Master of Science, The Ohio State University, 2005, Graduate School

Committee: Not Provided (Other) Subjects:

PhD, University of Cincinnati, 2024, Medicine: Pathobiology and Molecular Medicine

Myocardial infarction (MI) is currently responsible for over 150,000 deaths annually in the United States. Even when successfully treated, MI imparts lasting cardiovascular defects that lead to increased morbidity and mortality. One of the contributors to these observed outcomes is cardiac reperfusion injury (CRI), which manifests as cardiomyocyte death after ischemia is treated. CRI is caused by several events triggered by the ischemic microenvironment during the MI, including metabolic changes, perturbation in Ca2+ signaling, pro-thrombotic inflammation, endothelial dysfunction, and reactive oxygen species (ROS) formation. ROS scavenging in particular has drawn the attention of many investigators as a means of preventing the CRI. However, the rapid nature of free radical formation during reperfusion is a major pharmacokinetic obstacle in using antioxidants for this indication. Controlled hypoxic reperfusion (CHR) is the transient introduction of hypoxic reperfusate into the ischemic heart and subsequent reperfusion with a fully oxygenated solution. CHR was shown to be effective in reducing the infarct size and improving the heart function compared to normal reperfusion. It has been hypothesized that the cardioprotective effects of CHR are achieved by reducing the amount of ROS formed in the heart after reperfusion. Radhakrishnan et al. first showed in 2016 that during acoustic droplet vaporization (ADV), the ultrasound-mediated conversion of liquid perfluorocarbon droplets into gas microbubbles, oxygen (O2) diffused from the surrounding fluid into the microbubbles. This process has since been extensively described in buffers. In this dissertation, O2 scavenging from physiologically prepared whole blood is evaluated and a novel method for quantifying phase transition efficiency via flow cytometry is proposed. First, whole blood was prepared to mimic arterial whole blood in vivo. Next, oxygen scavenging and was assessed in an in vitro flow phantom via blood gas a (open full item for complete abstract)

Committee: Kevin Haworth Ph.D. (Committee Chair); Christy Holland Ph.D. (Committee Member); Onur Kanisicak Ph.D. (Committee Member); Karin Przyklenk Ph.D. (Committee Member); Yi-Gang Wang M.D. (Committee Member) Subjects: Biomedical Research

PhD, University of Cincinnati, 2022, Medicine: Systems Biology and Physiology

Heart failure (HF) is a chronic condition that is the result of pathological cardiac events including cardiac hypertrophy and myocardial infarction, being the most prevalent. Pathological cardiac hypertrophy is a mal-adaptive response contributing to heart failure via loss of cardiomyocytes, decreased contractile properties, and increased interstitial fibrosis. Along with hypertension, myocardial ischemia/reperfusion (I/R) injury is a common mediator of pathological cardiac hypertrophy and remodeling through cardiomyocyte cell death and the activation of the innate immune response. Human Antigen R (HuR) is a widely expressed mRNA binding protein that our lab has previously shown to play a key role in cardiomyocyte hypertrophy in vitro and in vivo. However, the specific mechanism, activation, and post-transcriptional modulation of HuR in pathological cardiac hypertrophy and post-ischemic cardiac remodeling has not been delineated. Firstly, we sought to determine the role of HuR in cardiomyocyte hypertrophy. We demonstrate that HuR undergoes cytoplasmic translocation following treatment with phenylephrine or angiotensin II, agonists of two independent Gaq-coupled GPCRs known to induce hypertrophy. Gq-mediated HuR activation is dependent on p38 MAP kinase, but not canonical Gq-PKC signaling. Furthermore, HuR activation is necessary for Gq-mediated hypertrophic growth of cardiomyocytes as siRNA-mediated knockdown of HuR inhibits in vitro cardiomyocyte hypertrophy. Additionally, overexpressing HuR in cardiomyocytes is sufficient to induce hypertrophic cell growth. Next, to delineate the downstream mechanisms of HuR's translocation promoting cardiomyocyte hypertrophy, our results suggest that HuR mediates the transcriptional activity of NFAT (nuclear factor of activated T cells), a hallmark of pathological cardiac hypertrophy. The results presented here identify HuR as a novel mediator of cardiac hypertrophy downstream of the Gq-p38 MAPK pathway. To furthe (open full item for complete abstract)

Committee: Michael Tranter Ph.D. (Committee Member); Walter Jones Ph.D. (Committee Member); Jo El Schultz Ph.D. (Committee Member); John Lorenz Ph.D. (Committee Member); Sakthivel Sadayappan Ph.D. (Committee Member); Onur Kanisicak PhD (Committee Member) Subjects: Physiology

PhD, University of Cincinnati, 2020, Medicine: Molecular, Cellular and Biochemical Pharmacology

Mitochondrial Calcium loading augments oxidative metabolism to match functional demands during times of increased work or injury. Physiological range of mitochondrial Calcium dynamics regulate energy production by activating key enzymes in metabolic pathways. Disruption of mitochondrial Calcium flux alters energy production leading to metabolic dysfunctions. Moreover, mitochondrial Calcium overload also directly causes mitochondrial rupture and cell death by inducing mitochondrial permeability transition. Thus, control of mitochondrial Calcium dynamics is essential for maintaining mitochondrial function and cell function. The mitochondrial Calcium uniporter (MCU) is the complex that mediates mitochondrial Calcium influx, and its activity is modulated by partner proteins in its molecular complex. While the pore-forming subunit MCU is responsible for acute mitochondrial Calcium uptake, MCUb is suggested as an inhibitory subunit of the pore preventing acute Calcium uptake into mitochondria. In skeletal muscle, its unique feature of varying metabolic rate depending on muscle demand marks the importance of mitochondrial Calcium dynamics in regulating energy production. Here, we examined the role of MCU and MCUb in skeletal muscle function and metabolic function by generating mouse models for skeletal muscle-specific deletion of MCU and MCUb, separately. Skeletal muscle-specific deletion of MCU in mice inhibited acute mitochondrial Calcium influx and Calcium-stimulated mitochondrial respiration, resulting in a preferential shift towards fatty acid metabolism with reduced body fat with aging. On the other hand, MCUb deletion in skeletal muscle resulted in an increase in glycolysis, as well as a decrease in fatty acid oxidation with increased body fat mass with aging. Together, these results demonstrate that mitochondrial Calcium regulation underlies skeletal muscle fuel selection and impacts total homeostatic metabolism. In the heart, mitochondrial Calcium overloa (open full item for complete abstract)

Committee: Jeffery Molkentin Ph.D. (Committee Chair); Taosheng Huang M.D. Ph.D. (Committee Member); Evangelia Kranias Ph.D. (Committee Member); Sakthivel Sadayappan Ph.D. (Committee Member); Jo El Schultz Ph.D. (Committee Member) Subjects: Molecular Biology

Master of Science, The Ohio State University, 2018, Biomedical Engineering

The mechanisms underlying CaMKII-induced arrhythmias in ischemia/reperfusion (I/R) are not fully understood. My thesis research tested the hypothesis that CaMKII increases late Na+ current (INa,L) via phosphorylation of Nav1.5 at Ser571 during I/R, thereby increasing arrhythmia susceptibility. Action potential duration (APD) and arrhythmic events were measured by optical mapping in isolated, Langendorff-perfused mouse hearts during global ischemia and reperfusion. To provide mechanistic information on the role of CaMKII-dependent phosphorylation of Nav1.5 in arrhythmia, Scn5a knockin mice expressing Nav1.5 with constitutive phosphorylation [Nav1.5-Ser571Glut (S571E)] or ablation [Nav1.5-Ser571Ala (S571A)] of the CaMKII site at Ser571 were used. Wildtype (WT) hearts showed a significant increase in the levels of phosphorylated CaMKII and Nav1.5 at Ser 571 [(p-Nav1.5(S571)] following 15 minutes of ischemia (just before onset of reperfusion). Optical mapping studies revealed a significant prolongation of APD, increased recovery time, and increased arrhythmia susceptibility during I/R in S571E and WT mice compared to S571A mice. Pretreatment of hearts with Na+ channel blocker mexiletine (10 uM) increased recovery of APD and reduced arrhythmia susceptibility in WT mice during I/R. We conclude that CaMKII-dependent phosphorylation of Nav1.5 is a crucial driver for increased INa,L, arrhythmia susceptibility during I/R. Selective targeting of this CaMKII-dependent pathway may have therapeutic potential for reducing arrhythmias in the setting of I/R.

Committee: Tom Hund Dr. (Advisor); Sakima Smith Dr. (Committee Member) Subjects: Biomedical Engineering

Master of Science, Northeast Ohio Medical University, 2017, Integrated Pharmaceutical Medicine

Myocardial ischemia reperfusion (IR) injury has been shown to cause mitochondrial dysfunction. The electron transport chain (ETC) is a major source of superoxide and other superoxide derived reactive oxygen species during ischemia and reperfusion. Previous studies suggest that the downregulation of ETC, Krebs cycle, and antioxidant enzymes in the mitochondria occur as a result of increased oxidative stress. SOD2 is one of the primary antioxidants in the mitochondrial matrix. It is capable of scavenging superoxide into hydrogen peroxide. To test the therapeutic potential of increased superoxide scavenging in murine models, we subjected cardiac specific human SOD2 overexpressing (SOD2TG) murine hearts to 30 minutes of ischemia and 45 minutes of reperfusion using the Langendorff isolated heart system. SOD2TG hearts were relatively protected from impairment of electron transport activity in complex I-IV as well as downregulation of Krebs cycle enzyme activities. However, SOD2 overexpressing hearts had selectively decreased basal respiratory enzyme kinetics without indication of impairment of respiratory coupling and hydrogen peroxide scavenging.

Committee: Yeong-Renn Chen Dr. (Advisor); Denise Inman Dr. (Committee Member); William Chilian Dr. (Committee Member) Subjects: Biology

Doctor of Philosophy, The Ohio State University, 2014, Chemical and Biomolecular Engineering

Hemorrhagic shock is sudden loss of intravascular blood volume which induces tissue ischemia, characterized by limited oxygen (O2) transport to tissues coupled with an accumulation of tissue excretory products eventually leading to cell death. Clinicians normally stop the bleeding and transfuse the patient with either red blood cells (RBCs) or plasma expanders in order to restore the lost blood volume. Re-establishment of blood flow and restoration of tissue oxygenation is known as reperfusion. This abrupt change in tissue oxygenation can paradoxically induce cell apoptosis, tissue inflammation, infarct formation and has been shown to elicit multiple organ dysfunctions by activating cytotoxic injury processes such as reactive O2 species (ROS) generation, neutrophil-endothelium interactions, and hypercontracture. These collective set of side-effects that occur during the ischemic and reperfusion phases is classified as ischemia reperfusion injury (IRI) and is a major obstacle towards successful treatment of hemorrhagic shock. Therefore, it is vital to develop novel therapeutics to protect the cardiovascular system during acute ischemic and post-ischemic phases that occur during resuscitation from hemorrhagic shock. Neutrophils, activated by elevated ROS levels post reperfusion, infiltrate into the extravascular compartment and damage the endothelium by secreting cytotoxic molecules such as ROS and cytokines. The damaged endothelium may further aggravate tissue injury by the suppression of vasoactive molecules such as nitric oxide (NO), adenosine, and endothelin; which can disrupt homeostasis of coronary vasculature and lead to reduced tissue perfusion. In light of the anti-apoptotic, anti-inflammatory and vasoactive properties of carbon monoxide (CO) and NO, their presence in the systemic circulation could inhibit the release of cytotoxic molecules during reperfusion. Previously, inhalation-based delivery of NO to ischemic tissues has been successful in treati (open full item for complete abstract)

Committee: Andre Palmer (Advisor); David Wood (Committee Member); Jeffrey Chalmers (Committee Member) Subjects: Chemical Engineering

PhD, University of Cincinnati, 2014, Medicine: Systems Biology and Physiology

Abstract Background and Significance: Evidence from large-scale clinical studies shows a paradoxical relationship between a high fat diet and myocardial pathophysiology. Termed the `obesity paradox', data from these studies indicate that obesity and a high BMI have an inverse relationship with mortality after myocardial infarction (MI), even with increased risk for an initial coronary event. Chronically, high fat diets lead to dyslipidemia, obesity-induced inflammation, adipogenesis, glucose resistance, diabetes, and sustained elevation of serum cholesterol levels. This work will investigate the discovery that cardioprotection against ischemia/reperfusion (I/R) injury occurs after a very short duration of high fat feeding. This timeline suggests that this cardioprotection is independent from the chronic effects of high fat feeding. Rather, there must be an acute effect, the nature of which has not previously been studied. Objectives: These studies investigated the effects of the high fat diet on infarct size post-MI, on NF-?B activation in the heart, and the potential mechanistic relationship between NF-?B and high fat diet (HFD) induced cardioprotection. We hypothesize that NF-?B is activated acutely in the heart via high fat diet, and contributes to the regulation of a cardioprotective gene network. NF-?B is known to be activated in inflammatory states and also is activated by specific oxidized lipids in tissues. NF-?B has been shown to play a pro-cell death role in I/R as well as a protective role in ischemic preconditioning. Thus, it is a likely mediator of the effects of a high fat diet on cardiac myocyte signaling. Understanding this mechanism is essential to revealing new therapeutic targets (genes and their products) that can be manipulated to utilize cardioprotection in the clinical setting. Major Findings: The primary finding of this study shows that short-term high fat diet elicits a cardioprotective effect against I/R injury. This effect is a (open full item for complete abstract)

Committee: Walter Jones Ph.D. (Committee Chair); Jack Rubinstein M.D. (Committee Member); Hamid Eghbalnia Ph.D. (Committee Member); Nelson Horseman Ph.D. (Committee Member); John Lorenz Ph.D. (Committee Member); Patrick P.W. Tso Ph.D. (Committee Member) Subjects: Physiological Psychology

PHD, Kent State University, 2014, College of Arts and Sciences / School of Biomedical Sciences

Ischemic postconditioning has been shown to reduce injury in response to ischemia/reperfusion. Because of limitations on the clinical use of ischemic postconditioning protocols, pharmacological agents that elicit a postconditioning (PostC) effect are highly desired. Previous studies have shown that stimulation of alpha1-adrenergic receptors (α1-ARs) is cardioprotective, thus, the first aim of this dissertation was to examine the effects of post-ischemic stimulation of α1-ARs on cardiac myocyte cell death. Adult rat ventricular myocytes and HL-1 cardiac myocytes were subjected to simulated ischemia-reperfusion injury. Cell membrane permeability, evaluated by measuring released lactate dehydrogenase (LDH) or propidium iodide uptake (PI), was used as an estimate of cell death. Lower amounts of LDH and PI uptake were detected when α1-ARs were stimulated at the onset of reperfusion. Further, lower levels of apoptosis were measured using TUNEL and DNA laddering to evaluate DNA cleavage and Annexin V staining to evaluate outer membrane phosphatidylserine. Prior studies suggest that increased autophagy following ischemia is protective. The second aim of this dissertation was to determine whether post-ischemic α1-AR stimulation inhibits cardiac myocyte death through modulation of autophagy. Alpha1-AR-mediated reductions in cell death were reversed in the presence of ATG inhibitor, 3-Methyladenine. Western blot for autophagosomal marker, LC3-II indicated modulation of autophagy, and two methods were used to measure autophagic flux. LC3-II turnover examined with and without autophagosome-lysosome fusion inhibitor chloroquine revealed an increase in autophagic flux or induction. HL-1 cells transfected with plasmid to express a tandem fluorescent-tagged LC3 molecule also indicated an increase in autophagic flux or induction. Finally, the third aim of this dissertation was to examine the molecular pathways stimulated by α1-ARs that lead to decreased cell death. PI fluorescence as (open full item for complete abstract)

Committee: June Yun Ph.D. (Advisor); J. Gary Meszaros Ph.D. (Committee Member); Angelo DeLucia Ph.D. (Committee Member); Werner Geldenhuys Ph.D. (Committee Member); Joel Hughes Ph.D. (Committee Member) Subjects: Biology; Biomedical Research

MS, University of Cincinnati, 2014, Medicine: Clinical and Translational Research

Introduction: Recent endovascular trials including Interventional Management of Stroke (IMS) III trial did not demonstrate a significant difference in outcomes between the combined intravenous t-PA/endovascular and IV t-PA treatment groups. A suggested reason for lack of effect with the endovascular approach is that good clinical outcomes following angiographic reperfusion are strongly time dependent. Our purpose was to use decision modeling to compare the two treatment strategies in a subgroup of patients with large vessel occlusion in the anterior circulation based on varying times to angiographic reperfusion and varying rates of reperfusion. Methods: We developed a decision analytic model using IMS III trial data and a comprehensive literature review. Base case for this analysis: Acute ischemic stroke patient with large vessel (ICAT/M1/M2) occlusion, IV t-PA initiated within 3 hours, time from stroke onset to reperfusion of 325 minutes. Utilities were assigned to modified Rankin Score outcome levels and effectiveness of the treatment was measured in quality-adjusted life years (QALYs). One-way sensitivity analyses for time to reperfusion, and two-way sensitivity analyses for time to reperfusion and rate of reperfusion success, were performed. We also performed Monte Carlo simulation with 10,000 iterations addressing variation in the total time to angiographic reperfusion for the endovascular approach. Results: The endovascular approach yielded a higher expected utility of 6.38 QALYs compared to 5.42 QALYs for the IV only arm. One-way sensitivity analyses for time to reperfusion demonstrated superiority of endovascular treatment as compared to IV only arm until time to reperfusion exceeded a threshold of 347 minutes. Two-way sensitivity analyses of time to reperfusion and probability of reperfusion showed that endovascular treatment was preferred when rate of reperfusion is high and time to reperfusion is small. Monte Carlo results demonstrated an e (open full item for complete abstract)

Committee: Erin Nicole Haynes Dr. P.H. (Committee Chair); Mark Eckman M.D. (Committee Member); Pooja Khatri M.D. (Committee Member) Subjects: Radiology

Doctor of Philosophy (PhD), University of Toledo, 2014, College of Medicine

Acute myocardial infarction, the clinical manifestation of ischemia-reperfusion (IR) injury, is a leading cause of death worldwide. Although percutaneous coronary interventions and thrombolytic therapies are effective in limiting the duration of ischemia, the re-introduction of blood flow to previously ischemic area causes additional damage, collectively known as reperfusion injury. One of the most effective ways to reduce reperfusion injury is ischemic preconditioning (IPC), which is induced by several cycles of brief ischemia and reperfusion bouts prior to the prolonged ischemia. IPC was found to be mediated through signaling pathways (including activation of Src, PI3K-IB, and PKCe), and mimicked by a number of pharmacological or mechanical interventions. However, 25 years after the first report of IPC, preconditioning research has not translated into clinical application against cardiac reperfusion injury. Contributing to this somewhat surprising and disappointing failure to translate preconditioning into the clinic, the applicability and efficacy of preconditioning treatments in the setting of acute myocardial infarction (MI) have not always been carefully considered in the research setting. In particular, the impact of comorbidities on cardioprotective signaling or the unpredictable nature of MI has limited the impact of IPC. Against this background, the overall objective of this work was to investigate the potential benefit of using cardiac glycosides (CG) drugs to trigger cardioprotection in conditions relevant to acute myocardial infarction. Indeed, treatment with low doses of the CG ouabain before ischemia has been shown to induce cardioprotective effects against IR injury through a mechanism known as ouabain preconditioning (OPC). Rather than the classic specific inhibition of Na/K-ATPase-mediated ion transport, the mechanism underlying OPC is the activation of the more recently recognized signaling function of Na/K-ATPase, which includes Src-PKCe, ROS a (open full item for complete abstract)

Committee: Sandrine Pierre Ph.D (Advisor); Sandrine Pierre Ph.D (Committee Chair); Zi-Jian Xie Ph.D (Committee Member); Jiang Tian Ph.D (Committee Member); Lijun Liu M.S., M.D. (Committee Member); Guillermo Vazquez Ph.D (Committee Member); Andrew Beavis Ph.D (Committee Member) Subjects: Biomedical Research

PhD, University of Cincinnati, 2010, Medicine : Molecular, Cellular and Biochemical Pharmacology

The small heat shock protein (sHsp) with apparent molecular mass of 20 kD (Hsp20) is one of 10 members of the sHsp family. Interestingly, Hsp20 is the only member within this family that contains a consensus peptide motif (RRAS) for protein kinase A (PKA)/protein kinase G (PKG)-dependent phosphorylation at Ser16. Recent studies have shown that enhanced myocardial function was associated with increased expression levels of Hsp20 and its phosphorylation. To further elucidate the possible mechanisms underlying the inotropic effects of Hsp20 and its phosphorylation, as well as their possible roles in ischemia/reperfusion-induced cardiac injury, the present study employed in vitro adenoviral-gene transfer and in vivo transgenic approaches. Our study firstly revealed that acute overexpression of wild-type Hsp20 by adenoviral infection augmented cardiac myocyte contractility, which was further confirmed in Hsp20-transgenic murine hearts (10-fold overexpression). This hypercontractility was associated with increased activation of phospholamban (PLN), evidenced by ≈ 2-fold higher expression of Ser16/Thr17-phosphorylated PLN in Hsp20-transgenic hearts related to non-transgenic controls. Furthermore, co-immunoprecipitation experiments indicated that Hsp20 was associated with type 1 phosphatase (PP1), suggesting Hsp20 may regulate PP1 activity in the mouse heart. Indeed, PP1 activity was significantly reduced in Hsp20-transgenic hearts, compared to non-transgenic hearts. These results imply that Hsp20 positively regulate cardiac function via inhibition of PP1 activity, and its downstream target, PLN phosphorylation. Secondly, to further assess the functional significance of p-Ser16 Hsp20 in vivo and its possible roles in regulation of I/R-induced apoptosis and autophagy, we generated a transgenic mouse model with cardiac-specific expression of a non-phosphorylatable Hsp20 (Hsp20S16A). Our findings indicate that increased Hsp20S16A expression in the heart failed to protect hea (open full item for complete abstract)

Committee: Evangelia Kranias PhD (Committee Chair); Guochang Fan PhD (Committee Chair); Walter Jones PhD (Committee Member); Hongsheng Wang PhD (Committee Member); Muhammad Ashraf PhD (Committee Member); Jo El Schultz PhD (Committee Member) Subjects: Pharmacology

PhD, University of Cincinnati, 2008, Medicine : Molecular, Cellular and Biochemical Pharmacology

Cardiovascular disease, which remains the leading cause of mortality in the Western world, is manifested in contractile dysfunction, myocardial infarction and arrhythmias. These detrimental effects are partially attributed to impaired Ca cycling and cell death. Since calsequestrin (CSQ) and inhibitor-1 (I-1) are key regulators of Ca cycling and the anti-apoptotic small heat shock protein 20 (Hsp20) is an important mediator of cardioprotection, this dissertation sought to gain further insights into the role of these proteins in cardiac pathophysiology. CSQ is a crucial regulator of Ca load in the sarcoplasmic reticulum and the Ca-release channel, the ryanodine receptor. Interestingly, human CSQ null mutations have been associated with catecholaminergic polymorphic ventricular tachycardia (CPVT). To further address the significance of CSQ and CSQ null mutations, this dissertation attempted to generate a mouse model with ablation of CSQ. I-1 and its phosphorylation at Thr35 are important mediators of the heart's beta-adrenergic responses. To address any potential beneficial effects of enhanced I-1 activity in the adult heart, a mouse model with inducible expression of active I-1 (T35D) was generated. Active I-1 expression significantly enhanced contractility, associated with preferential phospholamban (PLN) and myosin light chain 2a phosphorylation. Upon ischemia/reperfusion (I/R), active I-1 augmented contractile function, associated with increased pThr17-PLN phosphorylation. Further examination revealed that the infarct region and apoptotic as well as necrotic injury were significantly attenuated by enhanced I-1 activity, associated with suppression of the endoplasmic reticulum stress response. These findings indicate that active I-1 may represent a potential therapeutic strategy in myocardial infarction. Hsp20 and its phosphorylation at Ser16 protect cardiomyocytes against apoptosis. To determine whether genetic variants exist in human Hsp20, which may modify t (open full item for complete abstract)

Committee: Evangelia Kranias (Committee Chair); Keith Jones (Committee Member); Jeff Molkentin (Committee Member); Jo El Schultz (Committee Member); Hong-Sheng Wang (Committee Member) Subjects: Biomedical Research

PhD, University of Cincinnati, 2008, Medicine : Molecular, Cellular and Biochemical Pharmacology

Cardiovascular disease (CVD) remains the leading cause of death in the United States and in the developing world, with ischemic heart disease the second most common form of CVD. Experimental and clinical studies have demonstrated that a number of interventions, including brief periods of ischemia or hypoxia and certain endogenous molecules such as growth factors, opioids, adenosine or pharmacological agents are capable of protecting the heart against post-ischemic cardiac dysfunction, arrhythmias and myocardial infarction. One of these growth factors, fibroblast growth factor-2 (FGF2), has been implicated to be a cardioprotective molecule. FGF2 consists of multiple protein isoforms (low molecular weight, LMW, and high molecular weight, HMW) produced by alternative translation from the Fgf2 gene and these protein isoforms are localized to different cellular compartments indicating unique biological activity. Currently, the roles of the FGF2 isoforms in ischemia-reperfusion injury and cardioprotection remain to be elucidated. Understanding the biological function(s) of the FGF2 isoforms in cardioprotection is of a great clinical importance and may lead to the development of novel pharmacological or gene therapy strategies for ischemic heart disease. This dissertation research utilized mice with a targeted ablation of a specific FGF2 isoform (FGF2 LMWKO or FGF2 HMWKO) or mice in which all FGF2 isoforms (Fgf2 KO) were absent, and mice with a ubiquitous overexpression of the human FGF2 HMW 24 kD isoform (24 kD Tg) to evaluate the role(s) of the FGF2 protein isoforms in ischemia-reperfusion (I/R) injury. Cardioprotection in mice subjected to an isolated work-performing heart model of global, low-flow ischemia-reperfusion injury was indicated as an improvement in post-ischemic recovery of cardiac function and/or a reduction in creatine kinase release into coronary effluent or a reduction in myocardial infarct size. FGF2 LMWKO hearts had a significant decrease in post-is (open full item for complete abstract)

Committee: Jo El Schultz PhD (Committee Chair); Thomas Doetschman PhD (Committee Member); W. Keith Jones PhD (Committee Member); Evangelia G Kranias PhD (Committee Member); Mark Olah PhD (Committee Member); Hong-Sheng Wang PhD (Committee Member) Subjects: Pharmacology

PhD, University of Cincinnati, 2007, Medicine : Molecular and Developmental Biology

Neurological disorders caused by acute disruption of cerebral blood flow are a major clinical concern in both the adult and newborn. Loss of oxygen utilization despite adequate blood flow marks brain tissue fated for death in stroke, but the reason for this is not clear. In this study, we used a cerebral ischemia-hypoxia model in mice to determine the effects of hypoxia on partially ischemic tissue. We found this engaged simultaneous cell survival and death signaling, as well as autophagy, a process by which the cell digests its contents to stay alive during an energy crisis. This was associated with oxidative stress, extensive clotting, and impaired reperfusion after ischemia-hypoxia. This perfusion impairment was prevented in fibrinogen deficient mice, who also exhibited less injury. These results indicate the loss of tissue oxygen utilization in stroke may lead to clotting in the vasculature, and that this must be resolved for effective recovery. In contrast, in neonatal rat hypoxia-ischemia, a model of hypoxic-ischemic encephalopathy, perfusion impairment was restored by 4 hours recovery, and the mechanism for this is also unclear. We found this restoration was associated with an induction of the clot busters tissue-type (tPA) and urokinase-type (uPA) plasminogen activators. tPA deficient mice had greater fibrin deposition and mortality during hypoxia than wildtype mice, confirming a protective role. However, the induction of tPA, which can also be potentially damaging, was sustained throughout the future lesion in rats, and associated with blood-brain-barrier damage, white matter degradation, neuronal axon loss, and apoptosis. Inhibition of the downstream plasmin with alpha-2 antiplasmin offered significant protection, and the injection of additional tPA made the injury worse. These results indicate that inhibition of deleterious plasminogen activator / plasmin effects may aid in treatment of hypoxic-ischemic encephalopathy. All together, this study shows a dif (open full item for complete abstract)

Committee: Dr. Chia-Yi Kuan (Advisor) Subjects:

PhD, University of Cincinnati, 2005, Medicine : Molecular, Cellular and Biochemical Pharmacology

Heart failure is a complex syndrome characterized by left ventricular dysfunction, myocardial remodeling, and biochemical alterations. Several signaling pathways are involved in the induction of pathological remodeling and heart failure; many of these pathways are linked to cardiac sarcoplasmic reticulum (SR) Ca2+ cycling, as intracellular Ca2+ handling is the central coordinator of cardiac function. Since defects in SR Ca2+ cycling are a common pathophysiological characteristic of heart failure, targeting defects in Ca2+ handling is proposed as adjunctive therapy in end-stage heart failure. Further investigating the roles of known proteins and novel proteins in the Ca2+ cycling pathway is critical in identifying the best potential targets for therapeutic drugs. A recently discovered histidine-rich calcium binding protein (HRC) may play a role in Ca2+ homeostasis in the SR. However, its specific role in SR Ca2+ cycling remains to be elucidated. Our data indicate that: (a) HRC regulates SR Ca2+ uptake and is an integral regulatory protein in the cardiac muscle Ca2+ cycling cascade; (b) an increase in HRC protein levels results in cardiac dysfunction; and (c) HRC may be a therapeutic target for heart failure. We also further investigated the role of another important Ca2+ cycling regulatory protein, phospholamban (PLN), in the context of ischemia and reperfusion. Our data reveal that decreased particulate partitioning of protein kinase C epsilon (PKCε) contributes to the increased susceptibility to ischemic injury in PLN deficient hearts and that augmentation of PKCε particulate partitioning through myocardial specific expression of a selective PKCε translocation activator, ψεRACK, in hearts at an increased risk for ischemia is sufficient to confer cardioprotection. The data generated and implications of these data suggest a promising therapeutic target for heart failure may be the recently discovered regulator of SR Ca2+ uptake, HRC, while there should be caution in (open full item for complete abstract)

Committee: Dr. Evangelia Kranias (Advisor) Subjects: Biology, Molecular

Master of Science in Exercise Science, University of Toledo, 2011, College of Health Sciences

Cardiovascular diseases are a major cause of death throughout the world. Furthermore, the primary pathological cause of coronary artery disease is myocardial damage due to ischemic-reperfusion (IR) injury, the vascular dysfunction and tissue damage due to reperfusion following a long duration of ischemia. According to the literature, IR injury leads to endothelial dysfunction. It has been well established that endothelial dysfunction is one of the first identifiable markers of atherogenesis and vascular disease. Furthermore, it has also been demonstrated that participation in regular, physical activity can lead to both ischemic preconditioning as well as improved endothelial function. However, it is not currently known if an acute bout of exercise performed prior to experiencing an IR injury can lead to a protective condition whereby endothelial dysfunction is either prevented or reduced. Therefore, the purpose of the present study is to determine whether an acute bout of moderate intensity exercise, such as jogging on a treadmill, can provide an alternative method of preconditioning to either prevent or reduce the effects of IR injury. The study consisted of 6 male and 3 female subjects (n=9, age = 21.7 ± 3.2 years). All subjects were all healthy, sedentary individuals (height = 174.43 ± 8.12 cm, body mass = 77.87 ± 21.03 kg, body mass index = 25.46 ± 6.26 kg/m²) and were not currently engaged in any type of resistance or endurance exercise training. Each subject performed all three protocols; ischemic-reperfusion injury (IRI), exercise (EXER), and preconditioning (EXER/IRI) which included performing exercise prior to ischemic-reperfusion injury. Endothelial function was assessed using flow-mediated dilation (FMD) of the brachial artery, a surrogate model to the coronary arteries. The ANOVA analysis indicated that there was a significant main effect for time, however no main effect for protocol (p=0.08) or interaction was observed. Compared to the initial FMD trial (open full item for complete abstract)

Committee: Barry Scheuermann PhD (Committee Chair); Suzanne Wambold PhD (Committee Member); David Weldy PhD (Committee Member) Subjects: Health Sciences

Doctor of Philosophy, The Ohio State University, 2012, Integrated Biomedical Science Graduate Program

Induction of ischemia/reperfusion (IR) injury has been shown to render endothelial nitric oxide synthase (eNOS) dysfunctional; limiting the endogenous mechanisms which regulate vasodilation in the vessel. In the heart, this results in limited tissue perfusion via coronary arteries, which when persistent, results in pump failure. Recently it has been shown that in the ex vivo, isolated heart model, IR results in depletion of the critical NOS cofactor, tetrahydrobiopterin (BH4). When the lost eNOS cofactor is repleted the activity of the dysfunctional enzyme can be partially ameliorated and vasodilation, while incomplete, is markedly improved. The lack of complete restoration in vasodilation led to this thesis work, which sought to explore the role of reduced nicotinamide adenine dinucleotide phosphate (NADPH), a critical NOS substrate, in enzymatic function after IR injury. The levels of all pyridine nucleotides where measured throughout ischemia, and subsequent reperfusion to determine any fluctuations in levels as a result of the injurious stimuli. It was found that within the whole-heart, the levels of both NADPH and NADP+ (oxidized form of NADPH) were depleted during reperfusion. Furthermore, this depletion appears to be targeted to the endothelium, where the degree of NADP(H) depletion was most severe. Repletion of lost NADPH after IR resulted in a robust increase in coronary flow, when repletion of NADPH was performed with the addition of the eNOS inhibitor, L-NAME, these benefits were lost. Furthermore, repletion of NADPH was vastly superior to BH4 repletion, but when given together the improvement to coronary flow was cumulative. In our model of the isolated heart we show the decline of NADP+ coincides with the production of 2'-phospho-cyclic ADP-ribose (2'-P-cADPR), a signaling molecule produced from the ADP-ribosyl cyclase activity of CD38. Originally identified as an antigen marker on B-Cells, CD38 was later found to contain sequence homology with ADP- (open full item for complete abstract)

Committee: Jay L. Zweier MD (Advisor); Mark T. Ziolo PhD (Committee Member); Richard J. Gumina MD, PhD (Committee Member); Arthur R. Strauch PhD (Committee Member) Subjects: Biomedical Research

Doctor of Philosophy, The Ohio State University, 2012, Biophysics

Reperfusion of the ischemic myocardium occurs in nearly 2 million people annually in the United States as a complication of cardiovascular disease, in patients experiencing cardiac arrest, myocardial infarction or undergoing cardioplegic arrest during cardiac surgery. Various levels of low flow are induced by such ischemic events, most notably in the moments following ischemia. However, the post-ischemic low flow period has hardly been examined in the literature. The work presented in this dissertation explores the role of reactive oxygen species (ROS) generation in global ischemia, post-ischemic low flow, and subsequent full reperfusion of the myocardium. This dissertation consists of three parts. In Chapter 2, an isolated buffer-perfused rat heart model was employed to explore both low pressure and low coronary flow as interventions in global cardiac ischemia. The ROS burst was observed upon full reperfusion in rat hearts, with differences in ROS generation between the cellular and vascular compartments. Differences in recovery of left ventricular (LV) function were also observed, with LV functional preservation at 10% low flow, but not at 0.5% low flow intervention. In Chapter 3, a novel model of the isolated heart is described, in which whole blood is recirculated throughout experimentation. Blood-perfused and buffer-perfused hearts were noted to respond similarly to global ischemia and low flow intervention. Also, a method describing detection of the ROS burst at reperfusion in blood-perfused hearts is described. A characteristic acute, short-lived formation of hydrogen peroxide was discovered in blood-perfused hearts subjected to ischemia and reperfusion. In Chapter 4, the neutrophil elastase inhibitor Sivelestat is examined for putative cardioprotective properties. Sivelestat was noted to possess dramatic infarct-sparing properties in the isolated heart, along with the ability to preserve LV function. ROS production was examined, and Sivelestat was shown to r (open full item for complete abstract)

Committee: Mark Angelos M.D. (Committee Chair); Periannan Kuppusamy Ph.D. (Committee Member); Valery Khramtsov Ph.D. (Committee Member); Jonathan Davis Ph.D. (Committee Member); Michael Bisesi Ph.D. (Committee Member) Subjects: Biophysics

Doctor of Philosophy, The Ohio State University, 2012, Biomedical Engineering

This work was conducted in order to assess the role that the mitochondrial network plays in cardiovascular disease. More specifically, we first conducted studies to determine which bioenergetic factors control changes in the mitochondrial network by exposing cultured endothelial cells to specific chemical treatments. Following this work, we used a parallel plate flow chamber and media recirculation system to expose cultured endothelial cells to simulated ischemia (I)/ reperfusion (RP) injury in order to determine if changes in the mitochondrial network occur upon I/RP and delineate the molecular mechanisms that govern them. The mitochondrial network is dynamic with conformations that vary between a tubular continuum and fragmented state. The equilibrium between mitochondrial fusion/fission, as well as the organelle motility, determine network morphology and ultimately mitochondrial/cell function. Network morphology has been linked with the energy state in different cell types. As stated, in the first part of this study, we examined how bioenergetic factors affect mitochondrial dynamics/motility in cultured vascular endothelial cells (ECs). ECs were transduced with mitochondria-targeted green fluorescent protein (mito-GFP) and exposed to inhibitors of oxidative phosphorylation (OXPHOS) or ATP synthesis. Time-lapse fluorescence videos were acquired and a mathematical program that calculates size and speed of each mitochondrial object at each time frame was developed. Our data showed that inner mitochondrial membrane potential, ATP produced by glycolysis, and, to a lesser degree, ATP produced by mitochondria are critical for maintaining the mitochondrial network, and different metabolic stresses induce distinct morphological patterns (e.g., mitochondrial depolarization is necessary for “donut” formation). Mitochondrial movement, characterized by Brownian diffusion with occasional bursts in displacement magnitude, was inhibited under the same conditions that resulted i (open full item for complete abstract)

Committee: B. Rita Alevriadou PhD (Advisor); Keith Gooch PhD (Committee Member); Richard Hart PhD (Committee Member); Thomas Lemberger PhD (Committee Member) Subjects: Biology; Biomedical Engineering; Biomedical Research; Biophysics; Cellular Biology; Computer Science; Engineering; Mathematics; Mechanical Engineering