David Wunder

Publications (2)7.17 Total impact

• Article: Human salivary histatin 5 fungicidal action does not induce programmed cell death pathways in Candida albicans.

  David Wunder, Jin Dong, Didi Baev, Mira Edgerton
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  ABSTRACT: Salivary histatins (Hsts) are potent candidacidal proteins that induce a nonlytic form of cell death in Candida albicans accompanied by loss of mean cell volume, cell cycle arrest, and elevation of intracellular levels of reactive oxygen species (ROS). Since these phenotypes are often markers of programmed cell death and apoptosis, we investigated whether other classical markers of apoptosis, including generation of intracellular ROS and protein carbonyl groups, chromosomal fragmentation (laddering), and cytochrome c release, are found in Hst 5-mediated cell death. Increased intracellular levels of ROS in C. albicans were detected in cells both following exogenous application of Hst 5 and following intracellular expression of Hst 5. However, Western blot analysis failed to detect specifically increased protein carbonylation in Hst 5-treated cells. There was no evidence of chromosomal laddering and no cytochrome c release was observed following treatment of C. albicans mitochondria with Hst 5. Superoxide dismutase enzymes of C. albicans and Saccharomyces cerevisiae provide essential protection against oxidative stress; therefore, we tested whether SOD mutants have increased susceptibility to Hst 5, as expected if ROS mediate fungicidal effects. Cell survival of S. cerevisiae SOD1/SOD2 mutants and C. albicans SOD1 mutants following Hst 5 treatment (31 micro M) was indistinguishable from the survival of wild-type cells treated with Hst 5. We conclude that ROS may not play a direct role in fungicidal activity and that Hst 5 does not initiate apoptosis or programmed cell death pathways.
  Antimicrobial Agents and Chemotherapy 02/2004; 48(1):110-5. · 4.84 Impact Factor
• Article: Influence of antibody on the structure of glucans.

  Leslie K Kopec, Anne M Vacca Smith, David Wunder, Linda Ng-Evans, William H Bowen
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  ABSTRACT: Glucosyltransferase (GTF) plays an essential role in the formation of the biofilm known as dental plaque and in the pathogenesis of dental caries. Mutans streptococci produce at least three distinct GTFs (GtfB, C and D), each of which forms a glucan polymer from sucrose. Glucan is a major constituent of plaque biofilm. GTF adsorbed to a surface forms glucans that differ in structure from those formed by the same enzyme in solution. In the present study, activities of GtfB and GtfC in solution or adsorbed on a surface were inhibited in the presence of a polyclonal antiserum (DS-1) to a mixture of GTFs and by immunoglobulin G (IgG) prepared from DS-1; in contrast, enzyme activity was enhanced by normal rabbit serum (NRS) and IgG from NRS. GtfD activity on a surface was enhanced by both antiserum DS-1 and NRS, and IgG prepared from either serum; GtfD activity in solution was slightly inhibited by each of the sera. The structure of GtfB and GtfC glucans formed in the presence of antiserum differed from that of controls based on linkage analyses, and on their susceptibilities to the glucanohydrolases mutanase (alpha-1,3 hydrolase) and dextranase (alpha-1,6 hydrolase); soluble products from the enzymatic digestion also differed. The results show that the effects of antibody on enzyme activity are more complex than simple inhibition or enhancement and that the presence of antibody may influence glucan structure, which clearly could impact plaque formation. The results have implications for the formation and properties of biofilms formed in other environments.
  Caries Research 36(2):108-15. · 2.33 Impact Factor