to inhibition by the combination of oil of fennel and methyl paraben but very susceptible to inhibition by oil of fennel in combination with propyl paraben where after 4 h there was <10 cf units/mL. Synergistic inhibition by one or more combinations was evident against each microbe.
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    Murine HIV p24 specific T lymphocyte activation by different antigen presenting cells: B lumphocytes from immunised mice present core protein to T-cells
    (Elsevier, 1993-01) Fyfe, Lorna; Maingay, J P.; Howie, S. E. M.
    Mice were injected with three doses of baculovirus-produced recombinant HIV-1 p24 core protein in alum adjuvant. CD4 positive T lymphocytes from immunized animals proliferated in vitro in the presence of antigen and peritoneal macrophages (Mps) or splenic dendritic cells (DCs) from non-immunized mice as antigen presenting cells (APCs). DCs were approximately three times more efficient than Mps on a cell for cell basis. No synergy was observed between Mps and DCs in this system. B lymphocytes from immunized animals also presented p24 antigen to the specific T cells. Mps did synergize with B cells to enhance the level of T lymphocyte proliferation. This may have implications for the induction of specific immune responses to pathogens after administration of single protein vaccines.