UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Cardiovascular Physiological Monitoring Based on Video(2023) Gebeyehu, Henok; Wu, Min; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Regular, continuous monitoring of the heart is advantageous to maintaining one’s cardiovascular health as it enables the early detection of potentially life-threatening cardiovascular diseases. Typically, the required devices for continuous monitoring are found in a clinical setting, but recent research developments have advanced remote physiological monitoring capabilities and expanded the options for continuous monitoring from home. This thesis focuses on further extending the monitoring capabilities of consumer electronic devices to motivate the feasibility of reconstructing Electrocardiograms via a smartphone camera. First, the relationship between skin tone and remote physiological sensing is examined as variations in melanin concentrations for people of diverse skin tones can affect remote physiological sensing. In this work, a study is performed to observe the prospect of reducing the performance disparity caused by melanin differences by exploring the sites from which the physiological signal is collected. Second, the physiological signals obtained from the previous part are enhanced to improve the signal-to-noise ratio and utilized to infer ECG as parts of a novel technique that emphasizes interpretability as a guiding principle. The findings in this work have the potential to enable and promote the remote sensing of a physiological signal that is more informative than what is currently possible with remote sensing.Item Sex- and Race-Based Differences in the Effects of Acute and Chronic Exercise on Vascular Function and Circulating MicroRNA(2021) Sapp, Ryan M; Hagberg, James M; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cardiovascular disease (CVD) is the leading global cause of death. Disparities in CVD development exist, with greater rates observed in men than women and in African Americans (AA) than Caucasian Americans (CA). It is crucial to determine the molecular mechanisms underlying these disparities in order to formulate preventative strategies. Regular aerobic exercise reduces CVD risk, while acute exercise is a useful stimulus to reveal impairments in cardiovascular function not apparent at rest. This dissertation utilizes approaches to identify sex- and race-based differences in vascular function within young, healthy individuals, indicative of future CVD risk, including the use of acute exercise as a cardiovascular stimulus and the exercise-trained individual as a model of superior cardiovascular health. Aim #1 shows that exercise training is associated with beneficial effects of the circulating factors in serum on vascular endothelial cells, in a sex-specific manner, suggesting that circulating factors are differently affected by exercise training in men and women. Aim #2 shows that endothelial function and central arterial stiffness respond similarly to acute exercise in AA and CA. Carotid arterial compliance, however, is increased only in CA during exercise recovery. MicroRNAs (miRs) are epigenetic modulators of gene expression implicated in CVD development. Blood-borne circulating miRs (ci-miRs) are paracrine/endocrine molecules and preclinical biomarkers, yet sex- and race-based differences in ci-miRs are understudied. Additionally, ci-miRs are altered with exercise and may mediate training-induced vascular adaptations. Aim #3 of this dissertation reveals that the resting concentrations of select vascular-related ci-miRs differ based on sex and exercise training status, but not race. In response to acute exercise however, several anti-inflammatory ci-miRs increased significantly in CA, but not AA. Additionally, the changes in one anti-inflammatory ci-miR exhibited race-specific correlations with the changes in carotid arterial compliance identified in Aim #2. Aim #4 investigates the hypothesis that exercise elicits endothelial integral damage, and that this may mediate changes in vascular function and endothelial-derived ci-miRs. By measuring different endothelial-derived circulating factors, we show that exercise likely does not cause endothelial cell detachment or apoptosis. Thus, ci-miR are likely released via a selective method of secretion, rather than passively leaking from damaged endothelium.Item NOVEL METHODOLOGY FOR CALCIUM MEASUREMENTS IN CONSCIOUS MICE: AN APPLICATION TO ARTERIOLAR VASOMOTION(2015) Zviman, Adam Lyle; Wier, Withrow G; Chen, Yu; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)We developed a method employing two-photon microscopy and genetically engineered ‘Ca2+- biosensor’ mice to measure Ca2+ signaling in arteries of conscious, head-fixed mice. Arterial blood pressure was measured simultaneously via implanted telemetric pressure transducers. These methods allowed, for the first time, the study of control of arterial [Ca2+], diameter, and blood pressure by sympathetic nerve activity (SNA) as it normally exists in conscious animals. We tested the hypothesis that arterial vasomotion, observed more frequently in conscious animals than in anesthetized animals, was generated by SNA that caused synchronous Ca2+-oscillations in smooth muscle. We also measured the changes in arterial [Ca2+] that occur during the time course of experimental hypertension. Pharmacological block of SNA and isoflurane anesthesia eliminated and attenuated, respectively, vasomotion and reduced arterial [Ca2+] (320 ± 48 nM to 241 ± 20 nM and 302 ± 48 nM). This method allows for longitudinal studies of important chronic vascular pathologies.