Doctor of Philosophy (PhD), Ohio University, 2013, Chemistry and Biochemistry (Arts and Sciences)

Both diabetes and hypertension are risk factors for cardiovascular diseases. Diabetes mellitus and high blood pressure complications are associated with dysfunctional endothelium, where the molecular mechanism is still unclear. Endothelial dysfunction refers to the loss of nitric oxide (NO). The objective of this research was to study the molecular mechanisms of NO, peroxynitrite (ONOO-) (using electrochemical nanosensors) and L-arginine transport in type 2 diabetes and salt-induced hypertension in human umbilical vein endothelial cells (HUVECs). The influence of various concentrations of glucose, sodium chloride (NaCl), sodium (Na+) and chloride (Cl-) on NO, ONOO- release and L-arginine transport was measured in human endothelial cells. Exposure of HUVECs to elevated concentrations of glucose, NaCl, Na+ and Cl- reduced significantly NO release and increased nitroxidative stress levels (elevated ONOO-). L-arginine transport was significantly inhibited under hyperglycemic and hypertensive conditions. NO bioavailability ameliorated under physiological and elevated glucose and salt concentration after the administration of L-arginine. In contrast, ONOO- concentrations decreased significantly after the supplementation of L-arginine. Similar study on African American HUVECs was performed to elucidate the influence of glucose and salt on NO, ONOO- and L-arginine transport. This study showed a decrease in NO and L-arginine transport and an increase in oxidative stress under elevated glucose and NaCl levels. African American HUVECs also produced a lower NO concentration and higher ONOO- level than White American HUVECs. A low ratio of NO to ONOO- [NO]/[ONOO-] in HUVECs under hyperglycemic and hypertensive conditions clearly imply a dysfunctional endothelium. Similarly, the effect of glucose on NO, ONOO-, L-arginine transport and insulin secretion was studied in hamster pancreatic beta cells (HIT-T15) under various glucose concentrations. Elevated glucose concentrations (open full item for complete abstract)

Committee: Tadeusz Malinski Dr. (Advisor) Subjects: Biochemistry

PhD, University of Cincinnati, 2000, Medicine : Molecular and Cellular Physiology

Although previous studies have described a mouse model for diet-induced Type II diabetes mellitus, renal function in these animals has not been characterized. The aim of the first study of this thesis was to measure cardiovascular and renal function, including the renal transport capacity for glucose, in male and female C57BL/6J mice with diet-induced Type II diabetes mellitus. Results from the first portion of the thesis indicated that C57BL/6J mice are valuable tools for studying diet-induced obesity, hyperglycemia, and hyperinsulinemia; however, no hypertension or kidney dysfunction is apparent within the time frame (3 – 6 months) of the current study. Information regarding the renal glucose transport capacity in diabetes mellitus is limited. These data are needed because two weeks following injection of streptozotocin (STZ), mRNA and protein levels of the glucose transporter, GLUT2, are upregulated in the proximal tubule of the rat. In the second part of the thesis renal glucose transport and GLUT2 protein levels were measured in female control rats, and in rats one (STZ-1), two (STZ-2), and three weeks (STZ-3) after STZ injection (65 mg kg-1, ip). Data from these studies suggest that other factors, functioning either in conjunction with or independent of GLUT2, are required to support an elevated renal glucose transport capacity. The final part of the thesis was designed to determine to what extent nitric oxide (NO) mediates the natriuretic and diuretic responses to acute isotonic saline volume expansion (SVE). Studies were performed on pentobarbital anesthetized female Sprague-Dawley rats with or without a NO synthase inhibitor, Nw-nitro-L-arginine (LNA). The data demonstrate that 1) NO does not mediate SVE-induced hyperfiltration in the rat, 2) NO also does not mediate SVE-induced natriuresis or diuresis, and 3), consistent with other reports, NO appears to mediate pressure natriuresis and diuresis.

Committee: Robert Banks (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2011, Chemical and Biomolecular Engineering

Blood transfusion can be compromised by a number of physiological and practical issues such as the risk of contracting infectious diseases, initiation of harmful immunological responses, the red blood cell (RBC) storage lesion and the shrinking availability of RBCs. Thus, there is a need to develop safe and efficacious O2 carriers for use in transfusion medicine as RBC substitutes in order to maintain proper tissue and organ oxygenation. Hemoglobin (Hb) is the most prevalent protein inside the RBC and is the natural carrier of O2 in vivo. Therefore, Hb-based O2 carriers (HBOCs) are considered as good candidates for RBC substitutes. Currently, HBOCs can be manufactured by conjugation of molecules to the surface of Hb, encapsulation of Hb inside particles, site-directed mutagenesis of Hb and cross-linking/polymerizing Hb. Among these approaches, polymerization of human or bovine Hb with the difunctional cross-linking reagent glutaraldehyde represents a simple strategy to synthesize HBOCs. In fact, the two commercial polymerized Hb (PolyHb) products Hemopure® (glutaraldehyde polymerized bovine Hb, OPK Biotech, Cambridge, MA) and PolyHeme® (pyridoxalated glutaraldehyde polymerized human Hb, Northfield Laboratories Inc., Evanston, IL), which have failed Phase III clinical trials, are based on this approach. These commercial PolyHb solutions face serious safety issues including the induction of vasoconstriction in the microcirculation and the development of systemic hypertension. These side-effects are due to the existence of the Hb tetramer or αβ dimer in the blood, which subsequently extravasate through the blood vessel wall and scavenge the vasodilator nitric oxide (NO) or trigger an autoregulatory response of the blood vessel to reduce the oversupply of O2 to surrounding tissues. Therefore, the goal of this research is to synthesize a new generation of HBOCs with fewer side-effects, longer circulation lifetime in the blood and better oxygenation potential. In this (open full item for complete abstract)

Committee: Andre Palmer Dr. (Advisor); Shang-Tian Yang Dr. (Committee Member); Jeffrey Chalmers Dr. (Committee Member); Robert Gustafson Dr. (Committee Member) Subjects: Chemical Engineering