The aim of this study was to determine and compare the subjective and objective food label knowledge of consumers from Potchefstroom (South Africa) and Fayetteville (Arkansas, USA), therefore in a developing and developed country context. The question was asked whether the knowledge of consumers in such contexts differed and whether consumers’ demographics are associated with their food label knowledge. No specific research on food label knowledge has been done in a comparative context between a developing and developed country previously. A quantitative study using purposive sampling was conducted among respondents in these contexts by means of interviewer-administered questionnaires. Descriptive and inferential statistics were applied. The total study sample (N = 713) included respondents from South Africa (a developing country) and the United States of America (a developed country) with specific reference to respondents from Potchefstroom (n = 400) and Fayetteville (n = 313). The researcher strived to include respondents from each ethnic, demographic, gender and age group. No differences were found regarding respondents’ subjective knowledge (SK) of food labels. With respect to respondents from Potchefstroom and Fayetteville, practically significant differences regarding objective knowledge (OK) were found only within the factors of locating information (OK-L) and manipulating information (OK-M) with a similar pattern for symbol information (OK-S), although respondents from Fayetteville had higher mean scores for OK-L, OK-M and OK-S, which indicates that respondents from Fayetteville were more knowledgeable on these factors than respondents from Potchefstroom. Within the study populations, better OK was only observed among respondents from Potchefstroom who were young and well educated, whereas respondents from Fayetteville had high levels of knowledge regardless of demographic variables. It was observed that respondents from Potchefstroom were not as knowledgeable (OK-L, OK-M and OK-S) as respondents from Fayetteville. The results from this study serve as evidence for a need to improve food label knowledge in the Potchefstroom context, and raise the question about similar needs in other developing countries. It can be concluded that educational efforts should be developed and implemented to increase objective food label knowledge among consumers from developing country contexts, as OK may have an impact on health. Development of consumer education programmes should focus on the vulnerabilities identified with regard to age and education groups as well as the problems identified regarding label and symbol information provided, whereby consumers might acquire optimal food label knowledge to use these labels for improved decision-making and health. This research about food label knowledge in South Africa and the United States of America, may serve as a foundation for future studies to be conducted in developing and developed country contexts. This might result in a better understanding about factors that contribute to consumers’ confusion, distrust and lack of understanding of food label information, which may hinder food label knowledge in developing country contexts. Demographic, label-reading and health-related factors that may contribute to increased knowledge could also be further explored in addressing specific needs among particular groups in developing country contexts regarding their food label knowledge. / M Consumer Sciences, North-West University, Potchefstroom Campus, 2015

The aim of this study was to determine and compare the subjective and objective food label knowledge of consumers from Potchefstroom (South Africa) and Fayetteville (Arkansas, USA), therefore in a developing and developed country context. The question was asked whether the knowledge of consumers in such contexts differed and whether consumers’ demographics are associated with their food label knowledge. No specific research on food label knowledge has been done in a comparative context between a developing and developed country previously. A quantitative study using purposive sampling was conducted among respondents in these contexts by means of interviewer-administered questionnaires. Descriptive and inferential statistics were applied. The total study sample (N = 713) included respondents from South Africa (a developing country) and the United States of America (a developed country) with specific reference to respondents from Potchefstroom (n = 400) and Fayetteville (n = 313). The researcher strived to include respondents from each ethnic, demographic, gender and age group. No differences were found regarding respondents’ subjective knowledge (SK) of food labels. With respect to respondents from Potchefstroom and Fayetteville, practically significant differences regarding objective knowledge (OK) were found only within the factors of locating information (OK-L) and manipulating information (OK-M) with a similar pattern for symbol information (OK-S), although respondents from Fayetteville had higher mean scores for OK-L, OK-M and OK-S, which indicates that respondents from Fayetteville were more knowledgeable on these factors than respondents from Potchefstroom. Within the study populations, better OK was only observed among respondents from Potchefstroom who were young and well educated, whereas respondents from Fayetteville had high levels of knowledge regardless of demographic variables. It was observed that respondents from Potchefstroom were not as knowledgeable (OK-L, OK-M and OK-S) as respondents from Fayetteville. The results from this study serve as evidence for a need to improve food label knowledge in the Potchefstroom context, and raise the question about similar needs in other developing countries. It can be concluded that educational efforts should be developed and implemented to increase objective food label knowledge among consumers from developing country contexts, as OK may have an impact on health. Development of consumer education programmes should focus on the vulnerabilities identified with regard to age and education groups as well as the problems identified regarding label and symbol information provided, whereby consumers might acquire optimal food label knowledge to use these labels for improved decision-making and health. This research about food label knowledge in South Africa and the United States of America, may serve as a foundation for future studies to be conducted in developing and developed country contexts. This might result in a better understanding about factors that contribute to consumers’ confusion, distrust and lack of understanding of food label information, which may hinder food label knowledge in developing country contexts. Demographic, label-reading and health-related factors that may contribute to increased knowledge could also be further explored in addressing specific needs among particular groups in developing country contexts regarding their food label knowledge. / M Consumer Sciences, North-West University, Potchefstroom Campus, 2015

Arterial Spin Labeling (ASL) is a Magnetic Resonance Imaging (MRI) technique that is able to non-invasively quantify the rate of delivery of arterial blood to tissue, known as perfusion. In this thesis a method that uses Velocity Selective (VS) preparations to generate contrast between blood and tissue spins is investigated. The systematic errors associated with performing a VSASL experiment on imperfect hardware is first investigated. It is shown through simulations and experiments that some VS preparations will underestimate perfusion due to static and transmit magnetic field errors, and that eddy currents caused by switching of magnetic gradients lead to an overestimation of perfusion with VSASL by up to a factor 2. A novel VS preparation, BIR-8, is presented which is shown to be the most robust to these imperfections. The BIR-8 VSASL technique is then applied in brain tumours where it is found that significant VSASL signal can be detected in less than 5 minutes. However, in a comparison with a spatially selective ASL technique it is found that VSASL overestimates perfusion in these tumours, despite agreeing in Grey Matter. The systematic errors due to physiology are then modelled, and it is shown that both diffusion and bulk motion will systematically bias the VSASL measurement. A diffusion insensitive VSASL technique, VS-TILT, is then developed and it is found that a significant proportion of the VSASL signal originates from diffusion effects. Theoretical models for the shape of the bolus in vascular networks are also derived, and it is shown that an isotropic network of laminar vessels produces the most efficient saturation, but saturation is also achieved with plug flow. The diffusion insensitive VS preparation is then applied in an attempt to isolate the venous compartment in order to measure Oxygen Extraction Fraction. A kinetic model is derived in order to optimise the acquisition. However, it is found that accurate measurements of OEF would not be produced by this sequence in a clinically realistic time.

published_or_final_version / Social Work / Master / Master of Social Work

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Although African Americans endorse more stigma towards those with mental illnesses than European Americans and are quite susceptible to stigma’s detrimental effects on help-seeking for mental health problems, stigma has not been adequately studied for African Americans. Given that stigma is a key barrier to obtaining help for mental health problems, it is imperative that we gain a more nuanced understanding of stigma. This study used experimental design and vignettes to examine the influence of acculturation and labeling on African Americans’ stigmatization of depression, social phobia, alcohol dependence, and schizophrenia. Results indicated that schizophrenia was generally the most stigmatized disorder and social phobia was least stigmatized. Having a label predicted increased desire for social distance from vignette subjects with depressive symptoms only. Additionally, acculturation predicted stigmatization of depression and social phobia.

<p>Thermodynamic stability measurements on proteins and protein-ligand complexes can offer insights not only into the fundamental properties of protein folding reactions and protein functions, but also into the development of protein-directed therapeutic agents to combat disease. Conventional calorimetric or spectroscopic approaches for measuring protein stability typically require large amounts of purified protein. This requirement has precluded their use in proteomic applications. Stability of Proteins from Rates of Oxidation (SPROX) is a recently developed mass spectrometry-based approach for proteome-wide thermodynamic stability analysis. Since the proteomic coverage of SPROX is fundamentally limited by the detection of methionine-containing peptides, the use of tryptophan-containing peptides was investigated in this dissertation. A new SPROX-like protocol was developed that measured protein folding free energies using the denaturant dependence of the rate at which globally protected tryptophan and methionine residues are modified with dimethyl (2-hydroxyl-5-nitrobenzyl) sulfonium bromide and hydrogen peroxide, respectively. This so-called Hybrid protocol was applied to proteins in yeast and MCF-7 cell lysates and achieved a ~50% increase in proteomic coverage compared to probing only methionine-containing peptides. Subsequently, the Hybrid protocol was successfully utilized to identify and quantify both known and novel protein-ligand interactions in cell lysates. The ligands under study included the well-known Hsp90 inhibitor geldanamycin and the less well-understood omeprazole sulfide that inhibits liver-stage malaria. In addition to protein-small molecule interactions, protein-protein interactions involving Puf6 were investigated using the SPROX technique in comparative thermodynamic analyses performed on wild-type and Puf6-deletion yeast strains. A total of 39 proteins were detected as Puf6 targets and 36 of these targets were previously unknown to interact with Puf6. Finally, to facilitate the SPROX/Hybrid data analysis process and minimize human errors, a Bayesian algorithm was developed for transition midpoint assignment. In summary, the work in this dissertation expanded the scope of SPROX and evaluated the use of SPROX/Hybrid protocols for characterizing protein-ligand interactions in complex biological mixtures.</p> / Dissertation

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Affibody molecules are a promising class of scaffold-based targeting proteins for radionuclide-based imaging and therapy of cancer. This thesis work is based on 5 original research articles (papers I-V), which focus on optimization of molecular design of HER2-binding Affibody variants for high contrast imaging of this predictive biomarker as well as development of Affibody molecules suitable for radionuclide-based targeted therapies.  Papers I and II were dedicated to evaluation of the influence of the macrocyclic chelator DOTA positioning at N-terminus, in the middle of helix-3 and at C terminus of a synthetic Affibody molecule, ZHER2:S1. These synthetic variants were labelled with different radionuclides i.e. 111In and 68Ga to study also the effect of different labels on their biodistribution properties. In paper III a 2-helix variant, Z342min, was developed using native ligation cyclization to cross-link helices one and two resulting in a stable 2-helix scaffold and characterized in vivo. This study was performed with the aim to obtain structure-properties relationship for development of smaller Affibody molecules.   Papers IV and V were devoted to development of therapeutic strategies. In paper IV, a series of peptide based chelators was investigated for labelling of Affibody molecules with 188Re to provide low renal retention. In paper V, a pretargeting approach using peptide nucleic acid was investigated. These studies were performed with the aim to overcome the high renal retention of Affibody molecules when labelled with residualizing therapeutic radionuclides. Otherwise, the particle emitting radiometals could damage the kidneys more than the tumours. The results obtained for anti-HER2 Affibody molecules summarized in this thesis might be of importance for the development of other scaffold protein based targeting agents.