When cultivated properly in bioreactors, microalgae have been found to produce vast amounts of biomass. In the case of diatom cultivation where the organisms will fall out of suspension quite easily, paddle wheels or pumps are the primary means to maintain the necessary velocity in the raceway. This study will focus on the potentially harmful shear stress these devices may impart onto the organisms. The system used to impart shear stress to a diatom culture was a cone and plate viscometer. Cells were counted using a fluorescein diacetate staining method with a fluorescent and brightfield microscope. Under the white light all cells were visible while only the healthy cells were visible under fluorescent light. The sample was exposed to shear stress with the cone and plate viscometer at 6 Pascals for 10 minutes and compared against a non-sheared sample. For each sample, 5 pairs of white and fluorescent light images were captured, counted, and averaged. A non-sheared sample was paired with a sheared sample to calculate the decrease in cell viability. The slope was calculated from the plot of shear stress and cell viability for 9 strains. In each case shear stress resulted in a significant decrease in cell viability; however, there was no statistical difference between strains. While effective, this method would be impractical for a commercial algae cultivation facility as the viscometer in this study costs approximately $100,000. Therefore, tests were performed to determine if a rotary mixer could be substituted for the viscometer. The hypothesis was that the cell damage was a product of shear stress and exposure time. For the viscometer test, the shear exposure was 3600 Pa s. Two rotational mixer tests were performed, one at 1250 RPM for 7 hours and one at 313 RPM for 28 hours, providing the same 3600 Pa s shear exposure. After staining, cell viability decreased 35.62% and 11.07% in the 1250 RPM and 313 RPM test, respectively. This difference was significant compared to the 6.04% decrease in the viscometer test. The increased cell damage was attributed to turbulence in the mixer tests and the basis for further study.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / This study investigated the effects of TKIs on the growth and proliferation of MCF-7 breast carcinoma cells in culture. MCF-7 cells were exposed to different concentrations of TKIs alone and in combination with each other. Inhibition of cell growth by TKIs used individually occurred in a dose- and time-dependent manner. When EGFR Inhibitor I, EGFR Inhibitor II/BIBX1382 and the multi-specific EGFR/ErbB-2/ErB-4 Inhibitor were used in combination with each other at equimolar log dose concentrations, the combined effects on cell growth was significantly different to inhibitors used individually as reflected in a decreased EC50 (IC50) during combination treatments. Generally, for the combinations with DOX, CPL and the TKIs, synergistic as well as antagonistic effects were observed at isoeffective concentrations with resultant decreases in dose reduction indices (DRIs) implying greater efficacies with the respective combinations. In this study, conventional PCR was used to detect and illustrate the presence of the EGFR gene in the samples, while RT-qPCR was used to determine the mRNA expression levels of this gene in MCF-7 breast carcinoma cells