Graduation date: 1999

Biological toxins such as ricin and the Bacillus anthracis toxins have become an increasing bioterrorism threat due to the relative availability, extreme potency and ease of production of these agents. Extensive research has been conducted investigating methods for decontaminating spaces affected by biological agents such as bacteria and viruses, but little research has been done to determine the efficacy of these methods on toxins. The efficacy of gaseous chlorine dioxide (GCD) and vaporous hydrogen peroxide (VHP) at inactivating ricin and B. anthracis lethal factor and protective antigen was tested. The presence and activity of the toxins after exposure to the decontamination methods was detected using a cytotoxicity assay and protein gel electrophoresis. Both VHP and GCD were found to be effective at detoxifying the anthrax toxins within a short exposure, with close to complete inactivation observed during longer exposures. Ricin proved to be more resistant to inactivation, with longer exposures needed to achieve similar levels of detoxification to the anthrax toxins. Overall, GCD and VHP have great potential for use in inactivating biological toxins.

Biological toxins such as ricin and the Bacillus anthracis toxins have become an increasing bioterrorism threat due to the relative availability, extreme potency and ease of production of these agents. Extensive research has been conducted investigating methods for decontaminating spaces affected by biological agents such as bacteria and viruses, but little research has been done to determine the efficacy of these methods on toxins. The efficacy of gaseous chlorine dioxide (GCD) and vaporous hydrogen peroxide (VHP) at inactivating ricin and B. anthracis lethal factor and protective antigen was tested. The presence and activity of the toxins after exposure to the decontamination methods was detected using a cytotoxicity assay and protein gel electrophoresis. Both VHP and GCD were found to be effective at detoxifying the anthrax toxins within a short exposure, with close to complete inactivation observed during longer exposures. Ricin proved to be more resistant to inactivation, with longer exposures needed to achieve similar levels of detoxification to the anthrax toxins. Overall, GCD and VHP have great potential for use in inactivating biological toxins.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 66-67). Also available on the World Wide Web.

Graduation date: 1999

Mode of access: Internet via World Wide Web. Available at http://hdl.handle.net/1947/8654. / "February 2007"

MSc, Physiotherapy, Faculty of Health Sciences, University of the Witwatersrand / Background: Jet nebulisers are one of the primary devices used in the nebulisation of ventilated patients. It has been observed that due to cost restraints devices marked as “single use” are inadvertently being used as “single-patient-use” devices. This has both ethical and medico legal implications for the ICU. Ventilator-associated pneumonia (VAP) in limited-resource countries carries a large burden of increased mortality, morbidity and cost. Ineffective or absent nebuliser decontamination in ventilated patients can increase the risk of the development of VAP as well as the risk of antibiotic resistance. Objectives: The aim of this study was to examine the current practice of nebuliser decontamination and the incidence of contamination of nebulisers after use within a ventilator circuit, in ICUs in Johannesburg, South Africa. The secondary objectives of the study were to assess the presence of and adherence to a decontamination protocol in intensive care units (ICU) in Johannesburg and to identify which practices were associated with lower or no bacterial growth. Methods: A cross-sectional study design was used which included an interview with the unit manager and an audit of current nebuliser practice in the ICU. Nebulisers that were identified in the interview were then swabbed and streaked on blood agar plates (BAPs). Blood agar plates were then incubated and assessed for bacterial colonisation, number of colony forming units (CFUs) and number of different species of CFUs that were formed. Results: Single-use jet nebulisers represented 93% of nebulisers used within a ventilator circuit. All of the single-use jet nebulisers were being re-used (n=42). None of the hospitals studied had a nebuliser decontamination protocol. The contamination rate for jet nebulisers that had been re-used within the ventilator circuit was 52%. In the group of nebulisers that had bacterial colonisation, the nebulisers that were stored in a sterile drape had a significantly higher concentration of bacterial growth, than those that were not stored in a sterile drape (p=0.03). Nebulisers are often used in the administration of bronchodilators in ICUs in Johannesburg, South Africa. Colonised nebulisers can create bacterial aerosol when used within a ventilator circuit. A change to single-patient-use devices, such as vibrating mesh nebulisers, may assist in reducing the problem of colonisation of jet nebulisers. Conclusion: The rate of colonisation of jet nebulisers that have been re-used is unacceptably high. ICUs need to develop nebuliser decontamination protocols. Physiotherapists should assist with creating awareness and driving the creation of these protocols. ICUs should be encouraged to change single-use devices to single-patient-use devices. Nebulisers should not be stored in sterile drapes after use in a ventilator circuit.

No description available.

The chelating agent ethylene diamine tetraacetic acid (EDTA) is promising. The ligand is more effective in removing the metal contaminants from soils than HCl. In a batch experiment, EDTA released a large portion of metals from soils to soil extracts. A batch method was also developed for recovering the metal contaminants in the resulting EDTA soil-extracts. Using an anion exchange resin (AER) AG 3-x4, up to 99% of the Cd, Cu, Pb, and Zn were removed from the leachates. / To increase the efficacy of the extraction method we tested different reagent, amount, and technical application strategies using soil columns. Mixing the reagent with the whole soil column was found to be the most efficient method for the application of the chelating agent for the purpose of metal extraction from soils. It was found that EDTA was superior to citric acid in removing Cd, Cu, Pb, and Zn from the soils investigated. Up to 27% more Cd, 23% more Cu, 42% more Pb, and 21% more Zn were removed by the EDTA and the removal was further increased with the addition of an acid/salt solution (1.0 M HCl and 1.0 M KCl) to the columns. Other promising results are that the AER in columns is an effective method for extracting metals from EDTA soil-extracts with different properties. The resin column method was found to be more efficient than the resin batch procedure. / The results of the simulated field experiment confirmed that the remediation of contaminated soils can be achieved using EDTA. The majority of the contaminated soils were decreased to the point that they could be reused for commercial and/or residential use. / Computer models can be used to predict the possible metal speciation and interaction with solid surfaces in soils. Using the MINEQL+ program, the models estimated that most of the metal species in the soil extracts (in the presence of EDTA, chloro, hydroxo, and carbonato ligands and humate and hydrous ferric oxide (HFO) solid phases) were present as soluble metal-EDTA complexes. It appears that the metal-EDTA complexes found in the systems are very stable over a wide range of soil pH. Our surface complexation models also indicated that the EDTA is much stronger than the humate and the HFO solid phases in forming complexes with the metals. As a consequence, the adsorption of the Cd, Cu, Pb, and Zn by the solid surfaces was negligible in the presence of EDTA. (Abstract shortened by UMI.)

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 79-81). Also available on the World Wide Web.