MPU Noon Seminar Series
Speaker: Marlene Kontcho, MSc
Canadian Nuclear Laboratories, Chalk River, Ontario
Title:
“Investigating the Oxygen Effect on the Irradiation of Lens Epithelial Cells: Role in Cataract Formation”
Abstract:
Exposure of the human lens to ionizing radiations is known to induce the development of cataracts, especially posterior sub-capsular caratacts. The radiation oxygen effect states that in the presence of oxygen, ionizing radiation causes more severe cellular lesions that can be irreparable, resulting in permanent cellular damage or cell death. The hypoxic nature of the eye lens makes it particularly sensitive to oxygen tension changes and ionizing radiations, yet no radiation in vitro studies reported to date have accounted for this. The oxygen enhancement ratio (OER) is a value describing the enhanced radiosensitivity of biological samples at different oxygen levels. In this study, we evaluate the oxygen effect curve using SV40-virus modified humans lens epithelial cells irradiated with low-LET gamma rays under oxic and hypoxic conditions. A maximum OER value of 3.80 was calculated, with a half-maximal oxygen concentration of 0.6% (4.56mmHg), based on the expression of γ-H2AX as a result of radiation-induced DNA double-stranded breaks. The non-mitotic and extremely hypoxic nature of the lens fiber cells makes the lens more radioresistant to help survive the effects of oxidative stress and aging. However, any changes in oxygen level caused by ionizing radiation may have considerable consequences and could be a reason for the high radiosensitivity of the lens.
Biographical Summary:
Marlene Kontcho obtained a bachelor degree in Biochemistry and a master’s degree in Applied Molecular Biology from the University of Maryland Baltimore County. She worked in the pharmaceutical industry in upstream and downstream monoclonal antibodies manufacturing and process improvement. Currently, she is a research technologist in the Radiology and Health Branch at the Canadian Nuclear Laboratories (CNL), Chalk River, Ontario, Canada, researching low and high doses radiation effects on biological systems. She is working with Dr. Richardson studying how the oxygen effect is impacting the development of radiation-induced cataracts.
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