Experimental Background

Through experimental data, we sought to determine whether the glutathione pathway or another source of electrons was used for reduction of selenium for incorporation into glutathione peroxidase (GPx) in whole cells. Relative selenium deficiency was first achieved in the cells, allowing for a measure of baseline selenite-dependent GPx activity in the absence of selenite. Selenite was also added to a portion of the selenium-deficient cells, and the rate of GPx synthesis was measured to compare to baseline GPx activity. This comparison between selenium treatment and control, referred to as an "experiment," was repeated for cells also treated with buthionine sulfoximine (BSO), 1,3 bis-(2 chloroethyl)-1-nitrosourea (BCNU), or methylene blue (MB), or a combination of these compounds, referred to as "cell treatments." Trials were conducted over 13 days, and on each day, experiments were performed to test between two and four of the above combination of compounds. The rate of GPx synthesis was measured by the GPx activity present in the cell after a specified amount of time. Five imperfectly measured, unpaired values comprise a single specific activity (ratio of activity to protein) measurement: three activity measurements and two protein measurements. Thus, the difference in GPx activity between selenium-deficient and selenium-supplemented cells would be the effect on GPx activity due to selenium. It was the goal of the research to examine how the rate of selenite-dependent GPx activity changes when the cell lines were prepared with a variety of treatments.