Physiology Commons^™

Inhibition Of Bruton Tyrosine Kinase Reduces Neuroimmune Cascade And Promotes Recovery After Spinal Cord Injury, Chen Guang Yu, Vimala Bondada, Hina Iqbal, Kate L. Moore, John C. Gensel, Subbarao Bondada, James W. Geddes

Physiology Faculty Publications

Microglia/astrocyte and B cell neuroimmune responses are major contributors to the neurological deficits after traumatic spinal cord injury (SCI). Bruton tyrosine kinase (BTK) activation mechanistically links these neuroimmune mechanisms. Our objective is to use Ibrutinib, an FDA-approved BTK inhibitor, to inhibit the neuroimmune cascade thereby improving locomotor recovery after SCI. Rat models of contusive SCI, Western blot, immunofluorescence staining imaging, flow cytometry analysis, histological staining, and behavioral assessment were used to evaluate BTK activity, neuroimmune cascades, and functional outcomes. Both BTK expression and phosphorylation were increased at the lesion site at 2, 7, 14, and 28 days after SCI. Ibrutinib …

Fibroblast Growth Factor 19 Increases The Excitability Of Pre-Motor Glutamatergic Dorsal Vagal Complex Neurons From Hyperglycemic Mice, Jordan B. Wean, Bret N. Smith

Physiology Faculty Publications

Intracerebroventricular administration of the protein hormone fibroblast growth factor 19 (FGF19) to the hindbrain produces potent antidiabetic effects in hyperglycemic mice that are likely mediated through a vagal parasympathetic mechanism. FGF19 increases the synaptic excitability of parasympathetic motor neurons in the dorsal motor nucleus of the vagus (DMV) from hyperglycemic, but not normoglycemic, mice but the source of this synaptic input is unknown. Neurons in the area postrema (AP) and nucleus tractus solitarius (NTS) express high levels of FGF receptors and exert glutamatergic control over the DMV. This study tested the hypothesis that FGF19 increases glutamate release in the DMV …

Editorial: Recent Advances In Cardiotoxicity Testing, Tamer M. A. Mohamed, Javid Moslehi, Jonathan Satin

Physiology Faculty Publications

No abstract provided.

Editorial: The Metabolism Of The Neuron-Glia Unit, Yannick Poitelon, Lance A. Johnson, Marie-Ève Tremblay

Physiology Faculty Publications

No abstract provided.

Apoε4 Lowers Energy Expenditure In Females And Impairs Glucose Oxidation By Increasing Flux Through Aerobic Glycolysis, Brandon C. Farmer, Holden C. Williams, Nicholas A. Devanney, Margaret A. Piron, Grant K. Nation, David J. Carter, Adeline E. Walsh, Rebika Khanal, Lyndsay E. A. Young, Jude C. Kluemper, Gabriela Hernandez, Elizabeth J. Allenger, Rachel Mooney, Lesley R. Golden, Cathryn T. Smith, J. Anthony Brandon, Vedant A. Gupta, Philip A. Kern, Matthew S. Gentry, Josh M. Morganti, Ramon C. Sun, Lance A. Johnson

Physiology Faculty Publications

BACKGROUND: Cerebral glucose hypometabolism is consistently observed in individuals with Alzheimer's disease (AD), as well as in young cognitively normal carriers of the Ε4 allele of Apolipoprotein E (APOE), the strongest genetic predictor of late-onset AD. While this clinical feature has been described for over two decades, the mechanism underlying these changes in cerebral glucose metabolism remains a critical knowledge gap in the field.

METHODS: Here, we undertook a multi-omic approach by combining single-cell RNA sequencing (scRNAseq) and stable isotope resolved metabolomics (SIRM) to define a metabolic rewiring across astrocytes, brain tissue, mice, and human subjects expressing APOE4.

RESULTS: Single-cell …

Reduced Mitochondrial Dna And Oxphos Protein Content In Skeletal Muscle Of Children With Cerebral Palsy, Ferdinand Von Walden, Ivan J. Vechetti Jr., Davis A. Englund, Vandré C. Figueiredo, Rodrigo Fernandez-Gonzalo, Kevin A. Murach, Jessica Pingel, John J. Mccarthy, Per Stål, Eva Pontén

Physiology Faculty Publications

AIM: To provide a detailed gene and protein expression analysis related to mitochondrial biogenesis and assess mitochondrial content in skeletal muscle of children with cerebral palsy (CP).

METHOD: Biceps brachii muscle samples were collected from 19 children with CP (mean [SD] age 15y 4mo [2y 6mo], range 9-18y, 16 males, three females) and 10 typically developing comparison children (mean [SD] age 15y [4y], range 7-21y, eight males, two females). Gene expression (quantitative reverse transcription polymerase chain reaction [PCR]), mitochondrial DNA (mtDNA) to genomic DNA ratio (quantitative PCR), and protein abundance (western blotting) were analyzed. Microarray data sets (CP/aging/bed rest) were …

Acute Inflammatory Profiles Differ With Sex And Age After Spinal Cord Injury, Andrew N. Stewart, John L. Lowe, Ethan P. Glaser, Caitlin A. Mott, Ryan K. Shahidehpour, Katelyn E. Mcfarlane, William M. Bailey, Bei Zhang, John C. Gensel

Physiology Faculty Publications

Background

Sex and age are emerging as influential variables that affect spinal cord injury (SCI) recovery. Despite a changing demographic towards older age at the time of SCI, the effects of sex or age on inflammation remain to be elucidated. This study determined the sex- and age-dependency of the innate immune response acutely after SCI.

Methods

Male and female mice of ages 4- and 14-month-old received T9 contusion SCI and the proportion of microglia, monocyte-derived macrophages (MDM), and neutrophils surrounding the lesion were determined at 3- and 7-day post-injury (DPI) using flow cytometry. Cell counts of microglia and MDMs were …

The Effects Of Myelin On Macrophage Activation Are Phenotypic Specific Via Cpla2 In The Context Of Spinal Cord Injury Inflammation, Timothy J. Kopper, Bei Zhang, William M. Bailey, Kara E. Bethel, John C. Gensel

Physiology Faculty Publications

Spinal cord injury (SCI) produces chronic, pro-inflammatory macrophage activation that impairs recovery. The mechanisms driving this chronic inflammation are not well understood. Here, we detail the effects of myelin debris on macrophage physiology and demonstrate a novel, activation state-dependent role for cytosolic phospholipase-A2 (cPLA₂) in myelin-mediated potentiation of pro-inflammatory macrophage activation. We hypothesized that cPLA₂ and myelin debris are key mediators of persistent pro-inflammatory macrophage responses after SCI. To test this, we examined spinal cord tissue 28-days after thoracic contusion SCI in 3-month-old female mice and observed both cPLA₂ activation and intracellular accumulation of lipid-rich myelin …

Broad Kinase Inhibition Mitigates Early Neuronal Dysfunction In Tauopathy, Shon A. Koren, Matthew J. Hamm, Ryan Cloyd, Sarah N. Fontaine, Emad Chishti, Chiara Lanzillotta, Jennifer Rodriguez-Rivera, Alexandria Ingram, Michelle Bell, Sara M. Galvis-Escobar, Nicholas Zulia, Fabio Di Domenico, Duc Duong, Nicholas T. Seyfried, David K. Powell, Moriel Vandsburger, Tal Frolinger, Anika M. S. Hartz, John Koren Iii, Jeffrey M. Axten, Nicholas J. Laping, Jose F. Abisambra

Sanders-Brown Center on Aging Faculty Publications

Tauopathies are a group of more than twenty known disorders that involve progressive neurodegeneration, cognitive decline and pathological tau accumulation. Current therapeutic strategies provide only limited, late-stage symptomatic treatment. This is partly due to lack of understanding of the molecular mechanisms linking tau and cellular dysfunction, especially during the early stages of disease progression. In this study, we treated early stage tau transgenic mice with a multi-target kinase inhibitor to identify novel substrates that contribute to cognitive impairment and exhibit therapeutic potential. Drug treatment significantly ameliorated brain atrophy and cognitive function as determined by behavioral testing and a sensitive imaging …

Arginase 1 Insufficiency Precipitates Amyloid-Β Deposition And Hastens Behavioral Impairment In A Mouse Model Of Amyloidosis, Chao Ma, Jerry B. Hunt, Maj-Linda B. Selenica, Awa Sanneh, Leslie A. Sandusky-Beltran, Mallory Watler, Rana Daas, Andrii Kovalenko, Huimin Liang, Devon Placides, Chuanhai Cao, Xiaoyang Lin, Michael B. Orr, Bei Zhang, John C. Gensel, David J. Feola, Marcia N. Gordon, Dave Morgan, Paula C. Bickford, Daniel C. Lee

Sanders-Brown Center on Aging Faculty Publications

Alzheimer’s disease (AD) includes several hallmarks comprised of amyloid-β (Aβ) deposition, tau neuropathology, inflammation, and memory impairment. Brain metabolism becomes uncoupled due to aging and other AD risk factors, which ultimately lead to impaired protein clearance and aggregation. Increasing evidence indicates a role of arginine metabolism in AD, where arginases are key enzymes in neurons and glia capable of depleting arginine and producing ornithine and polyamines. However, currently, it remains unknown if the reduction of arginase 1 (Arg1) in myeloid cell impacts amyloidosis. Herein, we produced haploinsufficiency of Arg1 by the hemizygous deletion in myeloid cells using Arg1 …

Mitochondria Exert Age-Divergent Effects On Recovery From Spinal Cord Injury, Andrew N. Stewart, Katelyn E. Mcfarlane, Hemendra J. Vekaria, William M. Bailey, Stacey A. Slone, Lauren A. Tranthem, Bei Zhang, Samir P. Patel, Patrick G. Sullivan, John C. Gensel

Physiology Faculty Publications

The extent that age-dependent mitochondrial dysfunction drives neurodegeneration is not well understood. This study tested the hypothesis that mitochondria contribute to spinal cord injury (SCI)-induced neurodegeneration in an age-dependent manner by using 2,4-dinitrophenol (DNP) to uncouple electron transport, thereby increasing cellular respiration and reducing reactive oxygen species (ROS) production. We directly compared the effects of graded DNP doses in 4- and 14-month-old (MO) SCI-mice and found DNP to have increased efficacy in mitochondria isolated from 14-MO animals. In vivo, all DNP doses significantly exacerbated 4-MO SCI neurodegeneration coincident with worsened recovery. In contrast, low DNP doses (1.0-mg/kg/day) improved tissue …

Novel Mammalian Models For Understanding And Treating Spinal Cord Injury, Michael B. Orr

Theses and Dissertations--Physiology

Spinal cord injury (SCI) is devastating and often leaves the injured individual with persistent dysfunction. The injury persists because humans have poor wound repair and there are no pharmacologic treatments to induce wound repair after SCI. The continued efforts to discover therapeutic targets and develop treatments heavily relies on animal models. The purpose of this project is to develop and study novel mammalian models of SCI to provide insights for the development and effective implementation of SCI therapies.

Lab mice (Mus musculus) are a powerful tool for recapitulating the progression and persistent damage evident in human SCI, but …

Ceramide Analog [18F]F-Hpa-12 Detects Sphingolipid Disbalance In The Brain Of Alzheimer’S Disease Transgenic Mice By Functioning As A Metabolic Probe, Simone M. Crivelli, Daan Van Kruining, Qian Luo, Jo A. A. Stevens, Caterina Giovagnoni, Andreas Paulus, Matthias Bauwens, Dusan Berkes, Helga E. De Vries, Monique T. Mulder, Jochen Walter, Etienne Waelkens, Rita Derua, Johannes V. Swinnen, Jonas Dehairs, Felix M. Mottaghy, Mario Losen, Erhard Bieberich, Pilar Martinez-Martinez

Physiology Faculty Publications

The metabolism of ceramides is deregulated in the brain of Alzheimer’s disease (AD) patients and is associated with apolipoprotein (APO) APOE4 and amyloid-β pathology. However, how the ceramide metabolism changes over time in AD, in vivo, remains unknown. Distribution and metabolism of [¹⁸F]F-HPA-12, a radio-fluorinated version of the ceramide analog N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl) dodecanamide, was investigated in the brain of AD transgenic mouse models (FAD) on an APOE4 or APOE3 genetic background, by positron emission tomography and by gamma counter. We found that FAD mice displayed a higher uptake of [¹⁸F]F-HPA-12 in the brain, independently from the APOE4 …

Modulation Of Epileptogenesis: A Paradigm For The Integration Of Enzyme-Based Microelectrode Arrays And Optogenetics, Corwin R. Butler, Jeffery A. Boychuk, Francois Pomerleau, Ramona Alcala, Peter Huettl, Yi Ai, Johan Jakobsson, Sidney W. Whiteheart, Greg A. Gerhardt, Bret N. Smith, John T. Slevin

Physiology Faculty Publications

BACKGROUND: Genesis of acquired epilepsy includes transformations spanning genetic-to- network-level modifications, disrupting the regional excitatory/inhibitory balance. Methodology concurrently tracking changes at multiple levels is lacking. Here, viral vectors are used to differentially express two opsin proteins in neuronal populations within dentate gyrus (DG) of hippocampus. When activated, these opsins induced excitatory or inhibitory neural output that differentially affected neural networks and epileptogenesis. In vivo measures included behavioral observation coupled to real-time measures of regional glutamate flux using ceramic-based amperometric microelectrode arrays (MEAs).

RESULTS: Using MEA technology, phasic increases of extracellular glutamate were recorded immediately upon application of blue light/488 nm …

Macrolide Derivatives Reduce Proinflammatory Macrophage Activation And Macrophage‐Mediated Neurotoxicity, Bei Zhang, Timothy J. Kopper, Xiaodong Liu, Zheng Cui, Steven G. Van Lanen, John C. Gensel

Physiology Faculty Publications

Introduction: Azithromycin (AZM) and other macrolide antibiotics are applied as immunomodulatory treatments for CNS disorders. The immunomodulatory and antibiotic properties of AZM are purportedly independent.

Aims: To improve the efficacy and reduce antibiotic resistance risk of AZM‐based therapies, we evaluated the immunomodulatory and neuroprotective properties of novel AZM derivatives. We semisynthetically prepared derivatives by altering sugar moieties established as important for inhibiting bacterial protein synthesis. Bone marrow‐derived macrophages (BMDMs) were stimulated in vitro with proinflammatory, M1, stimuli (LPS + INF‐gamma) with and without derivative costimulation. Pro‐ and anti‐inflammatory cytokine production, IL‐12 and IL‐10, respectively, was quantified using ELISA. Neuron culture …

Manganese-Enhanced Magnetic Resonance Imaging: Overview And Central Nervous System Applications With A Focus On Neurodegeneration, Ryan A. Cloyd, Shon A. Koren, Jose F. Abisambra

Physiology Faculty Publications

Manganese-enhanced magnetic resonance imaging (MEMRI) rose to prominence in the 1990s as a sensitive approach to high contrast imaging. Following the discovery of manganese conductance through calcium-permeable channels, MEMRI applications expanded to include functional imaging in the central nervous system (CNS) and other body systems. MEMRI has since been employed in the investigation of physiology in many animal models and in humans. Here, we review historical perspectives that follow the evolution of applied MRI research into MEMRI with particular focus on its potential toxicity. Furthermore, we discuss the more current in vivo investigative uses of MEMRI in CNS investigations and …

Hyperhomocysteinemia As A Risk Factor For Vascular Contributions To Cognitive Impairment And Dementia, Brittani R. Price, Donna M. Wilcock, Erica M. Weekman

Physiology Faculty Publications

Behind only Alzheimer’s disease, vascular contributions to cognitive impairment and dementia (VCID) is the second most common cause of dementia, affecting roughly 10–40% of dementia patients. While there is no cure for VCID, several risk factors for VCID, such as diabetes, hypertension, and stroke, have been identified. Elevated plasma levels of homocysteine, termed hyperhomocysteinemia (HHcy), are a major, yet underrecognized, risk factor for VCID. B vitamin deficiency, which is the most common cause of HHcy, is common in the elderly. With B vitamin supplementation being a relatively safe and inexpensive therapeutic, the treatment of HHcy-induced VCID would seem straightforward; however, …

Editorial: Ion Channel Trafficking And Cardiac Arrhythmias, Marcel A. G. Van Der Heyden, Brian P. Delisle, Hugues Abriel

Physiology Faculty Publications

No abstract provided.

Overexpression Of Cyb5r3 And Nqo1, Two Nad+-Producing Enzymes, Mimics Aspects Of Caloric Restriction, Alberto Diaz-Ruiz, Michael Lanasa, Joseph Garcia, Hector Mora, Frances Fan, Alejandro Martin-Montalvo, Andrea Di Francesco, Miguel Calvo-Rubio, Andrea Salvador-Pascual, Miguel A. Aon, Kenneth W. Fishbein, Kevin J. Pearson, Jose Manuel Villalba, Placido Navas, Michel Bernier, Rafael De Cabo

Pharmacology and Nutritional Sciences Faculty Publications

Calorie restriction (CR) is one of the most robust means to improve health and survival in model organisms. CR imposes a metabolic program that leads to increased stress resistance and delayed onset of chronic diseases, including cancer. In rodents, CR induces the upregulation of two NADH‐dehydrogenases, namely NAD(P)H:quinone oxidoreductase 1 (Nqo1) and cytochrome b₅ reductase 3 (Cyb5r3), which provide electrons for energy metabolism. It has been proposed that this upregulation may be responsible for some of the beneficial effects of CR, and defects in their activity are linked to aging and several age‐associated diseases. However, …

Physiological Differences Between Low Versus High Skeletal Muscle Hypertrophic Responders To Resistance Exercise Training: Current Perspectives And Future Research Directions, Michael D. Roberts, Cody T. Haun, Christopher B. Mobley, Petey W. Mumford, Matthew A. Romero, Paul A. Roberson, Christopher G. Vann, John J. Mccarthy

Physiology Faculty Publications

Numerous reports suggest there are low and high skeletal muscle hypertrophic responders following weeks to months of structured resistance exercise training (referred to as low and high responders herein). Specifically, divergent alterations in muscle fiber cross sectional area (fCSA), vastus lateralis thickness, and whole body lean tissue mass have been shown to occur in high versus low responders. Differential responses in ribosome biogenesis and subsequent protein synthetic rates during training seemingly explain some of this individual variation in humans, and mechanistic in vitro and rodent studies provide further evidence that ribosome biogenesis is critical for muscle hypertrophy. High responders may …

Apoe And Alzheimer’S Disease: Neuroimaging Of Metabolic And Cerebrovascular Dysfunction, Jason A. Brandon, Brandon C. Farmer, Holden C. Williams, Lance A. Johnson

Physiology Faculty Publications

Apolipoprotein E4 (ApoE4) is the strongest genetic risk factor for late onset Alzheimer’s Disease (AD), and is associated with impairments in cerebral metabolism and cerebrovascular function. A substantial body of literature now points to E4 as a driver of multiple impairments seen in AD, including blunted brain insulin signaling, mismanagement of brain cholesterol and fatty acids, reductions in blood brain barrier (BBB) integrity, and decreased cerebral glucose uptake. Various neuroimaging techniques, in particular positron emission topography (PET) and magnetic resonance imaging (MRI), have been instrumental in characterizing these metabolic and vascular deficits associated with this important AD risk factor. In …

Adropin: An Endocrine Link Between The Biological Clock And Cholesterol Homeostasis, Sarbani Ghoshal, Joseph R. Stevens, Cyrielle Billon, Clemence Girardet, Sadichha Sitaula, Arthur S. Leon, D.C. Rao, James S. Skinner, Tuomo Rankinen, Claude Bouchard, Marinelle V. Nuñez, Kimber L. Stanhope, Deborah A. Howatt, Alan Daugherty, Jinsong Zhang, Matthew Schuelke, Edward P. Weiss, Alisha R. Coffey, Brian J. Bennett, Praveen Sethupathy, Thomas P. Burris, Peter J. Havel, Andrew A. Butler

Physiology Faculty Publications

Objective

Identify determinants of plasma adropin concentrations, a secreted peptide translated from the Energy Homeostasis Associated (ENHO) gene linked to metabolic control and vascular function.

Methods

Associations between plasma adropin concentrations, demographics (sex, age, BMI) and circulating biomarkers of lipid and glucose metabolism were assessed in plasma obtained after an overnight fast in humans. The regulation of adropin expression was then assessed in silico, in cultured human cells, and in animal models.

Results

In humans, plasma adropin concentrations are inversely related to atherogenic LDL-cholesterol (LDL-C) levels in men (n = 349), but not in women (n = …

Myosin-Xva Is Key Molecule In Establishing The Architecture Of Mechanosensory Stereocilia Bundles Of The Inner Ear Hair Cells, Shadan Hadi

Theses and Dissertations--Medical Sciences

Development of hair cell stereocilia bundles involves three stages: elongation, thickening, and supernumerary stereocilia retraction. Although Myo-XVa is known to be essential for stereocilia elongation, its role in retraction/thickening remains unknown. We quantified stereocilia numbers/diameters in shaker-2 mice (Myo15^sh2) that have deficiencies in “long” and “short” isoforms of myosin-XVa, and in mice lacking only the “long” myosin-XVa isoform (Myo15^ΔN). Our data showed that myosin-XVa is largely not involved in the developmental retraction of supernumerary stereocilia. In normal development, the diameters of the first (tallest)/second row stereocilia within a bundle are equal and grow simultaneously. …

Calpain Inhibition Attenuates Adipose Tissue Inflammation And Fibrosis In Diet-Induced Obese Mice, Latha Muniappan, Aida Javidan, Weihua Jiang, Shayan Mohammadmoradi, Jessica J. Moorleghen, Wendy S. Katz, Anju Balakrishnan, Deborah A. Howatt, Venkateswaran Subramanian

Saha Cardiovascular Research Center Faculty Publications

Adipose tissue macrophages have been proposed as a link between obesity and insulin resistance. However, the mechanisms underlying these processes are not completely defined. Calpains are calcium-dependent neutral cysteine proteases that modulate cellular function and have been implicated in various inflammatory diseases. To define whether activated calpains influence diet-induced obesity and adipose tissue macrophage accumulation, mice that were either wild type (WT) or overexpressing calpastatin (CAST Tg), the endogenous inhibitor of calpains were fed with high (60% kcal) fat diet for 16 weeks. CAST overexpression did not influence high fat diet-induced body weight and fat mass gain throughout the study. …

Functional Neuroplasticity In The Nucleus Tractus Solitarius And Increased Risk Of Sudden Death In Mice With Acquired Temporal Lobe Epilepsy, Isabel D. Derera, Brian P. Delisle, Bret N. Smith

Physiology Faculty Publications

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in individuals with refractory acquired epilepsy. Cardiorespiratory failure is the most likely cause in most cases, and central autonomic dysfunction has been implicated as a contributing factor to SUDEP. Neurons of the nucleus tractus solitarius (NTS) in the brainstem vagal complex receive and integrate vagally mediated information regarding cardiorespiratory and other autonomic functions, and GABAergic inhibitory NTS neurons play an essential role in modulating autonomic output. We assessed the activity of GABAergic NTS neurons as a function of epilepsy development in the pilocarpine-induced status epilepticus (SE) model of …

Deletion Of The Nr4a Nuclear Receptor Nor1 In Hematopoietic Stem Cells Reduces Inflammation But Not Abdominal Aortic Aneurysm Formation, Hua Qing, Karrie L. Jones, Elizabeth B. Heywood, Hong Lu, Alan Daugherty, Dennis Bruemmer

Pharmacology and Nutritional Sciences Faculty Publications

Background: The NR4A3 orphan nuclear hormone receptor, NOR1, functions as a constitutively active transcription factor to regulate inflammation, proliferation, and cell survival during pathological vascular remodeling. Inflammatory processes represent key mechanisms leading to abdominal aortic aneurysm (AAA) formation. However, a role of NOR1 in AAA formation has not been investigated previously.

Methods: Inflammatory gene expression was analyzed in bone marrow-derived macrophages isolated from NOR1-deficient mice. Low-density lipoprotein receptor-deficient (LDLr^−/−) mice were irradiated and reconstituted with hematopoietic stem cells obtained from NOR1−/− or wild-type littermate mice. Animals were infused with angiotensin II and fed a diet enriched in saturated …

No Difference In Myosin Kinetics And Spatial Distribution Of The Lever Arm In The Left And Right Ventricles Of Human Hearts, Divya Duggal, S. Requena, Janhavi Nagwekar, Sangram Raut, Ryan Rich, Hriday Das, Vipul Patel, Ignacy Gryczynski, Rafal Fudala, Zygmunt Gryczynski, Cheavar Blair, Kenneth S. Campbell, Julian Borejdo

Physiology Faculty Publications

The systemic circulation offers larger resistance to the blood flow than the pulmonary system. Consequently, the left ventricle (LV) must pump blood with more force than the right ventricle (RV). The question arises whether the stronger pumping action of the LV is due to a more efficient action of left ventricular myosin, or whether it is due to the morphological differences between ventricles. Such a question cannot be answered by studying the entire ventricles or myocytes because any observed differences would be wiped out by averaging the information obtained from trillions of myosin molecules present in a ventricle or myocyte. …

Adipose Tissue As A Site Of Toxin Accumulation, Erin Jackson, Robin C. Shoemaker, Nika Larian, Lisa A. Cassis

Pharmacology and Nutritional Sciences Faculty Publications

We examine the role of adipose tissue, typically considered an energy storage site, as a potential site of toxicant accumulation. Although the production of most persistent organic pollutants (POPs) was banned years ago, these toxicants persist in the environment due to their resistance to biodegradation and widespread distribution in various environmental forms (e.g., vapor, sediment, and water). As a result, human exposure to these toxicants is inevitable. Largely due to their lipophilicity, POPs bioaccumulate in adipose tissue, resulting in greater body burdens of these environmental toxicants with obesity. POPs of major concern include polychlorinated biphenyls (PCBs), polychlorinated dibenzo‐p‐dioxins and furans …

Hypersensitivity Of Vagal Pulmonary Afferents Induced By Tumor Necrosis Factor Alpha In Mice, Ruei-Lung Lin, Qihai Gu, Lu-Yuan Lee

Physiology Faculty Publications

Tumor necrosis factor alpha (TNFα), a pro-inflammatory cytokine, plays a significant role in the pathogenesis of allergic asthma. Inhalation of TNFα also induces airway hyperresponsiveness in healthy human subjects, and the underlying mechanism is not fully understood. A recent study reported that TNFα caused airway inflammation and a sustained elevation of pulmonary chemoreflex responses in mice, suggesting a possible involvement of heightened sensitivity of vagal pulmonary C-fibers. To investigate this possibility, the present study aimed to investigate the effect of a pretreatment with TNFα on the sensitivity of vagal pulmonary afferents in anesthetized mice. After TNFα (10 μg/ml, 0.03 ml) …

Novel Interconnections In Lipid Metabolism Revealed By Overexpression Of Sphingomyelin Synthase-1, Gergana M. Deevska, Patrick P. Dotson Ii, Alexander A. Karakashian, Giorgis Isaac, Mark Wrona, Samuel B. Kelly, Alfred H. Merrill Jr., Mariana N. Nikolova‑Karakashian

Physiology Faculty Publications

This study investigates the consequences of elevating sphingomyelin synthase 1 (SMS1) activity, which generates the main mammalian sphingolipid, sphingomyelin. HepG2 cells stably transfected with SMS1 (HepG2-SMS1) exhibit elevated enzyme activity in vitro and increased sphingomyelin content (mainly C22:0- and C24:0-sphingomyelin) but lower hexosylceramide (Hex-Cer) levels. HepG2-SMS1 cells have fewer triacylglycerols than controls but similar diacylglycerol acyltransferase activity, triacylglycerol secretion, and mitochondrial function. Treatment with 1 mm palmitate increases de novo ceramide synthesis in both cell lines to a similar degree, causing accumulation of C16:0-ceramide (and some C18:0-, C20:0-, and C22:0-ceramides) as well as C16:0- and C18:0-Hex-Cers. In these experiments, the …