Life Sciences Commons^™

Chronic Muscle Weakness And Mitochondrial Dysfunction In The Absence Of Sustained Atrophy In A Preclinical Sepsis Model, Allison M. Owen, Samir P. Patel, Jeffrey D. Smith, Beverly K. Balasuriya, Stephanie F. Mori, Gregory S. Hawk, Arnold J. Stromberg, Naohide Kuriyama, Masao Kaneki, Alexander G. Rabchevsky, Timothy A. Butterfield, Karyn A. Esser, Charlotte A. Peterson, Marlene E. Starr, Hiroshi Saito

Physiology Faculty Publications

Chronic critical illness is a global clinical issue affecting millions of sepsis survivors annually. Survivors report chronic skeletal muscle weakness and development of new functional limitations that persist for years. To delineate mechanisms of sepsis-induced chronic weakness, we first surpassed a critical barrier by establishing a murine model of sepsis with ICU-like interventions that allows for the study of survivors. We show that sepsis survivors have profound weakness for at least 1 month, even after recovery of muscle mass. Abnormal mitochondrial ultrastructure, impaired respiration and electron transport chain activities, and persistent protein oxidative damage were evident in the muscle of …

Macrophage-Derived Netrin-1 Promotes Abdominal Aortic Aneurysm Formation By Activating Mmp3 In Vascular Smooth Muscle Cells, Tarik Hadi, Ludovic Boytard, Michele Silvestro, Dornazsadat Alebrahim, Samson Jacob, Jordyn Feinstein, Krista Barone, Wes Spiro, Susan Hutchison, Russell Simon, Debra L. Rateri, Florence Pinet, David Fenyo, Mark Adelman, Kathryn J. Moore, Holger K. Eltzschig, Alan Daugherty, Bhama Ramkhelawon

Physiology Faculty Publications

Abdominal aortic aneurysms (AAA) are characterized by extensive extracellular matrix (ECM) fragmentation and inflammation. However, the mechanisms by which these events are coupled thereby fueling focal vascular damage are undefined. Here we report through single-cell RNA-sequencing of diseased aorta that the neuronal guidance cue netrin-1 can act at the interface of macrophage-driven injury and ECM degradation. Netrin-1 expression peaks in human and murine aneurysmal macrophages. Targeted deletion of netrin-1 in macrophages protects mice from developing AAA. Through its receptor neogenin-1, netrin-1 induces a robust intracellular calcium flux necessary for the transcriptional regulation and persistent catalytic activation of matrix metalloproteinase-3 (MMP3) …

Autonomic Dysreflexia After Spinal Cord Injury: Systemic Pathophysiology And Methods Of Management, Khalid C. Eldahan, Alexander G. Rabchevsky

Physiology Faculty Publications

Traumatic spinal cord injury (SCI) has widespread physiological effects beyond the disruption of sensory and motor function, notably the loss of normal autonomic and cardiovascular control. Injury at or above the sixth thoracic spinal cord segment segregates critical spinal sympathetic neurons from supraspinal modulation which can result in a syndrome known as autonomic dysreflexia (AD). AD is defined as episodic hypertension and concomitant baroreflex-mediated bradycardia initiated by unmodulated sympathetic reflexes in the decentralized cord. This condition is often triggered by noxious yet unperceived visceral or somatic stimuli below the injury level and if severe enough can require immediate medical attention. …

Sustained Sensitizing Effects Of Tumor Necrosis Factor Alpha On Sensory Nerves In Lung And Airways, Ruei-Lung Lin, Qihai Gu, Mehdi Khosravi, Lu-Yuan Lee

Physiology Faculty Publications

Tumor necrosis factor alpha (TNFα) plays a significant role in the pathogenesis of airway inflammatory diseases. Inhalation of aerosolized TNFα induced airway hyperresponsiveness accompanied by airway inflammation in healthy human subjects, but the underlying mechanism is not fully understood. We recently reported a series of studies aimed to investigate if TNFα elevates the sensitivity of vagal bronchopulmonary sensory nerves in a mouse model; these studies are summarized in this mini-review. Our results showed that intratracheal instillation of TNFα induced pronounced airway inflammation 24 hours later, as illustrated by infiltration of eosinophils and neutrophils and the release of inflammatory mediators and …

Complement 3a Receptor In Dorsal Horn Microglia Mediates Pronociceptive Neuropeptide Signaling, Suzanne Doolen, Jennifer Cook, Maureen Riedl, Kelley Kitto, Shinichi Kohsaka, Christopher N. Honda, Carolyn A. Fairbanks, Bradley K. Taylor, Lucy Vulchanova

Physiology Faculty Publications

The complement 3a receptor (C3aR1) participates in microglial signaling under pathological conditions and was recently shown to be activated by the neuropeptide TLQP‐21. We previously demonstrated that TLQP‐21 elicits hyperalgesia and contributes to nerve injury‐induced hypersensitivity through an unknown mechanism in the spinal cord. Here we determined that this mechanism requires C3aR1 and that microglia are the cellular target for TLQP‐21. We propose a novel neuroimmune signaling pathway involving TLQP‐21‐induced activation of microglial C3aR1 that then contributes to spinal neuroplasticity and neuropathic pain. This unique dual‐ligand activation of C3aR1 by a neuropeptide (TLQP‐21) and an immune mediator (C3a) represents a …

Cib2 Interacts With Tmc1 And Tmc2 And Is Essential For Mechanotransduction In Auditory Hair Cells, Arnaud P. J. Giese, Yi-Quan Tang, Ghanshyam P. Sinha, Michael R. Bowl, Adam C. Goldring, Andrew Parker, Mary J. Freeman, Steve D. M. Brown, Saima Riazuddin, Robert Fettiplace, William R. Schafer, Gregory I. Frolenkov, Zubair M. Ahmed

Physiology Faculty Publications

Inner ear hair cells detect sound through deflection of stereocilia, the microvilli-like projections that are arranged in rows of graded heights. Calcium and integrin-binding protein 2 is essential for hearing and localizes to stereocilia, but its exact function is unknown. Here, we have characterized two mutant mouse lines, one lacking calcium and integrin-binding protein 2 and one carrying a human deafness-related Cib2 mutation, and show that both are deaf and exhibit no mechanotransduction in auditory hair cells, despite the presence of tip links that gate the mechanotransducer channels. In addition, mechanotransducing shorter row stereocilia overgrow in hair cell bundles of …

Reduced Skeletal Muscle Satellite Cell Number Alters Muscle Morphology After Chronic Stretch But Allows Limited Serial Sarcomere Addition, Matthew C. Kinney, Sudarshan Dayanidhi, Peter B. Dykstra, John J. Mccarthy, Charlotte A. Peterson, Richard L. Lieber

Physiology Faculty Publications

Introduction: Muscles add sarcomeres in response to stretch, presumably to maintain optimal sarcomere length. Clinical evidence from patients with cerebral palsy, who have both decreased serial sarcomere number and reduced satellite cells (SCs), suggests a hypothesis that SCs may be involved in sarcomere addition. Methods: A transgenic Pax7‐DTA mouse model underwent conditional SC depletion, and their soleii were then stretch‐immobilized to assess the capacity for sarcomere addition. Muscle architecture, morphology, and extracellular matrix (ECM) changes were also evaluated. Results: Mice in the SC‐reduced group achieved normal serial sarcomere addition in response to stretch. However, muscle fiber cross‐sectional …

Myocardial Relaxation Is Accelerated By Fast Stretch, Not Reduced Afterload, Charles S. Chung, Charles W. Hoopes, Kenneth S. Campbell

Physiology Faculty Publications

Fast relaxation of cross-bridge generated force in the myocardium facilitates efficient diastolic function. Recently published research studying mechanisms that modulate the relaxation rate has focused on molecular factors. Mechanical factors have received less attention since the 1980s when seminal work established the theory that reducing afterload accelerates the relaxation rate. Clinical trials using afterload reducing drugs, partially based on this theory, have thus far failed to improve outcomes for patients with diastolic dysfunction. Therefore, we reevaluated the protocols that suggest reducing afterload accelerates the relaxation rate and identified that myocardial relengthening was a potential confounding factor. We hypothesized that the …

Multiorgan Chronic Inflammatory Hepatobiliary Pancreatic Murine Model Deficient In Tumor Necrosis Factor Receptors 1 And 2, Helieh S. Oz

Physiology Faculty Publications

AIM: To provoke persistent/chronic multiorgan inflammatory response and to contribute to stones formation followed by fibrosis in hepatobiliary and pancreatic tissues.

METHODS: Tumor necrosis factor receptors 1 and 2 (TNFR1/R2) deficient mice reared in-house were given dibutyltin dichloride (DBTC) twice within 10 d by oral gavage delivery. Sham control animals received vehicle treatment and naïve animals remained untreated throughout the study. Animals were monitored daily for symptoms of pain and discomfort. The abdominal and hindpaw hypersensitivity were assessed with von Frey microfilaments. Exploratory behaviors were recorded at the baseline, after initiation of treatment, and before study termination. Histopathological …

Protease-Activated Receptor 4 Induces Bladder Pain Through High Mobility Group Box-1, Dimitrios E. Kouzoukas, Fei Ma, Katherine L. Meyer-Siegler, Karin N. Westlund, David E. Hunt, Pedro L. Vera

Physiology Faculty Publications

Pain is the significant presenting symptom in Interstitial Cystitis/Painful Bladder Syndrome (IC/PBS). Activation of urothelial protease activated receptor 4 (PAR4) causes pain through release of urothelial macrophage migration inhibitory factor (MIF). High Mobility Group Box-1 (HMGB1), a chromatin-binding protein, mediates bladder pain (but not inflammation) in an experimental model (cyclophosphamide) of cystitis. To determine if PAR4-induced bladder hypersensitivity depends on HMGB1 downstream, we tested whether: 1) bladder PAR4 stimulation affected urothelial HMGB1 release; 2) blocking MIF inhibited urothelial HMGB1 release; and 3) blocking HMGB1 prevented PAR4-induced bladder hypersensitivity. HMGB1 release was examined in immortalized human urothelial cultures (UROtsa) exposed to …

Myonuclear Transcription Is Responsive To Mechanical Load And Dna Content But Uncoupled From Cell Size During Hypertrophy, Tyler J. Kirby, Rooshil M. Patel, Timothy S. Mcclintock, Esther E. Dupont-Versteegden, Charlotte A. Peterson, John J. Mccarthy

Physiology Faculty Publications

Myofibers increase size and DNA content in response to a hypertrophic stimulus, thus providing a physiological model with which to study how these factors affect global transcription. Using 5-ethynyl uridine (EU) to metabolically label nascent RNA, we measured a sevenfold increase in myofiber transcription during early hypertrophy before a change in cell size and DNA content. The typical increase in myofiber DNA content observed at the later stage of hypertrophy was associated with a significant decrease in the percentage of EU-positive myonuclei; however, when DNA content was held constant by preventing myonuclear accretion via satellite cell depletion, both the number …

Mechanical Conflict System: A Novel Operant Method For The Assessment Of Nociceptive Behavior, Steven E. Harte, Jessica B. Meyers, Renee R. Donahue, Bradley K. Taylor, Thomas J. Morrow

Physiology Faculty Publications

A new operant test for preclinical pain research, termed the Mechanical Conflict System (MCS), is presented. Rats were given a choice either to remain in a brightly lit compartment or to escape to a dark compartment by crossing an array of height-adjustable nociceptive probes. Latency to escape the light compartment was evaluated with varying probe heights (0, .5, 1, 2, 3, and 4 mm above compartment floor) in rats with neuropathic pain induced by constriction nerve injury (CCI) and in naive control rats. Escape responses in CCI rats were assessed following intraperitoneal administration of pregabalin (10 and 30 mg/kg), morphine …

Serum Amyloid A Impairs The Antiinflammatory Properties Of Hdl, Chang Yeop Han, Chongren Tang, Myriam E. Guevara, Hao Wei, Tomasz Wietecha, Baohai Shao, Savitha Subramanian, Mohamed Omer, Shari Wang, Kevin D. O'Brien, Santica M. Marcovina, Thomas N. Wight, Tomas Vaisar, Maria C. De Beer, Frederick C. De Beer, William R. Osborne, Keith B. Elkon, Alan Chait

Physiology Faculty Publications

HDL from healthy humans and lean mice inhibits palmitate-induced adipocyte inflammation; however, the effect of the inflammatory state on the functional properties of HDL on adipocytes is unknown. Here, we found that HDL from mice injected with AgNO₃ fails to inhibit palmitate-induced inflammation and reduces cholesterol efflux from 3T3-L1 adipocytes. Moreover, HDL isolated from obese mice with moderate inflammation and humans with systemic lupus erythematosus had similar effects. Since serum amyloid A (SAA) concentrations in HDL increase with inflammation, we investigated whether elevated SAA is a causal factor in HDL dysfunction. HDL from AgNO₃-injected mice lacking Saa1.1 …

Rfx Transcription Factors Are Essential For Hearing In Mice, Ran Elkon, Beatrice Milon, Laura Morrison, Manan Shah, Sarath Vijayakumar, Manoj Racherla, Carmen C. Leitch, Lorna Silipino, Shadan Hadi, Michèle Weiss-Gayet, Emmanuèle Barras, Christoph D. Schmid, Aouatef Ait-Lounis, Ashley Barnes, Yang Song, David J. Eisenman, Efrat Eliyahu, Gregory I. Frolenkov, Scott E. Strome, Bénédicte Durand, Norann A. Zaghloul, Sherri M. Jones, Walter Reith, Ronna Hertzano

Physiology Faculty Publications

Sensorineural hearing loss is a common and currently irreversible disorder, because mammalian hair cells (HCs) do not regenerate and current stem cell and gene delivery protocols result only in immature HC-like cells. Importantly, although the transcriptional regulators of embryonic HC development have been described, little is known about the postnatal regulators of maturating HCs. Here we apply a cell type-specific functional genomic analysis to the transcriptomes of auditory and vestibular sensory epithelia from early postnatal mice. We identify RFX transcription factors as essential and evolutionarily conserved regulators of the HC-specific transcriptomes, and detect Rfx1,2,3,5 and 7 in the developing HCs. …

Topological Data Analysis For Discovery In Preclinical Spinal Cord Injury And Traumatic Brain Injury, Jessica L. Nielson, Jesse Paquette, Aiwen W. Liu, Cristian F. Guandique, C. Amy Tovar, Tomoo Inoue, Karen-Amanda Irvine, John C. Gensel, Jennifer Kloke, Tanya C. Petrossian, Pek Y. Lum, Gunnar E. Carlsson, Geoffrey T. Manley, Wise Young, Michael S. Beattie, Jacqueline C. Bresnahan, Adam R. Ferguson

Physiology Faculty Publications

Data-driven discovery in complex neurological disorders has potential to extract meaningful syndromic knowledge from large, heterogeneous data sets to enhance potential for precision medicine. Here we describe the application of topological data analysis (TDA) for data-driven discovery in preclinical traumatic brain injury (TBI) and spinal cord injury (SCI) data sets mined from the Visualized Syndromic Information and Outcomes for Neurotrauma-SCI (VISION-SCI) repository. Through direct visualization of inter-related histopathological, functional and health outcomes, TDA detected novel patterns across the syndromic network, uncovering interactions between SCI and co-occurring TBI, as well as detrimental drug effects in unpublished multicentre preclinical drug trial data …

Macrophage Migration Inhibitory Factor Mediates Par-Induced Bladder Pain., Dimitrios E. Kouzoukas, Katherine L. Meyer-Siegler, Fei Ma, Karin N. Westlund, David E. Hunt, Pedro L. Vera

Physiology Faculty Publications

INTRODUCTION: Macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine, is constitutively expressed in urothelial cells that also express protease-activated receptors (PAR). Urothelial PAR1 receptors were shown to mediate bladder inflammation. We showed that PAR1 and PAR4 activator, thrombin, also mediates urothelial MIF release. We hypothesized that stimulation of urothelial PAR1 or PAR4 receptors elicits release of urothelial MIF that acts on MIF receptors in the urothelium to mediate bladder inflammation and pain. Thus, we examined the effect of activation of specific bladder PAR receptors on MIF release, bladder pain, micturition and histological changes.

METHODS: MIF release was measured …

Enhanced Nmda Receptor-Mediated Modulation Of Excitatory Neurotransmission In The Dorsal Vagal Complex Of Streptozotocin-Treated, Chronically Hyperglycemic Mice, Eva C. Bach, Katalin Cs. Halmos, Bret N. Smith

Physiology Faculty Publications

A variety of metabolic disorders, including complications experienced by diabetic patients, have been linked to altered neural activity in the dorsal vagal complex. This study tested the hypothesis that augmentation of N-Methyl-D-Aspartate (NMDA) receptor-mediated responses in the vagal complex contributes to increased glutamate release in the dorsal motor nucleus of the vagus nerve (DMV) in mice with streptozotocin-induced chronic hyperglycemia (i.e., hyperglycemic mice), a model of type 1 diabetes. Antagonism of NMDA receptors with AP-5 (100 μM) suppressed sEPSC frequency in vagal motor neurons recorded in vitro, confirming that constitutively active NMDA receptors regulate glutamate release in the DMV. There …

Smooth-Muscle Bmal1 Participates In Blood Pressure Circadian Rhythm Regulation, Zhongwen Xie, Wen Su, Shu Liu, Guogang Zhao, Karyn Esser, Elizabeth A. Schroder, Mellani Lefta, Harald M. Stauss, Zhenheng Guo, Ming Cui Gong

Physiology Faculty Publications

As the central pacemaker, the suprachiasmatic nucleus (SCN) has long been considered the primary regulator of blood pressure circadian rhythm; however, this dogma has been challenged by the discovery that each of the clock genes present in the SCN is also expressed and functions in peripheral tissues. The involvement and contribution of these peripheral clock genes in the circadian rhythm of blood pressure remains uncertain. Here, we demonstrate that selective deletion of the circadian clock transcriptional activator aryl hydrocarbon receptor nuclear translocator-like (Bmal1) from smooth muscle, but not from cardiomyocytes, compromised blood pressure circadian rhythm and decreased blood …

Cannabinoid Receptor 2 Agonist Attenuates Pain Related Behavior In Rats With Chronic Alcohol/High Fat Diet Induced Pancreatitis, Liping Zhang, Robert H. Kline Iv, Terry A. Mcnearney, Michael P. Johnson, Karin Westlund High

Physiology Faculty Publications

BACKGROUND: Chronic Pancreatitis (CP) is a complex and multifactorial syndrome. Many contributing factors result in development of dysfunctional pain in a significant number of patients. Drugs developed to treat a variety of pain states fall short of providing effective analgesia for patients with chronic pancreatitis, often providing minimal to partial pain relief over time with significant side effects. Recently, availability of selective pharmacological tools has enabled great advances in our knowledge of the role of the cannabinoid receptors in pathophysiology. In particular, cannabinoid receptor 2 (CB2) has emerged as an attractive target for management of chronic pain, as demonstrated in …

Neutral Sphingomyelinase-3 Mediates Tnf-Stimulated Oxidant Activity In Skeletal Muscle, Jennifer S. Moylan, Jeffrey D. Smith, Erin M. Wolf Horrell, Julie B. Mclean, Gergana M. Deevska, Mark R. Bonnell, Mariana N. Nikolova‑Karakashian, Michael B. Reid

Physiology Faculty Publications

AIMS: Sphingolipid and oxidant signaling affect glucose uptake, atrophy, and force production of skeletal muscle similarly and both are stimulated by tumor necrosis factor (TNF), suggesting a connection between systems. Sphingolipid signaling is initiated by neutral sphingomyelinase (nSMase), a family of agonist-activated effector enzymes. Northern blot analyses suggest that nSMase3 may be a striated muscle-specific nSMase. The present study tested the hypothesis that nSMase3 protein is expressed in skeletal muscle and functions to regulate TNF-stimulated oxidant production.

RESULTS: We demonstrate constitutive nSMase activity in skeletal muscles of healthy mice and humans and in differentiated C2C12 myotubes. nSMase3 ( …

Arrhythmogenic Calmodulin Mutations Disrupt Intracellular Cardiomyocyte Ca2+ Regulation By Distinct Mechanisms, Guo Yin, Faisal Hassan, Ayman R. Haroun, Lisa L. Murphy, Lia Crotti, Peter J. Schwartz, Alfred L. George, Jonathan Satin

Physiology Faculty Publications

BACKGROUND: Calmodulin (CaM) mutations have been identified recently in subjects with congenital long QT syndrome (LQTS) or catecholaminergic polymorphic ventricular tachycardia (CPVT), but the mechanisms responsible for these divergent arrhythmia-susceptibility syndromes in this context are unknown. We tested the hypothesis that LQTS-associated CaM mutants disrupt Ca²⁺ homeostasis in developing cardiomyocytes possibly by affecting either late Na current or Ca²⁺-dependent inactivation of L-type Ca²⁺ current.

METHODS AND RESULTS: We coexpressed CaM mutants with the human cardiac Na channel (Na_V1.5) in tsA201 cells, and we used mammalian fetal ventricular cardiomyocytes to investigate LQTS- and CPVT-associated CaM …

Analgesic Tolerance Of Opioid Agonists In Mutant Mu-Opioid Receptors Expressed In Sensory Neurons Following Intrathecal Plasmid Gene Delivery, Guangwen Li, Fei Ma, Yanping Gu, Li-Yen Mae Huang

Physiology Faculty Publications

Background: Phosphorylation sites in the C-terminus of mu-opioid receptors (MORs) are known to play critical roles in the receptor functions. Our understanding of their participation in opioid analgesia is mostly based on studies of opioid effects on mutant receptors expressed in in vitro preparations, including cell lines, isolated neurons and brain slices. The behavioral consequences of the mutation have not been fully explored due to the complexity in studies of mutant receptors in vivo. To facilitate the determination of the contribution of phosphorylation sites in MOR to opioid-induced analgesic behaviors, we expressed mutant and wild-type human MORs (hMORs) in sensory …

Derivation Of Multivariate Syndromic Outcome Metrics For Consistent Testing Across Multiple Models Of Cervical Spinal Cord Injury In Rats, Adam R. Ferguson, Karen-Amanda Irvine, John C. Gensel, Jessica L. Nielson, Amity Lin, Johnathan Ly, Mark R. Segal, Rajiv R. Ratan, Jacqueline C. Bresnahan, Michael S. Beattie

Physiology Faculty Publications

Spinal cord injury (SCI) and other neurological disorders involve complex biological and functional changes. Well-characterized preclinical models provide a powerful tool for understanding mechanisms of disease; however managing information produced by experimental models represents a significant challenge for translating findings across research projects and presents a substantial hurdle for translation of novel therapies to humans. In the present work we demonstrate a novel 'syndromic' information-processing approach for capitalizing on heterogeneous data from diverse preclinical models of SCI to discover translational outcomes for therapeutic testing. We first built a large, detailed repository of preclinical outcome data from 10 years of basic …

Effect Of Muscle Length On Cross-Bridge Kinetics In Intact Cardiac Trabeculae At Body Temperature, Nima Milani-Nejad, Ying Xu, Jonathan P. Davis, Kenneth S. Campbell, Paul M. L. Janssen

Physiology Faculty Publications

Dynamic force generation in cardiac muscle, which determines cardiac pumping activity, depends on both the number of sarcomeric cross-bridges and on their cycling kinetics. The Frank–Starling mechanism dictates that cardiac force development increases with increasing cardiac muscle length (corresponding to increased ventricular volume). It is, however, unclear to what extent this increase in cardiac muscle length affects the rate of cross-bridge cycling. Previous studies using permeabilized cardiac preparations, sub-physiological temperatures, or both have obtained conflicting results. Here, we developed a protocol that allowed us to reliably and reproducibly measure the rate of tension redevelopment (k_tr; which depends …

Orofacial Neuropathic Pain Mouse Model Induced By Trigeminal Inflammatory Compression (Tic) Of The Infraorbital Nerve, Fei Ma, Liping Zhang, Danielle Lyons, Karin N. Westlund

Physiology Faculty Publications

BACKGROUND: Trigeminal neuropathic pain attacks can be excruciating for patients, even after being lightly touched. Although there are rodent trigeminal nerve research models to study orofacial pain, few models have been applied to studies in mice. A mouse trigeminal inflammatory compression (TIC) model is introduced here which successfully and reliably promotes vibrissal whisker pad hypersensitivity.

RESULTS: The chronic orofacial neuropathic pain model is induced after surgical placement of chromic gut suture in the infraorbital nerve fissure in the maxillary bone. Slight compression and chemical effects of the chromic gut suture on the portion of the infraorbital nerve contacted cause mild …

Characterization Of Secretory Sphingomyelinase Activity, Lipoprotein Sphingolipid Content And Ldl Aggregation In Ldlr-/- Mice Fed On A High-Fat Diet, Gergana M. Deevska, Manjula Sunkara, Andrew J. Morris, Mariana N. Nikolova‑Karakashian

Physiology Faculty Publications

The propensity of LDLs (low-density lipoproteins) for aggregation and/or oxidation has been linked to their sphingolipid content, specifically the levels of SM (sphingomyelin) and ceramide. To investigate this association in vivo, ldlr (LDL receptor)-null mice (ldlr-/-) were fed on a modified (atherogenic) diet containing saturated fats and cholesterol. The diet led to significantly elevated SM content in all serum lipoproteins. In contrast, ceramide increased only in the LDL particles. MS-based analyses of the lipid acyl chain composition revealed a marked elevation in C16:0 fatty acid in SM and ceramide, consistent with the prevalence of palmitic acid in the modified diet. …

Atovaquone Ameliorate Gastrointestinal Toxoplasmosis Complications In A Pregnancy Model, Helieh S. Oz, Thomas Tobin

Physiology Faculty Publications

Background: Toxoplasma is an important source of foodborne hospitalization with no safe and effective therapy against chronic or congenital Toxopalsmosis. Atovaquone is a drug of choice but not approved for use in congenital Toxoplasmosis. We hypothesized atovaquone to be safe and effective against feto-maternal Toxoplasmosis.

Material/Methods: Programmed pregnant mice were i.p. infected with 50–2400 Tachyzoites from Type II strain (clone PTG). Dams were treated daily with atovaquone or sham and monitored for pain, and complications.

Results: Dams developed pain related abdominal hypersensitivity (allodynia) to mechanical stimuli in a Tachyzoites dose dependent manner. Infected dams were anemic and exhibited ascities and …

Genomics Of Mature And Immature Olfactory Sensory Neurons, Melissa D. Nickell, Patrick Breheny, Arnold J. Stromberg, Timothy S. Mcclintock

Physiology Faculty Publications

The continuous replacement of neurons in the olfactory epithelium provides an advantageous model for investigating neuronal differentiation and maturation. By calculating the relative enrichment of every mRNA detected in samples of mature mouse olfactory sensory neurons (OSNs), immature OSNs, and the residual population of neighboring cell types, and then comparing these ratios against the known expression patterns of >300 genes, enrichment criteria that accurately predicted the OSN expression patterns of nearly all genes were determined. We identified 847 immature OSN-specific and 691 mature OSN-specific genes. The control of gene expression by chromatin modification and transcription factors, and neurite growth, protein …

Peripheral Nerve Injury Increases Glutamate-Evoked Calcium Mobilization In Adult Spinal Cord Neurons, Suzanne Doolen, Camille B. Blake, Bret N. Smith, Bradley K. Taylor

Physiology Faculty Publications

BACKGROUND: Central sensitization in the spinal cord requires glutamate receptor activation and intracellular Ca2+ mobilization. We used Fura-2 AM bulk loading of mouse slices together with wide-field Ca2+ imaging to measure glutamate-evoked increases in extracellular Ca2+ to test the hypotheses that: 1. Exogenous application of glutamate causes Ca2+ mobilization in a preponderance of dorsal horn neurons within spinal cord slices taken from adult mice; 2. Glutamate-evoked Ca2+ mobilization is associated with spontaneous and/or evoked action potentials; 3. Glutamate acts at glutamate receptor subtypes to evoked Ca2+ transients; and 4. The magnitude of glutamate-evoked Ca2+ responses increases in the setting of …

Mice Deficient In Gem Gtpase Show Abnormal Glucose Homeostasis Due To Defects In Beta-Cell Calcium Handling, Jenny E. Gunton, Mary Sisavanh, Rebecca A. Stokes, Jon Satin, Leslie S. Satin, Min Zhang, Sue M. Liu, Weikang Cai, Kim Cheng, Gregory J. Cooney, D. Ross Laybutt, Trina So, Juan-Carlos Molero, Shane T. Grey, Douglas A. Andres, Michael S. Rolph, Charles R. Mackay

Physiology Faculty Publications

AIMS AND HYPOTHESIS: Glucose-stimulated insulin secretion from beta-cells is a tightly regulated process that requires calcium flux to trigger exocytosis of insulin-containing vesicles. Regulation of calcium handling in beta-cells remains incompletely understood. Gem, a member of the RGK (Rad/Gem/Kir) family regulates calcium channel handling in other cell types, and Gem over-expression inhibits insulin release in insulin-secreting Min6 cells. The aim of this study was to explore the role of Gem in insulin secretion. We hypothesised that Gem may regulate insulin secretion and thus affect glucose tolerance in vivo.

METHODS: Gem-deficient mice were generated and their metabolic phenotype characterised by in …