134 results on '"Brent A. Bell"'
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2. A comparison of optophysiological biomarkers of photoreceptor stress and phototoxicity in BALB/cJ, B6(Cg)-Tyrc-2J/J, and C57Bl/6J mouse strains
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Brent A. Bell, Charles Kaul, Joshua L. Dunaief, Joe G. Hollyfield, and Vera L. Bonilha
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mice ,retina ,photoreceptors ,imaging ,photooxidation ,phototoxicity ,Medicine - Abstract
IntroductionOphthalmic imaging instruments, including the confocal scanning laser ophthalmoscope and spectral-domain optical coherence tomography system, originally intended for revealing ocular microstructures in the human eye, have been deployed by vision researchers to evaluate the eyes of numerous small and large animal species for more than two decades. In this study, we have used these two instruments to obtain imaging data sequentially from the retinas of three prominent, widely used experimental mouse models to document changes induced by two contrasting vivarium lighting conditions. Mice studied include albino BALB/cJ and B6(Cg)-Tyrc-2J/J and pigmented C57Bl/6J.MethodsMice were reared under dim light conditions until ~8 weeks of age where they underwent baseline imaging. Following, mice were returned to the dim vivarium or relocated to the top rack cage position in a standard vivarium. Mice were then followed for several months by ocular imaging to catalog the retinal dynamics as a function of long-term dim vs. elevated, standard vivarium lighting exposure levels.ResultsUpon exposure to elevated light levels, B6(Cg)-Tyrc-2J/J underwent similar changes as BALB/cJ in regard to photoreceptor outer segment shortening, photoreceptor layer proximal aspect hyperreflective changes, and the development of retinal infoldings and autofluorescent sub-retinal inflammatory monocyte infiltrate. Noteworthy, however, is that infoldings and infiltrate occurred at a slower rate of progression in B6(Cg)-Tyrc-2J/J vs. BALB/cJ. The photoreceptor outer nuclear layer thickness of BALB/cJ degenerated steadily following elevated light onset. In contrast, B6(Cg)-Tyrc-2J/J degeneration was unremarkable for many weeks before experiencing a noticeable change in the rate of degeneration that was concomitant with a plateau and decreasing trend in number of retinal infoldings and monocyte infiltrate. Pathological changes in C57Bl/6J mice were unremarkable for all imaging biomarkers assessed with exception to autofluorescent sub-retinal inflammatory monocyte infiltrate, which showed significant accumulation in dim vs. elevated light exposed mice following ~1 year of observation. These data were evaluated using Spearman’s correlation and Predictive Power Score matrices to determine the best imaging optophysiological biomarkers for indicating vivarium light stress and light-induced photoreceptor degeneration.DiscussionThis study suggests that changes in proximal aspect hyperreflectivity, outer segment shortening, retinal infoldings and autofluorescent sub-retinal inflammatory monocyte infiltrate are excellent indicators of light stress and light-induced degeneration in albino B6(Cg)-Tyrc-2J/J and BALB/cJ mouse strains.
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- 2023
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3. CDCP1 regulates retinal pigmented epithelial barrier integrity for the development of experimental autoimmune uveitis
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Lingjun Zhang, Nozha Borjini, Yu Lun, Sweta Parab, Gospel Asonye, Rupesh Singh, Brent A. Bell, Vera L. Bonilha, Andrei Ivanov, David A. Fox, Rachel R. Caspi, and Feng Lin
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Autoimmunity ,Medicine - Abstract
Cub domain-containing protein 1 (CDCP1) is a protein that is highly expressed on the surface of many cancer cells. However, its distribution in normal tissues and its potential roles in nontumor cells are poorly understood. We found that CDCP1 is present on both human and mouse retinal pigment epithelial (RPE) cells. CDCP1-KO mice developed attenuated retinal inflammation in a passive model of autoimmune uveitis, with disrupted tight junctions and infiltrating T cells detected in RPE flat mounts from WT but not CDCP1-KO mice during EAU development. Mechanistically, we discovered that CDCP1 on RPE cells was upregulated by IFN-γ in vitro and after EAU induction in vivo. CD6 stimulation induced increased RPE barrier permeability of WT but not CDCP1-knockdown (CDCP1-KD) RPE cells, and activated T cells migrated through WT RPE monolayers more efficiently than the CDCP1-KD RPE monolayers. In addition, CD6 stimulation of WT but not the CDCP1-KD RPE cells induced massive stress fiber formation and focal adhesion disruption to reduce cell barrier tight junctions. These data suggest that CDCP1 on RPE cells interacts with CD6 on T cells to induce RPE cytoskeleton remodeling and focal adhesion disruption, which open up the tight junctions to facilitate T cell infiltration for the development of uveitis.
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- 2022
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4. Trends and Issues in Experiential and Outdoor Education Programs
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Andrew J. Bobilya, Tom Holman, Betsy Lindley, Esther Ayers, Christine Norton, Steve Smith, Denise Mitten, and Brent J. Bell
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This brief article summarizes five trends and issues discussed during a moderated panel and round table discussion at the Association for Experiential Education (AEE) Symposium on Experiential Education Research (SEER) in November 2023. The aim of this session was to expand on prior documented trends and disseminate current experiential and outdoor education (EOE) trends, issues, and related research. These are only a few of the many EOE trends and issues but they represent both meta trends/issues and program-specific trends. This session was designed for scholars and practitioners who teach, provide program administration, and/or conduct research and evaluation efforts for EOE and related disciplines. Topics included cultural representation in the outdoors, trauma and mental health trends, safety II: a new view of risk management, nature and outdoor programming, and whether college outdoor orientation leaders should be paid. We hope that you, the reader, are inspired to consider what trends and issues are impacting your work and explore areas for future research.
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- 2024
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5. Oxidative stress in the retina and retinal pigment epithelium (RPE): Role of aging, and DJ-1
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Mala Upadhyay, Caroline Milliner, Brent A. Bell, and Vera L. Bonilha
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Retina ,Retinal pigment epithelium ,Oxidative stress ,Aging ,DJ-1 ,Sodium iodate ,Medicine (General) ,R5-920 ,Biology (General) ,QH301-705.5 - Abstract
High levels of oxidative radicals generated by daily light exposure and high metabolic rate suggest that the antioxidant machinery of the retina and retinal pigment epithelium (RPE) is crucial for their survival. DJ-1 is a redox-sensitive protein that has been shown to have neuroprotective function in the brain in Parkinson's disease and other neurodegenerative diseases. Here, we analyzed the role of DJ-1 in the retina during oxidative stress and aging. We induced low-level oxidative stress in young (3-month-old) and old (15-month-old) C57BL/6J (WT) and DJ-1 knockout (KO) mice and evaluated effects in the RPE and retina. Absence of DJ-1 resulted in increased retinal dysfunction in response to low levels of oxidative stress. Our findings suggest that loss of DJ-1 affects the RPE antioxidant machinery, rendering it unable to combat and neutralize low-level oxidative stress, irrespective of age. Moreover, they draw a parallel to the retinal degeneration observed in AMD, where the occurrence of genetic variants may leave the retina and RPE unable to fight sustained, low-levels of oxidative stress.
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- 2020
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6. Cellular Changes in Retinas From Patients With BEST1 Mutations
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Vera L. Bonilha, Brent A. Bell, Meghan J. DeBenedictis, Stephanie A. Hagstrom, Gerald A. Fishman, and Joe G. Hollyfield
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best disease ,BEST1 gene ,histopathology ,retinal pigment epithelium ,photoreceptors ,Biology (General) ,QH301-705.5 - Abstract
Best disease (BD), also known as vitelliform macular dystrophy, is an inherited disease of the central retina caused by more than 300 pathogenic variants in the BEST1 gene. The phenotype of BD is variable, and there are just a few reports on the histopathology of eyes from donors with BD. Here, we describe the histopathological comparison of donor’s eyes from two patients with BD. Eyes obtained from 85-year-old (donor 1) and 65-year-old (donor 2) donors were fixed within 25 h postmortem. Perifoveal and peripheral retinal regions were processed for histology and immunocytochemistry using retinal-specific and retinal pigment epithelium (RPE)-specific antibodies. Three age-matched normal eyes were used as controls. DNA was obtained from donor blood samples. Sequence analysis of the entire BEST1 coding region was performed and identified a c.886A > C (p.Asn296His) variant in donor 1 and a c.602T > C (p.Ile201Thr) variant in donor 2; both mutations were heterozygous. Fundus examination showed that donor 1 displayed a macular lesion with considerable scarring while donor 2 displayed close to normal macular morphology. Our studies of histology and molecular pathology in the perifovea and periphery of these two BD donor eyes revealed panretinal abnormalities in both photoreceptors and RPE cellular levels in the periphery; donor 1 also displayed macular lesion. Our findings confirm the phenotypic variability of BD associated with BEST1 variants.
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- 2020
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7. Microtubule-Associated Protein 1 Light Chain 3B, (LC3B) Is Necessary to Maintain Lipid-Mediated Homeostasis in the Retinal Pigment Epithelium
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Anuradha Dhingra, Brent A. Bell, Neal S. Peachey, Lauren L. Daniele, Juan Reyes-Reveles, Rachel C. Sharp, Bokkyoo Jun, Nicolas G. Bazan, Janet R. Sparrow, Hye Jin Kim, Nancy J. Philp, and Kathleen Boesze-Battaglia
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LC3-associated phagocytosis (LAP) ,retinal pigment epithelium ,lipid metabolism ,oxidative stress ,mouse model ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Like other neurons, retinal cells utilize autophagic pathways to maintain cell homeostasis. The mammalian retina relies on heterophagy and selective autophagy to efficiently degrade and metabolize ingested lipids with disruption in autophagy associated degradation contributing to age related retinal disorders. The retinal pigment epithelium (RPE) supports photoreceptor cell renewal by daily phagocytosis of shed photoreceptor outer segments (OS). The daily ingestion of these lipid-rich OS imposes a constant degradative burden on these terminally differentiated cells. These cells rely on Microtubule-Associated Protein 1 Light Chain 3 (LC3) family of proteins for phagocytic clearance of the ingested OS. The LC3 family comprises of three highly homologous members, MAP1LC3A (LC3A), MAP1LC3B (LC3B), and MAP1LC3C (LC3C). The purpose of this study was to determine whether the LC3B isoform plays a specific role in maintaining RPE lipid homeostasis. We examined the RPE and retina of the LC3B-/- mouse as a function of age using in vivo ocular imaging and electroretinography coupled with ex vivo, lipidomic analyses of lipid mediators, assessment of bisretinoids as well as imaging of lipid aggregates. Deletion of LC3B resulted in defects within the RPE including increased phagosome accumulation, decreased fatty acid oxidation and a subsequent increase in RPE and sub-RPE lipid deposits. Age-dependent RPE changes included elevated levels of oxidized cholesterol, deposition of 4-HNE lipid peroxidation products, bisretinoid lipofuscin accumulation, and subretinal migration of microglia, collectively likely contributing to loss of retinal function. These observations are consistent with a critical role for LC3B-dependent processes in the maintenance of normal lipid homeostasis in the aging RPE, and suggest that LC3 isoform specific disruption in autophagic processes contribute to AMD-like pathogenesis.
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- 2018
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8. Complement Component C4 Regulates the Development of Experimental Autoimmune Uveitis through a T Cell-Intrinsic Mechanism
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Lingjun Zhang, Brent A. Bell, Yan Li, Rachel R. Caspi, and Feng Lin
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complement ,C4 ,autoimmune uveitis ,T cells ,animal models ,Immunologic diseases. Allergy ,RC581-607 - Abstract
In addition to its conventional roles in the innate immune system, complement has been found to directly regulate T cells in the adaptive immune system. Complement components, including C3, C5, and factor D, are important in regulating T cell responses. However, whether complement component C4 is involved in regulating T cell responses remains unclear. In this study, we used a T cell-dependent model of autoimmunity, experimental autoimmune uveitis (EAU) to address this issue. We compared disease severity in wild-type (WT) and C4 knockout (KO) mice using indirect ophthalmoscopy, scanning laser ophthalmoscopy, spectral-domain optical coherence tomography, and histopathological analysis. We also explored the underlying mechanism by examining T cell responses in ex vivo antigen-specific recall assays and in in vitro T cell priming assays using bone marrow-derived dendritic cells, splenic dendritic cells, and T cells from WT or C4 KO mice. We found that C4 KO mice develop less severe retinal inflammation than WT mice in EAU and show reduced autoreactive T cell responses and decreased retinal T cell infiltration. We also found that T cells, but not dendritic cells, from C4 KO mice have impaired function. These results demonstrate a previously unknown role of C4 in regulating T cell responses, which affects the development of T cell-mediated autoimmunity, as exemplified by EAU. Our data could shed light on the pathogenesis of autoimmune uveitis in humans.
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- 2017
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9. Overview of the Current Landscape of Outdoor Programs in Higher Education
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Jeff Turner, Jeremy Jostad, Brent J. Bell, Kellie Gerbers, Will Hobbs, Elizabeth Andre, and K.C. Collins
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Recent recognition of the growth and significance outdoor recreation industry indicates a need for outdoor-focused academic programs in higher education, yet broader trends affecting higher education may especially impact these programs. Our census methodology identified 128 undergraduate outdoor academic programs; more than previously identified in the literature. The most common higher education institutions to have an outdoor academic program are public, doctoral granting, and located in cities and in the southeast. However, those most likely to have an outdoor academic program are public and doctoral-granting, but are located in rural areas and the Rocky Mountain region. This research provides the foundation for future work which seeks to better understand the unique characteristics of these programs as well as to identify trends in program introduction and elimination.
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- 2022
10. Recent Advances in Low Power Asynchronous Circuit Design.
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Jia Di, Brent A. Bell, William Bouillon, John Brady, Thao Le 0001, Chien-Wei Lo, Liang Men, Spencer Nelson, Francis Sabado, and Andrew Suchanek
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- 2017
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11. An Examination of Social Capital in Outdoor Orientation Programs
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Guy deBrun, Kellie Gerbers, and Brent J. Bell
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Health (social science) ,Outdoor education ,05 social sciences ,050301 education ,Benchmarking ,Education ,Orientation (mental) ,Tourism, Leisure and Hospitality Management ,0502 economics and business ,Sociology ,Marketing ,0503 education ,Recreation ,050212 sport, leisure & tourism ,Social Sciences (miscellaneous) ,Social capital - Abstract
Social capital offers campus recreation professionals a framework to conceptualize the impacts of outdoor orientation programming (OOPs). Using data from The Outdoor Orientation Benchmarking Survey (TOOBS), researchers explored results of participants’ ( n = 1,154) responses to two constructs conceptually related to social capital: group trust and network closure. Researchers used factor analysis to examine the psychometric properties of TOOBS, finding group trust and network closure represented different aspects of social capital. Results of the study confirms trust and network closure are related, yet unique aspects of the social capital construct. The results provide an empirically-supported measure for evaluating social capital in outdoor orientation programs.
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- 2021
12. Glucose uptake by <scp>GLUT1</scp> in photoreceptors is essential for outer segment renewal and rod photoreceptor survival
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Lauren L. Daniele, John Y. S. Han, Ivy S. Samuels, Ravikiran Komirisetty, Nikhil Mehta, Jessica L. McCord, Minzhong Yu, Yekai Wang, Kathleen Boesze‐Battaglia, Brent A. Bell, Jianhai Du, Neal S. Peachey, and Nancy J. Philp
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Glucose Transporter Type 1 ,Glucose ,Retinal Degeneration ,Retinal Cone Photoreceptor Cells ,Genetics ,Humans ,Rod Cell Outer Segment ,Molecular Biology ,Biochemistry ,Biotechnology - Abstract
Photoreceptors consume glucose supplied by the choriocapillaris to support phototransduction and outer segment (OS) renewal. Reduced glucose supply underlies photoreceptor cell death in inherited retinal degeneration and age-related retinal disease. We have previously shown that restricting glucose transport into the outer retina by conditional deletion of Slc2a1 encoding GLUT1 resulted in photoreceptor loss and impaired OS renewal. However, retinal neurons, glia, and the retinal pigment epithelium play specialized, synergistic roles in metabolite supply and exchange, and the cell-specific map of glucose uptake and utilization in the retina is incomplete. In these studies, we conditionally deleted Slc2a1 in a pan-retinal or rod-specific manner to better understand how glucose is utilized in the retina. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic deletion of Slc2a1 from retinal neurons and Müller glia results in reduced OS growth and progressive rod but not cone photoreceptor cell death. Rhodopsin levels were severely decreased even at postnatal day 20 when OS length was relatively normal. Arrestin levels were not changed suggesting that glucose uptake is required to synthesize membrane glycoproteins. Rod-specific deletion of Slc2a1 resulted in similar changes in OS length and rod photoreceptor cell death. These studies demonstrate that glucose is an essential carbon source for rod photoreceptor cell OS maintenance and viability.
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- 2022
13. Social Status Equalization and Outdoor Orientation Programs: An Exploratory Study
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Renee’ Morrissette, Brent J. Bell, and Mason Trumble
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Outdoor education ,Orientation (mental) ,Applied psychology ,Exploratory research ,Contact theory ,Psychology ,Education ,Social status - Abstract
Background: Research results indicate outdoor orientation programs (OOPs) successfully help students transition to college and increase student retention, but an understanding of all the key variables involved in creating those positive transitions is unknown. Purpose: The aim of this study is to explore the role of subjective social status as a variable that may be important to the curricular design of OOPs. Methodology/Approach: Surveys asking questions about status were sent to students from 31 college OOPs between 2013 and 2017. Responses ( N = 4,484) were reviewed to understand students’ perceptions of within-group social status. Findings/Conclusions: OOP participants most often reported perceiving their social status as equal among group members. Equality perception was associated with traits such as vocality (defined as being able to verbalize ideas and be listened to in the group) and certain aspects of the trip structure (e.g., shared living conditions). Respondents who reported social status equality also reported positive experiences. Implications: Subjective perceptions of within-group status may have important implications for OOPs and may be an important consideration for program planning and curriculum.
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- 2020
14. Deuterated docosahexaenoic acid protects against oxidative stress and geographic atrophy-like retinal degeneration in a mouse model with iron overload
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Yingrui Liu, Brent A. Bell, Ying Song, Kevin Zhang, Brandon Anderson, Paul H. Axelsen, Whitney Bohannan, Martin‐Paul Agbaga, Hui Gyu Park, Genevieve James, J. Thomas Brenna, Karsten Schmidt, Joshua L. Dunaief, and Mikhail S. Shchepinov
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Aging ,Iron Overload ,Docosahexaenoic Acids ,Iron ,Retinal Degeneration ,Cell Biology ,Retinal Pigment Epithelium ,Disease Models, Animal ,Macular Degeneration ,Mice ,Oxidative Stress ,Geographic Atrophy ,Animals ,Humans - Abstract
Oxidative stress plays a central role in age-related macular degeneration (AMD). Iron, a potent generator of hydroxyl radicals through the Fenton reaction, has been implicated in AMD. One easily oxidized molecule is docosahexaenoic acid (DHA), the most abundant polyunsaturated fatty acid in photoreceptor membranes. Oxidation of DHA produces toxic oxidation products including carboxyethylpyrrole (CEP) adducts, which are increased in the retinas of AMD patients. In this study, we hypothesized that deuterium substitution on the bis-allylic sites of DHA in photoreceptor membranes could prevent iron-induced retinal degeneration by inhibiting oxidative stress and lipid peroxidation. Mice were fed with either DHA deuterated at the oxidation-prone positions (D-DHA) or control natural DHA and then given an intravitreal injection of iron or control saline. Orally administered D-DHA caused a dose-dependent increase in D-DHA levels in the neural retina and retinal pigment epithelium (RPE) as measured by mass spectrometry. At 1 week after iron injection, D-DHA provided nearly complete protection against iron-induced retinal autofluorescence and retinal degeneration, as determined by in vivo imaging, electroretinography, and histology. Iron injection resulted in carboxyethylpyrrole conjugate immunoreactivity in photoreceptors and RPE in mice fed with natural DHA but not D-DHA. Quantitative PCR results were consistent with iron-induced oxidative stress, inflammation, and retinal cell death in mice fed with natural DHA but not D-DHA. Taken together, our findings suggest that DHA oxidation is central to the pathogenesis of iron-induced retinal degeneration. They also provide preclinical evidence that dosing with D-DHA could be a viable therapeutic strategy for retinal diseases involving oxidative stress.
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- 2022
15. Transplanted human induced pluripotent stem cells- derived retinal ganglion cells embed within mouse retinas and are electrophysiologically functional
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Vrathasha Vrathasha, Sergei Nikonov, Brent Allen Bell, Jie He, Yajat Bungatavula, Katherine Elizabeth Uyhazi, and Venkata Ramana Murthy Chavali
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Multidisciplinary - Abstract
Glaucoma is an optic neuropathy characterized by permanent visual field loss caused by the death of retinal ganglion cells (RGCs) and it is the leading cause of irreversible blindness worldwide. Consequently, there is an unmet need for the development of new strategies for its treatment. We investigated RGC replacement therapy as a treatment for ganglion cell loss. Human-induced pluripotent stem cells (hiPSCs) were differentiated into mature, functional RGCs
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- 2022
16. Intraocular iron injection induces oxidative stress followed by elements of geographic atrophy and sympathetic ophthalmia
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Maura Poli, Janet R. Sparrow, Michelle Guo, Hye J. Kim, Jacob Sterling, Joshua L. Dunaief, Brent A. Bell, Y. Liu, Guanfang Su, Ying Song, Aditya M Rao, Benjamin J. Kim, and Kevin Zhang
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Male ,Aging ,genetic structures ,Iron ,photoreceptor cells ,Inflammation ,Retinal Pigment Epithelium ,Biology ,medicine.disease_cause ,Ferric Compounds ,Lipofuscin ,Pathogenesis ,chemistry.chemical_compound ,Mice ,Geographic Atrophy ,medicine ,Animals ,lipofuscin ,Retina ,Sympathetic ophthalmia ,Optical Imaging ,Retinal ,lipid peroxidation ,Cell Biology ,medicine.disease ,Molecular biology ,eye diseases ,Mice, Inbred C57BL ,Quaternary Ammonium Compounds ,Disease Models, Animal ,Oxidative Stress ,Choroidal neovascularization ,medicine.anatomical_structure ,chemistry ,Ophthalmia, Sympathetic ,Original Article ,sense organs ,medicine.symptom ,Injections, Intraocular ,Oxidative stress - Abstract
Iron has been implicated in the pathogenesis of age‐related retinal diseases, including age‐related macular degeneration (AMD). Previous work showed that intravitreal (IVT) injection of iron induces acute photoreceptor death, lipid peroxidation, and autofluorescence (AF). Herein, we extend this work, finding surprising chronic features of the model: geographic atrophy and sympathetic ophthalmia. We provide new mechanistic insights derived from focal AF in the photoreceptors, quantification of bisretinoids, and localization of carboxyethyl pyrrole, an oxidized adduct of docosahexaenoic acid associated with AMD. In mice given IVT ferric ammonium citrate (FAC), RPE died in patches that slowly expanded at their borders, like human geographic atrophy. There was green AF in the photoreceptor ellipsoid, a mitochondria‐rich region, 4 h after injection, followed later by gold AF in rod outer segments, RPE and subretinal myeloid cells. The green AF signature is consistent with flavin adenine dinucleotide, while measured increases in the bisretinoid all‐trans‐retinal dimer are consistent with the gold AF. FAC induced formation carboxyethyl pyrrole accumulation first in photoreceptors, then in RPE and myeloid cells. Quantitative PCR on neural retina and RPE indicated antioxidant upregulation and inflammation. Unexpectedly, reminiscent of sympathetic ophthalmia, autofluorescent myeloid cells containing abundant iron infiltrated the saline‐injected fellow eyes only if the contralateral eye had received IVT FAC. These findings provide mechanistic insights into the potential toxicity caused by AMD‐associated retinal iron accumulation. The mouse model will be useful for testing antioxidants, iron chelators, ferroptosis inhibitors, anti‐inflammatory medications, and choroidal neovascularization inhibitors., Intravitreal injection of iron induces photoreceptor oxidative stress, resulting in increased autofluorescence, lipid peroxidation, and myeloid cell infiltration associated with retinal degeneration, geographic atrophy, and choroidal neovascularization.
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- 2021
17. Mouse models of X-linked juvenile retinoschisis have an early onset phenotype, the severity of which varies with genotype
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Botir T. Sagdullaev, Elena Ivanova, Jingtai Cao, Yajun Tang, Neal S. Peachey, Yang Liu, Junzo Kinoshita, Tara Liao, Brent A. Bell, Duo Sun, Hong Li, Jacob M Wang, Carmelo Romano, and Susannah Brydges
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0301 basic medicine ,Pathology ,medicine.medical_specialty ,Genotype ,genetic structures ,Retinoschisis ,Mutant ,Biology ,Severity of Illness Index ,Retinal ganglion ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Genes, X-Linked ,Electroretinography ,Genetics ,medicine ,Animals ,Genetic Predisposition to Disease ,Eye Proteins ,Molecular Biology ,Genetic Association Studies ,Genetics (clinical) ,Retina ,medicine.diagnostic_test ,Genetic heterogeneity ,General Medicine ,Immunohistochemistry ,Phenotype ,eye diseases ,Disease Models, Animal ,030104 developmental biology ,medicine.anatomical_structure ,Mutation ,030221 ophthalmology & optometry ,General Article ,sense organs ,Cell Adhesion Molecules ,Biomarkers ,Photic Stimulation ,Tomography, Optical Coherence - Abstract
X-linked juvenile retinoschisis (XLRS) is an early-onset inherited condition that affects primarily males and is characterized by cystic lesions of the inner retina, decreased visual acuity and contrast sensitivity and a selective reduction of the electroretinogram (ERG) b-wave. Although XLRS is genetically heterogeneous, all mouse models developed to date involve engineered or spontaneous null mutations. In the present study, we have studied three new Rs1 mutant mouse models: (1) a knockout with inserted lacZ reporter gene; (2) a C59S point mutant substitution and (3) an R141C point mutant substitution. Mice were studied from postnatal day (P15) to 28 weeks by spectral domain optical coherence tomography and ERG. Retinas of P21–22 mice were examined using biochemistry, single cell electrophysiology of retinal ganglion cells (RGCs) and by immunohistochemistry. Each model developed intraretinal schisis and reductions in the ERG that were greater for the b-wave than the a-wave. The phenotype of the C59S mutant appeared less severe than the other mutants by ERG at adult ages. RGC electrophysiology demonstrated elevated activity in the absence of a visual stimulus and reduced signal-to-noise ratios in response to light stimuli. Immunohistochemical analysis documented early abnormalities in all cells of the outer retina. Together, these results provide significant insight into the early events of XLRS pathophysiology, from phenotype differences between disease-causing variants to common mechanistic events that may play critical roles in disease presentation and progression.
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- 2019
18. Modulating GLUT1 expression in retinal pigment epithelium decreases glucose levels in the retina: impact on photoreceptors and Müller glial cells
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Jianhai Du, Brent A. Bell, Kathleen Boesze-Battaglia, E. Dale Abel, Erik Massenzio, Ivy S. Samuels, Nancy J. Philp, John Y. S. Han, Neal S. Peachey, and Aditi Swarup
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0301 basic medicine ,Physiology ,Ependymoglial Cells ,Gene Expression ,Mice, Transgenic ,Retinal Pigment Epithelium ,Photoreceptor cell ,Mice ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Animals ,Photoreceptor Cells ,Mice, Knockout ,Glucose Transporter Type 1 ,Retina ,Retinal pigment epithelium ,biology ,Chemistry ,Cell Biology ,eye diseases ,Cell biology ,Glucose ,030104 developmental biology ,medicine.anatomical_structure ,biology.protein ,GLUT1 ,sense organs ,030217 neurology & neurosurgery ,Research Article - Abstract
The retina is one of the most metabolically active tissues in the body and utilizes glucose to produce energy and intermediates required for daily renewal of photoreceptor cell outer segments. Glucose transporter 1 (GLUT1) facilitates glucose transport across outer blood retinal barrier (BRB) formed by the retinal pigment epithelium (RPE) and the inner BRB formed by the endothelium. We used conditional knockout mice to study the impact of reducing glucose transport across the RPE on photoreceptor and Müller glial cells. Transgenic mice expressing Cre recombinase under control of the Bestrophin1 ( Best1) promoter were bred with Glut1flox/flox mice to generate Tg-Best1-Cre:Glut1flox/flox mice ( RPEΔGlut1). The RPEΔGlut1 mice displayed a mosaic pattern of Cre expression within the RPE that allowed us to analyze mice with ~50% ( RPEΔGlut1m) recombination and mice with >70% ( RPEΔGlut1h) recombination separately. Deletion of GLUT1 from the RPE did not affect its carrier or barrier functions, indicating that the RPE utilizes other substrates to support its metabolic needs thereby sparing glucose for the outer retina. RPEΔGlut1m mice had normal retinal morphology, function, and no cell death; however, where GLUT1 was absent from a span of RPE greater than 100 µm, there was shortening of the photoreceptor cell outer segments. RPEΔGlut1h mice showed outer segment shortening, cell death of photoreceptors, and activation of Müller glial cells. The severe phenotype seen in RPEΔGlut1h mice indicates that glucose transport via the GLUT1 transporter in the RPE is required to meet the anabolic and catabolic requirements of photoreceptors and maintain Müller glial cells in a quiescent state.
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- 2019
19. Geographic Atrophy: Confocal Scanning Laser Ophthalmoscopy, Histology, and Inflammation in the Region of Expanding Lesions
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Joe G. Hollyfield, Caroline Milliner, Jane Hu, Roxana A. Radu, Stephanie A. Hagstrom, Gayle J.T. Pauer, Brent A. Bell, and Vera L. Bonilha
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0301 basic medicine ,Male ,Pathology ,medicine.medical_specialty ,genetic structures ,Fundus Oculi ,Visual Acuity ,Retinal Pigment Epithelium ,Fundus (eye) ,autofluorescence ,Lesion ,histology ,03 medical and health sciences ,0302 clinical medicine ,Atrophy ,Geographic Atrophy ,medicine ,Humans ,Fluorescein Angiography ,age-related macular degeneration ,Aged ,Aged, 80 and over ,Retina ,Chemistry ,confocal scanning laser ophthalmoscopy ,Histology ,medicine.disease ,eye diseases ,Scanning laser ophthalmoscopy ,Ophthalmoscopy ,Autofluorescence ,030104 developmental biology ,medicine.anatomical_structure ,Retinal Cell Biology ,inflammation ,030221 ophthalmology & optometry ,Immunohistochemistry ,Female ,sense organs ,Bruch Membrane ,medicine.symptom ,Tomography, Optical Coherence - Abstract
Purpose To describe the pathology of AMD in eyes with geographic atrophy (GA) using confocal scanning laser ophthalmoscopy (SLO) blue light autofluorescence (BAF), and near-infrared (IR) AF and to correlate it with the histology and immunohistochemistry analysis at the margins of the GA lesion. Methods Enucleated, fixed eyes from seventeen donors with GA were imaged and analyzed by BAF-SLO, IRAF-SLO, and by fundus macroscopy (FM). Tissue from the margins of the GA lesions was cut and processed for resin embedding and histology or cryosectioning and fluorescence in the green and far-red channels, and immunohistochemistry to assess markers of inflammation. Isolated DNA from donors was genotyped for single nucleotide polymorphisms (SNPs) previously shown to be risk factors for the development and progression of AMD. Results Around the leading edge of the GA lesions we observed hypertrophic RPE cells with cytoplasm filled with granules fluorescent both in the far-red and green-red channels; abundant microglia and macrophage; deposition of complement factor H (CFH) in Bruch's membrane (BM) and increased membrane attack complex (MAC) on RPE cells. Conclusions Fluorescence imaging of cryosections of RPE cells around the leading edge of the GA lesions suggest that IRAF-SLO visualizes mostly melanin-related compounds. In addition, medium-size GA atrophy displayed the most significant changes in inflammation markers.
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- 2020
20. Treatment Potential for LCA5-Associated Leber Congenital Amaurosis
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Ivan Shpylchak, Vidyullatha Vasireddy, Katherine E. Uyhazi, Denise J. Pearson, Zhangyong Wei, Jean Bennett, Lanfranco Leo, Leona W. Serrano, Puya Aravand, Tomas S. Aleman, Brent A. Bell, and Jennifer Pham
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0301 basic medicine ,Retinal degeneration ,Male ,genetic structures ,Leber Congenital Amaurosis ,Visual Acuity ,Mice ,0302 clinical medicine ,lebercilin ,Child ,LCA5 ,medicine.diagnostic_test ,Optical Imaging ,Dependovirus ,gene therapy ,medicine.anatomical_structure ,Phenotype ,Female ,AAV8 ,Erg ,Microtubule-Associated Proteins ,Pupillometry ,Tomography, Optical Coherence ,Adult ,medicine.medical_specialty ,Genetic Vectors ,Retina ,03 medical and health sciences ,Young Adult ,Ophthalmology ,medicine ,Electroretinography ,Animals ,Humans ,Outer nuclear layer ,Eye Proteins ,business.industry ,Pupil ,Genetic Therapy ,medicine.disease ,eye diseases ,Tissue Degeneration ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,030221 ophthalmology & optometry ,Maculopathy ,Visual Field Tests ,sense organs ,Visual Fields ,business - Abstract
Purpose To determine the therapeutic window for gene augmentation for Leber congenital amaurosis (LCA) associated with mutations in LCA5. Methods Five patients (ages 6-31) with LCA and biallelic LCA5 mutations underwent an ophthalmic examination including optical coherence tomography (SD-OCT), full-field stimulus testing (FST), and pupillometry. The time course of photoreceptor degeneration in the Lca5gt/gt mouse model and the efficacy of subretinal gene augmentation therapy with AAV8-hLCA5 delivered at postnatal day 5 (P5) (early, n = 11 eyes), P15 (mid, n = 14), and P30 (late, n = 13) were assessed using SD-OCT, histologic study, electroretinography (ERG), and pupillometry. Comparisons were made with the human disease. Results Patients with LCA5-LCA showed a maculopathy with detectable outer nuclear layer (ONL) in the pericentral retina and at least 4 log units of dark-adapted sensitivity loss. The Lca5gt/gt mouse has a similarly severe and rapid photoreceptor degeneration. The ONL became progressively thinner and was undetectable by P60. Rod- and cone-mediated ERGs were severely reduced in amplitudes at P30 and became nondetectable by P60. Subretinal AAV8-hLCA5 administered to Lca5gt/gt mice at P5 and P15, but not at P30, resulted in structural and functional rescue. Conclusions LCA5-LCA is a particularly severe form of LCA that was recapitulated in the Lca5gt/gt mouse. Gene augmentation resulted in structural and functional rescue in the Lca5gt/gt mouse if delivered before P30. Retained photoreceptors were visible within the central retina in all patients with LCA5-LCA, at a level equivalent to that observed in rescued Lca5gt/gt mice, suggesting a window of opportunity for the treatment of patients with LCA5-LCA.
- Published
- 2020
21. Orientation to the Student Role
- Author
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Nicolas Haberek, Brent J. Bell, and Laura Zepko
- Subjects
social validation ,dependent ,higher education research institute (heri) ,transition ,Education (General) ,Geometry ,Orientation (graph theory) ,self-fulfilling prophecy ,authoritative ,ComputingMilieux_COMPUTERSANDEDUCATION ,role theory ,millennial ,cooperative institutional research program (cirp) ,L7-991 ,Psychology ,collaborative - Abstract
This article explores and challenges the idea that today's college students (Millennials) are substantially different and more difficult to work with than past generations of students. To investigate students' college preparation and performance, researchers examined data collected by the Higher Education Research Institute (HERI) and by the National Department for Educational Statistics. Researchers compared this data to college professionals' attitudes of current students using a survey developed from the HERI data. The comparison revealed misperceptions of both student academic attitudes and performance which highlight the need for skepticism regarding generational differences in Millennials. This study examines misconceptions about college students, explores how these misconceptions are detrimental to student development, and offers ways to move beyond these misconceptions.
- Published
- 2019
22. Role of monocarboxylate transporters in regulating metabolic homeostasis in the outer retina: Insight gained from cell-specific Bsg deletion
- Author
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Nancy J. Philp, John Y. S. Han, Sara Bisetto, Junzo Kinoshita, Romana A. Nowak, Neal S. Peachey, and Brent A. Bell
- Subjects
0301 basic medicine ,Monocarboxylic Acid Transporters ,genetic structures ,Retinal Pigment Epithelium ,Biology ,Biochemistry ,Article ,03 medical and health sciences ,chemistry.chemical_compound ,Mice ,0302 clinical medicine ,Retinal Rod Photoreceptor Cells ,Genetics ,medicine ,Animals ,Homeostasis ,Lactic Acid ,Molecular Biology ,Mice, Knockout ,Retina ,Transporter ,Retinal ,Biological Transport ,Phenotype ,eye diseases ,Cell biology ,Mice, Inbred C57BL ,030104 developmental biology ,medicine.anatomical_structure ,chemistry ,Anaerobic glycolysis ,Basigin ,Retinal Cone Photoreceptor Cells ,sense organs ,Flux (metabolism) ,030217 neurology & neurosurgery ,Function (biology) ,Biotechnology - Abstract
The neural retina metabolizes glucose through aerobic glycolysis generating large amounts of lactate. Lactate flux into and out of cells is regulated by proton-coupled monocarboxylate transporters (MCTs), which are encoded by members of the Slc16a family. MCT1, MCT3, and MCT4 are expressed in the retina and require association with the accessory protein basigin, encoded by Bsg, for maturation and trafficking to the plasma membrane. Bsg(−/−) mice have severely reduced electroretinograms (ERGs) and progressive photoreceptor degeneration, which is presumed to be driven by metabolic dysfunction resulting from loss of MCTs. To understand the basis of the Bsg(−/−) phenotype, we generated mice with conditional deletion of Bsg in rods (RodΔBsg), cones (Cone∆Bsg), or retinal pigment epithelial cells (RPEΔBsg). RodΔBsg mice showed a progressive loss of photoreceptors, while ConeΔBsg mice did not display a degenerative phenotype. The RPEΔBsg mice developed a distinct phenotype characterized by severely reduced ERG responses as early as 4 weeks of age. The loss of lactate transporters from the RPE most closely resembled the phenotype of the Bsg(−/−) mouse, suggesting that the regulation of lactate levels in the RPE and the subretinal space is essential for the viability and function of photoreceptors.
- Published
- 2019
23. Deletion of GLUT1 in mouse lens epithelium leads to cataract formation
- Author
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Aditi Swarup, E. Dale Abel, Paul G. FitzGerald, John Y. S. Han, Neal S. Peachey, Brent A. Bell, Arturo Bravo-Nuevo, Nancy J. Philp, Jianhai Du, and Jamie Soto
- Subjects
0301 basic medicine ,Aging ,Fluorescent Antibody Technique ,Medical Biochemistry and Metabolomics ,Ophthalmology & Optometry ,Transgenic ,Lens ,Mice ,Adenosine Triphosphate ,0302 clinical medicine ,Glycolysis ,Fluorescent Antibody Technique, Indirect ,Tomography ,Mice, Knockout ,Glucose Transporter Type 1 ,biology ,Blotting ,Chemistry ,Sensory Systems ,Lens Fiber ,Cell biology ,medicine.anatomical_structure ,Excitatory Amino Acid Transporter 2 ,Slc2a1 ,Western ,Tomography, Optical Coherence ,Biotechnology ,Genetically modified mouse ,Indirect ,Knockout ,Blotting, Western ,Cre recombinase ,Mice, Transgenic ,Real-Time Polymerase Chain Reaction ,Cataract ,Article ,Aqueous Humor ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Cataracts ,Opthalmology and Optometry ,Lens, Crystalline ,medicine ,Animals ,Eye Disease and Disorders of Vision ,Crystalline ,Optical coherence tomography ,Neurosciences ,Glucose transporter ,Epithelial Cells ,medicine.disease ,Glut1 ,Epithelium ,Ophthalmology ,Glucose ,030104 developmental biology ,Optical Coherence ,030221 ophthalmology & optometry ,biology.protein ,GLUT1 ,Gene Deletion - Abstract
The primary energy substrate of the lens is glucose and uptake of glucose from the aqueous humor is dependent on glucose transporters. GLUT1, the facilitated glucose transporter encoded by Slc2a1 is expressed in the epithelium of bovine, human and rat lenses. In the current study, we examined the expression of GLUT1 in the mouse lens and determined its role in maintaining lens transparency by studying effects of postnatal deletion of Slc2a1. In situ hybridization and immunofluorescence labeling were used to determine the expression and subcellular distribution of GLUT1 in the lens. Slc2a1 was knocked out of the lens epithelium by crossing transgenic mice expressing Cre recombinase under control of the GFAP promoter with Slc2a1(loxP/loxP) mice to generate Slc2a1(loxP/loxP);GFAP-Cre(+/0) (LensΔGlut1) mice. LensΔGlut1 mice developed visible lens opacities by around 3 months of age, which corresponded temporally with the total loss of detectable GLUT1 expression in the lens. Spectral domain optical coherence tomography (SD-OCT) imaging was used to monitor the formation of cataracts over time. SD-OCT imaging revealed that small nuclear cataracts were first apparent in the lenses of LensΔGlut1 mice beginning at about 2.7 months of age. Longitudinal SD-OCT imaging of LensΔGlut1 mice revealed disruption of mature secondary fiber cells after 3 months of age. Histological sections of eyes from LensΔGlut1 mice confirmed the disruption of the secondary fiber cells. The structural changes were most pronounced in fiber cells that had lost their organelles. In contrast, the histology of the lens epithelium in these mice appeared normal. Lactate and ATP were measured in lenses from LensΔGlut1 and control mice at 2 and 3 months of age. At 2 months of age, when GLUT1 was still detectable in the lens epithelium, albeit at low levels, the amount of lactate and ATP were not significantly different from controls. However, in lenses isolated from 3-month-old LensΔGlut1 mice, when GLUT1 was no longer detectable, levels of lactate and ATP were 50% lower than controls. Our findings demonstrate that in vivo, the transparency of mature lens fiber cells was dependent on glycolysis for ATP and the loss of GLUT1 transporters led to cataract formation. In contrast, lens epithelium and cortical fiber cells have mitochondria and could utilize other substrates to support their anabolic and catabolic needs.
- Published
- 2018
24. Retinoic acid signaling is essential for maintenance of the blood‐retinal barrier
- Author
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Bela Anand-Apte, Brent A. Bell, Lana M. Pollock, and Jing Xie
- Subjects
0301 basic medicine ,Retinal dehydrogenase ,Transgene ,Blood–retinal barrier ,Retinoic acid ,Tretinoin ,Biochemistry ,Animals, Genetically Modified ,03 medical and health sciences ,chemistry.chemical_compound ,CYP26A1 ,0302 clinical medicine ,Blood-Retinal Barrier ,Genetics ,medicine ,Animals ,Receptor ,Molecular Biology ,Zebrafish ,biology ,Research ,Retinal Dehydrogenase ,Retinal ,Retinoic Acid 4-Hydroxylase ,Zebrafish Proteins ,biology.organism_classification ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,chemistry ,sense organs ,030217 neurology & neurosurgery ,Signal Transduction ,Biotechnology - Abstract
The predominant function of the blood-retinal barrier (BRB) is to maintain retinal homeostasis by regulating the influx and efflux between the blood and retina. Breakdown of the BRB occurs in a number of ocular diseases that result in vision loss. Understanding the molecular and cellular pathways involved in the development and maintenance of the BRB is critical to developing therapeutics for these conditions. To visualize the BRB in vivo, we used the transgenic Tg(l-fabp:DBP-EGFP:flk1:mCherry) zebrafish model that expresses vitamin D binding protein (a member of the albumin gene family) tagged to green fluorescent protein. Retinoic acid (RA) plays a number of important roles in vertebrate development and has been shown to play a protective role during inflammation-induced blood-brain barrier disruption. The role of RA in BRB development and maintenance remains unknown. To disrupt RA signaling, Tg(l-fabp:DBP-EGFP:flk1:mCherry) zebrafish were treated with N, N-diethylaminobenzaldehyde and 4-[(1 E)-2-[5,6-dihydro-5,5-dimethyl-8-(2-phenylethynyl)-2-naphthalenyl]ethenyl]benzoic acid, which are antagonists of retinal dehydrogenase and the RA receptor, respectively. Treatment with either compound resulted in BRB disruption and reduced visual acuity, whereas cotreatment with all- trans RA effectively rescued BRB integrity. Additionally, transgenic overexpression of Cyp26a1, which catalyzes RA degradation, resulted in breakdown of the BRB. Our results demonstrate that RA signaling is critical for maintenance of the BRB and could play a role in diseases such as diabetic macular edema.-Pollock, L. M., Xie, J., Bell, B. A., Anand-Apte, B. Retinoic acid signaling is essential for maintenance of the blood-retinal barrier.
- Published
- 2018
25. Targeting CD6 for the treatment of experimental autoimmune uveitis
- Author
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Nina Dvorina, Timothy S. Kern, Lingjun Zhang, Rachel R. Caspi, Brent A. Bell, Yan Li, William M. Baldwin, Wen Qiu, David A. Fox, Feng Lin, and Nora G. Singer
- Subjects
Antigens, Differentiation, T-Lymphocyte ,0301 basic medicine ,Adoptive cell transfer ,T-Lymphocytes ,Inbred C57BL ,law.invention ,Mice ,chemistry.chemical_compound ,0302 clinical medicine ,Models ,law ,Monoclonal ,2.1 Biological and endogenous factors ,Immunology and Allergy ,Molecular Targeted Therapy ,Aetiology ,Cells, Cultured ,Mice, Knockout ,Cultured ,biology ,Antibodies, Monoclonal ,Adoptive Transfer ,CD ,medicine.anatomical_structure ,Mice, Inbred DBA ,Differentiation ,Models, Animal ,Recombinant DNA ,Antibody ,medicine.symptom ,Biotechnology ,medicine.drug_class ,Cells ,Knockout ,T cell ,Immunology ,Inflammation ,Monoclonal antibody ,Autoimmune Disease ,Antibodies ,Retina ,Article ,Autoimmune Diseases ,Uveitis ,03 medical and health sciences ,Antigen ,Antigens, CD ,medicine ,Inbred DBA ,Animals ,Humans ,Antigens ,Eye Disease and Disorders of Vision ,Animal ,business.industry ,Inflammatory and immune system ,Neurosciences ,Retinal ,Mice, Inbred C57BL ,030104 developmental biology ,T-Lymphocyte ,chemistry ,030221 ophthalmology & optometry ,biology.protein ,business - Abstract
Objective CD6 is emerging as a new target for treating many pathological conditions in which T cells are integrally involved, but even the latest data from studies of CD6 gene engineered mice were still contradictory. To address this issue, we studied experimental autoimmune uveitis (EAU), a model of autoimmune uveitis, in wild-type (WT) and CD6 knockout (KO) mice. Methods After EAU induction in WT and CD6 KO mice, we evaluated ocular inflammation and compared retinal antigen-specific T-cell responses using scanning laser ophthalmoscopy, spectral-domain optical coherence tomography, histopathology, and T cell recall assays. Uveitogenic T cells from WT and CD6 KO mice were adoptively transferred into WT naive mice to confirm the impact of CD6 on T cells. In addition, we immunized CD6 KO mice with recombinant CD6 protein to develop mouse anti-mouse CD6 monoclonal antibodies (mAbs) in which functional antibodies exhibiting cross-reactivity with human CD6 were screened and identified for treatment studies. Results In CD6 KO mice with EAU, we found significantly decreased retinal inflammation and reduced autoreactive T-cell responses, and confirmed the impaired uveitogenic capacity of T cells from these mice in an adoptive transfer experiment. Notably, one of these cross-reactive mAbs significantly ameliorated retinal inflammation in EAU induced by the adoptive transfer of uveitogenic T cells. Conclusions Together, these data strongly suggest that CD6 plays a previously unknown, but pivotal role in autoimmune uveitis, and may be a promising new treatment target for this blinding disease. In addition, the newly developed mouse anti-mouse/human CD6 mAbs could be valuable tools for testing CD6-targeted therapies in other mouse models of human diseases.
- Published
- 2018
26. When Outdoor Orientation Program Idioculture Changes: Understanding Student Resistance
- Author
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Brent J. Bell and Christa Ricker
- Subjects
Orientation (mental) ,Rehabilitation ,Physical Therapy, Sports Therapy and Rehabilitation ,Resistance (psychoanalysis) ,General Medicine ,Psychology ,Engineering physics - Published
- 2018
27. Recent Advances in Low Power Asynchronous Circuit Design
- Author
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John Brady, Francis Sabado, Thao Le, Chien-Wei Lo, Andrew Suchanek, Liang Men, Jia Di, Spencer Nelson, Brent A. Bell, and William Bouillon
- Subjects
Asynchronous circuit design ,Computer science ,020208 electrical & electronic engineering ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,02 engineering and technology ,Electrical and Electronic Engineering ,020202 computer hardware & architecture ,Power (physics) - Published
- 2017
28. Absence of DJ-1 causes age-related retinal abnormalities in association with increased oxidative stress
- Author
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Joe G. Hollyfield, Brent A. Bell, Mary E. Rayborn, Chengsong Xie, Ivy S. Samuels, Vera L. Bonilha, Anna King, and Huaibin Cai
- Subjects
0301 basic medicine ,Retinal degeneration ,Aging ,Rhodopsin ,Programmed cell death ,medicine.medical_specialty ,genetic structures ,Protein Deglycase DJ-1 ,Retinal Pigment Epithelium ,Biology ,medicine.disease_cause ,Biochemistry ,Article ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Physiology (medical) ,Internal medicine ,medicine ,Animals ,Humans ,Mice, Knockout ,Retina ,Retinal pigment epithelium ,Retinal Degeneration ,Retinal ,Anatomy ,medicine.disease ,eye diseases ,Mice, Inbred C57BL ,Disease Models, Animal ,Oxidative Stress ,030104 developmental biology ,Endocrinology ,medicine.anatomical_structure ,chemistry ,sense organs ,Erg ,030217 neurology & neurosurgery ,Oxidative stress ,Photoreceptor Cells, Vertebrate - Abstract
Oxidative stress alters physiological function in most biological tissues and can lead to cell death. In the retina, oxidative stress initiates a cascade of events leading to focal loss of RPE and photoreceptors, which is thought to be a major contributing factor to geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative stress under normal and pathological conditions remains largely unknown. A better understanding of the mechanisms involved in regulating RPE and photoreceptors oxidative stress response is greatly needed. To this end we evaluated photoreceptor and RPE changes in mice deficient in DJ-1, a protein that is thought to be important in protecting cells from oxidative stress. Young (3 months) and aged (18 months) DJ-1 knockout (DJ-1 KO) and age-matched wild-type mice were examined. In both group of aged mice, scanning laser ophthalmoscopy (SLO) showed the presence of a few autofluorescent foci. The 18 month-old DJ-1 KO retinas were also characterized by a noticeable increase in RPE fluorescence to wild-type. Optical coherence tomography (OCT) imaging demonstrated that all retinal layers were present in the eyes of both DJ-1 KO groups. ERG comparisons showed that older DJ-1 KO mice had reduced sensitivity under dark- and light-adapted conditions compared to age-matched control. Histologically, the RPE contained prominent vacuoles in young DJ-1 KO group with the appearance of enlarged irregularly shaped RPE cells in the older group. These were also evident in OCT and in whole mount RPE/choroid preparations labeled with phalloidin. Photoreceptors in the older DJ-1 KO mice displayed decreased immunoreactivity to rhodopsin and localized reduction in cone markers compared to the wild-type control group. Lower levels of activated Nrf2 were evident in retina/RPE lysates in both young and old DJ-1 KO mouse groups compared to wild-type control levels. Conversely, higher levels of protein carbonyl derivatives and iNOS immunoreactivity were detected in retina/RPE lysates from both young and old DJ-1 KO mice. These results demonstrate that DJ-1 KO mice display progressive signs of retinal/RPE degeneration in association with higher levels of oxidative stress markers. Collectively this analysis indicates that DJ-1 plays an important role in protecting photoreceptors and RPE from oxidative damage during aging.
- Published
- 2017
29. Assessing the Value of a College Degree in Outdoor Education or Recreation: Institutional Comparisons Using the College Scorecard and Surveys of Faculty and Employers
- Author
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Jayson O. Seaman, Brent J. Bell, and Nate E. Trauntvein
- Subjects
Balanced scorecard ,Higher education ,Outdoor education ,business.industry ,05 social sciences ,050109 social psychology ,Context (language use) ,Employability ,Family income ,Public relations ,Trend analysis ,0502 economics and business ,Pedagogy ,0501 psychology and cognitive sciences ,Sociology ,business ,Recreation ,050212 sport, leisure & tourism - Abstract
In this article, we report on research undertaken in 2016 to assess a number of trends influencing the current status of degree-granting outdoor programs in the United States, including factors that bear on the value of degrees. We analyze data provided by the U.S. Department of Education’s College Scorecard and results of a survey comparing 59 programs in the United States by size, geographic region, and public/private status, focusing on cost, postgraduate employment, and select program features tied to alumni employability. Results are discussed in the context of wider trends in higher education, projections for job growth in outdoor areas, and preferred qualifications as reported by employers. Findings are useful for identifying challenges and opportunities for active outdoor fields as a whole and may help individual programs situate themselves among comparators in a way that informs future planning.View Seaman and Bell talking about this article on Facebook.Subscribe to JOREL.
- Published
- 2017
30. An Investigation of the Connection Between Outdoor Orientation and Thriving
- Author
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Brent J. Bell, Andrew J. Bobilya, and Wally James Rude
- Subjects
Outdoor education ,05 social sciences ,Sense of community ,Ethnic group ,050301 education ,Structural equation modeling ,0502 economics and business ,Spirituality ,Well-being ,Thriving ,ComputingMilieux_COMPUTERSANDEDUCATION ,Spiritual development ,Psychology ,0503 education ,Social psychology ,050212 sport, leisure & tourism - Abstract
This study explored the contribution of outdoor orientation experiences to student thriving. Participants included 295 first-year college students from three institutions across North America. A thriving model was tested using structural equation modeling and included the following variables: outdoor orientation, thriving, involvement, spirituality, psychological sense of community, student–faculty interaction, and control variables. Although the predictive importance of outdoor orientation is modest (? = .048), it contributes significantly to a model explaining 72.8% of the variance in thriving levels. Outdoor orientation directly predicted campus involvement (? = .246) and spirituality (? = -.146). Findings indicate that participating in an outdoor orientation may create a propensity for students to become more involved in campus life, which may foster a greater sense of campus community, culminating in thriving. These results suggest that practitioners should enhance both a psychological sense of community among students and the durability of outdoor experiences back on campus.Subscribe to JOREL
- Published
- 2017
31. Outdoor Orientation Leaders: The Effects of Peer Leadership
- Author
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J. David Starbuck and Brent J. Bell
- Subjects
Semi-structured interview ,Outdoor education ,Leadership development ,business.industry ,education ,05 social sciences ,050301 education ,Peer group ,030229 sport sciences ,Interpersonal communication ,Shared leadership ,Peer leadership ,Personal development ,03 medical and health sciences ,0302 clinical medicine ,ComputingMilieux_COMPUTERSANDEDUCATION ,Psychology ,business ,0503 education ,Social psychology - Abstract
In this study, we investigated how student (peer) leaders of college outdoor orientation programs understand the effects of their leadership experience on personal growth and development. We collected data through in-depth interviews of 36 first-time student leaders at four colleges. Findings indicate that the majority of students at all four colleges placed high value on their leadership experiences. Students reported that the experience led to positive changes. The experiences of the leaders are explained in a four-stage model. Student leaders believe the outdoor leadership experience increased confidence to face adversity, increased confidence in exercising one’s voice appropriately, and increased leadership self-efficacy. Students also reported a positive change in interpersonal growth, describing a better ability to work well with others and facilitate social situations. Within faith-based programs, leaders also reported significant spiritual growth. Subscribe to JOREL
- Published
- 2017
32. Outdoor Orientation Programs: A Critical Review of Program Impacts on Retention and Graduation
- Author
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Hong Chang and Brent J. Bell
- Subjects
Selection bias ,Matching (statistics) ,Outdoor education ,media_common.quotation_subject ,05 social sciences ,Applied psychology ,050301 education ,Sampling (statistics) ,Regression analysis ,law.invention ,Randomized controlled trial ,law ,Pedagogy ,Covariate ,Psychology ,0503 education ,Graduation ,media_common - Abstract
Outdoor orientation programs have a growing literature demonstrating positive impacts with students transitioning to college (Bell, Gass, Nafizer, & Starbuck, 2014). One of the most valued outcomes for colleges and universities is retention of students until successful graduation. This is an outcome few outdoor orientation researchers have studied, but one that many programs claim to influence. This paper provides an overview of the literature of outdoor orientation programs retention studies, with specific attention placed on selection bias. This study used a control group (randomized selection), a convenience group (nonparticipants), and a comparison group (matched by covariates) to assess the differences in retention outcomes. Findings indicate (a) similarities between sampling through random selection and covariate matching, but not by convenience sampling and (b) generally positive retention results for participation in outdoor orientation programs, including small effect sizes for retention (OR = 1.91–2.38) and graduation (OR = 1.07–1.81), but few statistically significant results (p < .05).
- Published
- 2017
33. The adult zebrafish retina: In vivo optical sectioning with Confocal Scanning Laser Ophthalmoscopy and Spectral-Domain Optical Coherence Tomography
- Author
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Brian D Perkins, Joseph Fogerty, Emma M. Lessieur, Alex Yuan, Rose M DiCicco, and Brent A. Bell
- Subjects
Retinal Ganglion Cells ,0301 basic medicine ,Materials science ,genetic structures ,Optical sectioning ,Fundus Oculi ,Confocal ,Optical power ,Article ,law.invention ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,Optics ,Retinal Diseases ,Optical coherence tomography ,law ,medicine ,Animals ,Depth of field ,Fluorescein Angiography ,Zebrafish ,Retina ,medicine.diagnostic_test ,business.industry ,Reproducibility of Results ,Retinal ,eye diseases ,Sensory Systems ,Ophthalmoscopy ,Lens (optics) ,Disease Models, Animal ,Ophthalmology ,030104 developmental biology ,medicine.anatomical_structure ,chemistry ,sense organs ,business ,Tomography, Optical Coherence - Abstract
Non-invasive imaging is an invaluable diagnostic tool in ophthalmology. Two imaging devices, the scanning laser ophthalmoscope (SLO) and spectral domain optical coherence tomography (SDOCT), emerged from the clinical realm to provide research scientists with a real-time view of ocular morphology in living animals. We utilized these two independent imaging modalities in a complementary manner to perform in vivo optical sectioning of the adult zebrafish retina. Due to the very high optical power of the zebrafish lens, the confocal depth of field is narrow, allowing for detailed en face views of specific retinal layers, including the cone mosaic. Moreover, we demonstrate that both native reflectance, as well as fluorescent features observed by SLO, can be combined with axial in-depth information obtained by SDOCT. These imaging approaches can be used to screen for ocular phenotypes and monitor retinal pathology in a non-invasive manner.
- Published
- 2016
34. Sorsby Fundus Dystrophy Mutation in Tissue Inhibitor of Metalloproteinase 3 (TIMP3) promotes Choroidal Neovascularization via a Fibroblast Growth Factor-dependent Mechanism
- Author
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Julia C Batoki, Heidi Stoehr, Brent A. Bell, Bela Anand-Apte, Mariya Ali, Nicholas Prayson, Jian Hua Qi, Alyson Wolk, Alecia Cutler, and Rupesh Singh
- Subjects
0301 basic medicine ,MMP2 ,genetic structures ,DNA Copy Number Variations ,Angiogenesis ,Basic fibroblast growth factor ,lcsh:Medicine ,Gene Expression ,Fibroblast growth factor ,Article ,03 medical and health sciences ,chemistry.chemical_compound ,Macular Degeneration ,Mice ,0302 clinical medicine ,medicine ,Animals ,lcsh:Science ,Multidisciplinary ,business.industry ,lcsh:R ,Endothelial Cells ,Retinal ,Tissue Inhibitor of Metalloproteinases ,Tissue inhibitor of metalloproteinase ,Macular degeneration ,medicine.disease ,eye diseases ,Choroidal Neovascularization ,Extracellular Matrix ,Fibroblast Growth Factors ,Experimental models of disease ,030104 developmental biology ,Choroidal neovascularization ,chemistry ,030220 oncology & carcinogenesis ,Mutation ,Cancer research ,lcsh:Q ,Extracellular signalling molecules ,sense organs ,medicine.symptom ,business ,Biomarkers - Abstract
Choroidal neovascularization (CNV) leads to loss of vision in patients with Sorsby Fundus Dystrophy (SFD), an inherited, macular degenerative disorder, caused by mutations in the Tissue Inhibitor of Metalloproteinase-3 (TIMP3) gene. SFD closely resembles age-related macular degeneration (AMD), which is the leading cause of blindness in the elderly population of the Western hemisphere. Variants in TIMP3 gene have recently been identified in patients with AMD. A majority of patients with AMD also lose vision as a consequence of choroidal neovascularization (CNV). Thus, understanding the molecular mechanisms that contribute to CNV as a consequence of TIMP-3 mutations will provide insight into the pathophysiology in SFD and likely the neovascular component of the more commonly seen AMD. While the role of VEGF in CNV has been studied extensively, it is becoming increasingly clear that other factors likely play a significant role. The objective of this study was to test the hypothesis that basic Fibroblast Growth Factor (bFGF) regulates SFD-related CNV. In this study we demonstrate that mice expressing mutant TIMP3 (Timp3S179C/S179C) showed reduced MMP inhibitory activity with an increase in MMP2 activity and bFGF levels, as well as accentuated CNV leakage when subjected to laser injury. S179C mutant-TIMP3 in retinal pigment epithelial (RPE) cells showed increased secretion of bFGF and conditioned medium from these cells induced increased angiogenesis in endothelial cells. These studies suggest that S179C-TIMP3 may promote angiogenesis and CNV via a FGFR-1-dependent pathway by increasing bFGF release and activity.
- Published
- 2019
35. Prolonged Ocular Exposure Leads to the Formation of Retinal Lesions in Mice
- Author
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Bela Anand-Apte, Stephanie A. Hagstrom, Brent A. Bell, Vera L. Bonilha, Joe G. Hollyfield, and Ivy S. Samuels
- Subjects
0303 health sciences ,Retina ,medicine.medical_specialty ,Retinal pigment epithelium ,business.industry ,Posterior pole ,Retinal ,Fundus (eye) ,Posterior segment of eyeball ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,medicine.anatomical_structure ,chemistry ,Ophthalmology ,Cornea ,030221 ophthalmology & optometry ,medicine ,Mydriasis ,sense organs ,medicine.symptom ,business ,030304 developmental biology - Abstract
The observation of retinal lesions in the posterior pole of laboratory mice has been found to occur for many reasons, some of which are due to native, developmental abnormalities and those that are influenced by environmental or experimental conditions. Herein, we investigated the rate and extent of retinal lesions as a result of prolonged ocular exposure following general anesthesia. Mice were housed under standard animal care conditions and transported to the laboratory for experimental preparation induction procedures (EPIP) involving general anesthesia, mydriasis/cycloplegia, and topical anesthesia to the cornea. Following EPIP, two ocular recovery conditions (protected and unprotected) were tested within two different animal recovery chambers (open or closed). During anesthesia recovery, and extending up to 2.5 months thereafter, the anterior and posterior poles were evaluated using digital color photography, scanning laser ophthalmoscopy, and spectral-domain optical coherence tomography to document the effects of eye protection and chamber recovery type on the development of retinal lesions. In some mice, electroretinograms and histological evaluations were performed to assess functional and structural changes that accompanied the retinal lesions detected by in vivo imaging. We found that the anterior segments of mice recovered in the open chamber with unprotected eyes showed substantial acute changes. At 1-hour post-EPIP, the anterior chamber exhibited corneal thinning, severe media opacities, a reduction in anterior chamber depth, and ocular lens prolapse. These changes largely resolved upon recovery. At 3- and 14-days post-EPIP, inspection of the posterior pole by fundus imaging revealed prominent lesions in the outer retina in a significant proportion of mice recovered in the open chamber. ERG testing conducted at 1-month post-EPIP revealed compromised functional responses in the eyes of affected vs. unaffected mice. Imaging at 14-days post-EPIP revealed that the outer retina lesions in affected mice almost wholly resolve over time to nearly insignificant levels. However, data collected at 80-days post-EPIP demonstrates that some lingering effects persist long-term and appear to be confined to the retinal pigment epithelium. In comparison, mice recovered in the closed chamber with unprotected eyes experienced only mild lens opacities at 1-hr post EPIP that cleared following a full recovery from the effects of sedation. Furthermore, protected eyes of mice recovered in either the open or closed chamber were completely devoid of any anterior or posterior pole complications. In sum, prolonged ocular surface exposure to circulating ambient room air leads to significant anterior and posterior segment ocular complications. We interpret these changes to be caused by dehydration and desiccation of the corneal surface of the eye. The most abundant, semi-reversible complication observed was the development of lesions in the outer retina, which had a 90% probability of occurring after 45 minutes of exposure. The lesions largely absolved short-term but some imaging evidence suggests that they may persist months after their initial appearance.DisclosuresB.A. Bell, none; V.L. Bonilha, none; S.A. Hagstrom, none; B.Anand-Apte, none; 14 J.G. Hollyfield, none; I.S. Samuels, none.Grant InformationResearch reported in this publication was supported by the National Eye Institute of the National Institutes of Health under award numbers P30EY025585, R01EY016490, RO1EY026181, RO1EY027083, R01EY014240 and R01EY027750, US Dept. of Veterans Affairs Biomedical Laboratory Research and Development Service VA Merit Award I01BX002754, an unrestricted grant from the Research to Prevent Blindness to the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Foundation for Fighting Blindness Research Center Grant, The Wolf Family Foundation, the Llura and Gordon Gund Foundation and the Cleveland Clinic. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the US Dept. of Veterans Affairs.
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- 2019
36. Prolonged ocular exposure leads to retinal lesions in mice
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Stephanie A. Hagstrom, Joe G. Hollyfield, Bela Anand-Apte, Brent A. Bell, Ivy S. Samuels, and Vera L. Bonilha
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0301 basic medicine ,Male ,Xylazine ,Mydriatics ,genetic structures ,Posterior pole ,chemistry.chemical_compound ,Mice ,0302 clinical medicine ,Cornea ,Mydriasis ,Adrenergic alpha-2 Receptor Agonists ,Hypnotics and Sedatives ,Fluorescein Angiography ,Pentobarbital ,Immunohistochemistry ,Sensory Systems ,Anesthetics, Combined ,Scanning laser ophthalmoscopy ,medicine.anatomical_structure ,Female ,Ketamine ,medicine.symptom ,Tomography, Optical Coherence ,medicine.medical_specialty ,Retina ,Article ,Lesion ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Retinal Diseases ,Ophthalmology ,medicine ,Electroretinography ,Animals ,Night Vision ,Anesthetics, Dissociative ,Color Vision ,business.industry ,Retinal ,eye diseases ,Posterior segment of eyeball ,Mice, Inbred C57BL ,Ophthalmoscopy ,030104 developmental biology ,chemistry ,030221 ophthalmology & optometry ,sense organs ,business ,Biomarkers - Abstract
Retinal lesions in the posterior pole of laboratory mice occur due to native, developmental abnormalities or as a consequence of environmental or experimental conditions. In this study, we investigated the rate and extent of retinal lesions as a result of prolonged ocular exposure following general anesthesia. Following experimental preparation induction procedures (EPIP) involving general anesthesia, mydriasis/cycloplegia, and topical anesthesia to the cornea, two ocular recovery conditions (protected and unprotected) were tested within two different animal recovery chambers (open or closed). The anterior and posterior poles were evaluated for the development of retinal lesions using digital color photography, scanning laser ophthalmoscopy, and spectral-domain optical coherence during anesthesia recovery and up to 2.5 months thereafter. In some mice, electroretinograms, histological and immunohistological evaluations were performed to assess functional and structural changes that accompanied the retinal lesions detected by in vivo imaging. Our data suggests that prolonged ocular surface exposure to circulating ambient room air leads to significant anterior and posterior segment ocular complications. The most abundant, semi-reversible complication observed was the development of lesions in the outer retina, which had a 90% probability of occurring after 45 min of exposure. The lesions mostly resolved short-term, but functional and imaging evidence suggest that some perturbations to the outer retina may persist one or more months following initial development.
- Published
- 2019
37. Outdoor Education Academic Programs in the United States
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Jayson O. Seaman, Brent J. Bell, and Nate E. Trauntvein
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Gerontology ,Economic growth ,Higher education ,Outdoor education ,business.industry ,05 social sciences ,Adventure education ,050301 education ,Geography ,0502 economics and business ,Geographic regions ,business ,0503 education ,050212 sport, leisure & tourism - Published
- 2017
38. Trust in College Transitions
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Brent J. Bell
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Interpersonal relationship ,Outdoor education ,Psychology ,Social psychology - Published
- 2017
39. Oxidative stress in the retina and retinal pigment epithelium (RPE): Role of aging, and DJ-1
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Caroline Milliner, Mala Upadhyay, Brent A. Bell, and Vera L. Bonilha
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Male ,0301 basic medicine ,Retinal degeneration ,Aging ,DJ-1 ,Antioxidant ,medicine.medical_treatment ,Clinical Biochemistry ,Sodium iodate ,medicine.disease_cause ,PD, Parkinson's disease ,Biochemistry ,Mice ,chemistry.chemical_compound ,0302 clinical medicine ,CTCF, corrected total cell fluorescence ,AMD, age-related macular degeneration ,lcsh:QH301-705.5 ,lcsh:R5-920 ,Cell biology ,AGE, advanced glycation end product ,medicine.anatomical_structure ,Female ,lcsh:Medicine (General) ,Research Paper ,BM, Bruch's membrane ,RPE, retinal pigment epithelium ,GFAP, anti-glial fibrillary acidic protein ,Oxidative phosphorylation ,Biology ,Neuroprotection ,Retina ,03 medical and health sciences ,ROS, reactive oxygen species ,medicine ,Animals ,Retinal pigment epithelium ,Organic Chemistry ,medicine.disease ,eye diseases ,Mice, Inbred C57BL ,030104 developmental biology ,lcsh:Biology (General) ,chemistry ,Oxidative stress ,sense organs ,030217 neurology & neurosurgery - Abstract
High levels of oxidative radicals generated by daily light exposure and high metabolic rate suggest that the antioxidant machinery of the retina and retinal pigment epithelium (RPE) is crucial for their survival. DJ-1 is a redox-sensitive protein that has been shown to have neuroprotective function in the brain in Parkinson's disease and other neurodegenerative diseases. Here, we analyzed the role of DJ-1 in the retina during oxidative stress and aging. We induced low-level oxidative stress in young (3-month-old) and old (15-month-old) C57BL/6J (WT) and DJ-1 knockout (KO) mice and evaluated effects in the RPE and retina. Absence of DJ-1 resulted in increased retinal dysfunction in response to low levels of oxidative stress. Our findings suggest that loss of DJ-1 affects the RPE antioxidant machinery, rendering it unable to combat and neutralize low-level oxidative stress, irrespective of age. Moreover, they draw a parallel to the retinal degeneration observed in AMD, where the occurrence of genetic variants may leave the retina and RPE unable to fight sustained, low-levels of oxidative stress., Graphical abstract Image 1, Highlights • Antioxidants are upregulated in young DJ-1 KO RPE but downregulated in the retina. • DJ-1 KO retinas are degenerated under low-level oxidative stress, regardless of age. • Retinas of both young C57BL and DJ-1 KO were able to regulate antioxidant genes upon low-level oxidative stress. • Retinas of both aged C57BL and DJ-1 KO were unable to regulate antioxidant genes upon low-level oxidative stress. • RPE of aged C57BLl mice upregulated some antioxidant genes.
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- 2020
40. Retinal Glial and Choroidal Vascular Pathology in Donors Clinically Diagnosed With Stargardt Disease
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Malia M. Edwards, Vera L. Bonilha, D. Scott McLeod, Brent A. Bell, Joe G. Hollyfield, Imran Ahmed Bhutto, and Gerard A. Lutty
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Male ,0301 basic medicine ,Pathology ,medicine.medical_specialty ,glia ,Ependymoglial Cells ,Peripherins ,Retinal Pigment Epithelium ,Retina ,Macular Degeneration ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Atrophy ,Diagnosis ,medicine ,Humans ,Genetic Testing ,Peripherin 2 ,Aged ,Müller cells ,Glial fibrillary acidic protein ,biology ,Choroid ,business.industry ,Peripherin ,Retinal ,choriocapillaris degeneration ,medicine.disease ,eye diseases ,Stargardt disease ,retinal gliosis ,030104 developmental biology ,medicine.anatomical_structure ,Retinal Cell Biology ,chemistry ,Mutation ,030221 ophthalmology & optometry ,biology.protein ,ATP-Binding Cassette Transporters ,Female ,sense organs ,business - Abstract
Purpose The present study investigated retinal glia and choroidal vessels in flatmounts and sections from individuals with clinically diagnosed Stargardt disease (STGD). Methods Eyes from three donors clinically diagnosed with STGD were obtained through the Foundation Fighting Blindness (FFB). Genetic testing was performed to determine the disease-causing mutations. Eyes were enucleated and fixed in 4% paraformaldehyde and 0.5% glutaraldehyde. After imaging, retinas were dissected and immunostained for glial fibrillary acidic protein, vimentin, and peanut agglutin. Following RPE removal, the choroid was immunostained with Ulex europaeus agglutinin lectin. For each choroid, the area of affected vasculature, percent vascular area, and choriocapillaris luminal diameters were measured. The retina from one donor was hemisected and cryopreserved or embedded in JB-4 for cross-section analysis. Results Genetic testing confirmed the STGD diagnosis in donor 1, whereas a mutation in peripherin 2 was identified in donor 3. Genetic testing was not successful on donor 2. Therefore, only donor 1 can definitively be classified as having STGD. All donors had areas of RPE atrophy within the macular region, which correlated with underlying choriocapillaris loss. In addition, Muller cells formed pre- and subretinal membranes. Subretinal gliotic membranes correlated almost identically with RPE and choriocapillaris loss. Conclusions Despite bearing different genetic mutations, all donors demonstrated choriocapillaris loss and Muller cell membranes correlating with RPE loss. Muller cell remodeling was most extensive in the donor with the peripherin mutation, whereas choriocapillaris loss was greatest in the confirmed STGD donor. This study emphasizes the importance of genetic testing when diagnosing macular disease.
- Published
- 2020
41. Microtubule-Associated Protein 1 Light Chain 3B, (LC3B) Is Necessary to Maintain Lipid-Mediated Homeostasis in the Retinal Pigment Epithelium
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Bokkyoo Jun, Nancy J. Philp, Anuradha Dhingra, Kathleen Boesze-Battaglia, Janet R. Sparrow, Hye Jin Kim, Rachel C. Sharp, Neal S. Peachey, Juan Reyes-Reveles, Brent A. Bell, Nicolas G. Bazan, and Lauren L. Daniele
- Subjects
0301 basic medicine ,Retinal Disorder ,mouse model ,retinal pigment epithelium ,Photoreceptor cell ,lcsh:RC321-571 ,Lipid peroxidation ,03 medical and health sciences ,chemistry.chemical_compound ,Cellular and Molecular Neuroscience ,0302 clinical medicine ,lipid metabolism ,medicine ,oxidative stress ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,Original Research ,Retina ,Retinal pigment epithelium ,LC3-associated phagocytosis (LAP) ,Lipid metabolism ,Retinal ,eye diseases ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,chemistry ,sense organs ,MAP1LC3B ,030217 neurology & neurosurgery ,Neuroscience - Abstract
Like other neurons, retinal cells utilize autophagic pathways to maintain cell homeostasis. The mammalian retina relies on heterophagy and selective autophagy to efficiently degrade and metabolize ingested lipids with disruption in autophagy associated degradation contributing to age related retinal disorders. The retinal pigment epithelium (RPE) supports photoreceptor cell renewal by daily phagocytosis of shed photoreceptor outer segments (OS). The daily ingestion of these lipid-rich OS imposes a constant degradative burden on these terminally differentiated cells. These cells rely on Microtubule-Associated Protein 1 Light Chain 3 (LC3) family of proteins for phagocytic clearance of the ingested OS. The LC3 family comprises of three highly homologous members, MAP1LC3A (LC3A), MAP1LC3B (LC3B), and MAP1LC3C (LC3C). The purpose of this study was to determine whether the LC3B isoform plays a specific role in maintaining RPE lipid homeostasis. We examined the RPE and retina of the LC3B-/- mouse as a function of age using in vivo ocular imaging and electroretinography coupled with ex vivo, lipidomic analyses of lipid mediators, assessment of bisretinoids as well as imaging of lipid aggregates. Deletion of LC3B resulted in defects within the RPE including increased phagosome accumulation, decreased fatty acid oxidation and a subsequent increase in RPE and sub-RPE lipid deposits. Age-dependent RPE changes included elevated levels of oxidized cholesterol, deposition of 4-HNE lipid peroxidation products, bisretinoid lipofuscin accumulation, and subretinal migration of microglia, collectively likely contributing to loss of retinal function. These observations are consistent with a critical role for LC3B-dependent processes in the maintenance of normal lipid homeostasis in the aging RPE, and suggest that LC3 isoform specific disruption in autophagic processes contribute to AMD-like pathogenesis.
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- 2018
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42. Reduced expression of the
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Junzo, Kinoshita, Nazarul, Hasan, Brent A, Bell, and Neal S, Peachey
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Protein Kinase C-alpha ,genetic structures ,Dark Adaptation ,Receptors, Metabotropic Glutamate ,Retina ,Mice, Inbred C57BL ,Phenotype ,Gene Expression Regulation ,Electroretinography ,Animals ,Mutant Proteins ,sense organs ,Tomography, Optical Coherence ,Research Article - Abstract
Purpose The Grm6nob8 mouse carries a missense mutation in the Grm6 gene (p.Met66Leu), and exhibits a reduced b-wave of the electroretinogram (ERG), abnormal localization of metabotropic glutamate receptor 6 (mGluR6) to the depolarizing bipolar cell (DBC) soma, and a reduced level of mGluR6 at the DBC dendritic tips. Although the underlying mechanism remains unknown, one possible explanation is that DBCs cannot efficiently traffic the mutant mGluR6. In that scenario, reducing the total amount of mutant mGluR6 protein might normalize localization, and thus, improve the ERG phenotype as well. The second purpose of this study was to determine whether the abnormal cellular distribution of mutant mGluR6 in Grm6nob8 retinas might induce late onset DBC degeneration. Methods We crossed Grm6nob8 animals with Grm6nob3 mice, which carry a null mutation in Grm6, to generate Grm6nob3/nob8 compound heterozygotes. We used western blotting to measure the total mGluR6 content, and immunohistochemistry to document mGluR6 localization within DBCs. In addition, we examined outer retinal function with ERG and retinal architecture in vivo with spectral domain optical coherence tomography (SD-OCT). Results The retinal content of mGluR6 was reduced in the retinas of the Grm6nob3/nob8 compound heterozygotes compared to the Grm6nob8 homozygotes. The cellular distribution of mGluR6 in the Grm6nob3/nob8 compound heterozygotes matched that of the Grm6nob8 homozygotes, with extensive expression throughout the DBC cell body and limited expression at the DBC dendritic tips. The dark-adapted ERG b-waves of the Grm6nob3/nob8 mice were reduced in comparison to those of the Grm6nob8 homozygotes at postnatal day 21 and 28. The overall ERG waveforms obtained from 4- through 68-week old Grm6nob8 mice were in general agreement for dark- and light-adapted conditions. The maximum response and sensitivity of the dark-adapted ERG b-wave did not change statistically significantly with age. SD-OCT revealed the maintained laminar structure of the retina, including a clear inner nuclear layer (INL) at each age examined (from 11 to 57 weeks old), although the INL in the mice older than 39 weeks of age was somewhat thinner than that seen at 11 weeks. Conclusions Mislocalization of mutant mGluR6 is not normalized by reducing the total mGluR6. Mislocalized mutant mGluR6 does not trigger substantial loss of DBCs.
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- 2018
43. A Novel Approach for Integrating AF-SLO and SDOCT Imaging Data Demonstrates the Ability to Identify Early Retinal Abnormalities in Mutant Mice and Evaluate the Effects of Genetic and Pharmacological Manipulation
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Brent A, Bell, Vera L, Bonilha, and Ivy S, Samuels
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Mice, Knockout ,Retinal Bipolar Cells ,Diabetic Retinopathy ,Microscopy, Confocal ,Optical Imaging ,Retinal Pigment Epithelium ,Mice, Mutant Strains ,Retina ,Streptozocin ,Diabetes Mellitus, Experimental ,Mice, Inbred C57BL ,Ophthalmoscopy ,Disease Models, Animal ,Mice ,Random Allocation ,Retinal Diseases ,Animals ,Proteoglycans ,Tomography, Optical Coherence - Abstract
Noninvasive ocular imaging platforms are undeniably useful in identifying retinal abnormalities. The purpose of this study was to investigate a novel method for integrating information acquired from two independent imaging platforms, AF-SLO and SDOCT, in order to demonstrate retinal perturbations as a result of genetic or pharmacological manipulation. Two cohorts of mice were investigated, Nyx
- Published
- 2018
44. Development of a Cx46 targeting strategy for cancer stem cells
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Samuel A. Sprowls, James S. Hale, Brent A. Bell, Bartlomiej P Przychodzen, Masahiro Hitomi, Renliang Zhang, Artem Berezovsky, Jennifer T. Eurich, Daniel J. Silver, Tyler J. Alban, Emily Serbinowski, Paul R. Lockman, John Zhou, Erin E. Mulkearns-Hubert, Babal K. Jha, Luke A. Torre-Healy, and Justin D. Lathia
- Subjects
0303 health sciences ,Temozolomide ,Mutant ,Gap junction ,Connexin ,Biology ,3. Good health ,law.invention ,Clofazimine ,03 medical and health sciences ,0302 clinical medicine ,Cancer stem cell ,Apoptosis ,law ,030220 oncology & carcinogenesis ,medicine ,Cancer research ,Suppressor ,030304 developmental biology ,medicine.drug - Abstract
SummaryGap junction-mediated cell-cell communication enables tumor cells to synchronize the execution of complex processes. Despite the connexin family of gap junction proteins being considered tumor suppressors, we previously found that glioblastoma cancer stem cells (CSCs) express higher levels of Cx46 compared to non-stem tumor cells, and this was necessary and sufficient for CSC maintenance. To develop a Cx46 targeting strategy, we utilized point mutants to disrupt specific functions of Cx46 and found that gap junction coupling was the critical function of Cx46 for CSCs. Based on this finding, we screened a clinically relevant library of small molecules and identified clofazimine as an inhibitor of Cx46-specific cell-cell communication. Clofazimine attenuated proliferation, self-renewal, and tumor growth and synergized with temozolomide to induce apoptosis. These data suggest that combining clofazimine with standard-of-care therapies may target glioblastoma CSCs. Furthermore, these results demonstrate the importance of targeting cell-cell communication as an anti-cancer therapy.
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- 2018
- Full Text
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45. Development of a Cx46 Targeting Strategy for Cancer Stem Cells
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James S. Hale, Bartlomiej P Przychodzen, Renliang Zhang, Samuel A. Sprowls, Erin E. Mulkearns-Hubert, Babal K. Jha, Tyler J. Alban, Luke A. Torre-Healy, Brent A. Bell, Masahiro Hitomi, Paul R. Lockman, Emily Serbinowski, Artem Berezovsky, John Zhou, Daniel J. Silver, Jennifer T. Eurich, and Justin D. Lathia
- Subjects
Temozolomide ,Gap junction ,Connexin ,Biology ,law.invention ,Clofazimine ,Drug repositioning ,Cancer stem cell ,Apoptosis ,law ,Cancer research ,medicine ,Suppressor ,medicine.drug - Abstract
Gap junction-mediated cell-cell communication enables tumor cells to synchronize the execution of complex processes. Despite the connexin family of gap junction proteins being considered tumor suppressors, we previously found that glioblastoma cancer stem cells (CSCs) express higher levels of Cx46 compared to non-stem tumor cells, and this was necessary and sufficient for CSC maintenance. To develop a Cx46 targeting strategy, we utilized point mutants to disrupt specific functions of Cx46 and found that gap junction coupling was the critical function of Cx46 for CSCs. Based on this finding, we screened a clinically relevant library of small molecules and identified clofazimine as an inhibitor of Cx46-specific cell-cell communication. Clofazimine attenuated proliferation, self-renewal, and tumor growth and synergized with temozolomide to induce apoptosis. These data suggest that combining clofazimine with standard-of-care therapies may target glioblastoma CSCs. Furthermore, these results demonstrate the importance of targeting cell-cell communication as an anti-cancer therapy.
- Published
- 2018
46. A Novel Approach for Integrating AF-SLO and SDOCT Imaging Data Demonstrates the Ability to Identify Early Retinal Abnormalities in Mutant Mice and Evaluate the Effects of Genetic and Pharmacological Manipulation
- Author
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Ivy S. Samuels, Brent A. Bell, and Vera L. Bonilha
- Subjects
0301 basic medicine ,Retina ,Mutant ,Retinal ,Ocular imaging ,Biology ,Photoreceptor outer segment ,Imaging data ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,0302 clinical medicine ,medicine.anatomical_structure ,chemistry ,030221 ophthalmology & optometry ,medicine ,Neuroscience ,Nyctalopin - Abstract
Noninvasive ocular imaging platforms are undeniably useful in identifying retinal abnormalities. The purpose of this study was to investigate a novel method for integrating information acquired from two independent imaging platforms, AF-SLO and SDOCT, in order to demonstrate retinal perturbations as a result of genetic or pharmacological manipulation. Two cohorts of mice were investigated, Nyx nob and C57BL/6 J. In Nyx nob mice, SLO revealed an atypical but variable amount of autofluorescent foci (AFF); SDOCT showed altered photoreceptor outer segment architecture. Naive Nyx nob had significantly more AFF than C57BL/6 J, suggesting that Nyx nob have some predisposition for developing AFF. Interestingly, both findings were significantly ameliorated in diabetic Nyx nob mice as compared to the controls. These data were incorporated into a novel analysis plot comparing AF-SLO and SDOCT results. The integration of the qualitative changes and accompanying quantitative analysis approach described herein provide a sensitive means for detecting whether a mouse model is susceptible to degeneration before other hallmark indicators are observed.
- Published
- 2018
47. Histopathological comparison of eyes from patients with autosomal recessive retinitis pigmentosa caused by novel EYS mutations
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Craig D. Beight, Stephanie A. Hagstrom, Meghan J Marino, Brent A. Bell, Vera L. Bonilha, Mary E. Rayborn, John Chiang, Joe G. Hollyfield, Gayle J.T. Pauer, and Elias I. Traboulsi
- Subjects
medicine.medical_specialty ,Pathology ,genetic structures ,DNA Mutational Analysis ,Immunocytochemistry ,Biology ,Polymerase Chain Reaction ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,medicine ,Humans ,Eye Proteins ,Fluorescent Antibody Technique, Indirect ,Aged ,Aged, 80 and over ,Nucleic Acid Hybridization ,Retinal ,Histology ,Tissue Donors ,eye diseases ,Sensory Systems ,Pedigree ,Scanning laser ophthalmoscopy ,Ophthalmoscopy ,Ophthalmology ,medicine.anatomical_structure ,chemistry ,Mutation ,Inner nuclear layer ,Immunohistochemistry ,Female ,Histopathology ,sense organs ,Autosomal recessive retinitis pigmentosa ,Retinitis Pigmentosa ,Tomography, Optical Coherence - Abstract
To evaluate the retinal histopathology in donor eyes from patients with autosomal recessive retinitis pigmentosa (arRP) caused by EYS mutations. Eyes from a 72-year-old female (donor 1, family 1), a 91-year-old female (donor 2, family 2), and her 97-year-old sister (donor 3, family 2) were evaluated with macroscopic, scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) imaging. Age-similar normal eyes and an eye donated by donor 1’s asymptomatic mother (donor 4, family 1) were used as controls. The perifovea and peripheral retina were processed for microscopy and immunocytochemistry with markers for cone and rod photoreceptor cells. DNA analysis revealed EYS mutations c.2259 + 1G > A and c.2620C > T (p.Q874X) in family 1, and c.4350_4356del (p.I1451Pfs*3) and c.2739-?_3244 + ?del in family 2. Imaging studies revealed the presence of bone spicule pigment in arRP donor retinas. Histology of all three affected donor eyes showed very thin retinas with little evidence of stratified nuclear layers in the periphery. In contrast, the perifovea displayed a prominent inner nuclear layer. Immunocytochemistry analysis demonstrated advanced retinal degenerative changes in all eyes, with near-total absence of rod photoreceptors. In addition, we found that the perifoveal cones were more preserved in retinas from the donor with the midsize genomic rearrangement (c.4350_4356del (p.I1451Pfs*3) and c.2739-?_3244 + ?del) than in retinas from the donors with the truncating (c.2259 + 1G > A and c.2620C > T (p.Q874X) mutations. Advanced retinal degenerative changes with near-total absence of rods and preservation of some perifoveal cones are observed in arRP donor retinas with EYS mutations.
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- 2014
48. Retinal vasculature of adult zebrafish: In vivo imaging using confocal scanning laser ophthalmoscopy
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Jing Xie, Bela Anand-Apte, Joe G. Hollyfield, Charles Kaul, Alex Yuan, and Brent A. Bell
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Diagnostic Imaging ,Pathology ,medicine.medical_specialty ,Fundus Oculi ,Confocal ,Blood–retinal barrier ,Article ,Capillary Permeability ,Ophthalmoscopy ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,medicine ,Animal mortality ,Animals ,Zebrafish ,Retina ,medicine.diagnostic_test ,biology ,Retinal Vessels ,Retinal ,biology.organism_classification ,Sensory Systems ,Cell biology ,Ophthalmology ,medicine.anatomical_structure ,chemistry ,Preclinical imaging - Abstract
Over the past 3 decades the zebrafish (Danio rerio) has become an important biomedical research species. As their use continues to grow additional techniques and tools will be required to keep pace with ongoing research using this species. In this paper we describe a novel method for in vivo imaging of the retinal vasculature in adult animals using a commercially available confocal scanning laser ophthalmoscope (SLO). With this instrumentation, we demonstrate the ability to distinguish diverse vascular phenotypes in different transgenic GFP lines. In addition this technology allows repeated visualization of the vasculature in individual zebrafish over time to document vascular leakage progression and recovery induced by intraocular delivery of proteins that induce vascular permeability. SLO of the retinal vasculature was found to be highly informative, providing images of high contrast and resolution that were capable of resolving individual vascular endothelial cells. Finally, the procedures required to acquire SLO images from zebrafish are non-invasive, simple to perform and can be achieved with low animal mortality, allowing repeated imaging of individual fish.
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- 2014
49. Complement Component C4 Regulates the Development of Experimental Autoimmune Uveitis through a T Cell-Intrinsic Mechanism
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Yan Li, Brent A. Bell, Rachel R. Caspi, Feng Lin, and Lingjun Zhang
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0301 basic medicine ,lcsh:Immunologic diseases. Allergy ,T cell ,Immunology ,autoimmune uveitis ,T cells ,Priming (immunology) ,Biology ,medicine.disease_cause ,Autoimmunity ,03 medical and health sciences ,Interleukin 21 ,0302 clinical medicine ,medicine ,Immunology and Allergy ,Cytotoxic T cell ,complement ,IL-2 receptor ,Original Research ,C4 ,Innate immune system ,Acquired immune system ,animal models ,3. Good health ,030104 developmental biology ,medicine.anatomical_structure ,lcsh:RC581-607 ,030215 immunology - Abstract
In addition to its conventional roles in the innate immune system, complement has been found to directly regulate T cells in the adaptive immune system. Complement components, including C3, C5, and factor D, are important in regulating T cell responses. However, whether complement component C4 is involved in regulating T cell responses remains unclear. In this study, we used a T cell-dependent model of autoimmunity, experimental autoimmune uveitis (EAU) to address this issue. We compared disease severity in wild-type (WT) and C4 knockout (KO) mice using indirect ophthalmoscopy, scanning laser ophthalmoscopy, spectral-domain optical coherence tomography, and histopathological analysis. We also explored the underlying mechanism by examining T cell responses in ex vivo antigen-specific recall assays and in in vitro T cell priming assays using bone marrow-derived dendritic cells, splenic dendritic cells, and T cells from WT or C4 KO mice. We found that C4 KO mice develop less severe retinal inflammation than WT mice in EAU and show reduced autoreactive T cell responses and decreased retinal T cell infiltration. We also found that T cells, but not dendritic cells, from C4 KO mice have impaired function. These results demonstrate a previously unknown role of C4 in regulating T cell responses, which affects the development of T cell-mediated autoimmunity, as exemplified by EAU. Our data could shed light on the pathogenesis of autoimmune uveitis in humans.
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- 2017
50. A protective eye shield for prevention of media opacities during small animal ocular imaging
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Brent A. Bell, Joe G. Hollyfield, and Charles Kaul
- Subjects
Diagnostic Imaging ,medicine.medical_specialty ,genetic structures ,Protective shield ,Ocular imaging ,Cataract ,Article ,Rats, Sprague-Dawley ,Cellular and Molecular Neuroscience ,Radiation Protection ,Optical coherence tomography ,Anterior Eye Segment ,Ophthalmology ,Small animal ,Cornea ,Lens, Crystalline ,medicine ,Animals ,Humans ,Corneal reflex ,medicine.diagnostic_test ,business.industry ,eye diseases ,Sensory Systems ,Rats ,Scanning laser ophthalmoscopy ,Surgery ,Mice, Inbred C57BL ,Radiation Injuries, Experimental ,medicine.anatomical_structure ,Lens (anatomy) ,sense organs ,Eye Protective Devices ,business - Abstract
Optical coherence tomography (OCT), scanning laser ophthalmoscopy (SLO) and other non-invasive imaging techniques are increasingly used in eye research to document disease-related changes in rodent eyes. Corneal dehydration is a major contributor to the formation of ocular opacities that can limit the repeated application of these techniques to individual animals. General anesthesia is usually required for imaging, which is accompanied by the loss of the blink reflex. As a consequence, the tear film cannot be maintained, drying occurs and the cornea becomes dehydrated. Without supplemental hydration, structural damage to the cornea quickly follows. Soon thereafter, anterior lens opacities can also develop. Collectively these changes ultimately compromise image quality, especially for studies involving repeated use of the same animal over several weeks or months. To minimize these changes, a protective shield was designed for mice and rats that prevent ocular dehydration during anesthesia. The eye shield, along with a semi-viscous ophthalmic solution, is placed over the corneas as soon as the anesthesia immobilizes the animal. Eye shields are removed for only the brief periods required for imaging and then reapplied before the fellow eye is examined. As a result, the corneal surface of each eye is exposed only for the time required for imaging. The device and detailed methods described here minimize the corneal and lens changes associated with ocular surface desiccation. When these methods are used consistently, high quality images can be obtained repeatedly from individual animals.
- Published
- 2014
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