Matching Items (3)
Description
The prevalence of antibiotic resistant bacterial pathogens has increased since the introduction of penicillin in the 1940s. Insufficient development of novel antibacterial agents is leaving us with a failing arsenal of therapies to combat these pathogenic organisms. We have identified a clay mineral mixture (designated CB) that exhibits in vitro antibacterial activity against a broad spectrum of bacterial pathogens, yet the antibacterial mechanism of action remains unknown. Antibacterial susceptibility testing of four different clay samples collected from the same source revealed that these natural clays had markedly different antibacterial activity. X-ray diffraction analyses of these minerals revealed minor mineralogical differences across the samples; however, ICP analyses demonstrated that the concentrations of many elements, Fe, Co, Cu, Ni, and Zn in particular, vary greatly across the four clay mixture leachates. Supplementation of a non-antibacterial leachate containing lower concentrations of Fe, Co, Ni, Cu, and Zn to final ion concentrations and a pH equivalent to that of the antibacterial leachate resulted in antibacterial activity against E. coli and MRSA, confirming the role of these ions in the in vitro antibacterial clay mixture leachates. The prevailing hypothesis is that metal ions participate in redox cycling and produce ROS, leading to oxidative damage to macromolecules and resulting in cellular death. However, E. coli cells showed no increase in DNA or protein oxidative lesions and a slight increase in lipid peroxidation following exposure to CB-L. Supplementation of CB-L with ROS scavengers eliminated oxidative damage in E. coli, but did not rescue the cells from killing, indicating that in vitro killing is due to direct metal toxicity and not to indirect oxidative damage. Finally, we ion-exchanged non-antibacterial clays with Fe, Co, Cu, and Zn and established antibacterial activity in these samples. Treatment of MRSA skin infections with both natural and ion-exchanged clays significantly decreased the bacterial load after 7 days of treatment. We conclude that 1) in vitro clay-mediated killing is due to toxicity associated directly with released metal ions and not to indirect oxidative damage and 2) that in vivo killing is due to the physical properties of the clays rather than metal ion toxicity.
ContributorsOtto, Caitin Carol (Author) / Haydel, Shelley (Thesis advisor) / Stout, Valerie (Committee member) / Roberson, Robby (Committee member) / Sandrin, Todd (Committee member) / Rege, Kaushal (Committee member) / Arizona State University (Publisher)
Created2014
Description
Adolescents' clay sculpture has been researched significantly less than their drawings. I spent approximately six weeks in a ceramics class located at a high school in a suburb of Phoenix, Arizona in order to explore how gender affected subject matter preference in students' three dimensional clay sculpture. Gender studies on children's drawings reveal that males favor fantasy, violence, aggression, sports, and power, while females favor realism, domestic and social experience, physical appearance, care and concern, nature and animals. My three main research questions in this study were 1) How did gender affect subject matter in adolescents' three-dimensional clay sculpture? 2) What similarities or differences existed between females' and males' subject matter preference in sculpture and their subject matter preference in drawing? 3) Assuming that significant gender differences existed, how successful would the students be with a project that favored opposite gender themed subject matter? I found that although males and females had gender differences between subject matter in their clay sculptures, there were exceptions. In addition, the nature of clay affected this study in many ways. Teachers and students need to be well prepared for issues that arise during construction of clay sculptures so that students are able to use clay to fully express their ideas.
ContributorsMarsili, Teresa (Author) / Stokrocki, Mary (Thesis advisor) / Young, Bernard (Committee member) / Erickson, Mary (Committee member) / Arizona State University (Publisher)
Created2011
Description
Items that have once served as tools in the past become something of greater value in the future: art. Ceramics is a craft that has gone beyond its simple functions to become a representative medium. This ability makes ceramics an art. This will be demonstrated by representing enzyme-substrate binding and inhibition through the use of a dinner set.
ContributorsMahmud, Ali (Author) / Chung, Sam (Thesis director) / Weiser, Kurt (Committee member) / School of Art (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05