Healthy term pregnancy requires precisely timed coordination of multiple systems, including reproductive, neuroendocrine, immune and cardiovascular. Dynamic maternal alterations occur systemically as well as locally within the reproductive tract. Systemic cardiovascular changes during gestation are relatively conserved in mammals, permitting comparison. These physiological changes are relatively acute and reversible, in contrast to the pathological changes seen during cardiovascular disease development. Gestational hypertensive disorders, such as preeclampsia, are the leading causes of maternal and fetal morbidity and mortality. The pathogenesis of preeclampsia is not fully elucidated, but perturbation of the immune system is a fundamental component. The angiogenic and vascular properties of uterine NK lymphocytes have been well studied in mice and women, but their relationships to gestational blood pressure regulation and cardiovascular adaptations have not been addressed. In non-pregnant women and mice, T cells, but not B cells, have been found to alter cardiovascular functioning. NK cells in humans also possess these capabilities, but no functional studies have been completed. The aim of this thesis was to define the role of NK and T lymphocytes in cardiovascular adaptations during mouse gestation. Using chronic radiotelemetry, histology, post-mortem and other techniques, female inbred mice of differing genotypes that lack specific lymphocyte subsets were compared before and across gestation. In normal, immune competent mice, a five-phase gestational blood pressure profile was found. This dynamic profile corresponded to stages of placental development. In mice with a compound deficit in arterial modification and lymphocytes, no gestational hypertension was observed. To elevate the maternal challenge of pregnancy, studies of pregnant, autoimmune Type 1 Diabetic mice were conducted. Impaired spiral artery remodeling, dysfunctional lymphocytes and growth-restricted fetuses were identified. From mid-gestation, diabetic pregnant mice were hypotensive and bradycardic and showed signs of pre-renal failure (proteinuria and electrolyte imbalances). In pregnant mice lacking T cells, tachycardia was observed despite otherwise normal gestational outcomes. In pregnant mice lacking T cells with impaired NK cells, blood pressure was blunted and tachycardia was observed. These findings support the conclusion that impaired spiral artery remodeling is insufficient to cause gestational hypertension in mice. The data further identify a role for T and NK cells in cardiac function during gestation. / Thesis (Ph.D, Anatomy & Cell Biology) -- Queen's University, 2010-09-01 20:56:15.648

Tikslas: Išanalizuoti griaučių raumenų arterinės kraujotakos ir fizinio darbingumo kaita atliekant 120 mm Hg slėgio okliuzines treniruotes Uždaviniai: 1. Nustatyti arterinio kraujo spaudimo ir blauzdos raumenų arterinės kraujotakos intensyvumą ramybės būsenoje be okliuzijos ir su 120 mm Hg okliuzija. 2. Nustatyti arterinio kraujo spaudimo ir blauzdos raumenų darbingumo kaitą be okliuzijos ir su 120 mm Hg slėgio okliuzija. 3. Nustatyti arterinio kraujo spaudimo ir blauzdos raumenų arterinės kraujotakos ir darbingumo kaitą atliekant treniruotes, be okliuzijos ir su 120 mm Hg okliuzija. Tyrimo metodai: Dinamometrija, ergometrija, veninė okliuzinė pletizmografija, pulsometrija, arterinio kraujo spaudimo (AKS) matavimai. Tyrimų organizavimas: Pirmo etapo tyrimo, kontrolinėje grupėje – registruojama kraujotaka ir AKS ramybėje ir 15 min be okliuzijos, o eksperimentinėje – su 15 min okliuzija. Antro etapo tyrimo kontrolinėje grupėje registruojama arterinė kraujotaka ir AKS ramybėje ir po 75 % MVJ fizinio darbo kilnojant svarmenį iki visiško nuovargio. Eksperimentinėje grupėje tarp dviejų fizinių krūvių atliekama 15 min okliuzija. Trečio etapo tyrimo kontrolinėje grupėje registruojama arterinė kraujotaka, AKS, ŠSD, bei atliko vienos savaitės treniruočių ciklą. Analogiškai tyrimas buvo atliktas ir eksperimentinėje grupėje, tik buvo atliekama okliuzija. Rezultatai. Pirmo etapo tyrimo eksperimentinės grupės okliuzja 120 mm Hg mažina arterinę kraujotaką. Antro etapo kontrolinėje grupėje... [toliau žr. visą tekstą] / Objective: To analyze the skeletal muscle of arterial blood flow and changes in physical working capacity 120 mm Hg pressure occlusive workouts Goals: 1. Set of arterial blood pressure and arterial calf muscle blood flow at rest without occlusion and 120 mm Hg occlusion. Second Set of arterial blood pressure and calf muscle work change without occlusion and 120 mm Hg pressure occlusion. 3rd Set of arterial blood pressure and calf muscle blood flow and arterial capacity change during workouts without occlusion and 120 mm Hg occlusion. The research methods: Dynamometry, ergometry, venous occlusive plesthysmography, heart rate, arterial blood pressure (BP) measurements. Research Organization: The first phase of the study, the control group - keeping the blood flow and blood pressure at rest and 15 min without occlusion, and experimental - to 15-minute occlusion. The second phase of the study in the control group recorded arterial blood flow and blood pressure at rest and 75% MVC physical work lifting a weight up to full weariness. In the experimental group between two physical workloads performed 15 min occlusion. The third phase of the study in the control group recorded arterial blood flow, blood pressure, heart rate, and performed a one-week training cycle. Similarly, the study was conducted, and the experimental group, but occlusion was performed. Results. The first phase of the study the experimental group okliuzja 120 mm Hg reduces arterial blood flow. The second phase of... [to full text]

To assess the relationships of body mass index (BMI) on arterial stiffness at rest and post-maximal treadmill graded exercise testing (GXT). Forty-four apparently healthy, young adult males (22.1 ± 0.48 years) were recruited and divided into either a healthy weight (H, ≤24.9 kg/m2), overweight (OV, 24.9-29.9 kg/m2) or obese (OB, ≥29.9 kg/m2) group based on BMI. All subjects underwent arterial stiffness (carotid-femoral pulse wave velocity, cfPWV), blood pressure (BP), pulse pressure (PP), mean arterial pressure (MAP) and body composition (bioelectrical impedance analysis, BIA) measurements at rest. Following the GXT, measures of arterial stiffness (cfPWV) and BP were acquired. Resting measures of cfPWV, BMI, systolic BP, diastolic BP, MAP, and PP were significantly (p <0.05) greater in OV and OB compared with H. Compared with OV, OB had a greater BMI. Relative peak oxygen consumption (VP2peak) was greater in H compared with OV and OB (p<0.05). systolic BP was positively associated, whereas VO2peak was inversely related to cfPWV (p<0.05). No significant inter-group interactions were observed with cfPWV after the GXT. However, interactions were observed for SBP, DBP and PP (p<0.05). In young men with varying BMI, SBP and VO2peak were associated with resting cfPWV. However, similar cardiovascular responses were observed between groups after a maximal GXT.

Background: The epidemic of chronic diseases is largely neglected. Although a threatening burden of chronic diseases is emerging, developing public health efforts for their prevention and control is not yet a priority for trans-national and national health policy makers. Understanding the population burden of risk factors which predict chronic diseases is an important step in reducing the impact of the diseases themselves. Objective: This thesis responds to the increasing burden of chronic diseases worldwide, and aims to illustrate the gap in chronic disease risk factor research in developing countries. The thesis describes and analyses the distribution of chronic disease risk factors in a rural setting in Indonesia. It also describes how smoking, one of the most common risk factors, is viewed by rural Javanese boys. Ultimately, therefore, this thesis aims to contribute to policy and programme recommendations for community interventions in a rural setting in Indonesia Methods: The studies were conducted in Purworejo District, where a Demographic Surveillance System (DSS) has been running since 1994. The Purworejo DSS is part of the INDEPTH network (International Network of field sites for continuous Demographic Evaluation of Populations and Their Health in developing countries). Two representative cross-sectional studies (in 2001 and 2005) were conducted to assess the chronic disease risk factors (including smoking, elevated blood pressure, and overweight and obesity). The first cross-sectional study was followed up in 2002 and 2004. In each study, a total of 3 250 participants (approximately 250 individuals in each sex and age group among 15–74 year olds stratified into 10-year intervals) were randomly selected from the surveillance database from each enumeration area in the surveillance area. Instruments were adopted from the WHO STEPS survey and adapted to local setting. Since many Indonesians start to smoke at an earlier age, a qualitative study using a focus group discussion approach was conducted among school boys aged 13-17 years old to describe and explore beliefs, norms, and values about smoking in a rural setting in Java. Result: Both the rural and urban populations in Purworejo face an unequal distribution of risk factors for chronic diseases. The burden among the most well-off group in the rural area has already reached a level similar to that found in the urban area. Most of the risk factors increased in all age, sex and socioeconomic groups during the period of 2001 to 2005. However, women and the poorest group experienced the greatest increase in risk factor prevalence. The qualitative study showed that cultural resistance against women smoking in Indonesia remains strong. Smoking is being viewed as a culturally internalised habit that signifies transition into maturity and adulthood for boys. Smoking is utilised as a means for socialisation and signifies better socioeconomic status. The use of tobacco in the construction of masculinity underlines the importance of gender specific interventions. National tobacco control policy should emphasise a smoking free society as the norm, especially among boys and men, and regulations regarding the banning of smoking should be enforced at all levels and areas of the community. Within the demographic surveillance setting, it is possible to assess the population and health dynamics. Utilisation of a standardised methodology across sites in INDEPTH will produce comparable population-based data in developing countries. Such comparisons are important in global health. A comparison of smoking transition patterns between a Vietnamese DSS and an Indonesian DSS shows that Indonesian men started smoking regularly earlier and ceased less than Vietnamese men. Compared with Vietnam, which has already signed and ratified the Framework Convention on Tobacco Control, tobacco control activities in Indonesia are still deficient. Conclusion: The thesis concludes that the rural population is not spared from the emerging burden of chronic disease risk factors. The patterning of risks across different socioeconomic groups provides a macro picture of the vicious cycle between poverty and chronic diseases. Understanding of risk factors in a local context through a qualitative study provides insight into cultural aspects relating to risk factor adoption, and will allow the fostering and tailoring of culturally appropriate interventions. Combining data from demographic surveillance sites with the WHO STEP approach to chronic disease risk factor Surveillance addresses basic epidemiological questions on chronic diseases. The use of such data is a powerful advocacy tool in public health decision-making for chronic disease prevention in developing countries. With substantial existing evidence on the effectiveness of chronic disease prevention and intervention programmes, it is vital that Indonesia to starts planning intervention programmes to control the impending chronic disease epidemic, and most importantly, to translate all this evidence into public health action. Keywords: chronic disease, risk factor, demographic surveillance system, smoking, elevated blood pressure, overweight and obesity, population-based intervention

Background: The role of dietary calcium in weight management is gaining support in the nutrition research community. It has been hypothesized that high calcium diets protect against fat gain by creating a balance of lipolysis over lipogenesis in adipocytes (Zemel et al., 2000) and that a diet deficient in calcium is associated with higher body weight and that augmenting calcium intake may reduce weight and fat gain or enhance fat loss (Shapses et al., 2004). Objectives: A lack of baseline data on the physical, physiological and mental effects of obesity on urban African women was the motivation for the POWIRS (Profiles of Obese Women with Insulin Resistance Syndrome) study. The aim of the study was to assess the effects of obesity on health determinants of urban African and white women by comparing the lifestyle and risk factors for non-communicable diseases (NCDs) of lean, overweight and obese subjects. This led to a multi-disciplinary cross-sectional case-control study in which health determinants and health status, as well as the underlying mechanistic relationships between these factors were measured in a sample of African women volunteers. The study was repeated a year later, done in a sample of white women volunteers, POWIRS II. The effect of calcium intake on body composition was assessed during this study. Methods: One hundred and two apparently healthy urban African women, between the ages of 20 and 50 years participated in the first phase of this case-control cross-sectional survey. For a period of about three weeks, each afternoon ten subjects were to report at a Metabolic Unit Facility (consisting of 10 single bedrooms, 2 bathrooms, a living room and kitchen). Each subject received a "participant sheet" which guided them through the different research 'stations' where the various measurements were done. During the course of the evening demographic questionnaires were filled in and all anthropometric measurements were taken, except weight and height measurements. All participants received an identical light supper which excluded alcohol and caffeine at 20h00, went to sleep before 23h00 and fasted overnight. From 06h00 in the morning weight, height and blood pressure measurements were taken. After a fasting blood sample was taken, a two-hour glucose tolerance test commenced. Subjects received a breakfast and afterwards habitual dietary intake questionnaires were completed. Results: Mean total dietary calcium intake as significantly higher in white women (POWIRS II), with a mean intake 1053.8 mg per day, as opposed to a mean intake of 494.8 mg calcium per day in the blacks subjects (POWIRS I). Mean fat intake in the black subjects was 59.3 g per day, and in the white women 103.1 g per day. Thus the calcium:fat ratio in white women was higher than in black women (11.0 and 8.4 respectively). After adjustment for age and total dietary energy intake, significant negative correlations were found between dietary calcium intake and various variables, only in the white subjects. These were BMI (r=-0.255, p=0.01), percentage body fat (r=-0.252, p=0.01), fasting insulin (r=-0.205, p=0.05) and fasting glucose (r=-0.199, p=0.046). The calcium:fat ratio correlated negatively with BMI (r=-0.378, p<0.0001), percentage body fat (r=-0.401, p<0.0001), fasting glucose (r=-0.229, p=0.02), fasting insulin (r=-0.212, p=0.04) and plasma leptin (r=-0.284, p=0.004). Adjustment for smoking resulted in slightly different correlation coefficients, but similar significant correlations were still found. The only significant association that was found in the black population, was a negative correlation between dietary calcium intake and systolic blood pressure (p=0.03) as well as diastolic blood pressure (p=0.04). After adjustment for age, smoking and dietary energy intake no significant correlations were found in the black subjects. Conclusion: The results from the POWIRS study in white women are consistent with the hypothesis that there may be an inverse relationship between adiposity and calcium intake. In our study higher calcium intakes were associated with lower body fat, lower BMI, lower fasting glucose and insulin, as well as plasma leptin in white women. The association seems to be significant in subjects with high intakes of fat and calcium (as seen in the white women). / Thesis (M.Sc. (Dietetics))--North-West University, Potchefstroom Campus, 2005.

Background: In the past 37 years, increased efforts have been directed toward a better understanding of the importance of Hcy in disease and it has now become clear that hyperhomocysteinemia is a major independent risk factor for CVD. Extensive research on the influence of vitamin supplementation leading to reductions in Hcy levels and improvements in cardiovascular function has been done. The importance of exercise in the lowering of cardiovascular risk factors, as well as its favourable influence on cardiovascular function has also been indicated in several studies, however, the limited number of studies investigating the effect of exercise on Hcy concentrations revealed contradicting results. Furthermore, a relationship between Hcy concentration and cardiovascular function with the intervention of an exercise training and a vitamin supplementation programme respectively has also not been investigated. Objective: The objective of this study was to examine the effect of a 12-week exercise training and a 12-week vitamin supplementation intervention respectively on tHcy concentrations and cardiovascular function, and whether the change in tHcy concentration within the different interventions correlated with the change in cardiovascular function. Methods: In a randomised controlled cross-over intervention study, 52 men matched for age, cardiorespiratory fitness levels and cardiovascular risk factors were randomly assigned to one of 3 groups (Group A = exercise training programme, 20-30min. at 70-80% of HRmax; Group B = 400 g folic acid and 25 g vitamin B12 supplement; Group C = control). Group A and B were crossed over for phase 11, and Group C remained the control. The questionnaires were completed, and the body composition variables (BMI, WHR and body fat percentage), cardiovascular function (Finometer), tHcy concentrations and VO2max, were measured before and after each 12-week intervention period. A 6-week washout period separated the crossovers. Results: The ANCOVA, adjusted for age and BMI, showed that the percentage change from baseline to end, corrected for baseline of the tHcy concentration increased significantly (p ≤ .05) by 9.7% with the exercise training intervention and decreased significantly (p ≤ .05) by 12.9%, with the vitamin supplementation intervention. The ANCOVA of the percentage change from baseline to end in cardiovascular function showed that the vitamin supplementation intervention resulted in improvements in cardiovascular function (decreased resting MAP, TPR and increased resting SV, CO, Cw) in comparison to the impairment in cardiovascular function with the exercise training intervention (increased resting DBP, MAP and TPR). The relationship between the tHcy concentration and cardiovascular function at baseline and within each of the different interventions were assessed by partial correlations adjusted for age, BMI and VO2max. Significant (p ≤ .05) relationships only occurred within the vitamin supplementation intervention, where decreased percentage change in tHcy concentration significantly correlated with increased percentage change of resting SV and CO and decreased percentage change of resting TPR. Conclusion: The general conclusion that can be drawn is that a 12-week vitamin supplementation intervention showed increased health related results, e.g. a significant reduction in tHcy concentration, an improvement in cardiovascular function and a significant positive relationship between these b o factors, in comparison to the 12-week exercise training intervention that significantly increased the tHcy concentration and did not show increased health related results. Due to inadequate compliance to the exercise training intervention, no conclusion can be drawn with regard to the effect of exercise training on tHcy concentrations and cardiovascular function. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2007

Motivation Hypertension and type 2 diabetes mellitus are common in the black population of South Africa. The literature also shows that elevated blood glucose concentrations can lead to an increase in blood pressure and a blunted decline in nocturnal blood pressure. Therefore, the motivation for this study was to determine if blood glucose may play a role regarding the blunted nocturnal decline in blood pressure in African and Caucasian men. Aim The aim of this study was to investigate the relationship between a blunted nocturnal decline in blood pressure and blood glucose in African and Caucasian men. Methodology A comparative population study was preformed that consisted of 202 school teachers (101 African and 101 Caucasian) between the ages of 25–60 years from the North West Province, South Africa. Subjects were excluded if their body temperature was elevated, had a dependence or abuse of psychotropic substances, were regular blood donors and/or vaccinated in the previous three months. Ambulatory systolic (SBP) and diastolic blood pressure (DBP) were measured. Blood samples from the antebrachial vein were collected in sodium fluoride tubes to determine the serum glucose level and glycosylated hemoglobin A1c (HbA1c) percentage. Estimated average glucose (eAG) was determined from the percentage HbA1c by means of a regression formula. Means and proportions were compared by standard t–test and the chi–square test, respectively. Pearson correlations were used to determine unadjusted associations and multiple regression analysis to determine adjusted associations between variables. Results and Conclusion African men had an elevated HbA1c (p<0.001), eAG (p<0.001), nighttime SBP (p<0.001) and DBP (p<0.001). These results remained similar when non–dipping African and Caucasian men were compared. The Africans also smoked more (p=0.012), consumed more alcohol (p=0.049), had a higher percentage of non–dippers (p=0.054), HIV infected subjects (p<0.001) and a larger number of subjects that used anti–hypertensive medication (p=0.049). The unadjusted analysis showed positive correlations between all the blood pressure measurements and serum glucose, HbA1c and eAG in the African non–dipper men. While in the non–dipper Caucasian men, only daytime SBP and nighttime SBP (22:00–06:00) correlated positively with serum glucose, HbA1c and eAG. Furthermore, when viewing the relationship between carotid intima–media thickness (CIMT) and the blood pressure measurements in the African population, only nighttime (00:00– 04:00) SBP (r=0.581, p<0.001) and DBP (r=0.566, p<0.001) showed positive associations. After adjustments were made for age and body mass index the associations between the various blood pressure measurements and blood glucose disappeared in the non–dipper Caucasian men. However, in the non–dipper African men both nighttime (22:00–06:00) SBP and (00:00– 04:00) SBP showed positive correlations with serum glucose, HbA1c and eAG. After full adjustments (age, BMI, smoking, alcohol intake, physical activity, C–reactive protein and baroreceptor sensitivity) were made, nighttime (00:00–04:00) SBP was the only measure of blood pressure that correlated positively with HbA1c (p=0.069) and eAG (p<0.001) in the nondipper African men. No significant relationships were found for Caucasian men. Furthermore, to determine if the association between nighttime (00:00–04:00) SBP and eAG were independent of CIMT, we adjusted for CIMT. By doing so the positive association between SBP and eAG remained significant in the non–dipper African men (R2=0.617; =0.438; p=0.008) and nonsignificant in the non–dipper Caucasian men (R2=0.423; =0.169; p=0.33). However, the relationship between CIMT and eAG disappeared when we adjusted for SBP, suggesting that the SBP and eAG relationship drives CIMT. In conclusion, the association between the early morning SBP (00:00–04:00) and the blood glucose in non–dipping African men suggests that the blunted decline in nocturnal blood pressure during the early morning hours is associated with chronically elevated blood glucose. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2011.

Motivation: Recently, with urbanisation becoming an increasing trend, the African population have been introduced to the westernised lifestyle. This contributed to severe health implications and a rapid increase in cardiovascular morbidity and mortality in the African population. In South Africa and other sub–Saharan African countries, the prevalence of cardiovascular disease is increasing rapidly. The African population is thus regarded as a high risk group, and we deem it necessary and important to investigate additional possible cardiovascular risk markers in the attempt to improve the diagnosis of cardiovascular diseases and the treatment thereof. We investigate double product as a possible cardiovascular risk marker in African and Caucasian men from South Africa. Recent studies have suggested that increased double product values might be an independent predictor of cardiovascular morbidity and mortality. However, investigations on double product and endorgan damage are limited in this population group. The strength of associations between double product and various measurements of end–organ damage, including intima–media thickness, left ventricular hypertrophy and albumin–to–creatinine ratio, are compared with the associations between the more traditional risk factor, systolic blood pressure, and the measurements of end–organ damage. Aim: The aim of this study is to investigate the usability of double product as a possible cardiovascular risk marker in African and Caucasian men from South Africa. Methodology: The manuscript presented in Chapter 3 made use of the cross–sectional SABPA (Sympathetic Activity and Ambulatory Blood Pressure in Africans) study, where 101 urbanised African and 101 Caucasian male school teachers from the North West Province of South Africa were recruited. Anthropometric measurements were taken in triplicate using standard methods. The cardiovascular measurements included 24–hour ambulatory blood pressure and electrocardiogram measurements. Double products were calculated as the product of 24–hour, daytime and night–time mean systolic blood pressure and mean heart rate values. The carotid intima–media thickness was also obtained following the prescribed protocols. A registered nurse collected blood samples and the biochemical measurements were performed by independent laboratories, blinded to the subject’s cardiovascular profile. Means and proportions were compared by standard t–tests and the x2 –tests, respectively. The association between markers of end–organ damage and double product were investigated using single, partial and multiple regression analyses. All p–values <= 0.05 were deemed significant. Results and conclusions: Results from this study showed that Africans displayed significantly higher systolic blood pressure values, heart rate values and subsequent double product values compared to the Caucasians. Despite these significant differences, double product only showed borderline significant correlations with the markers of end–organ damage in African men, while no correlations were evident in Caucasian men. In African men, systolic blood pressure displayed stronger and significant correlations with intimamedia thickness, left ventricular hypertrophy, and albumin–to–creatinine ratio than double product. These findings suggest that double product may not be a good marker of increased risk for end–organ damage and subsequent cardiovascular–related mortality. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2011.

Motivation Hypertension and type 2 diabetes mellitus are common in the black population of South Africa. The literature also shows that elevated blood glucose concentrations can lead to an increase in blood pressure and a blunted decline in nocturnal blood pressure. Therefore, the motivation for this study was to determine if blood glucose may play a role regarding the blunted nocturnal decline in blood pressure in African and Caucasian men. Aim The aim of this study was to investigate the relationship between a blunted nocturnal decline in blood pressure and blood glucose in African and Caucasian men. Methodology A comparative population study was preformed that consisted of 202 school teachers (101 African and 101 Caucasian) between the ages of 25–60 years from the North West Province, South Africa. Subjects were excluded if their body temperature was elevated, had a dependence or abuse of psychotropic substances, were regular blood donors and/or vaccinated in the previous three months. Ambulatory systolic (SBP) and diastolic blood pressure (DBP) were measured. Blood samples from the antebrachial vein were collected in sodium fluoride tubes to determine the serum glucose level and glycosylated hemoglobin A1c (HbA1c) percentage. Estimated average glucose (eAG) was determined from the percentage HbA1c by means of a regression formula. Means and proportions were compared by standard t–test and the chi–square test, respectively. Pearson correlations were used to determine unadjusted associations and multiple regression analysis to determine adjusted associations between variables. Results and Conclusion African men had an elevated HbA1c (p<0.001), eAG (p<0.001), nighttime SBP (p<0.001) and DBP (p<0.001). These results remained similar when non–dipping African and Caucasian men were compared. The Africans also smoked more (p=0.012), consumed more alcohol (p=0.049), had a higher percentage of non–dippers (p=0.054), HIV infected subjects (p<0.001) and a larger number of subjects that used anti–hypertensive medication (p=0.049). The unadjusted analysis showed positive correlations between all the blood pressure measurements and serum glucose, HbA1c and eAG in the African non–dipper men. While in the non–dipper Caucasian men, only daytime SBP and nighttime SBP (22:00–06:00) correlated positively with serum glucose, HbA1c and eAG. Furthermore, when viewing the relationship between carotid intima–media thickness (CIMT) and the blood pressure measurements in the African population, only nighttime (00:00– 04:00) SBP (r=0.581, p<0.001) and DBP (r=0.566, p<0.001) showed positive associations. After adjustments were made for age and body mass index the associations between the various blood pressure measurements and blood glucose disappeared in the non–dipper Caucasian men. However, in the non–dipper African men both nighttime (22:00–06:00) SBP and (00:00– 04:00) SBP showed positive correlations with serum glucose, HbA1c and eAG. After full adjustments (age, BMI, smoking, alcohol intake, physical activity, C–reactive protein and baroreceptor sensitivity) were made, nighttime (00:00–04:00) SBP was the only measure of blood pressure that correlated positively with HbA1c (p=0.069) and eAG (p<0.001) in the nondipper African men. No significant relationships were found for Caucasian men. Furthermore, to determine if the association between nighttime (00:00–04:00) SBP and eAG were independent of CIMT, we adjusted for CIMT. By doing so the positive association between SBP and eAG remained significant in the non–dipper African men (R2=0.617; =0.438; p=0.008) and nonsignificant in the non–dipper Caucasian men (R2=0.423; =0.169; p=0.33). However, the relationship between CIMT and eAG disappeared when we adjusted for SBP, suggesting that the SBP and eAG relationship drives CIMT. In conclusion, the association between the early morning SBP (00:00–04:00) and the blood glucose in non–dipping African men suggests that the blunted decline in nocturnal blood pressure during the early morning hours is associated with chronically elevated blood glucose. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2011.

Motivation: Recently, with urbanisation becoming an increasing trend, the African population have been introduced to the westernised lifestyle. This contributed to severe health implications and a rapid increase in cardiovascular morbidity and mortality in the African population. In South Africa and other sub–Saharan African countries, the prevalence of cardiovascular disease is increasing rapidly. The African population is thus regarded as a high risk group, and we deem it necessary and important to investigate additional possible cardiovascular risk markers in the attempt to improve the diagnosis of cardiovascular diseases and the treatment thereof. We investigate double product as a possible cardiovascular risk marker in African and Caucasian men from South Africa. Recent studies have suggested that increased double product values might be an independent predictor of cardiovascular morbidity and mortality. However, investigations on double product and endorgan damage are limited in this population group. The strength of associations between double product and various measurements of end–organ damage, including intima–media thickness, left ventricular hypertrophy and albumin–to–creatinine ratio, are compared with the associations between the more traditional risk factor, systolic blood pressure, and the measurements of end–organ damage. Aim: The aim of this study is to investigate the usability of double product as a possible cardiovascular risk marker in African and Caucasian men from South Africa. Methodology: The manuscript presented in Chapter 3 made use of the cross–sectional SABPA (Sympathetic Activity and Ambulatory Blood Pressure in Africans) study, where 101 urbanised African and 101 Caucasian male school teachers from the North West Province of South Africa were recruited. Anthropometric measurements were taken in triplicate using standard methods. The cardiovascular measurements included 24–hour ambulatory blood pressure and electrocardiogram measurements. Double products were calculated as the product of 24–hour, daytime and night–time mean systolic blood pressure and mean heart rate values. The carotid intima–media thickness was also obtained following the prescribed protocols. A registered nurse collected blood samples and the biochemical measurements were performed by independent laboratories, blinded to the subject’s cardiovascular profile. Means and proportions were compared by standard t–tests and the x2 –tests, respectively. The association between markers of end–organ damage and double product were investigated using single, partial and multiple regression analyses. All p–values <= 0.05 were deemed significant. Results and conclusions: Results from this study showed that Africans displayed significantly higher systolic blood pressure values, heart rate values and subsequent double product values compared to the Caucasians. Despite these significant differences, double product only showed borderline significant correlations with the markers of end–organ damage in African men, while no correlations were evident in Caucasian men. In African men, systolic blood pressure displayed stronger and significant correlations with intimamedia thickness, left ventricular hypertrophy, and albumin–to–creatinine ratio than double product. These findings suggest that double product may not be a good marker of increased risk for end–organ damage and subsequent cardiovascular–related mortality. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2011.