TRPV4 Contributes to Resting Membrane Potential in Retinal Müller Cells: Implications in Cell Volume Regulation

Neural activity alters osmotic gradients favoring cell swelling in retinal Müller cells. This swelling is followed by a regulatory volume decrease (RVD), partially mediated by an efflux of KCl and water. The transient receptor potential channel 4 (TRPV4), a nonselective calcium channel, has been proposed as a candidate for mediating intracellular Ca2+ elevation induced by swelling. We previously demonstrated in a human Müller cell line (MIO-M1) that RVD strongly depends on ion channel activation and, consequently, on membrane potential (Vm ). The aim of this study was to investigate if Ca2+ influx via TRPV4 contributes to RVD by modifying intracellular Ca2+ concentration and/or modulating Vm in MIO-M1 cells. Cell volume, intracellular Ca2+ levels, and Vm changes were evaluated using fluorescent probes. Results showed that MIO-M1 cells express functional TRPV4 which determines the resting Vmassociated with K+ channels. Swelling-induced increases in Ca2+ levels was due to both Ca2+ release from intracellular stores and Ca2+ influx by a pathway alternative to TRPV4. TRPV4 blockage affected swelling-induced biphasic response (depolarization-repolarization), suggesting its participation in modulating Vm changes during RVD. Agonist stimulation of Ca2+ influx via TRPV4 activated K+ channels hyperpolarizing Vm and accelerating RVD. We propose that TRPV4 forms a signaling complex with Ca2+ and/or voltage-dependent K+ channels to define resting Vm and Vm changes during RVD. TRPV4 involvement in RVD depends on the type of stimuli and/or degree of channel activation, leading to a maximum RVD response when Ca2+ influx overcomes a threshold and activates further signaling pathways in cell volume regulation.Fil: Netti, Vanina Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Fernández, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Kalstein, Maia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Pizzoni, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Di Giusto, Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Rivarola, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Ford, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Capurro, Claudia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Ciencias Fisiológicas. Laboratorio de Biomembranas; Argentin

Simon Says (Fall 2014)

In this issue: New Electronic Databases Einstein\u27s Now Open - More Renovations in the Works New Music Acquisitions New Archival Acquisitions Research Clinic CSU ePress New Science Librarian - Paul Luft Upcoming Library Forum Events Upcoming Library Exhibits CSU Libraries Connectedhttps://csuepress.columbusstate.edu/library_newsletters/1015/thumbnail.jp

Simon Says (Spring 2011)

In this issue: Library 2.0 & CSU Libraries Tenth Annual Faculty Research Forums Information Commons Move Department Spotlight: Reference Blog Highlights Films on Demand National Library Week Interlibrary Loan Electronic Article Delivery CSU Libraries Offer Two New JSTOR Collections Rite of Passage Convocations Return New Employees Join the CSU Libraries On the Road with CSU Libraries African American Read-In Faculty Emeritus Designationshttps://csuepress.columbusstate.edu/library_newsletters/1014/thumbnail.jp

Simon Says (Spring 2008)

Inside this issue: CSU History Showcased in Digital Collections Expanded LIBR 1105: In Full Swing African American Read-In 2008-2013 CSU Libraries Strategic Plan Columbus State University Archives Receives Conservation Bookshelf Library Staff Development Day: Road Trip! Libraries Host Rite of Passage Convocations Georgia Depository Meeting Midland Middle School Tour Collection Analysis for a Trimmer Figure New Faculty/Staff WilsonWeb OmniFile Full Text Faculty Research Forum Series 2008: Seven Faculty Present their Research Findingshttps://csuepress.columbusstate.edu/library_newsletters/1010/thumbnail.jp

The local food environment and its association with obesity among low-income women across the urban-rural continuum

Doctor of PhilosophyDepartment of Human NutritionDavid A. DzewaltowskiThe prevalence of obesity within the U.S. has risen dramatically in the past thirty years. Recent changes in food and physical activity environments may contribute to increased obesity prevalence, suggesting that disparities in these environments may be linked to the increased risk of obesity observed in low-income, and racial/ethnic minority women. This dissertation characterizes the local food environment experienced by low-income women who participate in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) in Kansas, evaluates whether characteristics of the local food environment contribute to obesity risk, and examines how these relationships vary across the urban-rural continuum. Chapter One reviews the relevant literature examining the association between obesity and local food environments, and identifies three testable hypotheses that serve as the framework for later chapters. Chapter Two characterizes the local food environment and examines geographic, racial, ethnic, and socioeconomic disparities in the availability of small grocery stores and supermarkets. Chapter Three examines the association between store availability and obesity risk at an individual level among participants in the WIC Program, while Chapter Four utilizes multi-level modeling to examine the relationships between tract deprivation, tract store availability and body mass index (BMI). Significant geographic disparities were observed in the availability of small grocery and supermarkets. Racial and ethnic disparities observed within tracts were not observed when examining store availability in a 1-mile radius around the residence of WIC mothers. The majority of women participating in the WIC program resided within a 1-mile radius of a small grocery store, and micropolitan and metropolitan WIC mothers had a multiplicity of food stores available within a 3-mile radius of residence. Food store availability was associated with increased obesity risk only in micropolitan areas. The availability of food stores did not mediate the association between tract deprivation and BMI, which varied across the urban-rural continuum. Overall, these results suggest that the relationship between local food environments and eating behaviors is complex, that limited store availability does not contribute to increased obesity risk in vulnerable populations, and that the association between local food environments and obesity risk varies across the urban-rural continuum

Cognitive Styles within an Exploratory Search System for Digital Libraries

Purpose – The purpose of this paper is to investigate the effects of cognitive style on navigating a large digital library of cultural heritage information; specifically, the paper focus on the wholist/analytic dimension as experienced in the field of educational informatics. The hypothesis is that wholist and analytic users have characteristically different approaches when they explore, search and interact with digital libraries, which may have implications for system design. Design/methodology/approach – A detailed interactive IR evaluation of a large cultural heritage digital library was undertaken, along with the Riding CSA test. Participants carried out a range of information tasks, and the authors analysed their task performance, interactions and attitudes. Findings – The hypothesis on the differences in performance and behaviour between wholist and analytic users is supported. However, the authors also find that user attitudes towards the system are opposite to expectations and that users give positive feedback for functionality that supports activities in which they are cognitively weaker. Research limitations/implications – There is scope for testing results in a larger scale study, and/or with different systems. In particular, the findings on user attitudes warrant further investigation. Practical implications – Findings on user attitudes suggest that systems which support areas of weakness in users’ cognitive abilities are valued, indicating an opportunity to offer diverse functionality to support different cognitive weaknesses. Originality/value – A model is proposed suggesting a converse relationship between behaviour and attitudes; to support individual users displaying search/navigation behaviour mapped onto the strengths of their cognitive style, but placing greater value on interface features that support aspects in which they are weaker

Simon Says (Fall 2007)

Inside this issue: New GALILEO Databases Banned Books Information Illiteracy Access Ingenta: A CSU Faculty Development Initiative Student Assistants: Pow Wow, Practice, and Party Music Library SFX Implementation in GALILEO AV Emergency Assistance for Faculty Congratulations: Faculty and Staff Receive Promotions Beautification of Library Faculty Research Forumshttps://csuepress.columbusstate.edu/library_newsletters/1009/thumbnail.jp

Cell volume regulation and aquaporins

In the recent years, the importance of the volume of a given cell has been accepted not only in defining its intracellular osmolality and its shape, but also in defining other cellular functions, such as transepithelial transport, cell migration, cell growth, cell death and the regulation of intracellular metabolism (35). Since most cells have to perform these physiological functions under a variable osmotic stress, cell volume must be carefully regulated. Based on the origin of the disturbance, cell volume changes are frequently classified into two categories: anisosmotic (alterations in extracellular solute concentration) and isosmotic (alterations in intracellular solute concentration) volume changes. Because of the relatively high permeability of the plasma membrane for water, any such gradient results in the immediate flow of water into or out of the cell causing cell swelling or shrinkage. To regulate cell volume, cells use channels and transport systems to flux osmolytes across the plasma membrane, followed by the obligatory movement of water. The current review reflects these developments and focuses on the contributions of aquaporins water channels in regulatory volume processes in a variety of cells.Sociedad Argentina de Fisiologí

Simon Says (Fall 2008)

Inside this issue: Addressing Student Needs: Circulating Laptops and a New Décor Information Commons Workshop Digital Microfilm Reader/Printer SHHHHH: You Are Entering the QUIET ZONE Access Ingenta: A CSU Faculty Development Initiative LIBR 1105 Online The Robert Hardaway Diary: A Piece of Historical Treasure Faculty Media Production Services Available at ITS Department Spotlight: Interlibrary Loan Milestone CSU Library Service Anniversaries Welcome Aboard Library Budgethttps://csuepress.columbusstate.edu/library_newsletters/1011/thumbnail.jp

Aquaporin-4 facilitates cell proliferation in retinal müller cells: implications in neuromyelitis optica

Müller cells are involved in controlling extracellular homeostasis in the retina, regulating cell swelling by a regulatory volume decrease (RVD) mechanism that depends on the efflux of solutes and water through Aquaporin-4 (AQP4). Müller cells are also important for retinal integrity, as they respond to injury by re-entering the cell cycle for tissue repair. Since AQP4 was reported to modulate cell volume during cell cycle progression and facilitate proliferation in astrocytes, the aim of this study was to evaluate, using the novel inhibitor TGN-020, if AQP4 was involved in human Müller cells? proliferation in physiological conditions. Considering that AQP4 is the target of autoantibody IgG-NMO present in the sera of patients with Neuromyelitis Optica (NMO), we also evaluated if cell proliferation was altered in the presence of IgG-NMO. MIO-M1 human Müller cells were exposed to 100 nM TNG-020 or vehicle or to 1/50 dilution of IgG-NMO positive or control sera. Cell volume (videomicroscopy) and cell proliferation (cell count, cell cycle analysis by flow cytometry and BrdU incorporation by immunofluorescence) were measured. AQP4 inhibition with TGN-020 reduced osmotic water permeability (Pf, µm/s) from 20.3±1.2 to 12.2±0.4 (n=5, p<0.001) and %RVD 15min from 54±4 to 17±3 (n=5, p<0.001). MIO-M1 cell proliferation was decreased by TGN-020 (doubling time in hours, control vs. TGN-020: 31±1 vs. 40±3, n=4, p<0.05) without affecting cell viability. TGN-020 also increased the % of cells in G1/G0 phase, decreased the S phase of cell cycle and reduced BrdU incorporation by 20%. IgG-NMO positive sera decreased AQP4 plasma membrane expression in MIO-M1 cells, reducing Pf from 22.4±1.5 to 15.9±0.6 µm/s (n=6, p<0.001) and %RVD 15min from 66±5 to 48±4 (n=6, p<0.005), as well as cell proliferation (doubling time in hours, control vs. IgG-NMO: 59±5 vs. 86±4, n=3, p<0.05) in comparison to control sera. We propose that inhibition or removal of AQP4 from the plasma membrane reduces AQP4-mediated water permeability altering cell proliferation. This is of particular importance in NMO, as the decreased ability of Müller cells to proliferate may affect retinal tissue repair.Fil: Netti, Vanina Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: White, Alan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Di Giusto, Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Fernández, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Ford, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Echevarría, Miriam. Universidad de Sevilla; EspañaFil: Capurro, Claudia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaReunión Anual de la Sociedad Argentina de FisiologíaRosarioArgentinaSociedad Argentina de Fisiologi