One of the main reasons smokers struggle to quit is the cognitive deficits caused by abstinence. Bupropion (BUP) and nicotine replacement therapy (NRT) are two of the three FDA-approved efficacious pharmacotherapies to assist in nicotine abstinence. Very little is known about the differences between the neurocognitive effects of NRT and BUP. This dissertation analyzed a dataset of electroencephalogram (EEG) collected while participants performed a visuospatial dot-localization task (DOTLOC). In the study, 119 smokers were randomly divided into 4 groups (BUP, NRT, placebo, and delayed-quit controls) for 6 sessions – one baseline experimental session, four treatment sessions and one post-treatment session after 67 days of abstinence. During the task, source-localized theta, alpha, and beta activity were obtained for the four groups (NRT and BUP, placebo, and delay-quit smokers) at three network-related regions of interest (ROIs). After 3 and 24 days of abstinence, NRT contrasted with placebo showed increases in high frequency current source density (CSD) and decrease in low-frequency CSD. After 3 days of abstinence, BUP contrasted with placebo showed increase in theta and beta CSD at parietal sites and decrease in spectral CSD at frontal and temporal sites. When contrasted with NRT, BUP showed an increase in low-frequency CSD at parietal regions, and decrease in low and high-frequency at temporal and frontal regions. A significant difference was also found in abstinent smokers at 66 days compared to pre-quit session and smoking controls, with a significant increase in parietal alpha activity and a significant decrease in beta CSD. This was the first research to look at the neurocognitive effects of bupropion compared to NRT, as well as the first to identify the long-term changes caused by tobacco abstinence on task-related cortical activity.

No description available.

No description available.

Antibodies represent the largest group of biopharmaceuticals. Due to the nature of their clinical applications, they often need to be produced in large quantities. Plants have distinct advantages of producing large quantities of recombinant proteins, and tobacco is arguably the most promising plant for plant-made-pharmaceuticals (PMP) due to its high biomass yields and robust transformation technology. However, to produce proteins using transgenic tobacco for human applications, purification of the proteins is challenging. On the other hand, Protein A, a bacterial cell wall protein isolated from Staphylococcus aureus that binds to the Fc regions of immunoglobulins, is useful to the isolation and purification of antibodies. An affinity chromatography purification step utilizing Protein A resin introduced early in the purification process can reduce successive unit operations, thereby reducing the overall process cost. However, directly applying tobacco extract to Protein A chromatography columns may be problematic due to the non-specific binding of native tobacco proteins (NTP). In this project, three different Protein A resins, ProSepvA High Capacity, ProSep-vA Ultra, and ProSep Ultra Plus, marketed by Millipore, were studied to provide valuable information for future downstream processes for antibody purification from transgenic tobacco. The efficiency of the post load wash buffer to reduce non-specific binding of NTP to the ProSep A resins were evaluated by altering the ionic strength and pH. Lower salt concentrations of sodium chloride (NaCl) in the post load wash preformed best at reducing the non-specific binding of NTP to the ProSep A resins, while higher salt concentrations were more effective at reducing the amount of NTP contaminants present during elution of the columns. Using a post load wash buffer with an intermediate pH between the binding buffer and the elution buffer was more efficient at eluting our model antibody, human IgG. However, lowering the ionic strength and the pH of the post load wash buffer resulted in a greater presence of IgG prematurely eluting from the ProSep A resins. The non-specific binding of NTP to the resins reduced the dynamic binding capacity (DBC) of the resins after repeated cycles of tobacco extract samples were loaded onto the column. Nevertheless, cleaning the columns with denaturing solutions, such as urea or guanidine hydrochloride, every 8-10 cycles was effective in regenerating the DBC of the resins and prolonging the life cycle of the resins. This is important to evaluating the economic feasibility of directly using Protein A chromatography to recover antibodies from tobacco extract. Of the three Protein A resins studied, ProSep Ultra Plus performed best for antibody purification from tobacco using a PBS wash buffer with a lower ionic strength of 140mM NaCl and an intermediate pH of 5. / Master of Science

Students enrolled in Roanoke County Schools in 2003 became voluntary participants in the Communities That Care Youth Survey (CTCYS), which had been administered to a group (N = 3022) of 6th through 12th graders. The students answered multiple choice questions to determine their attitudes concerning many important topics within their home, school, and community domains. The carefully documented evaluation was conducted to determine the significance of two protective factors, which were employed to explain associations between students who stated that their parents had clear alcohol, tobacco, and drug use rules in the home as well as those who stated they frequently attended religious services and activities, termed parent efficacity and religiosity, respectively. Because risk factors are common among adolescents and few well-designed studies are addressing the benefits of parent efficacity or religiosity as protective factors, this study analyzed the CTCYS data utilizing meta-analyses to assess the efficacy of these two environmental factors in relation to students’ expressed perceptions of smoking cigarettes as a popular adolescent risk activity. Variables are unique to each individual and sample, therefore, multiple factors demonstrating risk and protective qualities were measured using a 0 to 8 point Likert summated rating scale. The various areas were examined according to frequency of risk behavior (i.e., smoking status - current, past, or never). Findings yielded statistically conclusive relationships within the participant responses using Chi-square analysis at the 0.05 level (2-sided), indicating a significant level of interaction between the select protective factors and tobacco use study variables. / Ph. D.

Master of Science

A field experiment was conducted to study the effect of rates of nitrogen and muriate and sulfate of potash upon the growth, chemical composition, and quality of the Burley 21 variety of tobacco. Rates of nitrogen applied were 75, 150, 225, and 300 pounds per acre. The muriate and sulfate sources of potash were combined on a equivalent basis in the following proportions: 100 SO₄/0 Cl, 75 SO₄ /25 Cl, 50 SO₄ /50 Cl, 25 SO₄/75 Cl, and 0 SO₄ /100 Cl. The application of nitrogen increased the nitrogen content in the plant during the growing season and of cured leaves, except for the 150 pound rate which decreased the content. Applied nitrogen rates had no effect upon growth or yield above soil derived nitrogen. Chlorine content of growing plants and cured leaves was increased by the addition of 150 pounds of nitrogen. Above 150 pounds, the chlorine content sharply decreased, indicating that anion competition occurred between nitrogen and chlorine ions. The sulfate-chlorine treatments increased the sulfate content as the proportion of sulfate increased and increased chlorine content as the proportion of chlorine increased. The treatments did not significantly alter yield or acre value of cured leaves. / Master of Science

Relaxin is a small peptide hormone that has demonstrated potential therapeutic actions for cardiovascular disease and fibrosis. Additionally, relaxin has demonstrated the ability to protect the heart from injuries caused by ischemia and reperfusion, promote the healing of ischemic ulcers, and counteract allergic responses. The objective of this research was to express fully processed porcine relaxin in transgenic tobacco plants, as an alternative to current methods of producing relaxin. Two recombinant relaxin genes were constructed that contained the patatin signal peptide cDNA fused in frame to prorelaxin cDNA, which was codon-optimized for expression in Nicotiana tabacum, under the control of either the "super" promoter or the dual enhanced cauliflower mosaic virus 35S promoter. Eighteen transgenic tobacco plants were generated that were transformed with the above recombinant genes. Preprorelaxin, mRNA was detected in 12 of the transgenic plants. Fully processed relaxin protein was not found in any tobacco plants that had demonstrated gene expression by northern blot analysis. Preprorelaxin was only identified in extracts from transgenic plants that contained the insoluble protein fraction, as determined by western blot analysis. Additionally, an increased yield of preprorelaxin was identified after incubation of tobacco leaves in an ubiquitin inhibitor. / Master of Science

No description available.

Regulations to reduce the consumption of tobacco products have dual effects on economies. Economies that are net consumers of tobacco products experience welfare enhancing effects as a result of these regulations. However, these regulations can have adverse welfare effects among net producing economies. Many studies have explored these welfare effects on net consuming economies, whereas the impacts among net producing economies have been neglected. This research paper examined the adverse welfare effects of smoking regulations on small tobacco exporting economies with, a comparative advantage in tobacco production.