RESUME DES TRAVAUX<p><p>La rigidification des gros troncs artériels (GTA) est physiologiquement liée à l’âge et s’accélère sous l’influence de certains facteurs de risque cardiovasculaire tels que l’hypertension artérielle (HTA), le diabète, le tabagisme, la dyslipidémie, l’obésité, la consommation excessive de sel, la sédentarité et l’hérédité. Le vieillissement artériel prématuré est un déterminant majeur du risque d’événements cardiovasculaires. Il se caractérise par une altération des propriétés élastiques des GTA, consécutive à l’épaississement de l’intima et surtout de la média se traduisant par une rigidification de leur paroi et une intensification de la réflexion de la courbe de pression aortique. Une artère rigide accélère la vitesse de propagation de l’onde de pouls (VOP) qui en est le marqueur direct et induit par conséquent un retour plus précoce des ondes de pression réfléchies de la périphérie vers l’aorte.<p>Nous avons testé l’hypothèse que le risque accru de maladies cardiovasculaires (MCV) documenté chez les sujets noirs africains serait lié en partie au vieillissement précoce de leurs artères et que son amplification chez les bantous serait largement attribuable aux facteurs environnementaux.<p>A cet effet, nous avons procédé dans un premier temps à la validation de la VOP, de la pression pulsée (pression systolique-pression diastolique) et de l’index d’augmentation de pression (AIx), tous deux dérivés de la courbe de pression aortique comme méthodes de mesure et d’évaluation non invasive de la distensibilité artérielle chez les sujets normotendus. Nos résultats révèlent que la stimulation bêta-adrénergique non cardio-sélective par l’isoproterenol atténue de façon significative la réflexion des ondes de pression aortique et augmente nettement la pression pulsée (PP) aortique alors que la VOP aortique qui constitue la mesure de référence de l’élasticité artérielle n’est pas affectée. Ces résultats suggèrent dès lors que la PP et l’AIx ne sont pas des marqueurs fiables de la rigidité artérielle lors de la stimulation bêta-adrénergique.<p><p>Nous avons ensuite évalué l’amplitude de cet effet de l’isoproterenol sur la paroi artérielle du sujet noir africain. C’est ainsi que nous avons observé que la stimulation bêta-adrénergique par l’isoproterenol engendre une accélération de la VOP aortique chez les sujets noirs, contrairement aux sujets caucasiens chez qui elle la ralentit considérablement. Ce résultat suggère que l’altération précoce des propriétés structurelles et fonctionnelles de la paroi aortique des sujets noirs sous l’effet de divers stress pourrait contribuer à la sévérité et à la précocité des MCV couramment rapportées au sein de ce groupe ethnique.<p><p>Nous avons ensuite testé une série d’hypothèses nécessitant des mesures non invasives de l’élasticité artérielle au sein de populations particulières au Cameroun.<p>C’est ainsi que nous avons investigué l’effet de l’anémie falciforme sur la rigidité artérielle et la réflexion de la courbe de pression aortique. L’hypothèse testée était que les complications cardiovasculaires couramment rapportées chez les drépanocytaires seraient dues à l’altération des propriétés viscoélastiques de leur paroi artérielle. Cette seconde partie de nos travaux nous a permis de démontrer que les patients drépanocytaires souffrant de la forme homozygote d’anémie falciforme (SS) ont des artères centrales aortiques très souples et des artères périphériques musculaires moins rigides. En effet, leur VOP est ralentie et leurs ondes de réflexion de la périphérie vers l’aorte sont fortement atténuées en comparaison aux contrôles sains (AA). L’anémie falciforme et la pression artérielle moyenne (PAM) sont apparues comme étant des déterminants indépendants de l’état d’élasticité aortique dans notre population d’étude (SS et AA). Cette étude a révélé toutefois une accélération paradoxale des VOP radiale et aortique dans les zones de basse pression artérielle, suggérant un effet délétère vasculaire de l’hypotension artérielle sévère chronique sur la paroi aortique.<p><p>Enfin, dans le troisième volet de notre travail, nous avons évalué l’effet du mode de vie chasseurs-pêcheurs-cueilleurs sur l’état d’élasticité aortique des pygmées traditionnels (TP) Camerounais. Nos travaux révèlent que ces TP ont des artères plus élastiques illustrées par une faible accélération de leur VOP aortique, comparée à celles des pygmées contemporains (CP) et des agriculteurs bantous partageant le même environnement semi-urbain et soumis tous à un mode de vie de type occidental. Fait important, cette faible accélération de la VOP aortique des TP est indépendante de la PAM et de leur âge chronologique qui en constituent pourtant des déterminants majeurs classiques bien documentés. Par contre, cette différence d’élasticité aortique entre TP, CP et bantous s’estompe nettement après correction pour le poids corporel.<p>Dans le même ordre d’idées, nous avons également démontré qu’en dépit de leur petite taille, les pygmées traditionnels réfléchissent leurs ondes de pression de la périphérie vers l’aorte avec une amplitude similaire à celle des pygmées contemporains et des bantous semi urbains.<p><p> <p>Conclusion.<p>Les résultats de nos travaux confortent la VOP comme marqueur de référence de la rigidité artérielle et suggèrent un vieillissement précoce de l’aorte chez les sujets noirs pouvant expliquer en partie la sévérité et la précocité des MCV couramment rapportées chez eux. Ce phénomène s’illustre notamment par l’accélération de la VOP aortique induite par l’isoproterenol chez les sujets noirs africains contrairement aux sujets caucasiens, chez qui la stimulation bêta-adrénergique par isoproterenol s’accompagne d’un ralentissement considérable de la VOP aortique. Cependant, l’état drépanocytaire pourrait atténuer et ralentir ce phénomène de vieillissement vasculaire précoce, ceci en dépit d’une accélération paradoxale de la VOP par l’hypotension artérielle chronique. Enfin, le mode de vie chasseurs-pêcheurs-cueilleurs protègerait l’aorte des pygmées traditionnels contre le risque de vieillissement prématuré, ceci indépendamment de la pression artérielle moyenne et de l’âge chronologique.<p> / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

Institute for Gender and Youth Studies / PHDGS / Historically, the cardiovascular disease (CVD) has internationally been viewed as a man’s disease. This is witnessed by the high number of males who have fallen victim to this scourge. However, with rapid changes in today’s societies, the disease has increasingly become a public health concern among women also. This study aimed to explore rural women’s perspectives of CVD in Gwanda South Rural District. The study was guided by a feminist perspective where theories of gender such as social construction feminism, intersectionality and standpoint theory, were employed as a theoretical framework. In this process, the research endeavoured to unearth some contradictions inherent in the manner in which women view CVD. The population of the study comprised of females aged 21-60 years residing in Gwanda South Rural District of Zimbabwe. An exploratory case study design was adopted and this guided the qualitative data collection and analysis. Purposeful sampling technique was used to select 16 participants for semi-structured interviews and six participants for focus group discussions. Data were analysed using thematic analysis which is an essential tool for qualitative data analysis. Data were presented and discussed as themes and subthemes. The concepts of credibility, transferability, dependability and confirmability were used to describe and ensure various aspects of trustworthiness. Ethical considerations like informed consent, confidentiality and anonymity and no harm to participants were ensured. The following seven themes were derived from the study; women’s knowledge of CVD, causes of CVD, prevention of CVD, perceived effects of CVD, difference in experiences of CVD, assistance of women with CVD and management of CVD. Findings revealed that women had limited knowledge of most CVDs but were familiar with hypertension and stroke. Various symptoms of CVD were identified. It was concluded that rural women do not have adequate knowledge of CVDs. A lot should be done by the government and other stakeholders to ameliorate cardiovascular health in rural women. / NRF

Indiana University-Purdue University Indianapolis (IUPUI) / Excess caloric intake and/or obesity currently remain the largest predisposing risk factors for the development of type 2 diabetes. Discerning the cellular and molecular mechanisms responsible and amendable to therapy represents a growing challenge in medicine. At a cellular level, increased activity of the hexosamine biosynthesis pathway (HBP), a sensor of excess energy status, has been suggested to promote the exacerbation of insulin resistance through increasing adipose tissue and skeletal muscle membrane cholesterol content. This in turn compromises cortical filamentous actin structure necessary for proper incorporation of the insulin-sensitive glucose transporter GLUT4 into the plasma membrane. The current studies attempted to elucidate the mechanism by which hexosamines provoke membrane cholesterol toxicity and insulin resistance. In 3T3-L1 adipocytes cultured with pathophysiologic hyperinsulinemia to induce insulin resistance, increased HBP flux was observed. This occurred concomitant with gains in the mRNA and protein levels of HMG-CoA reductase (HMGR), the rate limiting enzyme in cholesterol synthesis. Mechanistically, immunoprecipitation demonstrated increased HBP-induced N-acetylglucosamine (O-GlcNAc) modification of specificity protein 1 (Sp1), a regulator of HMGR synthesis. This was associated with increased affinity toward and activity of Hmgcr, the gene encoding HMGR. Global HBP inhibition or Sp1 binding to DNA prevented membrane cholesterol accrual, filamentous actin loss, and glucose transport dysfunction. Furthermore, hyperinsulinemia and HBP activation impaired cholesterol efflux in adipocytes, exacerbating cholesterol toxicity and potentially contributing to cardiovascular disease. In this regard, chromium picolinate (CrPic), known to have beneficial effects on glucose and lipoprotein metabolism, improved cholesterol efflux and restored membrane cholesterol content. To test the role of membrane cholesterol accumulation in vivo, studies were conducted on C57Bl/6J mice fed a low or high fat diet. High fat feeding promoted increased HBP activity, membrane cholesterol accumulation, and insulin resistance. Supplementation of mice with CrPic in their drinking water (8µg/kg/day) countered these derangements and improved insulin sensitivity. Together, these data provide mechanistic insight for the role of membrane cholesterol stress in the development of insulin resistance, as well as cardiovascular disease, and highlight a novel therapeutic action of chromium entailing inhibition of the HBP pathway.

Indiana University-Purdue University Indianapolis (IUPUI) / Prospective epidemiologic evidence indicates that both stressful life events (SLEs) and depression are associated with an increased risk of subclinical atherosclerosis and cardiovascular disease (CVD) events. Even though stressful life events (SLEs) and depression co-occur and may act together to influence cardiovascular disease (CVD) risk, these psychosocial factors have been mainly examined in isolation. For instance, depression may moderate the relationship between SLEs and CVD outcomes. I hypothesized that depressive symptoms would potentiate the deleterious effect of SLEs on subclinical atherosclerosis. This hypothesis is plausible, given that depressed adults exhibit exaggerated and prolonged sympathetic nervous system, hypothalamic-pituitary-adrenal (HPA) axis, and inflammatory responses to stress, which in turn could promote atherosclerosis. As compared to their nondepressed counterparts, depressed individuals may also be more likely to engage in maladaptive methods to cope with SLEs (e.g., increased tobacco use, alcohol use, and consumption of low-nutrient, energy dense foods), which could also promote atherosclerosis. I examined cross-sectional data from 274 to 279 (depending on the outcome measure) older, African American adults (mean age = 66 years, 67% female) with no evidence of clinical CVD or dementia who participated in the St. Louis African American Health-Heart study (2009–2011). Number of SLEs was assessed using the Life Events Calendar, a structured interview. From this interview, a continuous SLEs variable was computed (number of adult SLEs: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11+). Severity of depression symptoms was measured using the 17-item Hamilton Rating Scale for Depression (HAM-D). Two measures of subclinical atherosclerosis were obtained: carotid intima-media thickness (CIMT; assessed by ultrasonography) and coronary artery calcification (CAC; assessed by multi-detector computerized tomography). I conducted linear (CIMT) and logistic (CAC) regression models, first adjusted for demographics (age, sex, education) and then fully-adjusted (demographics; mean arterial pressure; low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C); hemoglobin A1c; BMI; tobacco use; diabetes diagnosis; and use of antihypertensitve, lipid lowering, antidiabetic, and antidepressant medications). No main effects of SLEs or HAM-D were found for CIMT or CAC. There were also no SLEs by HAM-D interactions for CIMT or CAC. Because the current results are largely inconsistent with prior literature and there is a paucity of studies utilizing African American samples, future research is needed to examine the independent and interactive associations of SLEs and depressive symptoms with measures of subclinical atherosclerosis. If the present results are replicated, it may suggest that SLEs, depressive symptoms, and their interactive effect are not cardiotoxic among African American adults.

M. Tech. (Department of Biotechnology, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Background: Increased serum homocysteine is well known as an independent cardiovascular risk factor. Hyperhomocysteinemia may be due to several factors such as nutritional deficiencies and genetics. The MTHFR C677T polymorphism is associated with increased serum homocysteine. Folate and vitamin B12 play essential roles in lowering homocysteine levels. Limitations have been identified using serum vitamin B12 as a marker for vitamin B12 status due to lack an efficient of test. Holotranscobalamin has been reported as a more accurate marker for vitamin B12 status. Cardiovascular risk due to hyperhomocysteinemia has been confirmed among the elderly in Sharpeville. Knowledge of the prevalence of MTHFR C677T polymorphism among Black elderlies in South Africa is limited. Objectives: The main aim of the study was to evaluate the prevalence of MTHFR C677T polymorphism as a cardiovascular risk in an elderly black population in Sharpeville. Correlations between the presence of MTHFR C677T polymorphism and homocysteine metabolic markers were evaluated. Holotranscobalamin as a diagnostic test for vitamin B12 status was also assessed in this study. Materials and methods: This study was ethically approved by the Vaal University of Technology ethics committee (20140827-1ms). It was an observational, experimental study conducted in 102 elderly (≥60 years) attending the day-care centre in Sharpeville. Real-Time PCR was used to determine MTHFR genotypes. Folate and vitamin B12 were measured with AIA-PACK. Homocysteine levels were determined with an automated Konelab™ 20i and holotranscobalamin by ELISA. STATA 12 software was used for analysis of descriptive and inferential statistics. Results: The prevalence of MTHFR C677T polymorphism in this sample population was 19%. Heterozygous CT single nucleotide polymorphism was 17% and mutant homozygous TT was 2%. The majority (81%) of the subjects had wild type homozygous CC genotypes. No associations were found between MTHFR C677T genotypes and homocysteine and folate levels. Hyperhomocysteinemia was high (54%) and low (5%) folate deficiency found. No vitamin B12 deficiency was found however 7% were on the category of likely to be deficient. Sensitivity and specificity of holotranscobalamin were 100% and 95% respectively. Conclusion: The conclusions drawn from the study is that the prevalence of MTHFR C677T polymorphism is low within elderly in Sharpeville. There is a high risk of cardiovascular disease as a result of high prevalence of hyperhomocysteinemia. An intervention to lower homocysteine concentration of elderlies residing in Sharpeville is needed. Other genetic predisposing factors of increased homocysteine levels should be investigated.

Indiana University-Purdue University Indianapolis (IUPUI) / A hierarchy of endothelial colony forming cells (ECFCs) with different levels of proliferative potential has been identified in human circulating blood and blood vessels. High proliferative potential ECFCs (HPP-ECFCs) display properties (robust proliferative potential in vitro and vessel-forming ability in vivo) consistent with stem/progenitor cells for the endothelial lineage. Corneal endothelial cells (CECs) are different from circulating and resident vascular endothelial cells (ECs). Whereas systemic vascular endothelium slowly proliferates throughout life, CECs fail to proliferate in situ and merely expand in size to accommodate areas of CEC loss due to injury or senescence. However, we have identified an entire hierarchy of ECFC resident in bovine CECs. Thus, this study provides a new conceptual framework for defining corneal endothelial progenitor cell potential. The identification of persistent corneal HPP-ECFCs in adult subjects might contribute to regenerative medicine in corneal transplantation. While human cord blood derived ECFCs are able to form vessels in vivo, it is unknown whether they are committed to an arterial or venous fate. We have demonstrated that human cord blood derived ECFCs heterogeneously express gene transcripts normally restricted to arterial or venous endothelium. They can be induced to display an arterial gene expression pattern after vascular endothelial growth factor 165 (VEGF165) or Notch ligand Dll1 (Delta1ext-IgG) stimulation in vitro. However, the in vitro Dll1 primed ECFCs fail to display significant skewing toward arterial EC phenotype and function in vivo upon implantation, suggesting that in vitro priming is not sufficient for in vivo specification. Future studies will determine whether ECFCs are amenable to specification in vivo by altering the properties of the implantation microenvironment. There is emerging evidence suggesting that the concentration of circulating ECFCs is closely related to the adverse progression of cardiovascular disorders. In a pig model of acute myocardial ischemia (AMI), we have demonstrated that AMI rapidly mobilizes ECFCs into the circulation, with a significant shift toward HPP-ECFCs. The exact role of the mobilized HPP-ECFCs in homing and participation in repair of the ischemic tissue remains unknown. In summary, these studies contribute to an improved understanding of ECFCs and suggest several possible therapeutic applications of ECFCs.

In conclusion, the current air pollution levels in Hong Kong had a risk for school children's respiratory and cardiovascular health. In comparison between the highly- and least-polluted districts, a rise of 8 mug/m 3 annual mean for PM10 concentration was significantly associated with increased risks for some respiratory symptoms such as wheezing, cough, and phlegm, with decreased lung function in FEF25-75% and FEF75%, and with decreased cardiopulmonary fitness in predicted VO2max, after adjustment for confounding factors. An increase of 13 mug/m3 annual mean for NO2 in the moderately-polluted district did not individually cause adverse effects on children's respiratory and cardiopulmonary health. Physical activity appears to have no positive health effects on the children's VO2max in moderately- and highly-polluted districts. / In the past year preceding the study (May 2003 to April 2004), the annual means for PM10, NO2, SO2 and O3 were respectively 55.1 mug/m3, 51.4 mug/m3, 15.4 mug/m3, and 42.5 mug/m3 in the least-polluted district (LPD); 56.3 mug/m3, 64.7 mug/m3, 15.2 mug/m3, and 35.2 mug/m3 in the moderately-polluted district (MPD); and 63.8 mug/m3, 64.1 mug/m3, 22.2 mug/m3, and 31.7 mug/m3 in the highly-polluted district (HPD). The 99th percentiles were 178 mug/m3, 158 mug/m 3, 104 mug/m3, and 140 mug/m3 in the LPD; 169 mug/m3, 181 mug/m3, 106 mug/m 3, and 113 mug/m3 in the MPD; and 226 mug/m 3, 177 mug/m3, 140 mug/m3, and 137 mug/m 3 in the HPD. The average daily 1-h maximum O3 (peak O 3) was 83.7 mug/m3 in the LPD, 73.6 mug/m 3 in the MPD, and 64.8 mug/m3 in the HPD. / Lung function indices included FVC, FEV1, FEV 1/FVC, FEF25-75%, FEF25%, and FEF75%. Children in the HPD had lower FEV 1/FVC, FEF25-75%, and FEF25% than those in both the LPD and MPD, after controlling for their corresponding confounders. In comparison between the LPD and HPD, the adjusted mean differences for FEV1/FVC, FEF25-75%, and FEF25% were respectively 1.39%, 85 ml, and 113 ml in boys, and 1.60%, 86 ml, and 225 ml in girls. In addition, the decreased FEF75% of HPD was found in boys (62 ml) but not in girls. When comparing the MPD with LPD, the increased FEF25% was observed in girls in the LPD (158 ml), whereas boys in the LPD had lower FEF75% than those in the MPD (81 ml). There were no significant differences in children's FVC and FEV1 between districts. / The multistage fitness test (MFT) with the Matsuzaka's function was employed to predict cardiopulmonary fitness (VO2max) of children. After adjustment for the factors, girls in the LPD had significantly higher VO 2max than those in the MPD and HPD by 0.19 and 0.75 ml&middot;kg -1 &middot;min-1 respectively. The VO 2max among boys in the LPD was 0.48 ml&middot;kg-1 &middot;min -1 higher than those in the HPD. When we compared the VO 2max between students in MPD and HPD, higher VO2max in both boys and girls in the MPD were observed---by 0.49 and 0.56 ml&middot;kg -1 &middot;min-1 respectively. In LPD, significantly higher VO2max values were observed in both boys and girls who were physically active (children who took part in sports and/or vigorous free play at least three times a week for at least 30 minutes each time) compared with those who were not (0.71 and 0.65 ml&middot;kg-1 &middot;min -1 respectively), but those differences in VO2max among students in MPD and HPD were small and insignificant. / There were totally 2,641 (82.9%) children who participated in the study, and 2,203 participants were involved in analyses. After adjustment for confounding factors, girls living in the HPD had significantly increased odds ratios (ORs) for wheezing without cold (4.75), cough at night (1.71), phlegm without cold (3.61), compared with those in the LPD. Boys in the HPD had increased OR only for phlegm without cold (1.88). When comparing the MPD with LPD, the adjusted OR for cough at night achieved significance in girls (1.74) and marginal significance in boys (1.40). Sneeze with itchy-watery eyes and current/ever allergic rhinitis had negative associations with district. In comparison with LPD, the decreased OR for sneeze with itchy-watery eye in girls in HPD (0.65) reached statistical significance. Both boys and girls in MPD had significantly decreased ORs for current allergic rhinitis (0.72 and 0.50 respectively) and for ever allergic rhinitis (0.74 and 0.55 respectively). There were no significant differences in the prevalence rates of asthma and bronchitis between districts. / To explore associations between air pollution and respiratory and cardiovascular health of school children, a cross-sectional study was conducted among 3,186 primary school children in P3 and P4 from three districts with different air pollution levels in Hong Kong during March to June in 2004. / Gao Yang. / "August 2005." / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6339. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 137-154). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Indiana University-Purdue University Indianapolis (IUPUI) / Phytoestrogens that abound in soy products, legumes, and chickpeas can induce biologic responses in animals and humans due to structural similarity to 17β-estradiol. Although experimental studies suggest that phytoestrogen intake may alter the risk of cancer and cardiovascular disease, few epidemiologic studies have investigated this research question. This dissertation investigated the associations of intake of total and individual phytoestrogens and their urinary biomarkers with these chronic conditions using data previously collected from two US national cohort studies (NHANES and PLCO). Utilizing NHANES data with urinary phytoestrogen concentrations and follow-up mortality, Cox proportional hazards regression (HR; 95% CI) were performed to evaluate the association between total cancer, cardiovascular disease, and all-cause mortality and urinary phytoestrogens. After adjustment for confounders, it was found that higher concentrations of lignans were associated with a reduced risk of death from cardiovascular disease (0.48; 0.24-0.97), whereas higher concentrations of isoflavones (2.14; 1.03-4.47) and daidzein (2.05; 1.02-4.11) were associated with an increased risk. A reduction in all-cause mortality was observed for elevated concentrations of lignans (0.65; 0.43-0.96) and enterolactone (0.65; 0.44-0.97). Utilizing PLCO data and dietary phytoestrogens, Cox proportional hazards regression examined the associations between dietary phytoestrogens and the risk of prostate cancer incidence. After adjustment for confounders, a positive association was found between dietary intake of isoflavones (1.58; 1.11-2.24), genistein (1.42; 1.02-1.98), daidzein (1.62; 1.13-2.32), and glycitein (1.53; 1.09-2.15) and the risk of advanced prostate cancer. Conversely, an inverse association existed between dietary intake of genistein and the risk of non-advanced prostate cancer (0.88; 0.78-0.99) and total prostate cancer (0.90; 0.81-1.00). C-reactive protein (CRP) concentration levels rise in response to inflammation and higher levels are a risk factor for some cancers and cardiovascular disease reported in epidemiologic studies. Logistic regression performed on NHANES data evaluated the association between CRP and urinary phytoestrogen concentrations. Higher concentrations of total and individual phytoestrogens were associated with lower concentrations of CRP. In summary, dietary intake of some phytoestrogens significantly modulates prostate cancer risk and cardiovascular disease mortality. It is possible that these associations may be in part mediated through the influence of phytoestrogen intake on circulating levels of C-reactive protein.

Thesis (MSCMedSc)--Stellenbosch University, 2012. / Includes bibliography / ENGLISH ABSTRACT: Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease in the world. The disease spectrum of NAFLD extends from steatosis (types 1,2) to non-alcoholic steatohepatitis (NASH) with inflammation (types 3,4). The aims of the study were 1) to analytically validate high-throughput real time polymerase chain reaction (RT-PCR) assays for three selected single nucleotide polymorphisms (SNPs), FTO rs9939609 (intron 1 T>A), TNF-α rs1800629 (-308 G>A) and PPARγ rs1801282 (Pro12Ala, 34 C>G), and 2) to perform genotype-phenotype association studies in relation to biochemical abnormalities, disease severity and age of onset. A total of 119 patients with fatty liver identified on ultrasound, including 88 histologically confirmed NAFLD patients, and 166 control individuals were genotyped for the three selected SNPs. RT-PCR validated against direct sequencing as the gold standard was used for detection of genetic variation. All three SNPs were in Hardy Weinberg equilibrium in the study population, except for a deviation in genotype distribution detected for PPARγ rs1801282 in the NAFLD patient subgroup (p<0.001). After adjustment for age and gender, the risk-associated FTO rs9939609 A-allele was detected at a significantly higher frequency in the Caucasian compared with Coloured patients (p=0.005). The opposite was detected for the risk-associated TNF-α rs1800629 A-allele, which occurred at a significantly higher frequency in the Coloured compared with Caucasian NAFLD patients (p=0.034). The onset of fatty liver disease symptoms was on average 5 years younger in the presence of each risk-associated TNF-α rs1800629 A-allele (p=0.028). When considered in the context of an inferred genotype risk score ranging from 0-6, disease onset occurred on average 3 years earlier (p=0.008) in the presence of each risk-associated FTO A-allele, TNF-α A-allele or PPARγ C-allele. After adjustment for age, gender and race, no differences in genotype distribution or allele frequencies were observed between histologically confirmed NAFLD (types 1,2) and NASH (types 3,4) patients, while the minor allele frequency for the TNF-α rs1800629 was significantly higher in the total NAFLD (types 1-4) (p=0.047) as well as NASH subgroup (NAFLD types 3,4) (p=0.030) compared with obese patients without a histologically confirmed NAFLD diagnosis. A significant correlation was furthermore observed between the number of TNF-α rs1800629 A-alleles and increasing CRP levels (p=0.029), with a favourable reduced effect in the presence of low- to moderate alcohol intake. The average waist circumference of physically active NAFLD patients was 12% lower than in physically inactive patients (p=0.004). In view of the results presented in this study, the inclusion of the selected SNPs, and in particular the pro-inflammatory TNF-α rs1800629 polymorphism, may be considered as part of a comprehensive cardiovascular risk evaluation of NAFLD patients. Ultimately, early detection of patients with fatty liver disease symptoms and effective intervention based on the underlying disease mechanism may prevent progression from NAFLD to NASH, shown to be an independent risk factor for cardiovascular diseases. / AFRIKAANSE OPSOMMING: Nie-alkoholiese lewervervetting (NALV) is die mees algemene kroniese lewersiekte in die wêreld. Die siektespektrum van NALV strek van steatose (vervette lewer tipes 1,2) tot steatohepatitis met inflammasie (NASH tipes 3,4). Die doel van die studie was 1) om analities die hoë omset polimerase kettingreaksie (RT-PKR) metode te valideer vir die geselekteerde enkel nukleotied polimorfismes (ENPs) FTO rs9939609 (intron 1 T>A), TNF-α rs1800629 (-308 G>A) en PPARγ rs1801282 (Pro12Ala, 34 C>G), en 2) om genotipe-fenotipe assosiasie studies uit te voer ten opsigte van relevante biochemiese abnormaliteite, graad van die siekte en aanvangsouderdom. ’n Totaal van 119 pasiënte met vervette lewers is geïdentifiseer met behulp van ultraklank, insluited 88 histologies-bevestigde NALV pasiënte, en 166 kontrole individue. Hierdie pasiënte is gegenotipeer vir die 3 geselekteerde ENP’s. RT-PKR gevalideer met direkte DNA volgorde bepaling as die goue standaard, is gebruik vir opsporing van genetiese variasie. Al die ENP’s was in Hardy Weinberg ekwilibrium in die studie populasie, behalwe vir ’n afwyking in genotipe verspreiding waargeneem vir PPARγ in die NALV subgroep (p<0.001). Nadat aanpassings gemaak is vir ouderdom en geslag, is die risiko-geassosieerde FTO rs9939609 A-alleel waargeneem teen ’n betekenisvol hoër frekwensie in die Kaukasiese pasiënte in vergelyking met Kleurling pasiënte (p=0.005). Die teenoorgestelde is waargeneem vir die risiko-geassosieerde TNF-α rs1800629 A-alleel wat voorgekom het teen ’n betekenisvol hoër frekwensie in die Kleurling NALV pasiënte, in vergelyking met Kaukasiese NALV pasiënte (p=0.034). Die aanvang van NALV was gemiddeld 5 jaar vroeër in die teenwoordigheid van elke risiko-geassosieerde TNF-α rs1800629 A-alleel (p=0.028). Met inagneming van ’n genotipe risiko telling tussen 0–6, het aanvang van siekte gemiddeld 3 jaar vroeër voorgekom (p=0.008) in die teenwoordigheid van elke toenemende risiko-geassosieerde FTO A-alleel, TNF-α A-alleel en PPARγ C-alleel. Nadat aanpassings gemaak is vir ouderdom, geslag en ras, is geen verskille waargeneem in genotipe verspreiding of alleel frekwensies tussen histologies bevestigde NALV (tipes 1,2) en NASH (tipes 3,4) pasiënte nie, terwyl die minor alleel telling vir die TNF-α rs1800629 betekenisvol hoër was in die totale NALV (tipes 1–4) (p=0.047) asook die NASH subgroep (NALV tipes 3,4) (p=0.03) in vergelyking met vetsugtige pasiënte sonder ’n histologies bevestigde diagnose. ‘n Statisties beteknisvolle korrelasie is verder waargeneem tussen die aantal TNF-α rs1800629 A-allele en toenemende CRP vlakke (p=0.029), met n gunstige verlaagde effek in die teenwoordigheid van lae alcohol gebruik. Die gemiddelde middellyf-omtrek van fisies aktiewe NALV pasiënte was 12% minder as fisies onaktiewe pasiente (p=0.004). Na aanleiding van die resultate van hierdie studie behoort insluiting van geselekteerde ENP’s, en in besonder die pro-inflammatoriese TNF-α rs1800629 polimorfisme, as deel van ’n omvattende kardiovaskulere risiko evaluasie oorweeg te word. Aan die einde van die dag mag vroeë identifikasie van NALV pasiente en effektieve intervensie gebasseer op die onderliggende siekte meganisme, vordering tot NASH verhoed wat getoon is om ’n onafhanklike risiko faktor vir kardiovaskulêre siekte te wees. / Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology

Numerous studies focusing on cardiovascular disease risk factors such as obesity, hypertension, smoking, diabetes mellitus, elevated serum lipids, inactivity and lack of physical fitness prevalent in children highlight the importance of the early diagnosis and prevention of conditions that are associated in adulthood with cardiovascular disease. The purpose of this study was to assess the impact of accumulative physical activity on the fitness profile, blood pressure and body composition in 14-16 year old school children in the Western Cape of South Africa.