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Investigating the Mechanism of Action of Colostrinin™ on Cells in Culture
The aim of this Ph.D. project was to investigate the effects of Colostrinin (CLN) on cells in culture, and its Aβility to prevent or alleviate cytotoxicity induced by reactive oxygen species (ROS) and beta-amyloid (Aβ). Two cell culture systems were used to analyse the effects of CLN; rat primary hippocampal cultures and the B50 rat neuronal cell line.
Bovine CLN was found to have no adverse effects on cell morphology or survival and to have a small, non-significant effect, on both menadione-induced, oxidative stress-mediated toxicity and Aβ1-42-induced toxicity of neurons in primary hippocampal cultures. This protective effect was found to potentially be related to the antioxidant effects of CLN. CLN was demonstrated to prevent a menadione-induced increase in ROS in the B50 cell line. Furthermore CLN was able to reverse a significant Aβ1-42-mediated increase in the protein levels of the antioxidant enzyme Cu/Zu superoxide dismutase (SOD) in primary hippocampal cultures, although CLN alone caused an increase in SOD1 protein in the B50 cell line.
Bovine CLN was shown, in both B50 cells and primary hippocampal cells, not to significantly decrease the protein levels of cyclin dependent kinase 5 (Cdk5) which has previously been demonstrated to be involved in the mechanism of tumour necrosis factor (TNF) α-mediated protection against Aβ-induced toxicity in primary hippocampal cultures. Furthermore CLN did not consistently alter the expression of activated caspase 3 in either B50 or primary hippocampal cells.
This study adds to the knowledge and understanding of the mechanism of action of CLN
PERMISSIVENESS OF SELECTED CELL LINES TO EQUINE ARTERITIS VIRUS: ESTABLISHMENT, CHARACTERIZATION, AND SIGNIFICANCE OF PERSISTENT INFECTION IN HELA CELLS
A major goal of this research was to evaluate a variety of cell lines for theirpermissiveness to equine arteritis virus (EAV) infection and then identify the mechanismthat restricts EAV infection in certain cell lines. The cell lines BHK-21, RK-13, andC2C12 were found to support productive infection with EAV strain VBS53, whereasHela, Hep-2, and L-M cell lines exhibited limited susceptibility to infection with thisvirus. In the course of the study, it was found that the Hela cell line became moresusceptible to infection with EAV strain VBS53 after extended serial passage. Therespective cell lines were referred to as Hela High (passage 170-221) and Hela Low(passage 95-115) lines. While the Hela High cell line was more susceptible than the HelaLow cell line, it was still considerably less susceptible than the BHK-21 cell line to EAVinfection. Subsequent studies demonstrated that infection with EAV strain VBS53 wasrestricted at the entry step in Hela, Hep-2, and L-M cell lines.The second major goal of this research was to establish an in vitro model ofpersistent EAV infection using cell culture and then use the persistently infected culturesas a tool to study virus-host cell interactions, and to investigate virus and host cellevolution. Persistent infection was successfully established in the Hela High cell line withthe VBS53 strain of EAV. Properties of the persistently infected Hela High cell line werecharacterized. Virus evolution with respect to virus growth characteristics, ability of thevirus to initiate secondary persistent infection, and genetic changes during persistentEAV infection in Hela cells was investigated. Neutralization phenotypic changes of viruses were observed during the course of persistent EAV infection in Hela cells. Reverse genetics studies identified that amino acid 98 of the GP5 protein is a new neutralization determinant of EAV. Using an in vitro assay, it was found that EAV probably became progressively less virulent during the course of persistent infection in Hela cells. The potential changes in pathogenicity of EAV during persistent infection of Hela cells need to be verified by inoculation of horses