Motivation: Cardiovascular heart disease (CVD) is the leading cause of death worldwide. Risk markers for CVD include, amongst others, the haemostatic factors tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor type 1 (PAI-1), factor VII (FVII) and fibrinogen and more recently, C-reactive protein (CRP), a sensitive marker of inflammation. Epidemiological studies have demonstrated an inverse association between dietary fibre (DF) consumption and risk factors for CVD and CVD prevalence. Some research indicates that this protection may be related to favourable changes in the haemostatic profile and inflammatory markers. This is applicable for the consumption of total DF, as well as soluble and insoluble fibre. However, clinical intervention trials report conflicting data on the effects of DF on t-PA, PAI-1, FVII, fibrinogen and CRP. In addition, available literature is not clear on the mechanisms through which DF may have favourable effects. Objective: The main objective of this study was to review the results of randomised controlled trials systematically on the effects of DF on the above-mentioned selected haemostatic variables and CRP in healthy adults and subjects with hypertriglyceridaemia and the metabolic syndrome. Methods: Human adult intervention trials, at least two weeks in duration, with an increased and measurable consumption of DF were included. Electronic databases were searched from the earliest record to May/July 2006 and supplemented by crosschecking reference lists of relevant publications. From the literature search, two reviewers identified studies that were rated for quality based on the published methodology. No formal statistical analysis was performed due to the large differences in the study designs of the dietary intervention trials. The primary outcome measures were percentage changes between intervention and control groups, or baseline to end comparisons for t-PA, PAI-1, FVII, fibrinogen and CRP. Results t-PA activity increased significantly (14-167%) over the short and long-term following increased fibre intakes. PAI-1 activity decreased significantly between 15-57% over periods ranging from two to six weeks. These favourable changes in t-PA and PAI-1 occurred in healthy, hypertriglyceridaemic and metabolic syndrome subjects following consumption of diets containing ≥3.3 g/MJ DF and ≥4.5 g/MJ DF respectively. Mechanisms through which DF may affect t-PA and PAI-1 include its lowering effect on insulinaemic and glycaemic responses, decreasing triglycerides which are a precursor of very-low-density lipoproteins, fermentation of DF to short-chain fatty acids, which may reduce free fatty acid concentrations, as well as the role of DF in promoting weight loss. High DF intakes did not have a significant effect on fibrinogen concentrations possibly because of relatively little weight loss, too low DF dosages and maintaining a good nutritional status. Inadequate study designs deterred from meaningful conclusions. Significant decreases in FVll coagulant activity (6-16%) were observed with DF intakes of ≥3.3 g/MJ and concomitant decreased saturated fat intakes and weight loss in healthy and hypertriglyceridaemic subjects. Confounding factors include weight loss and a simultaneous decreased intake of saturated fats. The type of fibre seems to play a role as well. Mechanisms through which DF may reduce FVll concentrations include its effects on triglyceride-rich lipoproteins, insulin and weight loss. Increased DF consumption with dosages ranging between 3.3-7.8 g/MJ were followed by significantly lower CRP concentrations (25-54%), however, simultaneous weight loss and altered fatty acid intakes were also present in all the studies. Mechanisms are inconclusive but may involve the effect of DF on weight loss, insulin, glucose, adiponectin, interleukin-6, free fatty acids and triglycerides. Conclusions: Epidemiological evidence indicates an association between DF and the CVD risk factors t-PA, PAI-1, FVII, fibrinogen and CRP. In general, the risk of CVD may improve with high-fibre intakes as indicated by the favourable changes in some of the parameters. However, simultaneous reduced fat intakes and weight loss presented difficulties in separating out the effects of specific components. Furthermore, DF is consumed in a variety of different forms and different dosages that may have different effects. Overall, the study designs used in the intervention trials prevented significant conclusions. DF did, however, play a role in modifying t-PA, PAI-1, FVII and CRP. Potential effects on fibrinogen were not quantifiable. Recommendations: The results from this investigation provide the motivation for additional controlled clinical research to establish the effect and mechanisms of DF on haemostatic variables and CRP. A critical aspect of future studies would be to set up suitable protocols. The amount of subjects, duration of the trials, confounding factors such as weight loss and altered fat intakes and differentiation between types and dosage of DF are important. DF supplemental studies are recommended as they may be the most suitable method to reach meaningful conclusions. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2007

Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2007.

Motivation: Cardiovascular heart disease (CVD) is the leading cause of death worldwide. Risk markers for CVD include, amongst others, the haemostatic factors tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor type 1 (PAI-1), factor VII (FVII) and fibrinogen and more recently, C-reactive protein (CRP), a sensitive marker of inflammation. Epidemiological studies have demonstrated an inverse association between dietary fibre (DF) consumption and risk factors for CVD and CVD prevalence. Some research indicates that this protection may be related to favourable changes in the haemostatic profile and inflammatory markers. This is applicable for the consumption of total DF, as well as soluble and insoluble fibre. However, clinical intervention trials report conflicting data on the effects of DF on t-PA, PAI-1, FVII, fibrinogen and CRP. In addition, available literature is not clear on the mechanisms through which DF may have favourable effects. Objective: The main objective of this study was to review the results of randomised controlled trials systematically on the effects of DF on the above-mentioned selected haemostatic variables and CRP in healthy adults and subjects with hypertriglyceridaemia and the metabolic syndrome. Methods: Human adult intervention trials, at least two weeks in duration, with an increased and measurable consumption of DF were included. Electronic databases were searched from the earliest record to May/July 2006 and supplemented by crosschecking reference lists of relevant publications. From the literature search, two reviewers identified studies that were rated for quality based on the published methodology. No formal statistical analysis was performed due to the large differences in the study designs of the dietary intervention trials. The primary outcome measures were percentage changes between intervention and control groups, or baseline to end comparisons for t-PA, PAI-1, FVII, fibrinogen and CRP. Results t-PA activity increased significantly (14-167%) over the short and long-term following increased fibre intakes. PAI-1 activity decreased significantly between 15-57% over periods ranging from two to six weeks. These favourable changes in t-PA and PAI-1 occurred in healthy, hypertriglyceridaemic and metabolic syndrome subjects following consumption of diets containing ≥3.3 g/MJ DF and ≥4.5 g/MJ DF respectively. Mechanisms through which DF may affect t-PA and PAI-1 include its lowering effect on insulinaemic and glycaemic responses, decreasing triglycerides which are a precursor of very-low-density lipoproteins, fermentation of DF to short-chain fatty acids, which may reduce free fatty acid concentrations, as well as the role of DF in promoting weight loss. High DF intakes did not have a significant effect on fibrinogen concentrations possibly because of relatively little weight loss, too low DF dosages and maintaining a good nutritional status. Inadequate study designs deterred from meaningful conclusions. Significant decreases in FVll coagulant activity (6-16%) were observed with DF intakes of ≥3.3 g/MJ and concomitant decreased saturated fat intakes and weight loss in healthy and hypertriglyceridaemic subjects. Confounding factors include weight loss and a simultaneous decreased intake of saturated fats. The type of fibre seems to play a role as well. Mechanisms through which DF may reduce FVll concentrations include its effects on triglyceride-rich lipoproteins, insulin and weight loss. Increased DF consumption with dosages ranging between 3.3-7.8 g/MJ were followed by significantly lower CRP concentrations (25-54%), however, simultaneous weight loss and altered fatty acid intakes were also present in all the studies. Mechanisms are inconclusive but may involve the effect of DF on weight loss, insulin, glucose, adiponectin, interleukin-6, free fatty acids and triglycerides. Conclusions: Epidemiological evidence indicates an association between DF and the CVD risk factors t-PA, PAI-1, FVII, fibrinogen and CRP. In general, the risk of CVD may improve with high-fibre intakes as indicated by the favourable changes in some of the parameters. However, simultaneous reduced fat intakes and weight loss presented difficulties in separating out the effects of specific components. Furthermore, DF is consumed in a variety of different forms and different dosages that may have different effects. Overall, the study designs used in the intervention trials prevented significant conclusions. DF did, however, play a role in modifying t-PA, PAI-1, FVII and CRP. Potential effects on fibrinogen were not quantifiable. Recommendations: The results from this investigation provide the motivation for additional controlled clinical research to establish the effect and mechanisms of DF on haemostatic variables and CRP. A critical aspect of future studies would be to set up suitable protocols. The amount of subjects, duration of the trials, confounding factors such as weight loss and altered fat intakes and differentiation between types and dosage of DF are important. DF supplemental studies are recommended as they may be the most suitable method to reach meaningful conclusions. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2007

Cardiovascular disease (CVD) is a major cause of adult morbidity and mortality in developed as well as in developing countries. In black population groups, stroke is more prominent than ischaemic heart disease. This may be attributed to a combination of risk factors seen in this population group inter alia raised haemostatic markers, which favour the development of stroke since it is well known that a disturbance in the haemostatic balance (a hypercoagulable and a hypofibrinolytic state) predisposes to CVD. It is generally accepted that childhood genetic, environmental and behavioural factors lay the groundwork for the manifestation of adult CVD. Therefore, one of the studies that form part of this dissertation was a cross-sectional study to determine whether haemostatic abnormalities are already present in black African adolescents and to determine whether high risk groups exist [in relation to the following haemostatic markers: fibrinogen, factor VIII (FVIII), plasminogen activator inhibitor type 1 activity (PAI-Iact), and thrombin anti-thrombin complex (TAT)] for the development of CVD later in life. The population subdivisions were made according to gender, body fat %, maturity status, height for age Z-score, and habitual PA levels. Since behavioural factors [diet, physical activity (PA), smoking and drinking habits] are controllable determinants, it could be possible to improve CVD risk to a certain degree. Therefore, the second study that forms part of this dissertation attempted to establish whether a PA programme will successfully reduce haemostatic variables in a subset of the study population used in the first study. The reader is referred to the abstracts at the beginning of each separate study manuscript (Chapters 3 and 4), for a description of the subjects, study design and methods used in each study. The results of the cross-sectional study showed that in African adolescents (a) gender independently contributed to the variability in PAI-Iact, but that the gender difference in fibrinogen and TAT could be explained by the significant differences in fat mass and PA levels observed between the genders; (b) fibrinogen was significantly higher in the stunted compared to the non-stunted children indicating that childhood chronic malnutrition may possibly predispose independently to CVD; (c) fitness influences TAT concentrations positively and that (d) no significant differences in FVIII could be found between any of the subdivisions. As these determinants seem to be modifiable through behavioural changes and optimal nutrition status through early life, it raises a sense of urgency to develop strategies for the prevention and treatment of these risk factors. The results of the intervention study showed that an 11-week outdoor PA intervention programme had no significant effect on the haemostatic markers of African adolescents, but the results of this study should be interpreted with caution since (a) seasonal variations could have clouded the effect of the PA intervention as baseline measurements were taken in the summer and end measurements in the winter; (b) attendance of the PA sessions does not necessarily implicate compliance to the exercises given; (c) baseline values seem to play a prominent role in the changes that could be expected during an intervention and, therefore, improvements in the haemostatic profile would most likely be more significant in individuals with raised baseline levels. Similar research on African children is warranted since studies investigating PA's effect on haemostatic variables remain a topic of debate and speculation and data on African population groups are scanty. / Thesis (M.Sc. (Nutrition))--North-West University, Potchefstroom Campus, 2007

Thesis (M.Sc. (Nutrition))--North-West University, Potchefstroom Campus, 2007.

Previous work has shown that thrombin activatable fibrinolysis inhibitor (TAFI) was unable to prolong lysis of purified clots in the presence of Lys-plasminogen (Lys-Pg), indicating a possible mechanism for fibrinolysis to circumvent prolongation mediated by activated TAFI (TAFIa). Therefore, the effects of TAFIa on Lys-Pg activation and Lys-plasmin (Lys-Pn) inhibition by antiplasmin (AP) were quantitatively investigated using a fluorescently labeled recombinant Pg mutant which does not produce active Pn. High molecular weight fibrin degradation products (HMW-FDPs), a soluble fibrin surrogate that models Pn modified fibrin, treated with TAFIa decreased the catalytic efficiency (kcat/Km) of 5IAF-Glu-Pg cleavage by 417-fold and of 5IAF-Lys-Pg cleavage by 55-fold. A previously devised intact clot system was used to measure the apparent second order rate constant (k2) for Pn inhibition by AP over time. While TAFIa was able to abolish the protection associated with Pn modified fibrin in clots formed with Glu-Pg, it was not able to abolish the protection in clots formed with Lys-Pg. However, TAFIa was still able to prolong the lysis of clots formed with Lys-Pg. TAFIa prolongs clot lysis by removing the positive feedback loop for Pn generation. The effect of TAFIa modification of the HMW-FDPs on the rate of tissue type plasminogen activator (tPA) inhibition by plasminogen activator inhibitor type 1 (PAI-1) was investigated using a previously devised end point assay. HMW-FDPs decreased the k2 for tPA inhibition rate by 3-fold. Thus, HMW-FDPs protect tPA from PAI-1. TAFIa treatment of the HMW-FDPs resulted in no change in protection. Vitronectin also did not appreciably affect tPA inhibition by PAI-1. Pg, in conjunction with HMW-FDPs, decreased the k2 for tPA inhibition by 30-fold. Hence, Pg, when bound to HMW-FDPs, protects tPA by an additional 10-fold. TAFIa treatment of the HMW-FDPs completely removed this additional protection provided by Pg. In conclusion, an additional mechanism was identified whereby TAFIa can prolong clot lysis by increasing the rate of tPA inhibition by PAI-1 by eliminating the protective effects of Pn-modified fibrin and Pg. Because TAFIa can suppress Lys-Pg activation but cannot attenuate Lys-Pn inhibition by AP, the Glu- to Lys-Pg/Pn conversion is able to act as a fibrinolytic switch to ultimately lyse the clot. / Thesis (Master, Biochemistry) -- Queen's University, 2008-01-31 17:04:50.447

Cardiovascular disease (CVD) is a major cause of adult morbidity and mortality in developed as well as in developing countries. In black population groups, stroke is more prominent than ischaemic heart disease. This may be attributed to a combination of risk factors seen in this population group inter alia raised haemostatic markers, which favour the development of stroke since it is well known that a disturbance in the haemostatic balance (a hypercoagulable and a hypofibrinolytic state) predisposes to CVD. It is generally accepted that childhood genetic, environmental and behavioural factors lay the groundwork for the manifestation of adult CVD. Therefore, one of the studies that form part of this dissertation was a cross-sectional study to determine whether haemostatic abnormalities are already present in black African adolescents and to determine whether high risk groups exist [in relation to the following haemostatic markers: fibrinogen, factor VIII (FVIII), plasminogen activator inhibitor type 1 activity (PAI-Iact), and thrombin anti-thrombin complex (TAT)] for the development of CVD later in life. The population subdivisions were made according to gender, body fat %, maturity status, height for age Z-score, and habitual PA levels. Since behavioural factors [diet, physical activity (PA), smoking and drinking habits] are controllable determinants, it could be possible to improve CVD risk to a certain degree. Therefore, the second study that forms part of this dissertation attempted to establish whether a PA programme will successfully reduce haemostatic variables in a subset of the study population used in the first study. The reader is referred to the abstracts at the beginning of each separate study manuscript (Chapters 3 and 4), for a description of the subjects, study design and methods used in each study. The results of the cross-sectional study showed that in African adolescents (a) gender independently contributed to the variability in PAI-Iact, but that the gender difference in fibrinogen and TAT could be explained by the significant differences in fat mass and PA levels observed between the genders; (b) fibrinogen was significantly higher in the stunted compared to the non-stunted children indicating that childhood chronic malnutrition may possibly predispose independently to CVD; (c) fitness influences TAT concentrations positively and that (d) no significant differences in FVIII could be found between any of the subdivisions. As these determinants seem to be modifiable through behavioural changes and optimal nutrition status through early life, it raises a sense of urgency to develop strategies for the prevention and treatment of these risk factors. The results of the intervention study showed that an 11-week outdoor PA intervention programme had no significant effect on the haemostatic markers of African adolescents, but the results of this study should be interpreted with caution since (a) seasonal variations could have clouded the effect of the PA intervention as baseline measurements were taken in the summer and end measurements in the winter; (b) attendance of the PA sessions does not necessarily implicate compliance to the exercises given; (c) baseline values seem to play a prominent role in the changes that could be expected during an intervention and, therefore, improvements in the haemostatic profile would most likely be more significant in individuals with raised baseline levels. Similar research on African children is warranted since studies investigating PA's effect on haemostatic variables remain a topic of debate and speculation and data on African population groups are scanty. / Thesis (M.Sc. (Nutrition))--North-West University, Potchefstroom Campus, 2007

Humans have two plasminogen activators (PAs), tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA), which generate plasmin to breakdown fibrin and other barriers to cell migration. Both PAs are used as pharmaceuticals but their efficacies are limited by their rapid clearance from the circulation, predominantly by parenchymal cells of the liver. At the commencement of the work presented here, the hepatic receptors responsible for mediating the catabolism of the PAs were little understood. tPA degradation by hepatic cell lines was known to depend on the formation of binary complexes with the major PA inhibitor, plasminogen activator inhibitor type-1 (PAI-1). Initial studies presented here established that uPA was catabolised in a fashion similar to tPA by the hepatoma cell line, HepG2. Other laboratories around this time found that the major receptor mediating the binding and endocytosis of the PAs is Low Density Lipoprotein Receptor-related Protein (LRP1). LRP1 is a giant 600 kDa protein that binds a range of structurally and functionally diverse ligands including, activated α2 macroglobulin, apolipoproteins, β amyloid precursor protein, and a number of serpin-enzymes complexes, including PA??PAI-1 complexes. Further studies for the work presented here centred on this receptor. By using radiolabelled binding assays, ligand blots, and Western blots on cultured cells, the major findings are that: (1) basal LRP1 expression on HepG2 is low compared to a clone termed, HepG2a16, but appears to increase in long term culture; (2) a soluble form of LRP1, which retains ligand-binding capacity, is present in human circulation; (3) soluble LRP1 is also present in cerebral spinal fluid where its role in neurological disorders such as Alzheimer??s disease is a developing area of interest; and (4) the release of LRP1 is a mechanism conserved in evolution, possibly as distantly as molluscs. The discovery, identification, and characterisation of soluble LRP1 introduces this protein in the human circulation, and presents a possible further level of regulation for its associated receptor system.