Systems and Integrative Physiology Commons^™

The Effect Of Central Chemoreceptors On The Peripheral Respiratory Chemoreflex Response To Hypoxia In Humans, Nasimi A. Guluzade

Electronic Thesis and Dissertation Repository

We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions (PCO₂) to determine the form of the relationship between PChS and central PCO₂. Twenty participants completed three repetitions of modified rebreathing tests with end-tidal PO₂ (P_ETO₂) clamped at 150, 70, 60, and 45 mmHg. PChS was computed at 1-mmHg intervals of P_ETCO₂ as follows: the differences in V̇_E between the three hypoxic profiles and the hyperoxic profile (∆V̇_E) were calculated; three ∆V̇_E values were plotted against corresponding calculated oxyhemoglobin …

The Role Of E-Liquid Constituents In E-Cigarette-Induced Cardiac Arrhythmia And Autonomic Imbalance., Cory Kucera

Electronic Theses and Dissertations

Introduction. Accumulating evidence indicates that exposure to electronic cigarettes (e-cigs) promotes sympathetic dominance and electrophysiologic instability in the heart, potentially culminating in arrhythmogenesis. E-liquids contain various formulations of nicotine and flavorings, but the effects of specific e-liquid constituents and their concentrations on e-cig-induced autonomic imbalance and electrical dysfunction are unresolved. To that end, we tested the hypothesis that e-cigs modify cardiac autonomic balance and ventricular arrhythmogenesis in mice dependent on e-liquid constituent type and concentration. Methods. Using a crossover design and a serial exposure regimen, ECG-telemetered male C57BL/6J mice underwent whole-body exposure to e-cig aerosols generated from e-liquids containing different …

The Sympathetic Neural Control Of The Circulation At Rest And During Exercise: Effects Of Age, Biological Sex, And Sex Hormones, Andrew W. D'Souza

Electronic Thesis and Dissertation Repository

The overall objective of this dissertation was to determine the impact of age, sex, and sex hormones on the discharge behaviours of muscle sympathetic action potentials (APs) as well as the corresponding changes in peripheral vasoconstriction and blood pressure at rest and during exercise. The microneurographic technique was employed to record multi-unit muscle sympathetic nerve activity (MSNA), with a continuous wavelet transform applied post-hoc to evaluate APs within the recorded neurogram. Study One examined the impact of aging on the central and peripheral arcs of the sympathetic baroreflex under resting conditions. This study revealed that middle-aged-to-older adults demonstrated heightened sympathetic …

Effects Of Intertidal Position On The Response To Oxygen And Desiccation Stress In The Common Acorn Barnacle, Balanus Glandula, Megan M. Dotterweich

Master's Theses

Sessile invertebrates in the rocky intertidal experience intermittent periods of air exposure due to tidal flux, presenting risks of temperature extremes, hypoxia, nutrient limitation, and most dangerously, desiccation. Microscale variation in severity and frequency of these risks is widely dependent on vertical position within the intertidal zone. Common acorn barnacles (Balanus glandula) have a wide vertical distribution in the intertidal, creating large differences in microhabitat between the highest and lowest individuals in the population. This study set out to explore whether tidal position dependent differences exist in the response to oxygen and desiccation stress in B. glandula. …

Multichannel Modulation Of Depolarizing And Repolarizing Ion Currents Increases The Positive Rate-Dependent Action Potential Prolongation, Candido Cabo

Publications and Research

Prolongation of the action potential duration (APD) could prevent reentrant arrhythmias if prolongation occurs at the fast excitation rates of tachycardia with minimal prolongation at slow excitation rates (i.e., if prolongation is positive rate-dependent). APD prolongation by current anti-arrhythmic agents is either reverse (larger APD prolongation at slow rates than at fast rates) or neutral (similar APD prolongation at slow and fast rates), which may not result in an effective anti-arrhythmic action. In this report we show that, in computer models of the human ventricular action potential, the combined modulation of both depolarizing and repolarizing ion currents results in a …

Review Of Biomedical Applications Of Cardiovascular Tissue Engineering, Natalie M. Howard

Honors College Theses

Tissue engineering can be defined as processes that aim to generate three-dimensional functional tissues in vitrothat have been favorably altered according to the structural, biochemical, electrophysiological, and biomechanical properties of the desired tissue before implantation into the human body. In relation to cardiac tissues, these properties would include the ability to conduct action potentials, withstand systolic pressure, permit sufficient O₂ and CO₂penetration, sufficient vascularization to supply nutrients for cellular activity, surface topology that enables cellular communication, and more. As heart diseases and instances of myocardial infarction continue to rise worldwide, there is an increasing need for …

Plantar Flexor Dynamic Contractile Rates Are Not Dependent On Calcaneal Tendon Stiffness, Sohum Kulkarni

Electronic Thesis and Dissertation Repository

The ability to rapidly generate muscular torque and velocity is important in specialized activities and daily tasks of living. Tendon stiffness is one factor in the neuromuscular system that influences musculoskeletal torque transmission. Previous studies have reported weak-to-moderate correlations between tendon stiffness and rate of torque development (RTD). However, these correlations have been reported only for isometric contractions which may not be relevant to contractions involving joint rotation (i.e., dynamic). The purpose was to investigate the effect of calcaneal tendon stiffness on the dynamic rates of torque (RTD) and velocity (RVD) development in plantar flexor muscles. Young adult males (n=13) …

Effects Of Equine Interaction On Mutual Autonomic Nervous System Responses And Interoception In A Learning Program For Older Adults, Ann L. Baldwin, Lisa Walters, Barbara K. Rector, Ann C. Alden

People and Animals: The International Journal of Research and Practice

Equine-assisted learning (EAL) may improve the health of older adults, but scientific data are sparse. This study investigated whether people aged 55 and older show increased heart rate variability (HRV) during EAL and awareness of bodily sensations that are overall pleasant. Subjects (n = 24) participated in mindful grooming during which they slowed their breathing and brushed a horse while noticing sensations in their body and watching the horse’s reactions. The subject’s and horse’s HRV were recorded simultaneously before, during, and after mindful grooming. For control, the same subjects performed mindful grooming with a plush simulation horse. During exit …

Endothelial Cell Nrf2-Ko Attenuates Endothelial Function And Skeletal Muscle Antioxidant Capacity, Elizabeth J. Pekas, Cody P. Anderson, Michael F. Allen, Kollyn B. Jallen, Dong Gun Jin, Andres Benitez-Albiter, Christian D. Sanchez Tato, Lie Gao, Neha Dhyani, Tara L. Rudebush, Irving H. Zucker, Song-Young Park

UNO Student Research and Creative Activity Fair

INTRODUCTION: Endothelial cells line the inner surface of blood vessels and play a major role in modulating blood flow and gas exchange. Endothelial dysfunction is thought to be a contributor to cardiovascular disease development, and it is well-accepted that excessive reactive oxygen species (harmful molecules) likely contribute to endothelial dysfunction. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is considered the master regulator of cellular protection in response to elevated reactive oxygen species. Therefore, Nrf2 may be a potential therapeutic target to protect against endothelial dysfunction. However, the roles of endothelial cell-specific Nrf2 on endothelial function are not …

Restoration Of Normal Blood Flow In Atherosclerotic Arteries Promotes Plaque Stabilization, Morgan A. Schake, Ian S. Mccue, Evan T. Curtis, Thomas J. Ripperda, Samuel Harvey, Bryan T. Hackfort, Anna Fitzwater, Yiannis S. Chatzizisis, Forrest M. Kievit, Ryan M. Pedrigi

Journal Articles: Cellular & Integrative Physiology

Blood flow is a key regulator of atherosclerosis. Disturbed blood flow promotes atherosclerotic plaque development, whereas normal blood flow protects against plaque development. We hypothesized that normal blood flow is also therapeutic, if it were able to be restored within atherosclerotic arteries. Apolipoprotein E-deficient (ApoE^−/−) mice were initially instrumented with a blood flow-modifying cuff to induce plaque development and then five weeks later the cuff was removed to allow restoration of normal blood flow. Plaques in decuffed mice exhibited compositional changes that indicated increased stability compared to plaques in mice with the cuff maintained. The therapeutic benefit of …

Repeated Social Defeat Stress Leads To Immunometabolic Shifts In Innate Immune Cells Of The Spleen, Mandakh Bekhbat, John Drake, Emily C. Reed, Tatlock H. Lauten, Tamara Natour, Vladimir I. Vladimirov, Adam J. Case

Journal Articles: Cellular & Integrative Physiology

Psychosocial stress has been shown to prime peripheral innate immune cells, which take on hyper-inflammatory phenotypes and are implicated in depressive-like behavior in mouse models. However, the impact of stress on cellular metabolic states that are thought to fuel inflammatory phenotypes in immune cells are unknown. Using single cell RNA-sequencing, we investigated mRNA enrichment of immunometabolic pathways in innate immune cells of the spleen in mice subjected to repeated social defeat stress (RSDS) or no stress (NS). RSDS mice displayed a significant increase in the number of splenic macrophages and granulocytes (p < 0.05) compared to NS littermates. RSDS-upregulated genes in macrophages, monocytes, and granulocytes significantly enriched immunometabolic pathways thought to play a role in myeloid-driven inflammation (glycolysis, HIF-1 signaling, MTORC1 signaling) as well as pathways related to oxidative phosphorylation (OXPHOS) and oxidative stress (p < 0.05 and FDR<0.1). These results suggest that the metabolic enhancement reflected by upregulation of glycolytic and OXPHOS pathways may be important for cellular proliferation of splenic macrophages and granulocytes following repeated stress exposure. A better understanding of these intracellular metabolic mechanisms may ultimately help develop novel strategies to reverse the impact of stress and associated peripheral immune changes on the brain and behavior.

Defining The Nuanced Nature Of Redox Biology In Post-Traumatic Stress Disorder, Emily C. Reed, Adam J. Case

Journal Articles: Cellular & Integrative Physiology

Post-traumatic stress disorder (PTSD) is a mental health disorder that arises after experiencing or witnessing a traumatic event. Despite affecting around 7% of the population, there are currently no definitive biological signatures or biomarkers used in the diagnosis of PTSD. Thus, the search for clinically relevant and reproducible biomarkers has been a major focus of the field. With significant advances of large-scale multi-omic studies that include genomic, proteomic, and metabolomic data, promising findings have been made, but the field still has fallen short. Amongst the possible biomarkers examined, one area is often overlooked, understudied, or inappropriately investigated: the field of …

Potential Of Synthetic And Natural Compounds As Novel Histone Deacetylase Inhibitors For The Treatment Of Hematological Malignancies, Dilipkumar Pal, Khushboo Raj, Shyam Sundar Nandi, Surajit Sinha, Abhishek Mishra, Arijit Mondal, Ricardo Lagoa, Jack T. Burcher, Anupam Bishayee

Journal Articles: Cellular & Integrative Physiology

Histone deacetylases (HDACs) and histone acetyltransferases (HATs) are enzymes that remove or add acetyl groups to lysine residues of histones, respectively. Histone deacetylation causes DNA to more snugly encircle histones and decreases gene expression, whereas acetylation has the opposite effect. Through these small alterations in chemical structure, HATs and HDACs regulate DNA expression. Recent research indicates histone deacetylase inhibitors (HDACis) may be used to treat malignancies, including leukemia, B-cell lymphoma, virus-associated tumors, and multiple myeloma. These data suggest that HDACis may boost the production of immune-related molecules, resulting in the growth of CD8-positive T-cells and the recognition of nonreactive tumor …

Repeated Social Defeat Stress Induces An Inflammatory Gut Milieu By Altering The Mucosal Barrier Integrity And Gut Microbiota Homeostasis, Santosh K. Yadav, Rizwan Ahmad, Cassandra M. Moshfegh, Jagadesan Sankarasubramanian, Vineet A. Joshi, Safwan K. Elkhatib, Yashpal S. Chhonker, Goeffrey A. Talmon, Chittibabu Guda, Adam Case, Amar B. Singh

Journal Articles: Cellular & Integrative Physiology

Background

Posttraumatic stress disorder (PTSD) is a mental health condition triggered by exposure to traumatic events in an individual’s life. Patients with PTSD are also at a higher risk for comorbidities. However, it is not well understood how PTSD affects human health and/or promotes the risk for comorbidities. Nevertheless, patients with PTSD harbor a proinflammatory milieu and dysbiotic gut microbiota. Gut barrier integrity helps to maintain normal gut homeostasis and its dysregulation promotes gut dysbiosis and inflammation.

Methods

We used a mouse model of repeated social defeat stress (RSDS), a preclinical model of PTSD. Behavioral studies, metagenomics analysis of the …

Elevated Crp And Tnf-Α Levels Are Associated With Blunted Neural Oscillations Serving Fluid Intelligence, Sarah M. Dietz, Mikki Schantell, Rachel K. Spooner, Megan E. Sandal, Amirsalar Mansouri, Yasra Arif, Hannah J. Okelberry, Jason A. John, Ryan Glesinger, Pamela E. May, Elizabeth Heinrichs-Graham, Adam J. Case, Matthew C. Zimmerman, Tony W. Wilson

Journal Articles: Cellular & Integrative Physiology

INTRODUCTION: Inflammatory processes help protect the body from potential threats such as bacterial or viral invasions. However, when such inflammatory processes become chronically engaged, synaptic impairments and neuronal cell death may occur. In particular, persistently high levels of C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-α) have been linked to deficits in cognition and several psychiatric disorders. Higher-order cognitive processes such as fluid intelligence (Gf) are thought to be particularly vulnerable to persistent inflammation. Herein, we investigated the relationship between elevated CRP and TNF-α and the neural oscillatory dynamics serving Gf.

METHODS: Seventy adults between the ages of 20-66 years …

Commonalities And Differences In Carotid Body Dysfunction In Hypertension And Heart Failure, Igor S. A. Felippe, Rodrigo Del Río, Harold D. Schultz, Benedito H. Machado, Julian F R Paton

Journal Articles: Cellular & Integrative Physiology

Carotid body pathophysiology is associated with many cardiovascular-respiratory-metabolic diseases. This pathophysiology reflects both hyper-sensitivity and hyper-tonicity. From both animal models and human patients, evidence indicates that amelioration of this pathophysiological signalling improves disease states such as a lowering of blood pressure in hypertension, a reduction of breathing disturbances with improved cardiac function in heart failure (HF) and a re-balancing of autonomic activity with lowered sympathetic discharge. Given this, we have reviewed the mechanisms of carotid body hyper-sensitivity and hyper-tonicity across disease models asking whether there is uniqueness related to specific disease states. Our analysis indicates some commonalities and some potential …

Enhanced Central Sympathetic Tone Induces Heart Failure With Preserved Ejection Fraction (Hfpef) In Rats, Shyam S. Nandi, Kenichi Katsurada, Michael J. Moulton, Hong Zheng, Kaushik K. Patel

Journal Articles: Cellular & Integrative Physiology

Heart failure with preserved ejection fraction (HFpEF) is a heterogenous clinical syndrome characterized by diastolic dysfunction, concentric cardiac left ventricular (LV) hypertrophy, and myocardial fibrosis with preserved systolic function. However, the underlying mechanisms of HFpEF are not clear. We hypothesize that an enhanced central sympathetic drive is sufficient to induce LV dysfunction and HFpEF in rats. Male Sprague-Dawley rats were subjected to central infusion of either saline controls (saline) or angiotensin II (Ang II, 20 ng/min, i.c.v) via osmotic mini-pumps for 14 days to elicit enhanced sympathetic drive. Echocardiography and invasive cardiac catheterization were used to measure systolic and diastolic …

A Critical Role For Staphylococcal Nitric Oxide Synthase In Controlling Flavohemoglobin Toxicity, Ryan M. Singh, Sujata S. Chaudhari, Sasmita Panda, Elizabeth H. Hutfless, Cortney E. Heim, Dhananjay Shinde, Abdulelah A. Alqarzaee, Margaret F. Sladek, Vineet Kumar, Matthew C. Zimmerman, Paul D. Fey, Tammy Kielian, Vinai Chittezham Thomas

Journal Articles: Cellular & Integrative Physiology

Most coagulase-negative staphylococcal species, including the opportunistic pathogen Staphylococcus epidermidis, struggle to maintain redox homeostasis and grow under nitrosative stress. Under these conditions, growth can only resume once nitric oxide (NO) is detoxified by the flavohemoglobin Hmp. Paradoxically, S. epidermidis produces endogenous NO through its genetically encoded nitric oxide synthase (seNOS) and heavily relies on its activity for growth. In this study, we investigate the basis of the growth advantage attributed to seNOS activity. Our findings reveal that seNOS supports growth by countering Hmp toxicity. S. epidermidis relies on Hmp activity for its survival in the host under NO stress. …

Frontiers In The Self-Assembly Of Charged Macromolecules, Khatcher O. Margossian

Doctoral Dissertations

The self-assembly of charged macromolecules forms the basis of all life on earth. From the synthesis and replication of nucleic acids, to the association of DNA to chromatin, to the targeting of RNA to various cellular compartments, to the astonishingly consistent folding of proteins, all life depends on the physics of the organization and dynamics of charged polymers. In this dissertation, I address several of the newest challenges in the assembly of these types of materials. First, I describe the exciting new physics of the complexation between polyzwitterions and polyelectrolytes. These materials open new questions and possibilities within the context …

Prefrontal Coding Of Naturalistic Working Memory: Mechanisms During Normal Maintenance And Modelled Disease, Megan P. Roussy

Electronic Thesis and Dissertation Repository

Neural activity in the primate lateral prefrontal cortex (LPFC) has been causally linked to working memory (WM) ⁠— the brief maintenance and mental manipulation of information. Primates use WM to perform tasks in complex contexts; however, neural mechanisms of WM and the pathophysiology related to WM deficits have traditionally been studied using simple tasks that deviate from naturalistic conditions. This raises the question, how is WM processed in naturalistic conditions? To explore this, I trained two macaque monkeys on a spatial WM task set in a naturalistic virtual environment. During the task, a target was presented in 1 of 9 …