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The purpose of this study was to determine the association of age, gender, and cardiorespiratory fitness level upon normative heart rate and systolic blood pressure (SBP) responses per MET during the BSU/Bruce Ramp protocol. This research was delimited to 451 subjects, 201 men (mean age 46.5 ± 11.9 yrs) and 250 women (mean age 42.9 ± 11.4 yrs), low to moderate risk subjects. The majority of subjects were tested to enter the Ball State University Adult Physical Fitness Program. These subjects were tested using the BSU/Bruce Ramp protocol between 1992 and 1998.Multiple regression showed gender had a positive association upon submaximal SBP values. Gender's association with heart rate was negative between minute 3-6 and positive between minute 6-9. Age only had an association upon submaximal heart rate, which was negative. Cardiorespiratory fitness had a negative association upon SBP between minute 6-9 and a negative association with heart rate between minute 3-6.SBP increased 6.6 ± 4.4 and 6.0 ± 4.2 mmHg/MET between minute 3-6 for men and women, respectively. Analysis of variance demonstrated gender was not statistically significant between minute 3-6. SBP increased 4.7 ± 3.1 and 3.8 + 2.7 mmHg/MET between minute 6-9 for men and women, respectively. Gender was statisticallysignificant between minute 6-9 (p<.05). Heart rate increased 8.5 + 2.3 and 10.7 + 3.3 bpm/MET between minute 3-6 for men and women, respectively. Analysis of variance demonstrated gender was statistically significant between minute 3-6 (p<.05). The increase was 9.5 + 2.3 and 9.2 + 2.7 bpm/MET between minute 6-9 for men and women, respectively. Gender was not statistically significant between minute 6-9.In conclusion, this study demonstrated that the normative hemodynamic responses during the BSU/Bruce Ramp protocol are similar to submaximal normative data previously reported in the literature for incremental type protocols. / School of Physical Education

Class of 2010 Abstract / OBJECTIVES: The purpose of this study was to evaluate the accuracy of automated blood pressure machines located within community-based pharmacies. METHODS: A descriptive, prospective study was performed comparing blood pressure readings obtained from community-based automated blood pressure machines to readings from a mercury manometer for 2 different arm sizes. Mercury manometer readings were obtained using the standardized technique and a standard cuff recommended by the American Heart Association RESULTS: For the subject with the small arm size, the automated blood pressure machines reported systolic pressure readings that were, on average, 16.1 mmHg higher than those obtained manually by the researcher. The mean systolic and pressure readings for the subject with the medium arm size were not significantly different between the automated machine and manual manometer readings, and the diastolic pressure readings were modestly different. CONCLUSIONS: We found that automated blood pressure machines located within a sample of representative community pharmacies were neither accurate nor reliable. The accuracy of the readings are especially inaccurate for subjects with a smaller than average arm size.

Hypertension is the major cause of cardio-vascular diseases and contributes to 13.5% of premature deaths worldwide. With a 10–year risk to develop organ damages estimated at 30%, severe hypertension exposes even more patients to premature death. Severe hypertension is a type of hypertension with systolic blood pressure ≥ 180mmHg and/or diastolic blood pressure ≥ 110 mmHg that may present with or without symptoms/signs or target organ damages, and may be classified accordingly as asymptomatic (without symptoms/signs) severe hypertension, hypertension urgency (with symptoms/signs, no target organ damage) or hypertension emergency (with target organ damage). Hypertension urgency and hypertension emergency are considered hypertension crisis. This study aimed to establish the socio-demographic and clinical characteristics of the patients who presented with severe hypertension at the Emergency Departments of two private hospitals of the Netcare Management (Pty) Limited in Johannesburg during the period from the 1st of January 2010 to 30th April 2011. These patients presumably receive quality health care and may not be expected to develop severe hypertension. Therefore, this study would contribute to efforts to identify patients at risk and those who may benefit from preventive measures. The methodology of this study was a retrospective, transversal and comparative study. One thousand and forty-two patients were included in the study. All of these participants had a medical aid cover or were able to pay for medical consultation at a private hospital. Data were collected from an electronic database, the Medibank™, and from manual patients’ registers kept in each hospital’s Emergency Department. Severe hypertension was found among 1.7% of all patients who presented to the studied emergency departments. Only 817 patients were classified in the different subtypes of SH. Asymptomatic severe hypertension was the most common (83.4%) type of severe hypertension and hypertension emergency was the least common (4.8%). At Mulbarton Hospital, 50.2% of severe hypertension patients were male and at Linksfield Hospital, 60.3% were female. Male patients were younger than female patients. White patients and elderly were mostly affected by severe hypertension in the studied population. Systolic blood pressures were similar among the different races and genders. Black patients had higher diastolic blood pressure compared to white patients. White patients were older and may have had a tendency of isolated systolic hypertension. Overall, the most common symptoms/signs in hypertension urgency were chest pains (46.4%), headache (34.0%) and epistaxis (11.3%). The most common target organ damages in hypertension emergency were stroke (58.9%), left ventricular failure/congestive cardiac failure (28.2%) and seizures (12.8%). None of the studied characteristics could be claimed predictors of hypertension crisis. Also, there was no association between seasons and days of presentation and onset of severe hypertension in each hospitals. Further studies are required to include other factors that are known to affect the occurrence of severe hypertension, such as co-morbidities, smoking, alcohol intake and poor adherence to medication by known hypertensive patients. Also, risk factors contributing to the occurrence of SH among younger black patients need to be analysed.

Ph.D., Faculty of Health Sciences, University of the Witwatersrand, 2011 / In groups of African ancestry, who have a high prevalence of “salt-sensitive, low-renin” hypertension, there is considerable uncertainty as to relevance of the renin-angiotensin-aldosterone system (RAAS) in the pathophysiology of primary hypertension. In the present thesis I explored the possibility that the RAAS, through interactions with environmental effects, contributes to blood pressure (BP) in this ethnic group. After excluding participants with aldosterone-to-renin ratios (ARR) above the threshold for primary aldosteronism, in 575 participants of African ancestry, I demonstrated that with adjustments for confounders, an interaction between ARR and urinary Na+/K+ (and index of salt intake obtained from 24-hour urine samples) was independently associated with BP (p<0.0001). This effect was accounted for by interactions between serum aldosterone concentrations and urinary Na+/K+ (p<0.0001), but not between plasma renin concentrations and urinary Na+/K+ (p=0.52). The interaction between ARR and urinary Na+/K+ translated into a marked difference in the relationship between urinary Na+/K+ and BP in participants above and below the median for ARR (p<0.0001 for a comparison of the relationships). Having demonstrated that circulating aldosterone concentrations may account for a substantial proportion of the relationship between salt intake and BP in this community sample, I subsequently assessed whether genetic factors contribute toward serum aldosterone concentrations. In 153 randomly selected nuclear families of African ancestry consisting of 448 participants without primary aldosteronism, with, but not without adjustments for plasma renin concentrations, independent correlations were noted for iii serum aldosterone concentrations between parents and children (p<0.05), with parent-child partial correlation coefficients being greater than those for father-mother relationships (p<0.05). Furthermore, after, but not before adjustments for plasma renin concentrations, serum aldosterone concentrations showed significant heritability (h2=0.25±0.12, p<0.02). No independent relationships between RAAS gene polymorphisms and serum aldosterone concentrations were observed. I also aimed to assess whether RAAS genes modify the relationship between cigarette smoking and BP in groups of African descent. However, as the impact of mild smoking on BP is uncertain, and in the community studied only 14.5% smoked and the majority of smokers were mild smokers (mean=7.4±4.6 cigarettes per day) in 689 randomly participants I initially assessed the relationship between smoking habits and out-of-office BP. In this regard, current smokers had higher unadjusted and multivariate adjusted 24-hour systolic/diastolic BP (SBP/DBP in mm Hg) (p<0.005-p<0.0005) than non-smokers, effects that were replicated in sex-specific groups, non-drinkers, and in the overweight and obese. Current smoking was second only to age and at least equivalent to body mass index in the quantitative impact on out-of-office BP and the risk of uncontrolled out-of-office BP was increased in smokers as compared to non-smokers. Thus, despite minimal effects on in-office BP, predominantly mild current smoking was independently associated with an appreciable proportion of out-of-office BP in a community of African ancestry. In 652 participants I subsequently assessed whether the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism accounts for the strong relationships between predominantly mild smoking and out-of-office BP. After iv appropriate adjustments, an interaction between ACE DD genotype and current cigarette smoking, or the number of cigarettes smoked per day was independently associated with 24-hour and day diastolic BP (DBP) (p<0.05-0.005). This effect translated into a relationship between smoking and out-of-office BP or the risk for uncontrolled out-of-office BP only in participants with the DD as compared to the ID + II genotypes. In conclusion therefore, I afford evidence to suggest that in groups of African ancestry, aldosterone, within ranges that cannot be accounted for by the presence of primary aldosteronism, modifies the relationship between salt intake and BP, and that genetic factors account for the variation in serum aldosterone concentrations in this group. Furthermore, I show that the ACE gene modifies the relationship between smoking and out-of-office BP and hence accounts for even predominantly mild smoking producing a marked and clinically important effect on out-of-office BP. The present thesis therefore provides further evidence in favour of an important pathophysiological role for the RAAS in contributing toward BP in groups of African ancestry.

Hypertension is a major risk factor for cardiovascular disease in both developed and developing countries. Blood pressure normally decreases at night and a number of studies have indicated that a reduced nocturnal decline in blood pressure (BP) increases the risk for cardiovascular disease. Nocturnal decreases in BP are attenuated in subjects of African as compared to European descent, but the mechanisms of this effect require clarity. In the present study I attempted to identify potentially modifiable factors that contribute toward nocturnal decreases in BP in a random sample of 171 nuclear families comprising 438 black South Africans living in Soweto. Prior studies have suggested that adiposity and salt intake may determine nocturnal decreases in BP. Adiposity and salt intake were considered to be potentially important factors to consider in the present study as 67% of the group studied were either overweight or obese and in 291 subjects that had complete 24-hour urine collections (used to assess salt intake) and BP measurements, Na+ and K+ intake was noted to be considerably higher and lower respectively than the recommended daily allowance in the majority of people. Moreover, a lack of relationship between either hypertension awareness and treatment and Na+ and K+ intake suggested that current recommendations for a reduced Na+ intake and increased K+ intake in hypertensives do not translate into clinical practice in this community. In order to assess whether adiposity or salt intake are associated with nocturnal decreases in BP in this community, ambulatory BP monitoring was performed using Spacelabs model 90207 oscillometric monitors. Of the 438 subjects recruited, 314 had ambulatory BP measurements that met pre-specified quality criteria (more than 20 hours of recordings and more than 10 and 5 readings for the computation of daytime and nighttime means respectively). To identify whether adiposity or salt intake are associated with a reduced nocturnal decline in BP, non-linear regression analysis was employed with indices of adiposity and urinary Na+ and K+ excretion rates and urine Na+: K+ ratios included in the regression model with adjustments for potential confounders. Neither body mass index, skin-fold thickness, waist circumference, waist-to hip ratio, urinary Na+ and K+ excretion rates, nor urine Na+: K+ ratios were associated with nocturnal decreases in systolic and diastolic BP. Indices of adiposity were however associated with 24 hour ambulatory systolic and diastolic BP. Unexpectedly, female gender was associated with an attenuated nocturnal decrease in BP. In conclusion, in the first random, community-based sample with large sample sizes conducted with ambulatory BP monitoring in Africa, I found that neither adiposity nor salt intake are associated with a reduced nocturnal decline in BP. The lack of association between either salt intake or adiposity and nocturnal decreases in BP was despite a high prevalence of excessive adiposity in the community, as well as clear evidence that current recommendations for a reduced Na+ intake and increased K+ intake do not translate into clinical practice in this community. Thus, based on this study, the question arises as to whether primordial prevention programs targeting excess adiposity or inappropriate salt intake are likely to modify nocturnal decreases in BP, in urban, developing communities of African ancestry in South Africa. However, unexpectedly I noted that females were more likely to have an attenuated nocturnal decrease in BP. Thus further work is required to explain this finding.