Pharmacology, Toxicology and Environmental Health Commons^™

Effects Of Exogenous Ketone Therapy On Performance, Cardiorespiration, And Seizure Genesis During Exposure To Hbo2 In The Sprague Dawley Rat, Nicole M. Stavitzski

USF Tampa Graduate Theses and Dissertations

Hyperbaric oxygen (HBO2) is used for clinical HBO2 therapy and in undersea and aerospace medicine. HBO2 is a humanmade extreme environment and protracted exposures can cause several adverse physiological effects on the body. For example, HBO2 increases the partial pressure of oxygen (PO2) in the body leading to redox stress. Redox stress is, in part, a cause of oxygen toxicity that manifests as seizures in its most severe form (central nervous system oxygen toxicity, CNS-OT). This dissertation focuses on strategies to be employed specifically for the warfighter breathing HBO2. Currently, the only way to prevent CNS-OT is to lower the …

Mitigation Strategies For Central Nervous System Oxygen Toxicity In Rodents: Ketone Metabolic Therapy And Mitochondrial Antioxidant Therapy, Christopher Manuel Hinojo

USF Tampa Graduate Theses and Dissertations

Hyperbaric oxygen (HBO2) is a frequently encountered condition in undersea medicine and hyperbaric oxygen therapy (HBOT). The risk of CNS oxygen toxicity (CNS-OT) seizures limits its use in hyperbaric medicine and limits bottom time for diving operations. In this study, we sought to understand the role of reactive oxygen species (ROS) in two mitigation strategies for CNS-OT; ketone metabolic therapy (KMT), which is known to delay onset of CNS-OT seizures, and mitochondria targeted antioxidant therapy (MitoTAT), which has never been tested under HBO2 conditions. We specifically focused on superoxide anions, one of the early reduction products of molecular oxygen, and …

A Study Of Trpa1 Activation Via Covalent Electrophilic Modification Of Cysteines, Thomas A. Parks

USF Tampa Graduate Theses and Dissertations

A subset of sensory nerves called nociceptors are stimulated by noxious stimuli and evoke nocifensive responses in different organ systems. Transient Receptor Potential Ankyrin 1 (TRPA1) is a tetrameric, nonselective, cation channel that initiates the generator potential that evokes afferent signaling in nociceptive nerves. TRPA1 is activated many harmful irritants, such as food chemicals, environmental pollutants, reactive oxygen species and other endogenous mediators. Most TRPA1 agonists have electrophilic properties, which covalently modify cysteine residues on the cytosolic side of the channel. Biochemical studies in our lab have identified four cysteines (C273, C621, C665, C1085) that rapidly bound iodoacetamide (irreversible electrophile); …

Functional Significance Of Endothelial Sigma-1 Receptors In Vascular Reactivity And Barrier Function, Zeinab Y. Motawe

USF Tampa Graduate Theses and Dissertations

The sigma-1 receptor (σ1) is a single 25 kD polypeptide that acts as a chaperone protein residing primarily in the endoplasmic reticulum Its interaction with mitochondria at the mitochondria-associated ER membrane domain is well-documented. Following activation, σ1 binds to the inositol trisphosphate receptor (Hayashi & Su), and modulates intracellular calcium homeostasis. Also, the activated σ1 modulates plasma membrane receptors and ion channel functions, and may regulate cellular excitability. Further, σ1 affects trafficking of lipids and proteins essential for neurotransmission, cell growth and motility. Activation of σ1 provides neuroprotection and cardio-protection in various models. Examples of neuroprotection include but not limited …

Identifying New Treatment Options And Risk Factors For Type 2 Diabetes: The Potential Role Of Thymoquinone And Persistent Organic Pollutants, Shpetim Karandrea

USF Tampa Graduate Theses and Dissertations

Type 2 Diabetes Mellitus (T2DM) is a metabolic disorder characterized by chronic hyperglycemia, which develops as a consequence of peripheral insulin resistance and defective insulin secretion from pancreatic β-cells. A high calorie diet coupled with physical inactivity are known risk factors for the development of T2DM; however, these alone fail to account for the rapid rise of the disease. Recent attention has turned to the role of environmental pollutants in the development of metabolic diseases. PBDEs (polybrominated diphenyl ethers) are environmental pollutants that have been linked to the development of type 2 diabetes (T2D), however, the precise mechanisms are not …

Hypercapnic Hyperoxia Increases Free Radical Production And Cellular Excitability In Rat Caudal Solitary Complex Brain Slice Neurons, Geoffrey Edward Ciarlone

USF Tampa Graduate Theses and Dissertations

The caudal solitary complex (cSC) is a cardiorespiratory integrative center in the dorsal medulla oblongata that plays a vital role in the central CO₂-chemoreceptive network. Neurons in this area respond to hypercapnic acidosis (HA) by a depolarization of the membrane potential and increase in firing rate, however a definitive mechanism for this response remains unknown. Likewise, CO₂-chemoreceptive neurons in the cSC respond to hyperoxia in a similar fashion, but via a free radical mediated mechanism. It remains unknown if the response to increased pO₂ is merely an increase in redox signaling, or if it’s the …

Cardiovascular Effects Evoked By Airway Nociceptive Reflexes In Healthy And Cardiovascular Diseased Rats, Justin Shane Hooper

USF Tampa Graduate Theses and Dissertations

Acute inhalation of airborne pollutants alters cardiovascular function and has been shown to have its greatest affects on individuals with pre-existing cardiovascular disease. Evidence suggests that pollutant-induced activation of airway sensory nerves via the gating of ion channels is critical to these systemic responses. Here, we have investigated the cardiovascular responses evoked by inhalation of AITC (TRPA1 agonist) and capsaicin (TRPV1 agonist) in healthy Sprague Dawley (SD) and Wistar Kyoto (WKY) rats, and cardiovascular diseased Spontaneously Hypertensive (SH) rats. Inhalation of the agonists by healthy SD and WKY rats caused significant bradycardia, atrio-ventricular (AV) block and prolonged PR-Intervals. Inhalation of …

Sigma Receptor Activation Mitigates Toxicity Evoked By The Convergence Of Ischemia, Acidosis And Amyloid-Beta, Adam Alexander Behensky

USF Tampa Graduate Theses and Dissertations

Stroke is the fifth leading cause of death in the United States and a major cause of long-term disability in industrialized countries. The core region of an ischemic stroke dies within minutes due to activation of necrotic pathways. Outside of this core region is the penumbral zone, where some perfusion is maintained via collateral arteries. Delayed cell death occurs in this area due to the triggering of apoptotic mechanisms, which expands the ischemic injury over time. The cellular and molecular events that produce the expansion of the ischemic core continue to be poorly understood. The increases in the amyloid precursor …

Store-Operated Calcium Channels In The Function Of Intracardiac Neurons, Timetria Bonds

USF Tampa Graduate Theses and Dissertations

Proper autonomic regulation of mammalian cardiac function is dependent upon very complex and precise communication among the intracardiac ganglia and individual neurons within the ganglia. An array of neuromodulators is found within the ganglia that direct neuronal activity by modulating the movement of calcium. The current study determines that opioidergic agonists, which have been found to contribute to severe cardiac disease states and intracellular calcium mobilization, are also responsible for changes in the function of the intracardiac neuron via their effects on store-operated calcium channels (SOCs).

Previous studies suggest that phosphorylation plays a role in SOC regulation. Using Fura-2 calcium …

Secreted Factors From Human Umbilical Cord Blood Cells Protect Oligodendrocytes From Ischemic Insult, Derrick Rowe

USF Tampa Graduate Theses and Dissertations

Oligodendrocytes (OL)s are the dominant cell type in the white matter and are integral for synaptic transmission essential for proper neuronal communication between brain areas. Previous studies have shown that intravenous administration of the mononuclear fraction of human umbilical cord blood (HUCB) cells in rat models of stroke reduced white matter injury, gray matter injury and behavioral deficits. Yet the mechanisms used by HUCB cells remain unknown in ischemic injury. These studies will investigate both in vitro and in vivo approaches to elucidate this mechanism in OLs. When mature primary OLs were coincubated with HUCB cells, HUCB cells secreted soluble …