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Diets high in heat-treated soybean meal reduce the histamine-induced epithelial response in the colon of weaned piglets and increase epithelial catabolism of histamine.
PLoS ONE
PUBLISHED: 01-01-2013
We examined the influence of dietary fermentable protein (fCP) and fermentable carbohydrates (fCHO) on the colonic epithelial response to histamine in pigs. Thirty-two weaned piglets were fed 4 diets in a 2 × 2 factorial design with low fCP/low fCHO, low fCP/high fCHO, high fCP/low fCHO and high fCP/high fCHO. After 21-23 days, the pigs were killed and tissue from the proximal colon was stimulated with carbachol, histamine, PGE2 or sodium hydrogen sulphide in Ussing chambers. Changes in short-circuit current and tissue conductance were measured. Diamine oxidase, histamine N-methyltransferase, stem cell growth factor receptor, Fc-epsilon receptor I and cystic fibrosis transmembrane conductance regulator gene expression was determined. Activities of diamine oxidase and histamine N-methyltransferase and numbers of colonic mast cells were measured. The change in the short-circuit current in response to histamine was lower (P = 0.002) and tended to be lower for PGE2 (P = 0.053) in high fCP groups compared to low fCP groups, irrespective of fCHO. Additionally, the change in tissue conductance after the application of histamine was lower (P = 0.005) in the high fCP groups. The expression of histamine N-methyltransferase mRNA (P = 0.033) and the activities of diamine oxidase (P = 0.001) and histamine N-methyltransferase (P = 0.006) were higher with high fCP in comparison with low fCP. The expression of mast cell markers, stem cell growth factor receptor (P = 0.005) and Fc-epsilon receptor I (P = 0.049) was higher with high fCP diets compared to diets low in fCP, whereas the mast cell count did not differ between groups. The expression of the cystic fibrosis transmembrane conductance regulator was reduced (P = 0.001) with high fCP diets compared to low fCP diets. The lower epithelial response to histamine and PGE2 and elevated epithelial histamine inactivation suggests an adaptation to high fCP diets.
Authors: Vijay Morampudi, Ganive Bhinder, Xiujuan Wu, Chuanbin Dai, Ho Pan Sham, Bruce A. Vallance, Kevan Jacobson.
Published: 02-27-2014
ABSTRACT
Inflammatory Bowel Diseases (IBD), including Crohn's Disease and Ulcerative Colitis, have long been associated with a genetic basis, and more recently host immune responses to microbial and environmental agents. Dinitrobenzene sulfonic acid (DNBS)-induced colitis allows one to study the pathogenesis of IBD associated environmental triggers such as stress and diet, the effects of potential therapies, and the mechanisms underlying intestinal inflammation and mucosal injury. In this paper, we investigated the effects of dietary n-3 and n-6 fatty acids on the colonic mucosal inflammatory response to DNBS-induced colitis in rats. All rats were fed identical diets with the exception of different types of fatty acids [safflower oil (SO), canola oil (CO), or fish oil (FO)] for three weeks prior to exposure to intrarectal DNBS. Control rats given intrarectal ethanol continued gaining weight over the 5 day study, whereas, DNBS-treated rats fed lipid diets all lost weight with FO and CO fed rats demonstrating significant weight loss by 48 hr and rats fed SO by 72 hr. Weight gain resumed after 72 hr post DNBS, and by 5 days post DNBS, the FO group had a higher body weight than SO or CO groups. Colonic sections collected 5 days post DNBS-treatment showed focal ulceration, crypt destruction, goblet cell depletion, and mucosal infiltration of both acute and chronic inflammatory cells that differed in severity among diet groups. The SO fed group showed the most severe damage followed by the CO, and FO fed groups that showed the mildest degree of tissue injury. Similarly, colonic myeloperoxidase (MPO) activity, a marker of neutrophil activity was significantly higher in SO followed by CO fed rats, with FO fed rats having significantly lower MPO activity. These results demonstrate the use of DNBS-induced colitis, as outlined in this protocol, to determine the impact of diet in the pathogenesis of IBD.
19 Related JoVE Articles!
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Measuring Local Anaphylaxis in Mice
Authors: Holly Evans, Kristin E. Killoran, Edward Mitre.
Institutions: Uniformed Services University of the Health Sciences.
Allergic responses are the result of the activation of mast cells and basophils, and the subsequent release of vasoactive and proinflammatory mediators. Exposure to an allergen in a sensitized individual can result in clinical symptoms that vary from minor erythema to life threatening anaphylaxis. In the laboratory, various animal models have been developed to understand the mechanisms driving allergic responses. Herein, we describe a detailed method for measuring changes in vascular permeability to quantify localized allergic responses. The local anaphylaxis assay was first reported in the 1920s, and has been adapted from the technique published by Kojima et al. in 20071. In this assay, mice sensitized to OVA are challenged in the left ear with vehicle and in the right ear with OVA. This is followed by an intravenous injection of Evans Blue dye. Ten min after injecting Evans Blue, the animal is euthanized and the dye that has extravasated into the ears is extracted overnight in formamide. The absorbance of the extracted dye is then quantified with a spectrophotometer. This method reliably results in a visual and quantifiable manifestation of a local allergic response.
Immunology, Issue 92, Allergy, sensitization, hypersensitivity, anaphylaxis, mouse, IgE, mast cell, activation, vascular permeability
52005
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An in vivo Assay to Test Blood Vessel Permeability
Authors: Maria Radu, Jonathan Chernoff.
Institutions: Fox Chase Cancer Center .
This method is based on the intravenous injection of Evans Blue in mice as the test animal model. Evans blue is a dye that binds albumin. Under physiologic conditions the endothelium is impermeable to albumin, so Evans blue bound albumin remains restricted within blood vessels. In pathologic conditions that promote increased vascular permeability endothelial cells partially lose their close contacts and the endothelium becomes permeable to small proteins such as albumin. This condition allows for extravasation of Evans Blue in tissues. A healthy endothelium prevents extravasation of the dye in the neighboring vascularized tissues. Organs with increased permeability will show significantly increased blue coloration compared to organs with intact endothelium. The level of vascular permeability can be assessed by simple visualization or by quantitative measurement of the dye incorporated per milligram of tissue of control versus experimental animal/tissue. Two powerful aspects of this assay are its simplicity and quantitative characteristics. Evans Blue dye can be extracted from tissues by incubating a specific amount of tissue in formamide. Evans Blue absorbance maximum is at 620 nm and absorbance minimum is at 740 nm. By using a standard curve for Evans Blue, optical density measurements can be converted into milligram dye captured per milligram of tissue. Statistical analysis should be used to assess significant differences in vascular permeability.
Medicine, Issue 73, Immunology, Physiology, Anatomy, Surgery, Hematology, Blood Vessels, Endothelium, Vascular, Vascular Cell Adhesion Molecule-1, permeability, in vivo, Evans Blue, Miles assay, assay, intravenous injection, mouse, animal model
50062
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Fat Preference: A Novel Model of Eating Behavior in Rats
Authors: James M Kasper, Sarah B Johnson, Jonathan D. Hommel.
Institutions: University of Texas Medical Branch.
Obesity is a growing problem in the United States of America, with more than a third of the population classified as obese. One factor contributing to this multifactorial disorder is the consumption of a high fat diet, a behavior that has been shown to increase both caloric intake and body fat content. However, the elements regulating preference for high fat food over other foods remain understudied. To overcome this deficit, a model to quickly and easily test changes in the preference for dietary fat was developed. The Fat Preference model presents rats with a series of choices between foods with differing fat content. Like humans, rats have a natural bias toward consuming high fat food, making the rat model ideal for translational studies. Changes in preference can be ascribed to the effect of either genetic differences or pharmacological interventions. This model allows for the exploration of determinates of fat preference and screening pharmacotherapeutic agents that influence acquisition of obesity.
Behavior, Issue 88, obesity, fat, preference, choice, diet, macronutrient, animal model
51575
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In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes
Authors: Yanning Wu, Shuo Wang, Chunying Li.
Institutions: Wayne State University School of Medicine, Wayne State University School of Medicine, Wayne State University School of Medicine.
Cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel located primarily at the apical membranes of epithelial cells, plays a crucial role in transepithelial fluid homeostasis1-3. CFTR has been implicated in two major diseases: cystic fibrosis (CF)4 and secretory diarrhea5. In CF, the synthesis or functional activity of the CFTR Cl- channel is reduced. This disorder affects approximately 1 in 2,500 Caucasians in the United States6. Excessive CFTR activity has also been implicated in cases of toxin-induced secretory diarrhea (e.g., by cholera toxin and heat stable E. coli enterotoxin) that stimulates cAMP or cGMP production in the gut7. Accumulating evidence suggest the existence of physical and functional interactions between CFTR and a growing number of other proteins, including transporters, ion channels, receptors, kinases, phosphatases, signaling molecules, and cytoskeletal elements, and these interactions between CFTR and its binding proteins have been shown to be critically involved in regulating CFTR-mediated transepithelial ion transport in vitro and also in vivo8-19. In this protocol, we focus only on the methods that aid in the study of the interactions between CFTR carboxyl terminal tail, which possesses a protein-binding motif [referred to as PSD95/Dlg1/ZO-1 (PDZ) motif], and a group of scaffold proteins, which contain a specific binding module referred to as PDZ domains. So far, several different PDZ scaffold proteins have been reported to bind to the carboxyl terminal tail of CFTR with various affinities, such as NHERF1, NHERF2, PDZK1, PDZK2, CAL (CFTR-associated ligand), Shank2, and GRASP20-27. The PDZ motif within CFTR that is recognized by PDZ scaffold proteins is the last four amino acids at the C terminus (i.e., 1477-DTRL-1480 in human CFTR)20. Interestingly, CFTR can bind more than one PDZ domain of both NHERFs and PDZK1, albeit with varying affinities22. This multivalency with respect to CFTR binding has been shown to be of functional significance, suggesting that PDZ scaffold proteins may facilitate formation of CFTR macromolecular signaling complexes for specific/selective and efficient signaling in cells16-18. Multiple biochemical assays have been developed to study CFTR-involving protein interactions, such as co-immunoprecipitation, pull-down assay, pair-wise binding assay, colorimetric pair-wise binding assay, and macromolecular complex assembly assay16-19,28,29. Here we focus on the detailed procedures of assembling a PDZ motif-dependent CFTR-containing macromolecular complex in vitro, which is used extensively by our laboratory to study protein-protein or domain-domain interactions involving CFTR16-19,28,29.
Biochemistry, Issue 66, Molecular Biology, Chemistry, CFTR, macromolecular complex, protein interaction, PDZ scaffold protein, epithelial cell, cystic fibrosis
4091
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Isolation of Functional Cardiac Immune Cells
Authors: Jennifer L. McLarty, Giselle C. Meléndez, William J. Spencer, Scott P. Levick, Gregory L. Brower, Joseph S. Janicki.
Institutions: University of South Carolina- School of Medicine.
Cardiac immune cells are gaining interest for the roles they play in the pathological remodeling in many cardiac diseases.1-5 These immune cells, which include mast cells, T-cells and macrophages; store and release a variety of biologically active mediators including cytokines and proteases such as tryptase.6-8 These mediators have been shown to be key players in extracellular matrix metabolism by activating matrix metalloproteinases or causing collagen accumulation by modulating the cardiac fibroblasts' function.9-11 However, available techniques for isolating cardiac immune cells have been problematic because they use bacterial collagenase to digest the myocardial tissue. This technique causes activation of the immune cells and thus a loss of function. For example, cardiac mast cells become significantly less responsive to compounds that cause degranulation.12 Therefore, we developed a technique that allows for the isolation of functional cardiac immune cells which would lead to a better understanding of the role of these cells in cardiac disease.13, 14 This method requires a familiarity with the anatomical location of the rat's xiphoid process, axilla and falciform ligament, and pericardium of the heart. These landmarks are important to increase success of the procedure and to ensure a higher yield of cardiac immune cells. These isolated cardiac immune cells can then be used for characterization of functionality, phenotype, maturity, and co-culture experiments with other cardiac cells to gain a better understanding of their interactions.
Immunology, Issue 58, Heart, Cardiac, Immune Cells, Isolation, Functional
3020
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Application of a NMDA Receptor Conductance in Rat Midbrain Dopaminergic Neurons Using the Dynamic Clamp Technique
Authors: Collin J Lobb, Carlos A Paladini.
Institutions: University of Texas San Antonio - UTSA.
Neuroscientists study the function of the brain by investigating how neurons in the brain communicate. Many investigators look at changes in the electrical activity of one or more neurons in response to an experimentally-controlled input. The electrical activity of neurons can be recorded in isolated brain slices using patch clamp techniques with glass micropipettes. Traditionally, experimenters can mimic neuronal input by direct injection of current through the pipette, electrical stimulation of the other cells or remaining axonal connections in the slice, or pharmacological manipulation by receptors located on the neuronal membrane of the recorded cell. Direct current injection has the advantages of passing a predetermined current waveform with high temporal precision at the site of the recording (usually the soma). However, it does not change the resistance of the neuronal membrane as no ion channels are physically opened. Current injection usually employs rectangular pulses and thus does not model the kinetics of ion channels. Finally, current injection cannot mimic the chemical changes in the cell that occurs with the opening of ion channels. Receptors can be physically activated by electrical or pharmacological stimulation. The experimenter has good temporal precision of receptor activation with electrical stimulation of the slice. However, there is limited spatial precision of receptor activation and the exact nature of what is activated upon stimulation is unknown. This latter problem can be partially alleviated by specific pharmacological agents. Unfortunately, the time course of activation of pharmacological agents is typically slow and the spatial precision of inputs onto the recorded cell is unknown. The dynamic clamp technique allows an experimenter to change the current passed directly into the cell based on real-time feedback of the membrane potential of the cell (Robinson and Kawai 1993, Sharp et al., 1993a,b; for review, see Prinz et al. 2004). This allows an experimenter to mimic the electrical changes that occur at the site of the recording in response to activation of a receptor. Real-time changes in applied current are determined by a mathematical equation implemented in hardware. We have recently used the dynamic clamp technique to investigate the generation of bursts of action potentials by phasic activation of NMDA receptors in dopaminergic neurons of the substantia nigra pars compacta (Deister et al., 2009; Lobb et al., 2010). In this video, we demonstrate the procedures needed to apply a NMDA receptor conductance into a dopaminergic neuron.
Neuroscience, Issue 46, electrophysiology, dynamic clamp, rat, dopamine, burst, RTXI
2275
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In vitro Coculture Assay to Assess Pathogen Induced Neutrophil Trans-epithelial Migration
Authors: Mark E. Kusek, Michael A. Pazos, Waheed Pirzai, Bryan P. Hurley.
Institutions: Harvard Medical School, MGH for Children, Massachusetts General Hospital.
Mucosal surfaces serve as protective barriers against pathogenic organisms. Innate immune responses are activated upon sensing pathogen leading to the infiltration of tissues with migrating inflammatory cells, primarily neutrophils. This process has the potential to be destructive to tissues if excessive or held in an unresolved state.  Cocultured in vitro models can be utilized to study the unique molecular mechanisms involved in pathogen induced neutrophil trans-epithelial migration. This type of model provides versatility in experimental design with opportunity for controlled manipulation of the pathogen, epithelial barrier, or neutrophil. Pathogenic infection of the apical surface of polarized epithelial monolayers grown on permeable transwell filters instigates physiologically relevant basolateral to apical trans-epithelial migration of neutrophils applied to the basolateral surface. The in vitro model described herein demonstrates the multiple steps necessary for demonstrating neutrophil migration across a polarized lung epithelial monolayer that has been infected with pathogenic P. aeruginosa (PAO1). Seeding and culturing of permeable transwells with human derived lung epithelial cells is described, along with isolation of neutrophils from whole human blood and culturing of PAO1 and nonpathogenic K12 E. coli (MC1000).  The emigrational process and quantitative analysis of successfully migrated neutrophils that have been mobilized in response to pathogenic infection is shown with representative data, including positive and negative controls. This in vitro model system can be manipulated and applied to other mucosal surfaces. Inflammatory responses that involve excessive neutrophil infiltration can be destructive to host tissues and can occur in the absence of pathogenic infections. A better understanding of the molecular mechanisms that promote neutrophil trans-epithelial migration through experimental manipulation of the in vitro coculture assay system described herein has significant potential to identify novel therapeutic targets for a range of mucosal infectious as well as inflammatory diseases.
Infection, Issue 83, Cellular Biology, Epithelium, Neutrophils, Pseudomonas aeruginosa, Respiratory Tract Diseases, Neutrophils, epithelial barriers, pathogens, transmigration
50823
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Induction and Analysis of Epithelial to Mesenchymal Transition
Authors: Yixin Tang, Greg Herr, Wade Johnson, Ernesto Resnik, Joy Aho.
Institutions: R&D Systems, Inc., R&D Systems, Inc..
Epithelial to mesenchymal transition (EMT) is essential for proper morphogenesis during development. Misregulation of this process has been implicated as a key event in fibrosis and the progression of carcinomas to a metastatic state. Understanding the processes that underlie EMT is imperative for the early diagnosis and clinical control of these disease states. Reliable induction of EMT in vitro is a useful tool for drug discovery as well as to identify common gene expression signatures for diagnostic purposes. Here we demonstrate a straightforward method for the induction of EMT in a variety of cell types. Methods for the analysis of cells pre- and post-EMT induction by immunocytochemistry are also included. Additionally, we demonstrate the effectiveness of this method through antibody-based array analysis and migration/invasion assays.
Molecular Biology, Issue 78, Cellular Biology, Biochemistry, Biomedical Engineering, Stem Cell Biology, Cancer Biology, Medicine, Bioengineering, Anatomy, Physiology, biology (general), Pathological Conditions, Signs and Symptoms, Wounds and Injuries, Neoplasms, Diagnosis, Therapeutics, Epithelial to mesenchymal transition, EMT, cancer, metastasis, cancer stem cell, cell, assay, immunohistochemistry
50478
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Development of an in vitro model system for studying the interaction of Equus caballus IgE with its high-affinity receptor FcεRI
Authors: Sari Sabban, Hongtu Ye, Birgit Helm.
Institutions: King Abdulaziz University, The University of Sheffield.
The interaction of IgE with its high-affinity Fc receptor (FcεRI) followed by an antigenic challenge is the principal pathway in IgE mediated allergic reactions. As a consequence of the high affinity binding between IgE and FcεRI, along with the continuous production of IgE by B cells, allergies usually persist throughout life, with currently no permanent cure available. Horses, especially race horses, which are commonly inbred, are a species of mammals that are very prone to the development of hypersensitivity responses, which can seriously affect their performance. Physiological responses to allergic sensitization in horses mirror that observed in humans and dogs. In this paper we describe the development of an in situ assay system for the quantitative assessment of the release of mediators of the allergic response pertaining to the equine system. To this end, the gene encoding equine FcεRIα was transfected into and expressed onto the surface of parental Rat Basophil Leukemia (RBL-2H3.1) cells. The gene product of the transfected equine α-chain formed a functional receptor complex with the endogenous rat β- and γ-chains 1. The resultant assay system facilitated an assessment of the quantity of mediator secreted from equine FcεRIα transfected RBL-2H3.1 cells following sensitization with equine IgE and antigenic challenge using β-hexosaminidase release as a readout 2, 3. Mediator release peaked at 36.68% ± 4.88% at 100 ng ml-1 of antigen. This assay was modified from previous assays used to study human and canine allergic responses 4, 5. We have also shown that this type of assay system has multiple applications for the development of diagnostic tools and the safety assessment of potential therapeutic intervention strategies in allergic disease 6, 2, 3.
Immunology, Issue 93, Allergy, Immunology, IgE, Fcε, RI, horse (Equus caballus), Immunoassay
52222
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Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein Expressed in Saccharomyces cerevisiae
Authors: Naomi Pollock, Natasha Cant, Tracy Rimington, Robert C. Ford.
Institutions: University of Manchester.
Defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein cause cystic fibrosis (CF), an autosomal recessive disease that currently limits the average life expectancy of sufferers to <40 years of age. The development of novel drug molecules to restore the activity of CFTR is an important goal in the treatment CF, and the isolation of functionally active CFTR is a useful step towards achieving this goal. We describe two methods for the purification of CFTR from a eukaryotic heterologous expression system, S. cerevisiae. Like prokaryotic systems, S. cerevisiae can be rapidly grown in the lab at low cost, but can also traffic and posttranslationally modify large membrane proteins. The selection of detergents for solubilization and purification is a critical step in the purification of any membrane protein. Having screened for the solubility of CFTR in several detergents, we have chosen two contrasting detergents for use in the purification that allow the final CFTR preparation to be tailored to the subsequently planned experiments. In this method, we provide comparison of the purification of CFTR in dodecyl-β-D-maltoside (DDM) and 1-tetradecanoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (LPG-14). Protein purified in DDM by this method shows ATPase activity in functional assays. Protein purified in LPG-14 shows high purity and yield, can be employed to study post-translational modifications, and can be used for structural methods such as small-angle X-ray scattering and electron microscopy. However it displays significantly lower ATPase activity.
Biochemistry, Issue 87, Membrane protein, cystic fibrosis, CFTR, ABCC7, protein purification, Cystic Fibrosis Foundation, green fluorescent protein
51447
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Measuring Changes in Tactile Sensitivity in the Hind Paw of Mice Using an Electronic von Frey Apparatus
Authors: Tijana Martinov, Madison Mack, Akilah Sykes, Devavani Chatterjea.
Institutions: Macalester College.
Measuring inflammation-induced changes in thresholds of hind paw withdrawal from mechanical pressure is a useful technique to assess changes in pain perception in rodents. Withdrawal thresholds can be measured first at baseline and then following drug, venom, injury, allergen, or otherwise evoked inflammation by applying an accurate force on very specific areas of the skin. An electronic von Frey apparatus allows precise assessment of mouse hind paw withdrawal thresholds that are not limited by the available filament sizes in contrast to classical von Frey measurements. The ease and rapidity of measurements allow for incorporation of assessment of tactile sensitivity outcomes in diverse models of rapid-onset inflammatory and neuropathic pain as multiple measurements can be taken within a short time period. Experimental measurements for individual rodent subjects can be internally controlled against individual baseline responses and exclusion criteria easily established to standardize baseline responses within and across experimental groups. Thus, measurements using an electronic von Frey apparatus represent a useful modification of the well-established classical von Frey filament-based assays for rodent mechanical allodynia that may also be applied to other nonhuman mammalian models.
Neuroscience, Issue 82, Natural Science Disciplines, Life Sciences (General), Behavioral Sciences, mechanical hyperalgesia, mice, electronic pressure meter, inflammation, snake venom
51212
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A Microplate Assay to Assess Chemical Effects on RBL-2H3 Mast Cell Degranulation: Effects of Triclosan without Use of an Organic Solvent
Authors: Lisa M. Weatherly, Rachel H. Kennedy, Juyoung Shim, Julie A. Gosse.
Institutions: University of Maine, Orono, University of Maine, Orono.
Mast cells play important roles in allergic disease and immune defense against parasites. Once activated (e.g. by an allergen), they degranulate, a process that results in the exocytosis of allergic mediators. Modulation of mast cell degranulation by drugs and toxicants may have positive or adverse effects on human health. Mast cell function has been dissected in detail with the use of rat basophilic leukemia mast cells (RBL-2H3), a widely accepted model of human mucosal mast cells3-5. Mast cell granule component and the allergic mediator β-hexosaminidase, which is released linearly in tandem with histamine from mast cells6, can easily and reliably be measured through reaction with a fluorogenic substrate, yielding measurable fluorescence intensity in a microplate assay that is amenable to high-throughput studies1. Originally published by Naal et al.1, we have adapted this degranulation assay for the screening of drugs and toxicants and demonstrate its use here. Triclosan is a broad-spectrum antibacterial agent that is present in many consumer products and has been found to be a therapeutic aid in human allergic skin disease7-11, although the mechanism for this effect is unknown. Here we demonstrate an assay for the effect of triclosan on mast cell degranulation. We recently showed that triclosan strongly affects mast cell function2. In an effort to avoid use of an organic solvent, triclosan is dissolved directly into aqueous buffer with heat and stirring, and resultant concentration is confirmed using UV-Vis spectrophotometry (using ε280 = 4,200 L/M/cm)12. This protocol has the potential to be used with a variety of chemicals to determine their effects on mast cell degranulation, and more broadly, their allergic potential.
Immunology, Issue 81, mast cell, basophil, degranulation, RBL-2H3, triclosan, irgasan, antibacterial, β-hexosaminidase, allergy, Asthma, toxicants, ionophore, antigen, fluorescence, microplate, UV-Vis
50671
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Inducing Plasticity of Astrocytic Receptors by Manipulation of Neuronal Firing Rates
Authors: Alison X. Xie, Kelli Lauderdale, Thomas Murphy, Timothy L. Myers, Todd A. Fiacco.
Institutions: University of California Riverside, University of California Riverside, University of California Riverside.
Close to two decades of research has established that astrocytes in situ and in vivo express numerous G protein-coupled receptors (GPCRs) that can be stimulated by neuronally-released transmitter. However, the ability of astrocytic receptors to exhibit plasticity in response to changes in neuronal activity has received little attention. Here we describe a model system that can be used to globally scale up or down astrocytic group I metabotropic glutamate receptors (mGluRs) in acute brain slices. Included are methods on how to prepare parasagittal hippocampal slices, construct chambers suitable for long-term slice incubation, bidirectionally manipulate neuronal action potential frequency, load astrocytes and astrocyte processes with fluorescent Ca2+ indicator, and measure changes in astrocytic Gq GPCR activity by recording spontaneous and evoked astrocyte Ca2+ events using confocal microscopy. In essence, a “calcium roadmap” is provided for how to measure plasticity of astrocytic Gq GPCRs. Applications of the technique for study of astrocytes are discussed. Having an understanding of how astrocytic receptor signaling is affected by changes in neuronal activity has important implications for both normal synaptic function as well as processes underlying neurological disorders and neurodegenerative disease.
Neuroscience, Issue 85, astrocyte, plasticity, mGluRs, neuronal Firing, electrophysiology, Gq GPCRs, Bolus-loading, calcium, microdomains, acute slices, Hippocampus, mouse
51458
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Mechanical Stimulation-induced Calcium Wave Propagation in Cell Monolayers: The Example of Bovine Corneal Endothelial Cells
Authors: Catheleyne D'hondt, Bernard Himpens, Geert Bultynck.
Institutions: KU Leuven.
Intercellular communication is essential for the coordination of physiological processes between cells in a variety of organs and tissues, including the brain, liver, retina, cochlea and vasculature. In experimental settings, intercellular Ca2+-waves can be elicited by applying a mechanical stimulus to a single cell. This leads to the release of the intracellular signaling molecules IP3 and Ca2+ that initiate the propagation of the Ca2+-wave concentrically from the mechanically stimulated cell to the neighboring cells. The main molecular pathways that control intercellular Ca2+-wave propagation are provided by gap junction channels through the direct transfer of IP3 and by hemichannels through the release of ATP. Identification and characterization of the properties and regulation of different connexin and pannexin isoforms as gap junction channels and hemichannels are allowed by the quantification of the spread of the intercellular Ca2+-wave, siRNA, and the use of inhibitors of gap junction channels and hemichannels. Here, we describe a method to measure intercellular Ca2+-wave in monolayers of primary corneal endothelial cells loaded with Fluo4-AM in response to a controlled and localized mechanical stimulus provoked by an acute, short-lasting deformation of the cell as a result of touching the cell membrane with a micromanipulator-controlled glass micropipette with a tip diameter of less than 1 μm. We also describe the isolation of primary bovine corneal endothelial cells and its use as model system to assess Cx43-hemichannel activity as the driven force for intercellular Ca2+-waves through the release of ATP. Finally, we discuss the use, advantages, limitations and alternatives of this method in the context of gap junction channel and hemichannel research.
Cellular Biology, Issue 77, Molecular Biology, Medicine, Biomedical Engineering, Biophysics, Immunology, Ophthalmology, Gap Junctions, Connexins, Connexin 43, Calcium Signaling, Ca2+, Cell Communication, Paracrine Communication, Intercellular communication, calcium wave propagation, gap junctions, hemichannels, endothelial cells, cell signaling, cell, isolation, cell culture
50443
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The Use of Gas Chromatography to Analyze Compositional Changes of Fatty Acids in Rat Liver Tissue during Pregnancy
Authors: Helena L. Fisk, Annette L. West, Caroline E. Childs, Graham C. Burdge, Philip C. Calder.
Institutions: University of Southampton.
Gas chromatography (GC) is a highly sensitive method used to identify and quantify the fatty acid content of lipids from tissues, cells, and plasma/serum, yielding results with high accuracy and high reproducibility. In metabolic and nutrition studies GC allows assessment of changes in fatty acid concentrations following interventions or during changes in physiological state such as pregnancy. Solid phase extraction (SPE) using aminopropyl silica cartridges allows separation of the major lipid classes including triacylglycerols, different phospholipids, and cholesteryl esters (CE). GC combined with SPE was used to analyze the changes in fatty acid composition of the CE fraction in the livers of virgin and pregnant rats that had been fed various high and low fat diets. There are significant diet/pregnancy interaction effects upon the omega-3 and omega-6 fatty acid content of liver CE, indicating that pregnant females have a different response to dietary manipulation than is seen among virgin females.
Chemistry, Issue 85, gas chromatography, fatty acid, pregnancy, cholesteryl ester, solid phase extraction, polyunsaturated fatty acids
51445
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Isolation of Primary Myofibroblasts from Mouse and Human Colon Tissue
Authors: Hassan Khalil, Wenxian Nie, Robert A Edwards, James Yoo.
Institutions: UCLA, UC Irvine.
The myofibroblast is a stromal cell of the gastrointestinal (GI) tract that has been gaining considerable attention for its critical role in many GI functions. While several myofibroblast cell lines are commercially available to study these cells in vitro, research results from a cell line exposed to experimental cell culture conditions have inherent limitations due to the overly reductionist nature of the work. Use of primary myofibroblasts offers a great advantage in terms of confirming experimental findings identified in a cell line. Isolation of primary myofibroblasts from an animal model allows for the study of myofibroblasts under conditions that more closely mimic the disease state being studied. Isolation of primary myofibroblasts from human colon tissue provides arguably the most relevant experimental data, since the cells come directly from patients with the underlying disease. We describe a well-established technique that can be utilized to isolate primary myofibroblasts from both mouse and human colon tissue. These isolated cells have been characterized to be alpha-smooth muscle actin and vimentin-positive, and desmin-negative, consistent with subepithelial intestinal myofibroblasts. Primary myofibroblast cells can be grown in cell culture and used for experimental purposes over a limited number of passages.
Cellular Biology, Issue 80, Myofibroblasts, Mesenchymal Stromal Cells, Gastrointestinal Tract, stroma, colon, primary cells
50611
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The Cell-based L-Glutathione Protection Assays to Study Endocytosis and Recycling of Plasma Membrane Proteins
Authors: Kristine M. Cihil, Agnieszka Swiatecka-Urban.
Institutions: Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine.
Membrane trafficking involves transport of proteins from the plasma membrane to the cell interior (i.e. endocytosis) followed by trafficking to lysosomes for degradation or to the plasma membrane for recycling. The cell based L-glutathione protection assays can be used to study endocytosis and recycling of protein receptors, channels, transporters, and adhesion molecules localized at the cell surface. The endocytic assay requires labeling of cell surface proteins with a cell membrane impermeable biotin containing a disulfide bond and the N-hydroxysuccinimide (NHS) ester at 4 ºC - a temperature at which membrane trafficking does not occur. Endocytosis of biotinylated plasma membrane proteins is induced by incubation at 37 ºC. Next, the temperature is decreased again to 4 ºC to stop endocytic trafficking and the disulfide bond in biotin covalently attached to proteins that have remained at the plasma membrane is reduced with L-glutathione. At this point, only proteins that were endocytosed remain protected from L-glutathione and thus remain biotinylated. After cell lysis, biotinylated proteins are isolated with streptavidin agarose, eluted from agarose, and the biotinylated protein of interest is detected by western blotting. During the recycling assay, after biotinylation cells are incubated at 37 °C to load endocytic vesicles with biotinylated proteins and the disulfide bond in biotin covalently attached to proteins remaining at the plasma membrane is reduced with L-glutathione at 4 ºC as in the endocytic assay. Next, cells are incubated again at 37 °C to allow biotinylated proteins from endocytic vesicles to recycle to the plasma membrane. Cells are then incubated at 4 ºC, and the disulfide bond in biotin attached to proteins that recycled to the plasma membranes is reduced with L-glutathione. The biotinylated proteins protected from L-glutathione are those that did not recycle to the plasma membrane.
Basic Protocol, Issue 82, Endocytosis, recycling, plasma membrane, cell surface, EZLink, Sulfo-NHS-SS-Biotin, L-Glutathione, GSH, thiol group, disulfide bond, epithelial cells, cell polarization
50867
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Meal Duration as a Measure of Orofacial Nociceptive Responses in Rodents
Authors: Phillip R. Kramer, Larry L. Bellinger.
Institutions: Texas A&M University Baylor College of Dentistry.
A lengthening in meal duration can be used to measure an increase in orofacial mechanical hyperalgesia having similarities to the guarding behavior of humans with orofacial pain. To measure meal duration unrestrained rats are continuously kept in sound attenuated, computerized feeding modules for days to weeks to record feeding behavior. These sound-attenuated chambers are equipped with chow pellet dispensers. The dispenser has a pellet trough with a photobeam placed at the bottom of the trough and when a rodent removes a pellet from the feeder trough this beam is no longer blocked, signaling the computer to drop another pellet. The computer records the date and time when the pellets were taken from the trough and from this data the experimenter can calculate the meal parameters. When calculating meal parameters a meal was defined based on previous work and was set at 10 min (in other words when the animal does not eat for 10 min that would be the end of the animal's meal) also the minimum meal size was set at 3 pellets. The meal duration, meal number, food intake, meal size and inter-meal interval can then be calculated by the software for any time period that the operator desires. Of the feeding parameters that can be calculated meal duration has been shown to be a continuous noninvasive biological marker of orofacial nociception in male rats and mice and female rats. Meal duration measurements are quantitative, require no training or animal manipulation, require cortical participation, and do not compete with other experimentally induced behaviors. These factors distinguish this assay from other operant or reflex methods for recording orofacial nociception.
Behavior, Issue 83, Pain, rat, nociception, myofacial, orofacial, tooth, temporomandibular joint (TMJ)
50745
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Testing Nicotine Tolerance in Aphids Using an Artificial Diet Experiment
Authors: John Sawyer Ramsey, Georg Jander.
Institutions: Cornell University.
Plants may upregulate the production of many different seconday metabolites in response to insect feeding. One of these metabolites, nicotine, is well know to have insecticidal properties. One response of tobacco plants to herbivory, or being gnawed upon by insects, is to increase the production of this neurotoxic alkaloid. Here, we will demonstrate how to set up an experiment to address this question of whether a tobacco-adapted strain of the green peach aphid, Myzus persicae, can tolerate higher levels of nicotine than the a strain of this insect that does not infest tobacco in the field.
Plant Biology, Issue 15, Annual Review, Nicotine, Aphids, Plant Feeding Resistance, Tobacco
701
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