Doctor of Philosophy (PhD), Ohio University, 2018, Chemistry and Biochemistry (Arts and Sciences)

Advancing age is the primary risk factor for cardiovascular, cerebrovascular and renal diseases. The imbalance between prooxidative and antioxidative processes increase with senescence. The decrease in cytoprotective nitric oxide (NO) and increase in reactive oxygen species (ROS) such as superoxide (O2¯) and peroxynitrite (ONOO¯) are suggested to be the main factors of endothelial dysfunction and aging. Endothelial dysfunction is associated with the impaired generation of NO and overproduction of O2¯ resulting in the formation of cytotoxic ONOO¯. Replicative senescence of human endothelial cells (ECs) was analyzed here using human umbilical vein endothelial cells (HUVECs). In this study, we employed a nanomedical system to measure the concentration of NO, O2¯, and ONOO¯ simultaneously. Peroxynitrite is a powerful cytotoxic oxidant formed from the reaction between NO and O2¯. Nanosensors were placed near the endothelium and calcium ionophore-stimulated NO, O2¯, and ONOO¯ were measured. The present work was performed to investigate endothelial nitric oxide synthase (eNOS) dysfunction during aging of endothelial cells. The age-related cardiovascular diseases such as heart failure, atherosclerosis, ischemic heart disease and myocardial infarction can be associated with endothelial dysfunction. The nanomedical approach enabled us to characterize changes in eNOS coupling/uncoupling as a function of biological aging. The release of NO and ONOO¯ was studied in different passages in ethnic groups (Caucasian Americans (CAs), African Americans (AAs) and Asian Americans (ASAs)). Our results suggest that HUVECs of AAs are more susceptible to endothelial dysfunction during aging. The shortening of relative telomere length in aging coincided with a decrease of NO and increase of ONOO¯ concentrations. The imbalance between [NO] and [ONOO¯] was due to endothelial dysfunction. The treatment of aging endothelium with factors affecting the eNOS pathway (e.g., VAS2870, PEG-SOD, and L-ar (open full item for complete abstract)

Committee: Tadeusz Malinski PhD (Advisor) Subjects: Aging; Alternative Medicine; Cellular Biology; Chemistry; Developmental Biology; Endocrinology; Environmental Science; Environmental Studies; Epidemiology; Health Care; Health Sciences; Immunology; Medicine; Microbiology; Molecular Biology; Molecular Chemistry; Molecules; Nanoscience; Nanotechnology; Neurobiology; Neurology; Neurosciences; Oncology; Organic Chemistry; Organismal Biology; Pharmaceuticals; Pharmacology; Pharmacy Sciences; Physiology; Polymer Chemistry; Sports Medicine; Therapy; Toxicology; Zoology

Master of Science (M.S.), University of Dayton, 2015, Bioengineering

Bioreactor systems used for tissue engineering applications are an essential component of understanding the development of new tissues and studying the biochemical interactions between cells and their environment. A bioreactor is typically designed to mimic physiological, environmental, and mechanical stimuli that occur in vivo, and bioreactors are generally created for a specific application, such as for studying 3-dimensional tissues or dynamic fluid flow in 1-dimensional cell monolayers. The leading cause of death in the United States is coronary artery disease, which is treated with bypass graft surgery using a left internal mammary artery or human saphenous vein as the graft. Since human saphenous vein grafts often fail, investigating vascular function as a whole will help to understand more about the method of graft failure. A bioreactor system to study vascular function was successfully developed using the application of endothelial cells under shear stress in a microfluidic slide. The temperature control and diffusion rate of CO2 were recorded inside the bioreactor to confirm the system could stay within a temperature range of 37ºC +/- 0.5ºC and a CO2 concentration between 56,000 ppm and 45,000 ppm. Also, a physiological level of shear stress was determined to be feasible with the peristaltic pump. The performance characteristics of the bioreactor were analyzed, and the apparatus was determined to be successful in generating physiological relevant conditions. Then, human umbilical vein endothelial cells were exposed to both static conditions and venous shear stress conditions for up to four days in an IBIDI® microfluidic chamber. The cell morphology, alignment, and elongation were also evaluated. The cells stayed viable during the duration of all of the dynamic flow experiments, and the cells showed evidence of cell division. The cells were also more aligned and elongated towards the direction of flow for the 48 and 72 hour flow experiments compared to th (open full item for complete abstract)

Committee: Robert Wilkens (Advisor); Carissa Krane (Advisor); Kristen Comfort (Committee Member) Subjects: Biology; Biomedical Engineering; Biomedical Research; Chemical Engineering; Engineering

Doctor of Philosophy in Clinical-Bioanalytical Chemistry, Cleveland State University, 2009, College of Science

Nitric oxide (NO) is an important intercellular messenger that acts in many tissues to regulate a diverse range of physiological and pathological processes. The physiologically implications of NO function are far from being completely understood. The multifaceted reactivity of NO prompted the need for accurate determination of the concentration of this molecule. However, it is difficult to detect nitric oxide, particularly in biological media and near live cells due to its short half-life, a result of its reactivity and the low levels of NO produced in vivo. As a result, the accurate and reliable detection of NO under varying experimental conditions has always posed a challenging task. The main goal was to develop ultra-sensitive electrocatalytic sensors for accurate quantification of NO. We report the fabrication and characterization of improved NO sensors based on electrocatalytic platforms such as ruthenium (colloids, nanoparticles, and nanotubes) and carbon (pastes and nanotubes), acting as catalytic sites for NO oxidation. These sensors are characterized using various surface analytical tools. The electrocatalytic oxidation of NO is assessed by cyclic voltammetry and amperometry both in solution phase and gas phase. Excellent sensitivity and linearity are observed for our modified electrodes towards NO quantification. Our new NO detection sensors also show superior limit of detection and selectivity against common interference species. Our NO sensors are tested for various applications including in the measurement of NO released from human umbilical vein endothelial cells (HUVECs).

Committee: Dr. Mekki Bayachou PhD (Advisor); Dr. Lily Ng PhD (Committee Member); Dr. Robert Wei PhD (Committee Member); Dr. John Turner PhD (Committee Member); Dr. Petru Fodor PhD (Committee Member) Subjects: Chemistry