No / Physical inactivity causes approximately 17% of premature mortality in the UK. Walking offers a promising method for lowering risk of cardiovascular disease at population level, though a recent synthesis of evidence is lacking. This study aimed to conduct a meta-analysis of randomised controlled trials that have assessed the effect of walking on risk factors for cardiovascular disease in previously inactive adults. We searched PubMed, Web of Science, ScienceDirect, and the Cochrane Central Register of Controlled Trials for studies published in English between Jan 1, 1970, and May 31, 2012, using the following search terms: "walking", "exercise", "health", and "cardiovascular risk". Two authors identified randomised controlled trials of interventions (>4 weeks' duration) that included at least one group with walking as the only treatment and a comparator no-exercise group. Participants were inactive but otherwise healthy at baseline. Pooled results were reported as weighted mean treatment effects and 95% CIs in a random effects model. 32 articles reported the effects of walking interventions on risk factors for cardiovascular disease in participants aged 30–83 years. Mean length of interventions was 18·7 weeks (range 8–52). Duration of walking was 20–60 min on 2–7 days per week. Walking interventions reduced systolic and diastolic blood pressure (−3·6 mm Hg, 95% CI −5·19 to −1·97; −1·5 mm Hg, −2·83 to −0·26). Interventions also improved waist circumference (−1·5 cm, −2·34 to −0·68), weight (−1·4 kg, −1·75 to −1·00), body fat (−1·2%, −1·70 to −0·73), and body-mass index (BMI) (−0·5 kg/m2, −0·72 to −0·35). Walking improved aerobic fitness (3·2 mL/kg per min, 95% CI 2·57 to 3·80) but did not alter blood lipids. Significant heterogeneity (I2 statistic) was noted for aerobic fitness, BMI, weight, and percentage body fat. Many studies did not provide sufficient information to make firm judgments about risk of bias. These findings support the important role of walking in physical activity for health promotion. Health professionals involved in the primary prevention of cardiovascular disease should prescribe walking confident of the benefits it can provide in fitness, blood pressure, and adiposity. / Mary Immaculate College Research Directorate Seed Funding Scheme

Thesis (M.S.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-01

The effects of space irradiation on the cardiovascular systems remain a great mystery. After conducting studies on survivors of the atomic bomb, radiotherapy as a treatment for cancer and other diseases, and health data of astronauts who have participated in short and long duration space missions, the overall conclusion is that ionizing irradiation of any type results in cardiovascular damage. Problems manifest decades after irradiation exposure and the accumulating health complications have led to fatalities. However, little is known about space irradiation and how it affects our bodies. Predictive models that were developed to date were created based on events that have occurred on earth. National Aeronautics and Space Administration (NASA) plans for manned missions to the Moon and Mars in the near future. There is a great need for ground-based studies about the effects of cosmic irradiation on the human body. We examined molecular pathways in the heart tissue of adult 7-9 months old mice, an equivalent of middle-age for astronauts (35-55), after receiving a single low dose full body of either 56Fe (iron) or 1H (proton) irradiation + aging of 1, 3, and 10 months. We also investigated mice after 56Fe or 1H irradiation + aging of 1, 3, and 10 months, and 3 days after an induced acute myocardial infarct (AMI). Western blot analyses were performed for proteins involved in cardiac function and cardiac recovery. Results indicated that 56Fe irradiation impaired cardiac function significantly during aging and continued to worsen with age. AMI results were less straightforward. The younger, 56Fe irradiated mice revealed a significant decrease in the expression of proteins associated with survival of cardiac tissue. The older, 1H irradiated mice group revealed a significantly decreased expression of proteins associated with survival of cardiac tissue. The 10 month 56Fe irradiated mice did not show compensatory mechanisms and the cardiac protein expression levels were attributed to aging. While the 10 month 1H irradiated mice compensated and required less repair activation.

Cardiovascular diseases (CVD) are the leading cause of death worldwide and the atherosclerotic process that precedes CVD starts during childhood. Physical activity (PA), cardiorespiratory fitness (CRF) and exercise are well known as preventive strategies for CVD. One possible mechanism for such prevention is the role of PA, CRF and exercise on the arterial and autonomic systems. The aim of this thesis was to investigate using observational and experimental studies the role of PA, CRF and exercise on the autonomic and arterial systems of healthy adolescents. Chapter 4 systematically reviewed observational cross-sectional studies and provided level one evidence for a significant and positive association between resting parasympathetic function and moderate-to-vigorous PA in youth. Chapter 4 also indicated that gaps exist in the literature such as the associations between PA intensities, CRF and heart rate variability (HRV). These findings were furthered in Chapter 5 which showed that vigorous PA (VPA) and moderate PA (MPA) were positively related with HRV at rest and cardiac autonomic recovery following exercise in adolescents. In Chapter 6 a high-fat meal was used aiming to increase CVD risk in the postprandial state, and it was demonstrated that PA levels and CRF are not significantly associated with postprandial HRV and arterial stiffness in adolescents. Aiming to investigate possible associations between the vascular and autonomic system, measures of baroreflex sensitivity (BRS) were introduced. Chapter 7 showed that BRS and its autonomic and vascular components present a between-day coefficient of variation lower than 20% whilst within day coefficient of variations were lower than 34% in adolescents. In Chapter 8 acutely following high- and moderate-intensity interval exercise a decrease in blood pressure was observed concomitantly with decreases in BRS. This was mainly mediated by decreases in the autonomic modulation, and the duration of the decreases in blood pressure was higher following high-intensity interval exercise. Chapter 9 extended these findings by demonstrating that the changes in BRS following the ingestion of glucose was not altered by the high or moderate-intensity exercise performed before glucose ingestion. Chapter 10 showed that following four weeks of high-intensity exercise interval training no improvements were observed in BRS and its autonomic and vascular components at rest or acutely following exercise. Collectively, the present thesis contributes significantly to the literature by providing novel evidence in healthy adolescents on the role of PA intensities, CRF and exercise on the arterial and autonomic systems at rest, acutely following exercise and in the postprandial state. The results gathered in this thesis indicate potential of the autonomic and vascular function as targets of CVD risk reduction in youth.

Heart disease is the leading cause of death among African Americans. Despite advances in treatment modalities, based on better understanding of the disease's pathology and access to health care, African Americans continue to die from heart disease at rates significantly higher than other races. The available literature on cardiovascular disease among African Americans does not adequately explore how social support affects heart health in this group. The purpose of this study was to examine the effects of social support on cardiac recurrence among African American adults. Cohen's ISEL support system variables: tangible, appraisal, belonging, and self-esteem; and five demographic variables: age, marital status, educational level, household income, and gender provided the conceptual/methodological base for data collection and analysis. The sample consisted of 83 African American men and women ages 22 to 84 that had experienced at least one cardiac event. Chi-square analysis showed a positive correlation between marital status and cardiac recurrence. Results suggest that living alone may increase an individual's chances of having a second cardiac event. Social change implications include (a) identification of essential social support elements and tailored treatment plans for heart patient and caregiver in order to promote better heart health outcomes for African Americans living with someone or alone; and (b) policy change that fosters effective prevention and treatment.

Although cardiovascular disease (CVD) does not occur until mid to late life for most adults, the presence of risk factors for CVD, such as high blood pressure (BP) and high cholesterol, has increased dramatically in young adults. Type D personality consists of two personality traits, negative affectivity (NA) and social inhibition (SI), and has repeatedly been shown to be an independent predictor of hard medical outcomes (e.g. morbidity and mortality) in cardiac patients. The present study examined the relationships between Type D personality (high NA and high SI), coping strategies, and physiological markers of cardiovascular health in a sample of non-medical, university students. Measures of cardiovascular risk included high frequency heart rate variability (HF HRV), calculated LDL cholesterol, and systolic blood pressure (SBP). Regression analyses revealed that higher use of social supportive coping was a significant predictor of calculated LDL cholesterol. Social supportive coping was also shown to moderate the relationship between Type D personality and HF HRV. Interventions that target psychological and physiological mechanisms associated with CVD are well developed. Clear identification of young adults who are at risk of developing CVD is necessary to intervene in a manner that could potentially save lives. Additional systematic research, especially if it is longitudinal, will help to clarify the ability of Type D personality and coping to predict CVD.

Motivation: The different coping styles used to respond to psychosocial stress have been linked to the development of cardiovascular disease (CVD). However, the manner in which the cardiovascular system is influenced differs between the coping styles. Of the different coping styles, defensive active coping (AC) has been shown to be the most detrimental to cardiovascular health. This is worsened by augmented α-adrenergic cardiac responses found in Africans. Furthermore, many studies have found that the prevalence of hypertension and other CVDs is much higher in urban Africans when compared to their Caucasian counterparts. This can be attributed to certain lifestyle changes implemented by Africans in the transition that occurs with urbanization, where they are forced to cope with an urban-dwelling lifestyle. One of these lifestyle factors, which also poses as a cardiovascular risk factor, is increased usage and in some cases abuse of alcohol. Certain discrepancies exist between ethnicities with regard to the metabolism of alcohol, which influences the effect of alcohol on the individual. Alcohol usage as a possible manner of coping has been supported in many instances, but the interdependent effects of alcohol usage and AC as cardiovascular risk factors has only been found in African men. Further investigation is needed to determine if coping and alcohol abuse act in tandem only in African men, or also in other ethnic or sex groups. What also needs to be discussed is whether the inconsistencies between ethnicities regarding alcohol metabolism, plays a part in the development of CVD in a bi-ethnic gender cohort. Objectives: The main aims of this study were to determine 1) receiver operated characteristic (ROC) ethnic specific cut points of alcohol usage in the prediction of ambulatory hypertension, and 2) to assess if these cut points in defensive active groups revealed increased cardiometabolic risk in a bi-ethnic sex cohort, and if so, whether the increased risk will be associated with a specific race or sex group? Methodology: This sub-study forms part of the SABPA (Sympathetic activity and Ambulatory Blood Pressure in Africans) study, conducted from 2008 to 2009. After exclusion criteria were applied, our bi-ethnic sex cohort consisted of 390 individuals. These participants were all from the Kenneth Kaunda Education District of the North-West province in South Africa, and they all signed informed consent prior to participation. The SABPA study was approved by the Ethics Review Board of the North-West University, with additional ethical approval for this sub-study. All procedures in this study complied with the guidelines of the Declaration of Helsinki. Each participant completed a psychosocial battery supervised by registered clinical psychologists, and information regarding their medication use and medical history was obtained. They also completed the Coping Style Indicator questionnaire which was developed by Amirkhan, to identify the coping style habitually used. Ambulatory blood pressure and ECG measurements were recorded for a 24h period with the Cardiotens CE120®. Anthropometric measurements were performed by ISAK (International Society for the Advancement of Kinanthropometry) level 2 accredited anthropometrists using calibrated instruments. Out of this, the body surface area were calculated. The physical activity of each participant was determined by use of the Actical® omnidirectional accelerometer. Resting blood samples were collected by a registered nurse. The following blood serum levels were determined: gamma-glutamyl transferase (γ-GT) as a marker for alcohol usage, C-reactive protein, cholesterol, high density lipoprotein, triglycerides, cotinine, reactive oxygen species and glycated haemoglobin levels. All statistical analyses were done using Statistica version 12.0. Descriptive statistics were conducted to state the baseline characteristics of the entire group, while Chi-square (X2) tests were used to determine prevalence for medications and pathology. ROC analyses were computed to establish a cut point for γ-GT predicting ambulatory hypertension in each ethnicity as well as in the entire group. Independent t-tests identified confounders, after which two-way analysis of covariance (ANCOVA) tests were computed to test a 2 x 2 main effects interaction (race x γ-GT cut points) for all cardiometabolic risk markers and to compare the different ethnic groups. ANCOVAs were then performed in the ethnic groups with high γ-GT as well as in above mean AC for the graphs that followed. Lastly, odds ratios (OR‟s) with 95% confidence intervals (CI‟s) were calculated in several models to highlight the odds of high alcohol intake to predict ambulatory hypertension in the ethnic-sex groups as well as in AC ethnic-sex groups. Significant values were noted as p ≤ 0.05. Results: The Africans revealed higher cardiometabolic risk markers, above mean defensive active coping, seeking social support with less avoidance coping scores. ROC analyses revealed that ambulatory hypertension commences at a much higher level of γ-GT in the Africans [55.7U/l (AUC=0.69; 95% CI: 0.61; 0.76)] with sensitivity /specificity of 47%/83% compared to the Caucasians [19.5U/l (AUC=0.747; 95% CI: 0.68; 0.82)] with sensitivity/specificity of 70%/73%. The Caucasians thus reveal an increased sensitivity for alcohol ingestion at a much lower γ-GT cut point compared to the Africans. When comparing ethnic specific ROC cut point groups, we found that certain levels of cardiometabolic risk factors such as C-reactive protein, systolic blood pressure, waist circumference and silent ischemic events, were significantly higher in the African group, especially in above mean AC groups. Out of the Africans with high γ-GT levels, 73% used the AC style, suggesting hypervigilant AC coping and increased CVD risk in Africans. Clinical significance was determined by OR‟s, which demonstrated that high γ-GT levels in AC African men predicted ambulatory hypertension with an OR of 7.37 (95% CI: 6.71 – 8.05). Higher alcohol intake predicted ambulatory hypertension in AC Caucasians with an OR of 2.77 (95% CI: 2.31 – 3.23) in men and 6.42 (95% CI: 5.85 – 7.0) in women respectively. Conclusion: γ-GT cut-points in defensive active groups revealed increased cardiometabolic risk markers in a bi-ethnic sex cohort. A possible hypermetabolic state in African men may initially protect them against CVD morbidity but if chronically challenged with no forthcoming social support, CVD risk is imminent. / MSc (Physiology), North-West University, Potchefstroom Campus, 2015

Motivation: The different coping styles used to respond to psychosocial stress have been linked to the development of cardiovascular disease (CVD). However, the manner in which the cardiovascular system is influenced differs between the coping styles. Of the different coping styles, defensive active coping (AC) has been shown to be the most detrimental to cardiovascular health. This is worsened by augmented α-adrenergic cardiac responses found in Africans. Furthermore, many studies have found that the prevalence of hypertension and other CVDs is much higher in urban Africans when compared to their Caucasian counterparts. This can be attributed to certain lifestyle changes implemented by Africans in the transition that occurs with urbanization, where they are forced to cope with an urban-dwelling lifestyle. One of these lifestyle factors, which also poses as a cardiovascular risk factor, is increased usage and in some cases abuse of alcohol. Certain discrepancies exist between ethnicities with regard to the metabolism of alcohol, which influences the effect of alcohol on the individual. Alcohol usage as a possible manner of coping has been supported in many instances, but the interdependent effects of alcohol usage and AC as cardiovascular risk factors has only been found in African men. Further investigation is needed to determine if coping and alcohol abuse act in tandem only in African men, or also in other ethnic or sex groups. What also needs to be discussed is whether the inconsistencies between ethnicities regarding alcohol metabolism, plays a part in the development of CVD in a bi-ethnic gender cohort. Objectives: The main aims of this study were to determine 1) receiver operated characteristic (ROC) ethnic specific cut points of alcohol usage in the prediction of ambulatory hypertension, and 2) to assess if these cut points in defensive active groups revealed increased cardiometabolic risk in a bi-ethnic sex cohort, and if so, whether the increased risk will be associated with a specific race or sex group? Methodology: This sub-study forms part of the SABPA (Sympathetic activity and Ambulatory Blood Pressure in Africans) study, conducted from 2008 to 2009. After exclusion criteria were applied, our bi-ethnic sex cohort consisted of 390 individuals. These participants were all from the Kenneth Kaunda Education District of the North-West province in South Africa, and they all signed informed consent prior to participation. The SABPA study was approved by the Ethics Review Board of the North-West University, with additional ethical approval for this sub-study. All procedures in this study complied with the guidelines of the Declaration of Helsinki. Each participant completed a psychosocial battery supervised by registered clinical psychologists, and information regarding their medication use and medical history was obtained. They also completed the Coping Style Indicator questionnaire which was developed by Amirkhan, to identify the coping style habitually used. Ambulatory blood pressure and ECG measurements were recorded for a 24h period with the Cardiotens CE120®. Anthropometric measurements were performed by ISAK (International Society for the Advancement of Kinanthropometry) level 2 accredited anthropometrists using calibrated instruments. Out of this, the body surface area were calculated. The physical activity of each participant was determined by use of the Actical® omnidirectional accelerometer. Resting blood samples were collected by a registered nurse. The following blood serum levels were determined: gamma-glutamyl transferase (γ-GT) as a marker for alcohol usage, C-reactive protein, cholesterol, high density lipoprotein, triglycerides, cotinine, reactive oxygen species and glycated haemoglobin levels. All statistical analyses were done using Statistica version 12.0. Descriptive statistics were conducted to state the baseline characteristics of the entire group, while Chi-square (X2) tests were used to determine prevalence for medications and pathology. ROC analyses were computed to establish a cut point for γ-GT predicting ambulatory hypertension in each ethnicity as well as in the entire group. Independent t-tests identified confounders, after which two-way analysis of covariance (ANCOVA) tests were computed to test a 2 x 2 main effects interaction (race x γ-GT cut points) for all cardiometabolic risk markers and to compare the different ethnic groups. ANCOVAs were then performed in the ethnic groups with high γ-GT as well as in above mean AC for the graphs that followed. Lastly, odds ratios (OR‟s) with 95% confidence intervals (CI‟s) were calculated in several models to highlight the odds of high alcohol intake to predict ambulatory hypertension in the ethnic-sex groups as well as in AC ethnic-sex groups. Significant values were noted as p ≤ 0.05. Results: The Africans revealed higher cardiometabolic risk markers, above mean defensive active coping, seeking social support with less avoidance coping scores. ROC analyses revealed that ambulatory hypertension commences at a much higher level of γ-GT in the Africans [55.7U/l (AUC=0.69; 95% CI: 0.61; 0.76)] with sensitivity /specificity of 47%/83% compared to the Caucasians [19.5U/l (AUC=0.747; 95% CI: 0.68; 0.82)] with sensitivity/specificity of 70%/73%. The Caucasians thus reveal an increased sensitivity for alcohol ingestion at a much lower γ-GT cut point compared to the Africans. When comparing ethnic specific ROC cut point groups, we found that certain levels of cardiometabolic risk factors such as C-reactive protein, systolic blood pressure, waist circumference and silent ischemic events, were significantly higher in the African group, especially in above mean AC groups. Out of the Africans with high γ-GT levels, 73% used the AC style, suggesting hypervigilant AC coping and increased CVD risk in Africans. Clinical significance was determined by OR‟s, which demonstrated that high γ-GT levels in AC African men predicted ambulatory hypertension with an OR of 7.37 (95% CI: 6.71 – 8.05). Higher alcohol intake predicted ambulatory hypertension in AC Caucasians with an OR of 2.77 (95% CI: 2.31 – 3.23) in men and 6.42 (95% CI: 5.85 – 7.0) in women respectively. Conclusion: γ-GT cut-points in defensive active groups revealed increased cardiometabolic risk markers in a bi-ethnic sex cohort. A possible hypermetabolic state in African men may initially protect them against CVD morbidity but if chronically challenged with no forthcoming social support, CVD risk is imminent. / MSc (Physiology), North-West University, Potchefstroom Campus, 2015

Cardiovascular disease (CVD) such as hypertension and stroke are serious illnesses that impact on the lives of millions all over the world, with 972 million (26% of the world’s population) suffering from hypertension in year 2000, and an estimated 1.56 billion to be affected by 2025. Hypertension, being one of the most common CVD is associated with the development of stroke, peripheral vascular diseases, myocardial infarction, renal failure as well as cardiac failure. Several studies have shown a seasonal correlation for both the systolic and diastolic blood pressure in mankind. A hypertension trial done by the Medical Research Council in the 1980s showed the average blood pressure being lower in summer than winter, and this difference was more significant in the elderly than the younger population. Other than seasonal variation, blood pressure (including hypertension prevalence) is also noted to correlate with latitude, being higher at places further away from the equator. Other cardiovascular related diseases such as stroke and acute coronary syndrome are also shown occur more frequently in winter. The morbidity and mortality of CVD could be due to various factors including diet, culture, race and social status, but within the United Kingdom, all cause mortality (with cerebral-vascular disease being the major one) correlates with latitude even after accounting for all known risk factors, with CVD risks highest in the north. We propose that this difference in cardiovascular mortality is caused by variations in ultraviolet exposure other than temperature. Known mechanisms of sunlight exposure that affect cardiovascular health include temperature and the ultraviolet B (UVB) mediated photolysis of 7-dehydrocholesterol in the skin to produce 1,25 dihydroxycholecalciferol (Vitamin D). UVB is however a potent skin carcinogen, and calculating risk-benefit ratios for exposure will be important. We believe that independently of vitamin D, nitric oxide plays an important role in blood pressure regulation and cardiovascular health, accounting for seasonal and latitude variation. In 1961, Furchgott demonstrated relaxation of rabbit aorta by irradiating them with ultraviolet light, and in later research he noted this effect is most significant in the ultraviolet A (UVA) spectrum. Recently, Mowbray showed a rich store of various nitro-species within human skin and Oplander showed a reduction of blood pressure in human after giving whole body UVA irradiation. We therefore hypothesize that independently of vitamin D, NO mediates the UVA induced beneficial effects on cardiovascular health. To support our hypothesis, in vivo as well as in vitro studies were conducted. We recruited a total of 63 healthy volunteers and monitored blood pressure, forearm blood flow as well as other cardiovascular parameters before and after UVA irradiation. Blood samples were also taken for the measurement of circulatory nitro-species. We have noted a significant reduction of blood pressure (from 84.5±1.76 to 81.33±1.37 mmHg) and increased forearm blood flow (1.95±0.28 to 2.94±0.47 mL/100mL of tissue/min) after UVA irradiation of human skin; simultaneously, we also noted a rise in circulatory nitrite (0.5±0.04 μM before irradiation to 0.72±0.04 μM) and a drop in circulatory nitrate (11.79±0.64 μM before irradiation and 8.99±0.4 μM). For us to further clarify the role of nitric oxide in different latitude, a monochromator machine that generates specific wavelength of light was been used to irradiate aqueous nitrite solution, and the total amount of nitric oxide release at different latitude was then calculated according to the irradiance of various wavelength across the globe. The results of our studies provide evidence suggesting that nitric oxide release induced by UVA irradiation of the skin can account for the difference in cardiovascular mortality and morbidity by latitude. The current public health advice of avoiding sun exposure to reduce the risk of developing skin cancer may need to be modified.

Background: Alcohol, marijuana and tobacco are the most common recreationally used substances in United States (US). However, unlike alcohol and tobacco, marijuana is an illicit substance. The increasing support for reclassification of marijuana as legal substance necessitates investigating its effect on health. These studies seek to examine the relationship of marijuana and tobacco with metabolic syndrome (a precursor of cardiovascular diseases - the primary cause of morbidities and mortalities). Method: Data from 2011 public-use linked mortality file of the National Center for Health Statistics, Centers for Disease Control and Prevention, and 2005-2006 & 2011-2012 US National Health and Nutrition Examination Survey was used to estimate the effect of marijuana and tobacco on metabolic syndrome. Odds ratios from logistic regression analyses were determined using four main diagnostic criteria for metabolic syndrome. Odds ratios were compared using: National Cholesterol Education Program Adult Treatment Panel III, World Health Organization, European Group for the study of Insulin Resistance and International Diabetes Federation definitions of metabolic syndrome. Hazard ratios (HRs) for cardiovascular mortality were estimated using cox proportional hazard regression. Results: Each year of marijuana use was associated with increased odds of metabolic syndrome [OR=1.05 (95% CI: 1.01, 1.09)] and hypertension [OR=1.04 (95% CI: 1.01, 1.07)]. Each additional year of cigarette smoking was associated with increased odds of hypertension [OR=1.03 (95% CI: 1.00, 1.06)] and hyperglycemia [OR=1.03 (95% CI: 1.01, 1.05)]. Adjusted HR for hypertension mortality for marijuana users compared to non-marijuana users was 3.42 (95% CI: 1.20, 9.79) and 1.04 (95% CI: 1.00, 1.07) for each year of marijuana use. Conclusion: Prolonged years of marijuana use was associated with increased odds of metabolic syndrome and hypertension irrespective of the criteria used to define metabolic syndrome. Our results also indicate that marijuana use is associated with increased risk for hypertension mortality. The association between prolonged use of marijuana and risk of cardiovascular morbidities and mortalities requires further investigation whilst developing global public health policies regarding legalization of marijuana use.