Introduction: In Africa, it is estimated that cardiovascular disease (CVD) will affect approximately 1.3 million people per annum over the following 20 years. C-reactive protein (CRP) is a predictor of CVD risk and certain CRP gene polymorphisms can result in altered CRP concentrations. The distribution of CRP gene polymorphisms is ethnic-specific and extrapolating information from other populations to the black South African population, reported to harbour considerable genetic variation, should be avoided. This highlights the fact that genetic research among black South Africans is necessary. Objectives: The main aim of this dissertation was to determine the association between various polymorphisms (reported and novel [single nucleotide polymorphisms (SNPs)] within the CRP gene with CRP concentrations [measured as high sensitivity (hs)-CRP concentrations] in a black South African population undergoing an epidemiological transition. Interactions between specific CRP polymorphisms and certain environmental factors on hs-CRP concentrations were also investigated. Methods: This cross-sectional study (n=1,588) was nested within the Prospective Urban and Rural Epidemiological (PURE) study. Genotyping was performed using Illumina VeraCode technology on the BeadXpress® platform. Hs-CRP concentrations were measured by the use of a sequential multiple analyser computer (SMAC) through a particle-enhanced immunoturbidometric assay. Results: All the SNPs adhered to the assumptions of Hardy-Weinberg equilibrium, although the distribution of several SNPs differed from that reported in other population groups. Three SNPs (rs3093058, rs3093062 and rs3093068) were associated with a significant (p ≤ 0.05) increase in CRP concentrations. Five SNPs (rs1205, rs1341665, rs2794520, rs7553007 and rs2027471) were associated with a significant (p ≤ 0.05) decrease in CRP concentrations. This difference in effect was most probably due to changes in gene function brought about by the localisation of these SNPs in the CRP gene. Men and urban individuals were more likely to present with significant associations between the SNPs investigated and CRP concentrations. The difference in the prevalence of the alleles associated with higher CRP concentrations in this population compared to non-African populations could possibly explain the increased CRP concentrations that are observed in the black South African population. Gene-gender (rs1205, rs1341665 and rs2027474) as well as gene-environmental (rs3093068) interactions were also observed. Conclusions: CRP concentrations are in themselves a complex trait and there are many factors at play that influence their expression. Numerous factors (both genetic and environmental) are involved and no single factor acting alone is likely to have enough of an influence to be used as a clinical diagnostic test of CRP concentrations. These results provide valuable information on the regulation of CRP in a black South African population as well as contribute to the literature of CRP on a global level. / Thesis (MSc (Nutrition))--North-West University, Potchefstroom Campus, 2013.

Introduction: In Africa, it is estimated that cardiovascular disease (CVD) will affect approximately 1.3 million people per annum over the following 20 years. C-reactive protein (CRP) is a predictor of CVD risk and certain CRP gene polymorphisms can result in altered CRP concentrations. The distribution of CRP gene polymorphisms is ethnic-specific and extrapolating information from other populations to the black South African population, reported to harbour considerable genetic variation, should be avoided. This highlights the fact that genetic research among black South Africans is necessary. Objectives: The main aim of this dissertation was to determine the association between various polymorphisms (reported and novel [single nucleotide polymorphisms (SNPs)] within the CRP gene with CRP concentrations [measured as high sensitivity (hs)-CRP concentrations] in a black South African population undergoing an epidemiological transition. Interactions between specific CRP polymorphisms and certain environmental factors on hs-CRP concentrations were also investigated. Methods: This cross-sectional study (n=1,588) was nested within the Prospective Urban and Rural Epidemiological (PURE) study. Genotyping was performed using Illumina VeraCode technology on the BeadXpress® platform. Hs-CRP concentrations were measured by the use of a sequential multiple analyser computer (SMAC) through a particle-enhanced immunoturbidometric assay. Results: All the SNPs adhered to the assumptions of Hardy-Weinberg equilibrium, although the distribution of several SNPs differed from that reported in other population groups. Three SNPs (rs3093058, rs3093062 and rs3093068) were associated with a significant (p ≤ 0.05) increase in CRP concentrations. Five SNPs (rs1205, rs1341665, rs2794520, rs7553007 and rs2027471) were associated with a significant (p ≤ 0.05) decrease in CRP concentrations. This difference in effect was most probably due to changes in gene function brought about by the localisation of these SNPs in the CRP gene. Men and urban individuals were more likely to present with significant associations between the SNPs investigated and CRP concentrations. The difference in the prevalence of the alleles associated with higher CRP concentrations in this population compared to non-African populations could possibly explain the increased CRP concentrations that are observed in the black South African population. Gene-gender (rs1205, rs1341665 and rs2027474) as well as gene-environmental (rs3093068) interactions were also observed. Conclusions: CRP concentrations are in themselves a complex trait and there are many factors at play that influence their expression. Numerous factors (both genetic and environmental) are involved and no single factor acting alone is likely to have enough of an influence to be used as a clinical diagnostic test of CRP concentrations. These results provide valuable information on the regulation of CRP in a black South African population as well as contribute to the literature of CRP on a global level. / Thesis (MSc (Nutrition))--North-West University, Potchefstroom Campus, 2013.

The phosphorylation and dephosphorylation of the tyrosine amino-acids in proteins play an important role in the regulation of many cellular processes in all eukariotic organisms, including the regulation of cell cycle control, growth control, cellular differentiation and gene and synaptic transmission. The involvement of the phosphatase genes in human carcinogenesis was long-suspected, but PTEN is the first important phosphatase gene proven to be a true tumour suppressor. The basic function of normal PTEN is the dephosphorylation of the kinases and inhibition of the integrin and growth factor mediated kinase signalling pathways. The central hypothesis of this study is that PTEN plays an important role in tumours of the upper female genital tract. The involvement of aberrations in the coding regions of this gene was studied in specific gynaecologic tumours and tissues using polymerase chain reaction based mutation analysis. The research model was to study both the malignant tumour and the closest available pre-malignant or benign counterpart to demonstrate different levels of involvement of PTEN in the evolving steps. The PTEN gene was found to be intimately involved in endometrial carcinogenesis. Involvement was demonstrated in hyperplasia and was common in endometroid carcinoma (54%). Pathogenic PTEN mutations were much more common in cancer than in hyperplasia (10%). Multiple mutations were found in some late stage tumours, suggesting that the already malignant tumour cells accumulate more genetic mutations over time. All tumours with more than one pathogenic mutation occurred in African patients. The latter twofindings are unique to the current study. Selective involvement of the PTEN gene was demonstrated in uterine soft tissue tumours. PTEN involvement was neither found in benign soft tissue tumours nor significantly in leiomyosarcoma or endometrial stromal sarcoma. However, PTEN plays a significant role in uterine carcinosarcoma (13%) and specifically in tumours with an endometroid epithelial component, where mutations were found in 17%. This finding is a highly significant and unique research result which supports the hypothesis of the endometrial origin of these tumours. It also supports the observation of a strong link between this gene and endometroid differentiation, with morphology strongly linked to cellular genetics. PTEN gene mutation was demonstrated in ovarian endometroid carcinoma in ~29% of cases investigated. This finding confirms PTEN involvement in carcinogenesis in this tumour type. The finding suggests that PTEN involvement is linked to endometroid epithelial morphology. We could not sufficiently test the involvement of the gene in benign or pre-malignant ovarian endometroid lesions and thus cannot comment on the chronology of mutations in this tissue type. When all tumour types were included, there was a tendency towards a lower frequency ofPTEN mutations in African women. PTEN mutations correlated with endometroid histology. In combination, these results confirm the racial disparity in tumour type distribution or morphology. In summary this study demonstrated significant though highly selective PTEN gene involvement and a strong and interesting association between genotype and histological phenotype was confirmed. The findings enhance our understanding of carcinogenesis and should lead to translational research into new anti-neoplastic drugs. AFRIKAANS: Fosforilering en defosforilering van die tirosien aminosure in proteine speel ‘n belangrike rol in die regulering van sellulêre prosesse in alle eukariotiese organismes. Dit sluit die regulering van selsikluskontrole, groeikontrole, sellulêre differensiasie sowel as genetiese en sinaptiese oordrag in. Dit word lank reeds gespekuleer dat die fosfatase-gene betrokke is in menslike karsinogenese, maar die PTEN geen is die eerste fosfatase geen wat bewys word om ‘n ware tumoronderdrukker geen te wees. As basiese funksie defosforileer normale PTEN die kinases en inhibeer dit die kinase sinjaal kontrolepaaie wat deur integrien en groeifaktor beheer word. Die sentrale hipotese van hierdie studie is dat PTEN ‘n belangrike rol speel in tumore van die boonste genitale traktus. Die frekwensie van abnormaliteite in die koderingsareas van hierdie geen is bestudeer in spesifieke ginekologiese tumore en weefsels met die gebruik van polimerase kettingreaksie gebaseerde mutasie-analise. Die maligne tumore sowel as die mees verwante pre-maligne of benigne weefsel- of tumortipes wat beskikbaar was, is gebruik as navorsingsmateriaal om sodoende die verskillende vlakke van PTEN betrokkenheid in die ontwikkeling van neoplasie te demonstreer.Intieme betrokkenheid van die PTEN geen is gevind in endometriële karsinogenese. PTEN mutasies is in hiperplasie gevind en dit was algemeen in endometroiede karsinoom (54%). Patogene mutasies was baie meer algemeen in kanker as in hiperplasie (10%). Veelvuldige mutasies is in sommige laat stadium tumore aangetoon, wat suggereer dat reeds maligne selle meer genetiese mutasies oor tyd verkry. Alle tumore waar meer as een patogeniese mutasie gevind is het voorgekom by swart pasiënte. Die laaste twee bevindinge is uniek tot hierdie studie.Selektiewe betrokkenheid van die PTEN geen is gevind in die ontwikkeling van sagte weefsel tumore van die uterus. PTEN mutasies is nie in benigne sagte weefsel tumore gevind nie en geen betekenisvolle betrokkenheid is in leiomiosarkome of endometriële stromale sarkome aangetoon nie. PTEN was egter betekenisvol betrokke in karsinosarkome van die uterus (13%) en veral in tumore met ‘n endometrioiede epiteelkomponent waar mutasies in 17% gevind is. Hierdie bevinding is ‘n hoogs betekenisvolle en unieke navorsingsbevinding wat die hipotese ondersteun dat hierdie tumore uit die endometrium ontstaan. Dit onderskryf ook die indruk dat ‘n sterk band bestaan tussen hierdie geen en endometroiede differensiasie, met morfologie sterk gekoppel aan sellulêre genetika.Mutasie in die PTEN geen is aangetoon in ovariële endometroiede karsinoom in ~29% van gevalle wat ondersoek is. Die bevinding bevestig PTEN betrokkenheid in karsinogenese in hierdie tumortipe. Weereens toon die resultaat dat PTEN betrokkenheid gekoppel is aan endometroiede morfologie. Die ondersoek van benign of pre-maligne letsels in hierdie orgaan was nie voldoende om kommentaar oor die tydsberekening van mutasie te kan lewer nie.Met alle tumortipes in ag genome, is daar ‘n tendens aangetoon van minder PTEN mutasies in swart vroue. PTEN mutasies korreleer met endometroiede histologie. In kombinasie bevestig hierdie resultaat ‘n rasse-diskrepansie in die distribusie van tumourtipe of morfologie. In opsomming is die bevinding van hierdie studie dat daar betekenisvolle dog hoogs selektiewe PTEN geen betrokkenheid in boonste genitale traktus tumore is. ‘n Sterk en interessante verband is bevestig tussen genotipe en histologiese fenotipe. Hierdie resultate verbeter die begrip van karsinogenese en behoort ‘n bydrae te lewer in die soeke na nuwe anti-neoplastiese middels. / Thesis (PhD)--University of Pretoria, 2011. / Obstetrics and Gynaecology / unrestricted

INTRODUCTION AND AIM - Cardiovascular disease is globally a major risk factor for morbidity and mortality. It is caused by various factors, one of which is an abnormal haemostatic process. Fibrinogen is a haemostatic factor that is considered to be an independent risk factor for cardiovascular disease. Elevated fibrinogen can be caused by environmental and genetic factors which increase the risk of the occurrence of thrombosis. The fibrinogen y' chain, which is one of the three chains of fibrinogen, has two different variants, the yA and y’. The presence of the fibrinogen y’ chain has been associated with thrombotic disorders. Many studies have investigated the fibrinogen variables in Caucasian individuals, but only a few such studies have been conducted on non-Caucasian individuals. The genetic diversity of ethnic groups differs and could cause differences in the fibrinogen variables between these groups. Fibrinogen is known to increase with age; therefore to explain changes over time in fibrinogen concentrations it was also important to investigate whether genetic determinants and possible gene–environment interactions influenced fibrinogen over time. In this study the main aim was to determine the change in the fibrinogen variables over a five-year period within a black South African cohort subdivided according to genotypes associated with fibrinogen variables, and to determine whether the observed changes were modulated by environmental factors. PARTICIPANTS AND METHODS - Data [baseline (n=2010) and follow-up (n=1288)] were collected in the Prospective Urban and Rural Epidemiology (PURE) study during 2005 and 2010 from apparently healthy black men and women aged between 35 and 65 years and residing in rural or urban settlements. Experimental methods included analysis of fibrinogen and fibrinogen y’ concentrations, single nucleotide polymorphisms (SNPs) and determination of environmental factors associated with the fibrinogen variables. RESULTS - The fibrinogen variables increased significantly from 2005 to 2010 in both the rural and urban participants, as well as in both men and women. The major environmental factors that affected the fibrinogen variables were C-reactive protein (CRP), interleukin-6 (IL-6), body mass index (BMI), glycated haemoglobin (HbA1c), age, blood lipids, human immunodeficiency virus (HIV) and tobacco use. Fibrinogen increased consistently from 2005 to 2010 in the respective genotypes of all SNPs analysed, except in the FGG 9340 T>C homozygous mutant carriers. Fibrinogen y’ also increased in general in most genotypes from 2005 to 2010, except in the FGG 10034 C>T mutant allele carriers, where a decrease was observed. It was determined that CRP was the only environmental factor that influenced the change in fibrinogen over time and that FGG 10034 C>T was the only SNP that influenced the change in fibrinogen y’ over the five years. Four gene–environment interactions also influenced fibrinogen on a cross-sectional level, i.e. FGA 2224 G>A with age, FGB Arg448Lys with HIV status, FGB 1643 C>T with urbanisation and FGB 1038 G>A with HbA1c. Only the FGG 9340 T>C with HbA1c interaction was found to predict change in fibrinogen concentrations over the five years. CONCLUSION - Both environmental and genetic factors significantly influenced the fibrinogen variables cross-sectionally as well as prospectively. It was clear that the influence of the environmental factors was mediated by genetic polymorphisms and vice versa, as can be seen by the gene–environment interactions found in this study. An important finding of this study was that the interaction of HbA1c with two SNPs on fibrinogen variables may explain the known inconsistent relationship found between fibrinogen concentrations and diabetes. / MSc (Dietetics), North-West University, Potchefstroom Campus, 2014

El presente trabajo de Tesis tiene como finalidad analizar el potencial de los líquidos iónicos como medios de reacción y separación en reacciones de transesterificación enzimáticas. Los ILs inmiscibles con agua han resultado medios muy adecuados para llevar a cabo la síntesis de ésteres catalizada por la lipasa B de Candida antarctica (CALB), incrementando la actividad y selectividad enzimática con respecto a los valores obtenidos en disolventes orgánicos convencionales como n-hexano. El uso de líquidos iónicos miscibles con agua ha dado lugar a menores valores de actividad enzimática que n-hexano, aunque la selectividad en estos medios es mucho mayor. Los ILs se han revelado también como prometedores disolventes en su empleo en procesos de separación, más concretamente como fase líquida en membranas líquidas soportadas (SLMs). Se han desarrollado SLMs basadas en ILs altamente estables que permiten llevar a cabo la separación selectiva de sustratos y productos de reacciones de transesterificación. / The main objective of this thesis is to analyze the potential use of ionic liquids as reaction and separation media in lipase-catalysed transesterification reactions. The use of ionic liquids in biocatalytic processes has been shown to be an environmentally attractive alternative to classical organic solvents. Water-immiscible ionic liquids appeared as suitable media for the transesterification reactions catalysed by Candida antarctica lipase B (CALB), increasing the activity and selectivity with respect to the values obtained with a classical organic solvent, n-hexane. The use of water-miscible ionic liquids led to lower activities than obtained in n-hexane, although the selectivity values were much higher in these media. Ionic liquids have also been shown to be promising solvents for the use in separation processes, more specifically as liquid phase in supported liquid membranes (SLMs). Highly stable SLMs based on ionic liquids have been succesfully used for the selective separation of different organic compounds which are substrates and products of transesterification reactions.

INTRODUCTION AND AIM - Cardiovascular disease is globally a major risk factor for morbidity and mortality. It is caused by various factors, one of which is an abnormal haemostatic process. Fibrinogen is a haemostatic factor that is considered to be an independent risk factor for cardiovascular disease. Elevated fibrinogen can be caused by environmental and genetic factors which increase the risk of the occurrence of thrombosis. The fibrinogen y' chain, which is one of the three chains of fibrinogen, has two different variants, the yA and y’. The presence of the fibrinogen y’ chain has been associated with thrombotic disorders. Many studies have investigated the fibrinogen variables in Caucasian individuals, but only a few such studies have been conducted on non-Caucasian individuals. The genetic diversity of ethnic groups differs and could cause differences in the fibrinogen variables between these groups. Fibrinogen is known to increase with age; therefore to explain changes over time in fibrinogen concentrations it was also important to investigate whether genetic determinants and possible gene–environment interactions influenced fibrinogen over time. In this study the main aim was to determine the change in the fibrinogen variables over a five-year period within a black South African cohort subdivided according to genotypes associated with fibrinogen variables, and to determine whether the observed changes were modulated by environmental factors. PARTICIPANTS AND METHODS - Data [baseline (n=2010) and follow-up (n=1288)] were collected in the Prospective Urban and Rural Epidemiology (PURE) study during 2005 and 2010 from apparently healthy black men and women aged between 35 and 65 years and residing in rural or urban settlements. Experimental methods included analysis of fibrinogen and fibrinogen y’ concentrations, single nucleotide polymorphisms (SNPs) and determination of environmental factors associated with the fibrinogen variables. RESULTS - The fibrinogen variables increased significantly from 2005 to 2010 in both the rural and urban participants, as well as in both men and women. The major environmental factors that affected the fibrinogen variables were C-reactive protein (CRP), interleukin-6 (IL-6), body mass index (BMI), glycated haemoglobin (HbA1c), age, blood lipids, human immunodeficiency virus (HIV) and tobacco use. Fibrinogen increased consistently from 2005 to 2010 in the respective genotypes of all SNPs analysed, except in the FGG 9340 T>C homozygous mutant carriers. Fibrinogen y’ also increased in general in most genotypes from 2005 to 2010, except in the FGG 10034 C>T mutant allele carriers, where a decrease was observed. It was determined that CRP was the only environmental factor that influenced the change in fibrinogen over time and that FGG 10034 C>T was the only SNP that influenced the change in fibrinogen y’ over the five years. Four gene–environment interactions also influenced fibrinogen on a cross-sectional level, i.e. FGA 2224 G>A with age, FGB Arg448Lys with HIV status, FGB 1643 C>T with urbanisation and FGB 1038 G>A with HbA1c. Only the FGG 9340 T>C with HbA1c interaction was found to predict change in fibrinogen concentrations over the five years. CONCLUSION - Both environmental and genetic factors significantly influenced the fibrinogen variables cross-sectionally as well as prospectively. It was clear that the influence of the environmental factors was mediated by genetic polymorphisms and vice versa, as can be seen by the gene–environment interactions found in this study. An important finding of this study was that the interaction of HbA1c with two SNPs on fibrinogen variables may explain the known inconsistent relationship found between fibrinogen concentrations and diabetes. / MSc (Dietetics), North-West University, Potchefstroom Campus, 2014