München, Techn. University, Diss., 2007.

FernUniversität Hagen, Diss., 2008.

Prion diseases are a group of fatal neurodegenerative diseases, including CJD and scrapie, which are thought to be caused by a protein termed a prion (PrP). As manganese has previously been suggested to be involved in prion disease we have investigated manganese binding to PrP and its role in the toxicity of the protein. We have shown that manganese bound PrP (MnPrP) has several of the characteristics of the disease form of PrP, including protease resistance and toxicity that is dependent on cellular PrP expression. Further investigation into the mechanism of toxicity revealed that MnPrP is significantly more toxic to neuronal cells than nonmanganese bound PrP and that toxicity requires the presence of known metal binding residues within the protein. We have demonstrated that treatment of neuronal cells with MnPrP causes caspase 3 activation and apoptosis, as demonstrated by DNA laddering, and we hypothesise that caspase 3 is activated by a p38 pathway. Treatment of neurones with MnPrP also caused a significant increase in cellular ROS production, although this did not appear to be a major cause of cell death as antioxidants were unable to save cells from cell death. We also investigated mechanisms by which cells can survive scrapie infection and MnPrP toxicity. We have shown that cells infected with scrapie have increased ERK activation which was important for their survival. Cells that survived MnPrP treatment were also found to have increased ERK activation. This suggests that ERK may have a protective role in prion diseases and may be a potential therapeutic target.

This thesis examines consumer behavior towards food risks in three different papers, focusing on two food concerns: genetically modified (GM) food and bovine spongiform encephalopathy (BSE). The first paper investigates the roles of different measures of trust on consumers stated choices for functional GM/nonGM canola oil products. These analyses show that consumers choices for GM/nonGM canola oil are influenced by both generalized trust and trust in food institutions. In general, trusting people are less likely to be in the group of respondents that can be characterized as being anti-GM; trusting people also tend to place a lower discount on the presence of a GM attribute. The second paper focuses on the modeling of consumers choices of foods with potential health and risk attributes. The analysis extends the linear compensatory utility model by allowing for use of attribute cutoffs in decision making. We find evidence that attribute cutoffs are commonly used by decision makers. Further, incorporating attribute cutoffs into the modeling of consumers choices significantly improved the model fit. This paper also examines a potential problem of endogeneity that may be associated with respondents self-reported cutoffs. Model estimates based on self-reported cutoffs differ substantially from those based on predicted cutoffs (where these are based on respondents demographic characteristics); potential reasons include the possibility that self-reported cutoffs may be endogenous. The third paper reports the impacts of habit and trust on consumers responses to a series of three BSE incidents in Canada. We observe that households reactions to the first two BSE events followed a similar pattern: households reduced their beef expenditure shares following the BSE announcements, but these subsequently recovered. We find that habit persistence reduced some households initial negative reactions to the first BSE incident, but that these households modified their beef consumption habits following recurring BSE incidents. Assessing the impacts of trust on households reactions to these BSE incidents, we find that trust tended to offset the negative effects of recurring BSE cases. / Agricultural and Resource Economics

This study examined coverage of the December 2003 bovine spongiform encephalopathy event to discover reporters’ sources for breaking agricultural news, the impact of reporter specialization on source choices, and the impact of newspaper differences, including location, circulation, and ownership, on coverage. Quantitative content analysis was performed on 62 stories selected through a keyword search for the period December 23, 2003 through October 31, 2004 from U.S. newspapers included in the LexisNexis database. These stories were divided into two equal groups based on reporter work-role identity and were analyzed by length, number of sources, and source variety, and by location, circulation, and ownership of the newspapers in which they appeared. ANOVA, bivariate correlation, and forced entry regression were statistical techniques used. Results indicated numbers of stories, story length, and numbers of sources per story appear related to newspaper location, and use of scientists and agricultural scientists as sources to be correlated with type of newspaper. Newspaper circulation and ownership type were found to explain a statistically significant amount of variance in number of sources used. No statistically significant differences between mean length or mean number of sources used were found between stories written by science-specialty beat reporters and those written by reporters not assigned to such beats, contradicting previous research. However, while mean overall source variety did not differ between the two reporters groups, work-role identity was found to be correlated with use of scientists and agricultural scientists as sources. Extrapolation from this study suggests it is open to question whether (a) reporters would be well-advised to pursue courses of study or to seek additional training to build defined areas of expertise, better equipping themselves to cover more complex issues; (b) editors should seek candidates with such special training and structure their newsroom routines to accommodate specialty reporters when considering adding employees to their reporting staffs; and (c) universities should offer journalism curricula that facilitate both acquisition of basic reporting skills and registration for substantive electives which build subject-matter knowledge. Answers to these questions should be actively pursued, since they may shape the future of journalism education and practice.

The emergence of the zoonotic disease, bovine spongiform encephalopathy (BSE) in Canada resulted in a severe agricultural crisis. However, little is known about the ways in which farmers and rural communities were affected. The overall objective of this study is to characterize and better understand the impacts on and responses of farmers and rural communities as they relate to this crisis. Research was undertaken in strata throughout the diverse three Canadian prairie provinces – Alberta, Saskatchewan and Alberta – by employing surveys and focus groups. Results indicated there were numerous direct and ‘spillover’ impacts on farmers and rural communities resulting from the BSE crisis. Declines in cattle prices, herd equity and cash flow, often resulting in the need for bank loans, farm credit or off farm employment, as well as emotional and psychological stress were all experienced by farmers as a result of BSE. Importantly, many additional factors such as adverse weather and market volatility compounded the impacts related to BSE, adding to what was already a crisis situation for many farmers. These impacts were not restricted to farms but, rather, extended into the surrounding community fabric in the form of financial and social stress. Results further indicated government policies contributed to the impacts and the effectiveness of farmer responses related to BSE. A longer-term policy shift that has embraced agro-industrialization and entrenchment into the global marketplace has resulted in clear disparities between the biggest and smallest players in the beef industry and agriculture as a whole. This was illustrated in the ways in which governments responded to the BSE crisis, favouring the needs of the largest farmers and agri-businesses over those of smaller-scale, cow-calf producers. This policy shift and response has left the Canadian beef industry, family farmers and rural communities more susceptible to the emergence of similar future risks. A more inclusive approach to risk research and policymaking that meaningfully involved farmers and their rich, longer-term local knowledge might help mitigate similar risks that will inevitably confront agriculture in the future. / February 2009

The increasing awareness of, and concern over, possible terrorist attacks using biological threats has increased attention and efforts for safeguarding U.S. agriculture. Whether intentional or unintentional, a biological event likely would cause substantial consequences well beyond the U.S. agricultural sector with considerable economic, social, and political costs. One significant impact would involve trade disruptions. This dissertation investigates biosecurity risk impacts with a focus on animal disease outbreaks using data from recent U.S. and Canada bovine spongiform encephalopathy (BSE) cases. An empirical study was carried out on the impact of the North American BSE cases. Using a time series approach, this study detected a significant structural break during the second half of 2003 when two BSE cases were confirmed in North America. Results showed that U.S. beef prices responded to the disruptions in cattle and beef trade caused by the BSE cases. The ban on beef and cattle imports from Canada and the ban on U.S. beef exports were major contributors to the fluctuation in beef prices. This showed that trade disruptions following the BSE discoveries in North America resulted in a supply shift and affected the movement of beef prices afterwards. The study did not find strong evidence that the 2003 North American BSE cases and associated trade disruptions greatly affected per capita beef consumption. In turn, a simulation study was conducted to examine the impact of major BSE outbreaks, associated trade disruptions, and demand shifts on U.S. welfare and the livestock industry. Six alternative scenarios were simulated and compared with the base scenario where there was no trade disruption and demand shift. The six scenarios consisted of various combinations of cattle and beef trade restrictions, livestock production adjustment, and beef demand shift. When beef and cattle trade, and market demand are greatly reduced in the wake of the BSE events in both Canada and the U.S., the impact on the U.S. welfare, meat trade, and regional livestock production would be the greatest. Beef price and production could reduce by 26% and 16% respectively. Regional impact on beef and livestock production would also be substantial in this case.

This study examined coverage of the December 2003 bovine spongiform encephalopathy event to discover reporters’ sources for breaking agricultural news, the impact of reporter specialization on source choices, and the impact of newspaper differences, including location, circulation, and ownership, on coverage. Quantitative content analysis was performed on 62 stories selected through a keyword search for the period December 23, 2003 through October 31, 2004 from U.S. newspapers included in the LexisNexis database. These stories were divided into two equal groups based on reporter work-role identity and were analyzed by length, number of sources, and source variety, and by location, circulation, and ownership of the newspapers in which they appeared. ANOVA, bivariate correlation, and forced entry regression were statistical techniques used. Results indicated numbers of stories, story length, and numbers of sources per story appear related to newspaper location, and use of scientists and agricultural scientists as sources to be correlated with type of newspaper. Newspaper circulation and ownership type were found to explain a statistically significant amount of variance in number of sources used. No statistically significant differences between mean length or mean number of sources used were found between stories written by science-specialty beat reporters and those written by reporters not assigned to such beats, contradicting previous research. However, while mean overall source variety did not differ between the two reporters groups, work-role identity was found to be correlated with use of scientists and agricultural scientists as sources. Extrapolation from this study suggests it is open to question whether (a) reporters would be well-advised to pursue courses of study or to seek additional training to build defined areas of expertise, better equipping themselves to cover more complex issues; (b) editors should seek candidates with such special training and structure their newsroom routines to accommodate specialty reporters when considering adding employees to their reporting staffs; and (c) universities should offer journalism curricula that facilitate both acquisition of basic reporting skills and registration for substantive electives which build subject-matter knowledge. Answers to these questions should be actively pursued, since they may shape the future of journalism education and practice.

Zugl.: Berlin, Freie Univ., Diss., 2008

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