Browsing by Subject "Cardiovascular disease"

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Byheart : a personalized heart-health companion
(2018-05) Barve, Ajinkya S.; Gorman, Carma
The number of people living with some form of chronic cardiovascular disease is growing worldwide. Studies have shown that people often lack sufficient information about their heart condition. This issue can be addressed by improving heart health literacy and by helping those with a chronic heart disease to understand and manage their condition so that they are empowered to make informed decisions regarding their health. Although many existing online resources provide heart-health-related information, most fall short on providing actionable content—namely, nudges, prompts, reminders, and tracking features—that would help heart patients and their families make that information actionable in ways that would improve health outcomes. Byheart is a personalized heart health web and mobile companion that helps heart patients and their caregivers understand, track, and more effectively manage chronic heart conditions.
A closed-loop multi-scale model of the cardiovascular system for evaluation of ventricular assist devices
(2007-05) Gohean, Jeffrey Robert; Moser, Robert deLancey
Cardiovascular disease is the number one killer in America as well as most Westernized countries and is the primary cause of congestive heart failure. Over five million Americans are currently living with heart failure and over half a million more are diagnosed each year. Mechanical assist devices are used as a bridge to transplant and as destination therapy in people with severe heart failure. While these devices are highly engineered, their optimal implant configuration and settings have yet to be determined. A computational model has been developed in order to study the effect of these assist devices on the cardiovascular system. The model is multi-dimensional, making use of a quasi-one-dimensional arterial tree model for the systemic arteries coupled with lumped parameter models for the venous return and pulmonary circulation. In addition, a dynamic aortic valve model has been developed to account for the brief period of backflow at the onset of diastole and a complex impedance representation of the small arteries has been used as the outflow boundary condition to the arterial tree to account for phase-lag and wave reflection. The model produces physiologically consistent pressure and flow curves for both healthy and disease states, and preliminary validation has been performed against clinical data from patients under various levels of mechanical assist.
The contribution of whole blood viscosity in assessment of vascular function
(2011-05) Parkhurst, Kristin Louise; Tanaka, Hirofumi, Ph. D.; Farrar, Roger
Although blood viscosity is an important component in determining vascular function, it is often assumed constant. Emerging evidence linking individual differences in viscosity to cardiovascular disease casts doubt on this assumption. The purpose of this study was to determine the contribution of whole blood viscosity to key measures of vascular function. To address this aim as comprehensively as possible, first, whole blood viscosity was compared with traditional risk factors for cardiovascular disease. Then flow-mediated dilation (FMD), carotid-femoral pulse wave velocity (cfPWV), and carotid artery compliance were calculated either with or without blood viscosity taken into account. Lastly, we tested whether the removal of blood viscosity could influence well-established associations between age and vascular function. Blood viscosity and vascular function were measured in 97 adults ranging in age from 18-63 years. No significant differences were observed between whole blood viscosity and traditional risk factors for cardiovascular disease. Whole blood viscosity was not significantly correlated with FMD, cfPWV, and carotid compliance. As expected, age was positively correlated with cfPWV (r=0.65, p<0.001) and negatively correlated with FMD (r=-0.21, p<0.05) and carotid compliance (r=-0.45, p<0.01). Even after controlling for viscosity, these relationships remained statistically significant (cfPWV r=0.65, p<0.001; FMD r=-0.24, p<0.05; carotid compliance r=-0.44, p<0.05). These results indicate that whole blood viscosity does not appear to significantly impact measures of vascular function and that the rationale for including whole blood viscosity in the calculation of vascular function remains weak.
Development and application of optical imaging techniques in diagnosing cardiovascular disease
(2012-05) Wang, Tianyi, 1982-; Milner, Thomas E.; Feldman, Marc; Johnston, Keith; Dunn, Andrew; Tunnell, James
Atherosclerosis and specifically rupture of vulnerable plaques account for 23% of all deaths worldwide, far surpassing both infectious diseases and cancer. Plaque-based macrophages, often associated with lipid deposits, contribute to atherogenesis from initiation through progression, plaque rupture and ultimately, thrombosis. Therefore, the macrophage is an important early cellular marker related to vulnerability of atherosclerotic plaques. The objective of my research is to assess the ability of multiple optical imaging modalities to detect, and further characterize the distribution of macrophages (having taken up plasmonic gold nanoparticles as a contrast agent) and lipid deposits in atherosclerotic plaques. Tissue phantoms and macrophage cell cultures were used to investigate the capability of nanorose as an imaging contrast agent to target macrophages. Ex vivo aorta segments from a rabbit model of atherosclerosis after intravenous nanorose injection were imaged by optical coherence tomography (OCT), photothermal imaging (PTW) and two-photon luminescence microscopy (TPLM), respectively. OCT images depicted detailed surface structure of atherosclerotic plaques. PTW images identified nanorose-loaded macrophages (confirmed by co-registration of a TPLM image and corresponding RAM-11 stain on a histological section) associated with lipid deposits at multiple depths. TPLM images showed three-dimensional distribution of nanorose-loaded macrophages with a high spatial resolution. Imaging results suggest that superficial nanorose-loaded macrophages are distributed at shoulders on the upstream side of atherosclerotic plaques at the edges of lipid deposits. Combination of OCT with PTW or TPLM can simultaneously reveal plaque structure and composition, permitting assessment of plaque vulnerability during cardiovascular interventions.
Development of a bioreactor imaging system for characterizing embryonic stem cell-derived cardiomyocytes
(2010-05) Abilez, Oscar John; Suggs, Laura J.; Roy, Krishnendu
Cardiovascular disease (CVD) affects more than 70 million Americans and is the number one cause of mortality in the United States. Because the regenerative capacity of adult tissues such as the heart is limited, human embryonic stem cells (hESC) have emerged as a source for potential cardiac therapies. However, despite the use of a variety of biochemical differentiation protocols, current yields of hESC-derived cardiomyocytes (CM) have been low. In the case of hESC-CM, which are inherently electromechanically active, additional forms of inducing a mature cardiac fate have not been fully explored. In order to non-invasively visualize and quantify biochemical, electrical, and mechanical stimulation on hESC-CM differentiation in future studies, a bioreactor imaging system has been developed and is described in this report.
The effects of acute muscle damage and autoimmune disease on vascular function : the potential role of inflammation
(2009-08) Barnes, Jill Nicole; Tanaka, Hirofumi, Ph. D.
Inflammation has been implicated in the development of cardiovascular disease and a potential underlying mechanism in the pathogenesis of impaired vascular function. Two different but complementary approaches were utilized to determine the role of inflammation on vascular function. First, to evaluate the effect of acute inflammation, we induced muscle damage to both small and large muscle mass and measured vascular function every 24 hours for up to 5 days of recovery. Eccentric exercise-induced muscle damage, in both small and large muscle mass, resulted in a transient increase in central arterial stiffness. Next, patients with systemic lupus erythematosus (SLE) were studied as a model of chronic inflammation. Measurements of vascular function were compared in habitually-exercising and sedentary SLE patients, and age-matched healthy controls. Individuals with SLE demonstrated lower vascular function than healthy controls. When SLE patients were grouped by exercise status, habitually-exercising SLE patients exhibited similar vascular function to healthy controls, and lower overall disease activity compared with sedentary SLE patients, supporting the beneficial effect of regular exercise in this population. Inflammatory biomarkers were associated with measures of macro- and microvascular function. In conclusion, acute muscle damage and chronic disease-related inflammation have a potent effect on measures of vascular function, suggesting that inflammation plays a role in the pathogenesis of vascular dysfunction and is an important biomarker for cardiovascular risk.
Effects of inactivity on cardio-metabolic responses to exercise
(2020-03-24) Burton, Heath Marcus; Coyle, Edward F., 1952-; Bray, Molly S; Stone, Audrey J; Kohl, Harold W
Physical inactivity has been known to cause deleterious health effects. New evidence suggests current physical activity recommendations may not be enough to reduce the risk of developing cardiovascular disease and mortality for those experiencing high levels of physical inactivity (e.g.; prolonged sitting). The purpose of study one was to determine if daily physical inactivity in a group taking low steps (i.e.; 4,767±377 steps/day, LS) impairs postprandial lipemia (PPL), fat oxidation, and submaximal exercise responses to short term training, compared to a group taking high steps (16,048±725 steps/day; HS). After an initial high fat tolerance test (HFTT) to establish baseline responses to a high fat meal, participants (n=16) completed an 11-day training program with assigned step counts and five exercise training bouts consisting of 20 minutes of cycling at 80% VO₂peak and two 5-minute intervals at 90% VO₂peak. The day following the first and final bouts of exercise training, participants completed a second and third HFTT, respectively, to assess acute responses of PPL to the training. Within HS, a 31% reduction (p<0.05) was observed in plasma triglyceride incremental area under the curve (AUCI) after acute, as well as a 27% reduction (p<0.05) following chronic training. Further in HS, but not LS, there were significant (p<0.05) reductions in markers of stress during submaximal exercise, such as blood lactate and heart rate, after training. These findings suggest step reductions can lead to an impaired ability to adapt to short term exercise training. The purpose of study two was to determine the effect of reducing step count over two days on the ability of a 1-h bout of exercise to reduce PPL. Participants (n= 10) completed three trials: Low (2,675±314 steps/day), Limited (4,759±276 steps/day) and Normal Activity (8,481±581 steps/day) for two days followed by a 1-h bout of treadmill running at 64% VO₂max with a HFTT the following morning. PPL responses following 2,675 and 4,759 step/day trials did not differ. However, following exercise in a condition of 8,481 steps/day, AUCI was reduced 22% and 23% (p<0.05) compared to the 2,675 and 4,759 step/day trials, respectively. This suggests that a 1-h bout of running has a decreased ability to lower PPL the next day when taking 4,759 steps/day or less. Taken together these studies highlight the importance of maintaining a healthy level of daily non-exercise physical activity, regardless of participation in exercise. From these studies it is recommended that individuals maintain a daily step count of at least 8,500 steps in additional to any planned exercise in order to achieve improvements in PPL as a result of acute or chronic exercise.
Effects of prolonged sitting on normal, exercise-induced metabolic improvements
(2017-08-08) Akins, John David; Coyle, Edward F., 1952-
Cardiovascular disease (CVD) is an ever-growing cause of mortality and has been coupled with a rise in sedentary behavior. A vast majority of people spend their time physically inactive with the occasional bout of acute exercise. Generally, acute exercise is able to improve postprandial lipemia (PPL), a risk factor for CVD. However, research is beginning to suggest that sedentary behavior might abolish the metabolic benefits normally seen from exercise. This study set out to elucidate the impact of an acute bout of exercise on PPL after four days of prolonged sitting (~13.5 h/day). Subjects participated in a counterbalanced, crossover study in which they completed two trials: prolonged sitting without exercise (SIT) and prolonged sitting with a one-hour bout of treadmill exercise (SIT+EX). Following each trial, plasma triglycerides and glucose were obtained and substrate oxidation via indirect calorimetry was collected to be analyzed for possible improvements caused by exercise. No differences (p>0.05) were found in triglyceride or glucose response during the high fat tolerance test, evidenced by triglyceride or glucose AUCₜ or AUCᵢ, or fat oxidation as measured by indirect calorimetry between trials. While the triglyceride temporal response was similar to expectation with a rise to peak around hour 3-4 postprandial, a noticeably flatter and more prolonged response was seen in the glucose temporal response. This lack of difference between trials comes with similar activity except for the one-hour bout of exercise. The results from this study suggest that prolonged sitting imposes some sort of resistance to the normal improvement in PPL and fat oxidation after acute exercise. This suggests that physical inactivity (e.g. prolonged sitting) creates a condition whereby people are resistant to the normal metabolic improvements in fat metabolism that are derived from a bout of acute exercise
Health disparities between blacks and whites with HIV/AIDS : an analysis of U.S. national health care surveys from 1996-2008
(2011-05) Oramasionwu, Christine Uzonna, 1982-; Frei, Christopher R.
Blacks are more affected by Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) than any other race or ethnicity in the United States. The purpose of this dissertation was to investigate potential race-based differences in cardiovascular disease (CVD)-related hospitalizations and use of opportunistic infection (OI) prophylaxis between Blacks and Whites with HIV/AIDS. This dissertation includes two systematic literature reviews that identified knowledge gaps in the areas of CVD diagnosis and OI prophylaxis use between Blacks and Whites with HIV/AIDS, as well as two independent studies that addressed some of the gaps identified in the literature. The first study evaluated the association between race and CVD-related hospitalization in Blacks and Whites with HIV/AIDS. Data were retrieved from the 1996-2008 National Hospital Discharge Surveys (NHDS). Approximately 1.5 million hospital discharges were identified. After controlling for confounders, the odds of CVD-related hospitalization were 45% higher for Blacks than Whites (OR=1.45, 95% CI, 1.39-1.51). There was a statistically significant difference in the proportions of CVD-related hospitalization type and race (x2=479.77; df=3; p<0.001). Compared to Whites with HIV/AIDS, Blacks with HIV/AIDS had greater proportions of heart failure and hypertension, but lower proportions of stroke and coronary heart disease. These results suggest that there is an influence of race on both the occurrence and type of CVD-related hospitalizations in patients with HIV/AIDS. The second study assessed if race was associated with the use of OI prophylaxis (Pneumocystis jiroveci pneumonia [PCP] and Mycobacterium avium complex [MAC]). Data for this study were retrieved from the 1996-2008 National Hospital Ambulatory Medical Care Surveys (NHAMCS). Approximately 9.1 million hospital ambulatory visits were identified. After controlling for confounders, the odds of PCP prophylaxis use were 16% higher for Blacks than for Whites (OR=1.16, 95% CI, 1.15-1.17). In a separate regression analysis, the odds of MAC prophylaxis use were 12% higher for Blacks than for Whites (OR=1.12, 95% CI, 1.10-1.13). These findings suggest that Blacks with HIV/AIDS may have increased odds for OI prophylaxis. Based on this work, there is a need for further research to confirm these findings and to identify the causes of these race-based disparities.
The impact of Medicare Part D coverage on medication adherence and health outcomes in end-stage renal disease (ESRD) patients
(2013-05) Park, Haesuk; Rascati, Karen L.
The purpose of this study was to investigate the impact of Medicare Part D coverage on medication adherence and health outcomes in dialysis patients. A retrospective analysis (2006-2010) using the United States Renal Data System was conducted for Medicare-eligible dialysis patients. Cardiovascular disease morbidity, healthcare utilization and expenditures, medication adherence, and mortality rates were compared, categorized based on patients’ Part D coverage in 2007 for those who: 1) did not reach the coverage gap (cohort 1); 2) reached the coverage gap but not catastrophic coverage (cohort 2); 3) reached catastrophic coverage (cohort 3); and 4) did not reach the coverage gap but received a low-income subsidy (cohort 4). Cox proportional hazards models, Kaplan-Meier methods, logistic regressions, generalized linear models, and generalized estimating equations were used. A total of 11,732 patients were included as meeting inclusion criteria: 1) cohort 1: 3,678 patients had out-of-pocket drug costs <$799; 2) cohort 2: 4,349 patients had out-of-pocket drug costs between $799 and $3,850; 3) cohort 3: 1,310 patients had out-of-pocket drug costs > $3,850; and 4) cohort 4: the remaining 2,395 patients had out-of-pocket drug costs <$799 but received a low-income subsidy. After adjusting for demographic and clinical factors, patients in cohort 2 and cohort 3 had 42 percent and 36 percent increased risk of cardiovascular disease (odds ratio (OR)=1.42, 95% confidence interval (CI):1.20-1.67; OR=1.38, 95% CI:1.10-1.72); and had 36 percent and 37 percent higher death rates compared to those in cohort 4, respectively (hazard ratio (HR)=1.36, 95% CI:1.27-1.44; HR=1.37, 95% CI:1.27-1.48). Patients in cohort 2 were more likely to be nonadherent to medications for diabetes (OR=1.72, 95% CI:1.48-1.99), hypertension (OR=1.69, 95% CI:1.54-1.85), hyperlipidemia (OR=2.01, 95% CI:1.76-2.29), hyperphosphatemia (OR=1.74, 95% CI:1.55-1.95), and hyperparathyroidism (OR=2.08, 95% CI:1.66-2.60) after reaching the coverage gap. These patients had total health care costs that were $2,644 higher due to increased rates of hospitalization and outpatient visits, despite $2,419 lower pharmacy costs compared to patients in cohort 4 after controlling for covariates (p<0.0001). Reaching the Part D coverage gap was associated with decreased medication adherence and unfavorable clinical and economic outcomes in dialysis patients.
Interaction of exercise and simvastatin on myocardial ischemia-reperfusion (I/R) injury and post-ischemic cardiac function
(2006-05) Meissner, Maxi; Starnes, Joseph W.
Simvastatin is one of the statins, which are a class of drugs originally developed to fight cardiovascular disease by lowering cholesterol. However, it is now clear that they have effects independent of cholesterol. For example, statin therapy, like exercise, induces adaptations within the heart that protect it against I/R injury. Patients are frequently advised to undergo a combination treatment of statins and chronic exercise, although little is known about how this combination treatment affects cardioprotective adaptations. Both treatments appear to exert their cardioprotective effects through different mechanisms, therefore it appears plausible that combining the two treatments would provide added cardioprotection than either treatment alone. Purpose: To investigate the effects of a combination treatment of statins and exercise upon parameters of post-ischemic myocardial function and damage. Methods: Female Sprague-Dawley rats (6 months of age) were separated into 4 groups for a period of 4 weeks: Sedentary (S, n=10), sedentary plus 10 mg simvastatin (Zocor®)/kg body wt/ day (SD, n=9), exercise (R, n=9), and exercise plus simvastatin (RD, n=9). R and RD were exercised identically on a treadmill for 5 days/week at an intensity of about 70% VO2max and for a duration that was gradually increased to 60 min/day. Twenty-four hrs following the last exercise bout, isolated perfused working hearts were subjected to 30 min of global ischemia followed by 30 min of normoxic reperfusion. Coronary effluents were used to determine lactate dehydrogenase (LDH) leakage and prostaglandin generation. Results: Cardiac function was similar in all groups prior to ischemia. Post I/R recovery of cardiac function in S was 17.6 [greater than or equal to]6.6% of pre-ischemic cardiac output times systolic pressure. Recovery was significantly higher in SD (37.7[greater than or equal to]7.7%) and R (40.1[greater than or equal to]7.8%) and tended to be highest in RD (49.7[greater than or equal to]7.1%). SD had significantly higher pre-ischemic coronary flow per g heart weight (CF/g) than all other groups. At 10 min post-ischemia, simvastatin treatment significantly increased CF/g compared to S (p<0.05). Exercise had an effect on increasing post-ischemic myocardial efficiency and RD had significantly higher post-ischemic myocardial efficiency vs. S (p<0.05). Compared to S, LDH leakage during reperfusion was dramatically decreased in SD, R and RD by approximately similar amounts. Simvastatin treatment doubled the basal production of protective prostaglandins, whereas exercise did not significantly alter their production and combining both treatments yielded a lower prostaglandin release than simvastatin treatment. SD had s significantly higher basal prostaglandin release than R (p<0.05). Conclusion: Although the combination treatment of simvastatin and exercise did not result in a statistically significant addition in cardioprotection compared to either treatment alone, there was a trend for improved parameters of post-ischemic cardiac function and damage upon combining both treatments compared to each treatment alone. Specifically, the prostaglandin, CF/g and efficiency data suggest that exercise and statininduced cardioprotection against I/R injury appears to occur by different mechanisms and combining the two treatments may provide greater protection than either alone.
Investigating mesenchymal stem cell therapy for ischemic repair
(2014-08) Ricles, Laura Michelle; Suggs, Laura J.; Emelianov, Stanislav Y.; Baker, Aaron B; Farrar, Roger P; Zoldan, Janeta
Cardiovascular diseases are the leading cause of death globally and continue to be a growing health concern. The currently available therapies are not suitable or effective for all patients, which has prompted investigation into stem cell-based therapies for vascular regeneration and ischemic repair. Clinical trials using stem cell therapy have shown promising outcomes for patients with cardiovascular diseases. However, the mechanisms of repair, and the contribution of stem cells to wound healing, are poorly understood. The objective of this dissertation is to evaluate the use of bone marrow-derived mesenchymal stem cells (MSCs) delivered within a PEGylated fibrin gel for revascularization therapies. Demonstrated in this dissertation is the design of nanoparticle contrast agents which are capable of labeling and tracking stem cells and infiltrating macrophages in vivo. In addition, the effect of hypoxia on MSC function and the resulting interaction with macrophages was studied. Hypoxia was shown to modulate MSCs to have pro-regenerative and angiogenic-promoting properties, which subsequently affected the interaction with macrophages. Lastly, functional recovery and vascular regeneration in an in vivo ischemia model were shown to be enhanced in response to MSCs delivered within PEGylated fibrin gels. The results of this work provide insights into the mechanisms of stem cell therapy in combination with PEGylated fibrin matrices and can contribute to the advancement of the field of regenerative medicine.
Mechanisms of cutaneous microvascular endothelial dysfunction in young black Americans
(2016-12) Kim, Kiyoung, active 2013; Tanaka, Hirofumi, Ph. D.; Farrar, Roger P.; Castelli, Darla M.; Brothers, Robert Matthew; Davis, Scott L.
Black Americans have an increased risk for developing a variety of cardiovascular disease (CVD) when compared to white Americans and other populations in the United States. It has also been demonstrated that the underlying impairments in black Americans manifest during early adulthood prior to any overt signs of risk, which leads to higher rates of CVD related morbidity and mortality in black Americans than other populations. Study 1 was designed to investigate the potential mechanisms of cutaneous microvascular dysfunction in young college-age black Americans. This was assessed by measuring the skin blood flow response to local heating while various vasoactive substances were delivered into the cutaneous interstitial space by intradermal microdialysis. We demonstrated that an attenuated nitric oxide (NO) mediated vasodilation due in part to a relative deficit of L-arginine in the endothelial cells is one mechanism by which microvascular dysfunction occurs in young black Americans. Study 2 conducted to investigate the effects of acute cocoa flavanol intake on cutaneous microvascular function in young black Americans. This was assessed by measuring the skin blood flow response to local heating and delivery of vasoactive substances (as described above) before and after consumption of a beverage high in flavanol content. Study 2 demonstrated that acute flavanol intake improved cutaneous microvascular function in response to local heating in young black Americans relative to young white Americans. Study 3 was designed to investigate the effects of acute flavonal intake on endothelium-dependent microvascular dilation in response to exogenous administration of methacholine (MCh) in young black Americans. This was assessed by skin blood flow responses to incremental dose of MCh, which was delivered by intradermal microdialysis, before and after consumption of a beverage high in polyphenol content. Study 3 identified that acute flavanol intake did not alter the dose-response curve of MCh-induced cutaneous vasodilation in either racial groups. Overall, the series of studies in this dissertation may provide evidence that young black Americans have attenuated microvascular function relative to young white Americans, and that a potential mechanism of decreased microvascular function is a decrease in NO bioavailability and/or NO mediated vasodilation, which is related to a deficit of L-arginine in the endothelial cells in young black Americans. Furthermore, our findings may provide evidence that the consumption of cocoa flavanols is an effective therapeutic strategy to prevent and/or delay the development of CVD at least in young black Americans.
The perception and knowledge of cardiovascular risk factors among Chinese Americans
(2006-08) Yu, Teng-Yuan; Clark, Angela P.
The purpose of this study was to evaluate Chinese Americans’ perceptions and knowledge about cardiovascular disease (CVD) risk factors and to determine if acculturation has systematic effects on perception of illness. Perception about the cause, seriousness, curability, and controllability of CVD were investigated. Relationships between the demographic characteristics of the participants and cardiovascular knowledge and perception were examined. The conceptual framework for this study was based on Leventhal’s (1970, 1984) Common Sense Model of Illness Representation. The influence of Kleinman’s Explanatory Model about the cultural and social consideration of illness representation was incorporated. A cross-sectional design was selected for this descriptive study with a convenience sampling technique. The target population was community-based Chinese Americans who live in the United States. Data collection was conducted using the Internet to access a population. The sample of the study was comprised of 124 adults with 68% being female. The majority of participants retained a high Asian identity. Participants identified Chinese over English for speaking, reading, writing preferences. Instruments included the Illness Perception Questionnaire-Revised (IPQ-R), Suinn-Lew Asian Self-Identity Acculturation Scale (SL-ASIA) and the Healthy Heart IQ. Findings included the following: the IPQ-R subscales were intercorrelated in a logical manner. Illness perceptions correlated positively with each other but were negatively correlated with optimistic perceptions like personal and treatment control. No difference was observed in the IPQ-R based on age, gender or educational level. Knowledge of CVD among Chinese Americans was lower than the general population. The level of acculturation had an impact on the illness perception. Acculturation level was significantly related to all seven illness perception dimensions of illness representation on the IPQ-R. There were significant relationships between acculturation level and knowledge of CVD. However, due to the low acculturation level presented by majority of participants, caution must be exercised in the interpretation of the study findings. The findings of this study have important implications for nursing practice, education, and theory. These results also provide directions for future research. Suggestions for health care professionals who care for patients with ethnic cultural backgrounds were given.
The acute effects of intermittent hypoxia on peripheral vascular function in young and older adults
(2023-04-18) Stray-Gundersen, Sten Oliver; Lalande, Sophie; Casey, Darren; Tanaka, Hirofumi; Coyle, Edward
Intermittent hypoxia, characterized by repeated bouts of breathing hypoxic air separated by bouts of breathing normoxic air, has gained considerable traction in recent years for its wide-ranging therapeutic effects. The overall theme for this dissertation is centered on the acute effects of intermittent hypoxia on peripheral vascular function in humans. In the first study, we demonstrate that although an intermittent hypoxia protocol consisting of eight 4-min hypoxic cycles induces brachial artery vasodilation, it does not acutely improve flow-mediated dilation, a key measure of endothelium-dependent peripheral vascular function, in young individuals. Similarly, in the second study, we demonstrate that the same intermittent hypoxia protocol consisting of eight 4-min hypoxic cycles can also induce brachial artery vasodilation without acutely affecting flow-mediated dilation in older adults. In the third study, we demonstrate that a short intermittent hypoxia protocol can attenuate the reduction in brachial artery flow-mediated dilation following ischemia-reperfusion injury in older adults. Taken together, the overall findings from this series of investigations highlight the effect of intermittent hypoxia on peripheral vascular function in both young and older adults.
The effect of clinical trial regulation changes on statin therapy for cardiovascular disease in randomized controlled trials
(2020-05-05) Browning, Savannah Grace; Brenna, James T. (James Thomas)
Cardiovascular disease continues to be of concern in many developed countries, especially in the United States where 1 out of 4 deaths is due to heart disease. High blood cholesterol levels are thought to be one of the major risk factors for heart disease, therefore statin therapy, alone or in combination with lifestyle changes, is one of the most common preventions and treatments for heart disease. From 2011-2012 approximately 28% of adults in the U.S 40+ reported taking a cholesterol lowering drug in the past 30 days, of those 28%, 93% report taking a statin. The believed effectiveness of statins stems from the multitude of clinical trials, and meta-analyses reporting statins were effective in decreasing the incidence of cardiac events. Clinical trial regulations have been modified substantively from time to time, with one of the largest set of changes being put into place in 2004. The changes put into place in 2004 require 1) clinical trials to be registered with a clinical trial registry, 2) registry to be kept up to date with all trial design changes, 3) all data and results must be published as it is available. Based on a set of visual evaluations, a recent comprehensive evaluation concluded that the statin clinical trials, occurring after this large scale change in regulations, reporting that statins are not efficacious as originally believed and are likely dangerous. In this thesis, de novo meta-analyses were performed evaluating the efficacy of statin therapy on the reduction in the incidence of primary cardiac outcomes, cardio-related mortality, and all-cause mortality. We posited that the 2004 regulations had an impact on reports of efficacy and thus subgroup analyses were performed distinguishing the studies that occurred prior to the major clinical trial regulation changes in 2004 (pre-2004), and those that occurred after (post-2004). Studies fitting the inclusion and exclusion criteria were identified, pertinent data were extracted, and data analyses were performed using the inverse variance heterogeneity model. In the total combined pooled analysis, studies showed results consistent with many other meta-analyses, that statin therapy was effective in reducing primary cardiac event incidence. However, among the subgroup of studies occurring after the 2004 changes, efficacy of statin therapy in reducing primary cardiac event incidence did not meet statistical significance. A similar pattern was seen in the analysis for cardio-related mortality, and all-cause mortality. We conclude that the clinical trial regulation changes that went into place in 2004 appeared to have an effect the published outcomes of clinical trials of statins. The clinical trial regulation changes altered the apparent efficacy of statin therapy regarding a decrease. Among trials conducted after the regulations, there was not a statistically significant reduction in the incidence of primary cardiac outcomes, cardio-related death, and all-cause mortality. This information shows that it will be important to continue to critically evaluate all new clinical trials, as well as the meta-analyses that include a large portion of pre-2004 studies.