Academic literature on the topic 'Blood retinal barrier'
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Journal articles on the topic "Blood retinal barrier"
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Yemanyi, Felix, Kiran Bora, Alexandra K. Blomfield, Zhongxiao Wang, and Jing Chen. "Wnt Signaling in Inner Blood–Retinal Barrier Maintenance." International Journal of Molecular Sciences 22, no. 21 (November 2, 2021): 11877. http://dx.doi.org/10.3390/ijms222111877.
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The retina is a light-sensing ocular tissue that sends information to the brain to enable vision. The blood–retinal barrier (BRB) contributes to maintaining homeostasis in the retinal microenvironment by selectively regulating flux of molecules between systemic circulation and the retina. Maintaining such physiological balance is fundamental to visual function by facilitating the delivery of nutrients and oxygen and for protection from blood-borne toxins. The inner BRB (iBRB), composed mostly of inner retinal vasculature, controls substance exchange mainly via transportation processes between (paracellular) and through (transcellular) the retinal microvascular endothelium. Disruption of iBRB, characterized by retinal edema, is observed in many eye diseases and disturbs the physiological quiescence in the retina’s extracellular space, resulting in vision loss. Consequently, understanding the mechanisms of iBRB formation, maintenance, and breakdown is pivotal to discovering potential targets to restore function to compromised physiological barriers. These unraveled targets can also inform potential drug delivery strategies across the BRB and the blood–brain barrier into retinas and brain tissues, respectively. This review summarizes mechanistic insights into the development and maintenance of iBRB in health and disease, with a specific focus on the Wnt signaling pathway and its regulatory role in both paracellular and transcellular transport across the retinal vascular endothelium.
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Cunha-Vaz, José. "The Blood–Retinal Barrier in Retinal Disease." European Ophthalmic Review 03, no. 02 (2009): 105. http://dx.doi.org/10.17925/eor.2009.03.02.105.
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The blood–ocular barrier system is formed by two main barriers: the blood–aqueous barrier and the blood–retinal barrier (BRB). The BRB is particularly tight and restrictive and is a physiological barrier that regulates ion, protein and water flux into and out of the retina. The BRB consists of inner and outer components, the inner BRB being formed of tight junctions between retinal capillary endothelial cells and the outer BRB of tight junctions between retinal pigment epithelial cells. The BRB is essential to maintaining the eye as a privileged site and is essential for normal visual function. Alterations of the BRB play a crucial role in the development of retinal diseases. The two most frequent and relevant retinal diseases, diabetic retinopathy and age-related macular degeneration (AMD), are directly associated with alterations of the BRB. Diabetic retinopathy is initiated by an alteration of the inner BRB and neovascular AMD is a result of an alteration of the outer BRB. Treatment of retinal diseases must also deal with the BRB either by using its specific transport mechanisms or by circumventing it through intravitreal injections
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Cunha-Vaz, José, Rui Bernardes, and Conceição Lobo. "Blood-Retinal Barrier." European Journal of Ophthalmology 21, no. 6_suppl (November 2011): 3–9. http://dx.doi.org/10.5301/ejo.2010.6049.
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Vinores, S. A., R. McGehee, A. Lee, C. Gadegbeku, and P. A. Campochiaro. "Ultrastructural localization of blood-retinal barrier breakdown in diabetic and galactosemic rats." Journal of Histochemistry & Cytochemistry 38, no. 9 (September 1990): 1341–52. http://dx.doi.org/10.1177/38.9.2117624.
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Breakdown of the blood-retinal barrier (BRB) is an early event in diabetic and galactosemic rats, but the location and nature of the specific defect(s) are controversial. Using an electron microscopic immunocytochemical technique, the retinas of normal, diabetic, and galactosemic rats were immunostained for endogenous albumin. Normal rats showed little evidence of BRB breakdown at either the inner barrier (retinal vasculature) or the outer barrier (retinal pigment epithelium) (RPE). In diabetic and galactosemic rats, as was true in human diabetics, BRB breakdown occurred predominantly at the inner BRB, but in some cases at the outer barrier as well. Treatment with the aldose reductase inhibitor sorbinil largely prevented BRB failure in galactosemic rats. In the inner retina of diabetic and galactosemic rats, albumin was frequently demonstrated on the abluminal side of the retinal capillary endothelium (RCE) in intercellular spaces, basal laminae, pericytes, ganglion cells, astrocytes, and the perinuclear cytoplasm of cells in the inner nuclear layer. Albumin did not appear to cross RCE cell junctions; however, it was occasionally seen in RCE cytoplasm of galactosemic rats. In the outer retina, albumin was frequently detected in the subretinal space, in the intercellular space between photoreceptors, and in the perinuclear cytoplasm of photoreceptor cells, but was only infrequently found in the RPE cells constituting the barrier. Albumin derived from the choroidal vasculature did not appear to cross the tight junctions of the RPE. These findings suggest that specific sites of BRB compromise are infrequent but that once albumin has crossed the RCE or RPE it freely permeates the retinal tissue by filling intercellular spaces and permeating the membranes of cells not implicated in BRB formation. The diffuse cytoplasmic staining of some RCE and RPE cells suggests that the predominant means of BRB breakdown in diabetes and galactosemia involves increased focal permeability of the surface membranes of the RCE and RPE cells rather than defective tight junctions or vesicular transport.
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Naylor, Aisling, Alan Hopkins, Natalie Hudson, and Matthew Campbell. "Tight Junctions of the Outer Blood Retina Barrier." International Journal of Molecular Sciences 21, no. 1 (December 27, 2019): 211. http://dx.doi.org/10.3390/ijms21010211.
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The outer blood retina barrier (oBRB) formed by the retinal pigment epithelium (RPE) is critical for maintaining retinal homeostasis. Critical to this modified neuro-epithelial barrier is the presence of the tight junction structure that is formed at the apical periphery of contacting cells. This tight junction complex mediates size-selective passive diffusion of solutes to and from the outer segments of the retina. Unlike other epithelial cells, the apical surface of the RPE is in direct contact with neural tissue and it is centrally involved in the daily phagocytosis of the effete tips of photoreceptor cells. While much is known about the intracellular trafficking of material within the RPE, less is known about the role of the tight junction complexes in health and diseased states. Here, we provide a succinct overview of the molecular composition of the RPE tight junction complex in addition to highlighting some of the most common retinopathies that involve a dysregulation of RPE integrity
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MENDES-JORGE, L., D. RAMOS, M. LUPPO, A. VALENçA, J. CATITA, CM DUARTE, M. SIMõES, et al. "Blood-retinal barrier serum ferritin transport in mouse retina." Acta Ophthalmologica 90 (August 6, 2012): 0. http://dx.doi.org/10.1111/j.1755-3768.2012.t029.x.
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Silva, Rufino M., J. R. Faria de Abreu, and J. G. Cunha-Vaz. "Blood-retina barrier in acute retinal branch vein occlusion." Graefe's Archive for Clinical and Experimental Ophthalmology 233, no. 11 (November 1995): 721–26. http://dx.doi.org/10.1007/bf00164677.
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Yanagi, Yasuo. "Role of Peoxisome Proliferator Activator Receptor on Blood Retinal Barrier Breakdown." PPAR Research 2008 (2008): 1–4. http://dx.doi.org/10.1155/2008/679237.
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The retinal vessels have two barriers: the retinal pigment epithelium and the retinal vascular endothelium. Each barrier exhibits increased permeability under various pathological conditions. This condition is referred to as blood retinal barrier (BRB) breakdown. Clinically, the most frequently encountered condition causing BRB breakdown is diabetic retinopathy. In recent studies, inflammation has been linked to BRB breakdown and vascular leakage in diabetic retinopathy. Biological support for the role of inflammation in early diabetes is the adhesion of leukocytes to the retinal vasculature (leukostasis) observed in diabetic retinopathy. is a member of a ligand-activated nuclear receptor superfamily and plays a critical role in a variety of biological processes, including adipogenesis, glucose metabolism, angiogenesis, and inflammation. There is now strong experimental evidence to support the theory that inhibits diabetes-induced retinal leukostasis and leakage, playing an important role in the pathogenesis of diabetic retinopathy. Therapeutic targeting of may be beneficial to diabetic retinopathy.
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Kubo, Yoshiyuki, Shinichi Akanuma, and Ken-ichi Hosoya. "The blood-retinal barrier transporters in retinal drug delivery." Drug Delivery System 27, no. 5 (2012): 361–69. http://dx.doi.org/10.2745/dds.27.361.
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D, Shah. "Resolution of Bilateral Exudative Retinal Detachment Secondary to Renal Hypertension with Systemic Management." Open Access Journal of Ophthalmology 7, no. 2 (July 1, 2022): 1–2. http://dx.doi.org/10.23880/oajo-16000252.
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Exudative retinal detachment (ERD) is an ocular condition, which develops from pathological conditions that disrupt the integrity of blood-retinal barrier due to fluid accumulation in sub retinal space or under neurosensory retina. Exudative retinal detachment is typically associated with inflammatory, infectious, neoplastic, and vascular pathological conditions. We report the management of bilateral exudative retinal detachment in young patients secondary to Renal Hypertension.
Dissertations / Theses on the topic "Blood retinal barrier"
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Bamforth, Simon David. "The effects of inflammatory agents on the blood-retinal barrier." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244263.
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Tretiach, Marina Louise. "Bovine Models of Human Retinal Disease: Effect of Perivascular Cells on Retinal Endothelial Cell Permeability." Thesis, The University of Sydney, 2005. http://hdl.handle.net/2123/1153.
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Background: Diabetic vascular complications affect both the macro- and microvasculature. Microvascular pathology in diabetes may be mediated by biochemical factors that precipitate cellular changes at both the gene and protein levels. In the diabetic retina, vascular pathology is found mainly in microvessels, including the retinal precapillary arterioles, capillaries and venules. Macular oedema secondary to breakdown of the inner blood-retinal barrier is the most common cause of vision impairment in diabetic retinopathy. Müller cells play a critical role in the trophic support of retinal neurons and blood vessels. In chronic diabetes, Müller cells are increasingly unable to maintain their supportive functions and may themselves undergo changes that exacerbate the retinal pathology. The consequences of early diabetic changes in retinal cells are primarily considered in this thesis. Aims: This thesis aims to investigate the effect of perivascular cells (Müller cells, RPE, pericytes) on retinal endothelial cell permeability using an established in vitro model. Methods: Immunohistochemistry, cell morphology and cell growth patterns were used to characterise primary bovine retinal cells (Müller cells, RPE, pericytes and endothelial cells). An in vitro model of the blood-retinal barrier was refined by coculturing retinal endothelial cells with perivascular cells (Müller cells or pericytes) on opposite sides of a permeable Transwell filter. The integrity of the barrier formed by endothelial cells was assessed by transendothelial electrical resistance (TEER) measurements. Functional characteristics of endothelial cells were compared with ultrastructural morphology to determine if different cell types have barrier-enhancing effects on endothelial cell cultures. Once the co-culture model was established, retinal endothelial cells and Müller cells were exposed to different environmental conditions (20% oxygen, normoxia; 1% oxygen, hypoxia) to examine the effect of perivascular cells on endothelial cell permeability under reduced oxygen conditions. Barrier integrity was assessed by TEER measurements and permeability was measured by passive diffusion of radiolabelled tracers from the luminal to the abluminal side of the endothelial cell barrier. A further study investigated the mechanism of laser therapy on re-establishment of retinal endothelial cell barrier integrity. Müller cells and RPE, that comprise the scar formed after laser photocoagulation, and control cells (Müller cells and pericytes, RPE cells and ECV304, an epithelial cell line) were grown in long-term culture and treated with blue-green argon laser. Lasered cells were placed underneath confluent retinal endothelial cells growing on a permeable filter, providing conditioned medium to the basal surface of endothelial cells. The effect of conditioned medium on endothelial cell permeability was determined, as above. Results: Co-cultures of retinal endothelial cells and Müller cells on opposite sides of a permeable filter showed that Müller cells can enhance the integrity of the endothelial cell barrier, most likely through soluble factors. Low basal resistances generated by endothelial cells from different retinal isolations may be the result of erratic growth characteristics (determined by ultrastructural studies) or the selection of vessel fragments without true â barrier characteristicsâ in the isolation step. When Müller cells were co-cultured in close apposition to endothelial cells under normoxic conditions, the barrier integrity was enhanced and permeability was reduced. Under hypoxic conditions, Müller cells had a detrimental effect on the integrity of the endothelial cell barrier and permeability was increased in closely apposed cells. Conditioned medium from long-term cultured Müller cells and RPE that typically comprise the scar formed after lasering, enhanced TEER and reduced permeability of cultured endothelial cells. Conclusions: These studies confirm that bovine tissues can be used as a suitable model to investigate the role of perivascular cells on the permeability of retinal endothelial cells. The dual effect of Müller cells on the retinal endothelial cell barrier under different environmental conditions, underscores the critical role of Müller cells in regulating the blood-retinal barrier in health and disease. These studies also raise the possibility that soluble factor(s) secreted by Müller cells and RPE subsequent to laser treatment reduce the permeability of retinal vascular endothelium. Future studies to identify these factor(s) may have implications for the clinical treatment of macular oedema secondary to diseases including diabetic retinopathy.
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Tretiach, Marina Louise. "Bovine Models of Human Retinal Disease: Effect of Perivascular Cells on Retinal Endothelial Cell Permeability." University of Sydney, 2005. http://hdl.handle.net/2123/1153.
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Doctor of Philosophy (Medicine)Background: Diabetic vascular complications affect both the macro- and microvasculature. Microvascular pathology in diabetes may be mediated by biochemical factors that precipitate cellular changes at both the gene and protein levels. In the diabetic retina, vascular pathology is found mainly in microvessels, including the retinal precapillary arterioles, capillaries and venules. Macular oedema secondary to breakdown of the inner blood-retinal barrier is the most common cause of vision impairment in diabetic retinopathy. Müller cells play a critical role in the trophic support of retinal neurons and blood vessels. In chronic diabetes, Müller cells are increasingly unable to maintain their supportive functions and may themselves undergo changes that exacerbate the retinal pathology. The consequences of early diabetic changes in retinal cells are primarily considered in this thesis. Aims: This thesis aims to investigate the effect of perivascular cells (Müller cells, RPE, pericytes) on retinal endothelial cell permeability using an established in vitro model. Methods: Immunohistochemistry, cell morphology and cell growth patterns were used to characterise primary bovine retinal cells (Müller cells, RPE, pericytes and endothelial cells). An in vitro model of the blood-retinal barrier was refined by coculturing retinal endothelial cells with perivascular cells (Müller cells or pericytes) on opposite sides of a permeable Transwell filter. The integrity of the barrier formed by endothelial cells was assessed by transendothelial electrical resistance (TEER) measurements. Functional characteristics of endothelial cells were compared with ultrastructural morphology to determine if different cell types have barrier-enhancing effects on endothelial cell cultures. Once the co-culture model was established, retinal endothelial cells and Müller cells were exposed to different environmental conditions (20% oxygen, normoxia; 1% oxygen, hypoxia) to examine the effect of perivascular cells on endothelial cell permeability under reduced oxygen conditions. Barrier integrity was assessed by TEER measurements and permeability was measured by passive diffusion of radiolabelled tracers from the luminal to the abluminal side of the endothelial cell barrier. A further study investigated the mechanism of laser therapy on re-establishment of retinal endothelial cell barrier integrity. Müller cells and RPE, that comprise the scar formed after laser photocoagulation, and control cells (Müller cells and pericytes, RPE cells and ECV304, an epithelial cell line) were grown in long-term culture and treated with blue-green argon laser. Lasered cells were placed underneath confluent retinal endothelial cells growing on a permeable filter, providing conditioned medium to the basal surface of endothelial cells. The effect of conditioned medium on endothelial cell permeability was determined, as above. Results: Co-cultures of retinal endothelial cells and Müller cells on opposite sides of a permeable filter showed that Müller cells can enhance the integrity of the endothelial cell barrier, most likely through soluble factors. Low basal resistances generated by endothelial cells from different retinal isolations may be the result of erratic growth characteristics (determined by ultrastructural studies) or the selection of vessel fragments without true âbarrier characteristicsâ in the isolation step. When Müller cells were co-cultured in close apposition to endothelial cells under normoxic conditions, the barrier integrity was enhanced and permeability was reduced. Under hypoxic conditions, Müller cells had a detrimental effect on the integrity of the endothelial cell barrier and permeability was increased in closely apposed cells. Conditioned medium from long-term cultured Müller cells and RPE that typically comprise the scar formed after lasering, enhanced TEER and reduced permeability of cultured endothelial cells. Conclusions: These studies confirm that bovine tissues can be used as a suitable model to investigate the role of perivascular cells on the permeability of retinal endothelial cells. The dual effect of Müller cells on the retinal endothelial cell barrier under different environmental conditions, underscores the critical role of Müller cells in regulating the blood-retinal barrier in health and disease. These studies also raise the possibility that soluble factor(s) secreted by Müller cells and RPE subsequent to laser treatment reduce the permeability of retinal vascular endothelium. Future studies to identify these factor(s) may have implications for the clinical treatment of macular oedema secondary to diseases including diabetic retinopathy.
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Ojima, Tomonari. "EphrinA1 inhibits vascular endothelial growth factor-induced intracellular signaling and suppresses retinal neovascularization and blood-retinal barrier breakdown." Kyoto University, 2006. http://hdl.handle.net/2433/143818.
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Moyer, Andrea Leigh. "Mechanisms of blood retina barrier permeability during Bacillus cereus endophthalmitis." Oklahoma City : [s.n.], 2008.
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Melhorn, Mark Ivan [Verfasser]. "A model to examine the outer blood-retinal barrier in rodents / Mark Ivan Melhorn." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2012. http://d-nb.info/102282631X/34.
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Lipski, Deborah. "Study of the mechanisms of local auto-antigen presentation and inner blood-retinal barrier breakdown during non-infectious uveitis." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/262873.
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Le développement de l’uvéite auto-immune expérimentale (UAE) se fait en plusieurs étapes, commençant par l’activation en périphérie de lymphocytes T auxiliaires auto-réactifs spécifiques d’antigènes rétiniens, leur migration vers l’œil, où ils sont réactivés de façon antigène-spécifique et CMH II (complexe majeur d’histocompatibilité de classe II)-dépendante pour enfin induire la rupture de la barrière hémato-rétinienne (BHR), permettant le recrutement aspécifique de cellules inflammatoires responsables des dommages tissulaires. Tous ces processus représentent des cibles potentielles pour des thérapies biologiques ciblées. Dans cette perspective, notre travail a pour but d’approfondir la compréhension des mécanismes impliqués dans le recrutement de cellules inflammatoires, la présentation locale d’antigènes rétiniens et la rupture de la BHR interne lors de l’induction de l’UAE par transfert adoptif.L’expression de molécules d’adhésion par les cellules de la BHR joue un rôle central dans l’infiltration de cellules inflammatoires dans l’œil. Dans ce contexte, nous avons d’abord montré qu’à l’instar de ce que nous avions démontré pour VCAM-1, l’expression d’ICAM-1 est fortement induite dans la rétine durant l’UAE, avec une intensité et une extension corrélées à la sévérité de la maladie. Cependant, alors que VCAM-1 est uniquement inductible, une expression basale d’ICAM-1 est détectée dans la rétine naïve. Le ligand d’ICAM-1, LFA-1, est exprimé de façon ubiquitaire par les cellules immunes circulantes, contrairement au ligand de VCAM-1, VLA-4, qui n’est exprimé que par une minorité de cellules. Par ailleurs, nous avons observé une répartition tissulaire différente de ces deux molécules d’adhésion dans la rétine. En effet, si ICAM-1 prédomine dans l’épithélium pigmentaire rétinien, VCAM-1 est fortement exprimé au niveau des lésions de vasculite, à la fois sur les cellules endothéliales et gliales péri- vasculaires. Ces 2 sites correspondent respectivement à la BHR externe et interne. Ces différences majeures en termes de distribution rétinienne des molécules d’adhésion pourraient refléter des voies d’entrée distinctes pour les cellules inflammatoires lors de leur pénétration dans l’œil.Comme les lymphocytes T auto-réactifs n’induisent la maladie qu’après avoir localement reconnu leur antigène, nous nous sommes ensuite intéressés à identifier les cellules présentatrices d’antigène (CPA) potentielles exprimant du CMH II dans la rétine lors de l’UAE. Nous avons tout d’abord observé une forte induction de l’expression de molécules du CMH II dans la rétine lors de l’inflammation intraoculaire, corrélée avec la sévérité de la maladie. Celle-ci est associée avec l’induction de l’expression de molécules de co-stimulation, particulièrement sur les cellules exprimant fortement le CMH II. L’expression la plus forte de CMH II se retrouve dans la rétine interne, au niveau des vaisseaux enflammés et s’étend vers les couches externes de la rétine et l’espace sous-rétinien dans les uvéites sévères. Nous avons identifié 3 populations de CPA potentielles exprimant le CMH II dans la rétine :des cellules CD45-CD11b- non-hématopoïétiques exprimant faiblement le CMH II et des cellules CD45+CD11b+ hématopoïétiques exprimant plus fortement le CMH II, pouvant être subdivisées en cellules Ly6C+ et Ly6C-. L’analyse bio-informatique à l’aveugle du transcriptome de ces 3 populations mène à une ségrégation claire des échantillons, avec un enrichissement en marqueurs de macrophages et de microglie dans les cellules Ly6C+ et Ly6C-, respectivement. Cependant, l’expression de Ly6C ne permet pas une ségrégation absolue entre macrophages infiltrants et microglie résidente. L’analyse fonctionnelle à l’aide de DAVID (Database for Annotation, Visualization and Integrated Discovery) révèle que les 2 populations de cellules hématopoïétiques sont plus compétentes dans la présentation d’antigène associée au CMH II et l’activation des lymphocytes T que les cellules non-hématopoïétiques.Paradoxalement, nos données n’ont pas mis en évidence d’expression de CMH II par les principales cellules de la BHR que sont les cellules endothéliales et les cellules de l’épithélium pigmentaire rétinien. Cependant, il est bien établi que les cellules endothéliales rétiniennes subissent un changement majeur de phénotype lors du développement d’une UAE. Afin d’investiguer de façon globale les mécanismes sous-jacents à la rupture de la BHR interne, nous avons étudié la régulation de l’expression génique des cellules endothéliales rétiniennes lors de l’uvéite non-infectieuse. En accord avec les données de nos travaux précédents, l’analyse du transcriptome des cellules endothéliales rétiniennes n’a pas mis en évidence d’expression de CMH II lors de l’UAE. En revanche, cette approche nous a permis d’identifier 65 gènes modulés dans les cellules endothéliales rétiniennes lors du développement d’une UAE, confirmant non seulement l’implication de certaines molécules dont le rôle pathogénique est déjà connu, mais procurant également une liste de nouveaux gènes candidats et de voies fonctionnelles potentiellement associées à la rupture de la BHR lors d’une uvéite non- infectieuse.Doctorat en Sciences médicales (Médecine)
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Rosales, Mariana Aparecida Brunini 1983. "O estresse nitrosativo na patogênese da retinopatia diabética = implicações na barreira hemato-retiniana externa e possíveis alvos terapêuticos = Nitrosative stress in the pathogenesis of diabetic retinopathy: implications in the outer blood retinal barrier and possible therapeutics targets." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309781.
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Orientadores: Jacqueline Mendonça Lópes de Faria, José Butori Lopes de FariaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: A patogênese da retinopatia diabética (RD) está associada ao estresse nitrosativo. Alterações na barreira hemato-retiniana (BHR) externa, formada pelas células do epitélio pigmentar da retina (EPR), estão associadas às fases precoces da RD e podem acarretar no desequilíbrio da manutenção dos fotorreceptores e consequentemente promoverem mudanças nas células neuronais da retina. O estresse nitrosativo como conseqüência do aumento da produção de óxido nítrico (NO¿) produzido pela super expressão da óxido nítrico sintetase induzida (iNOS) esteve presente em todas as camadas da retina, inclusive no EPR em condições de RD experimental in vivo precoce ou na linhagem celular humana do EPR (ARPE-19) expostas à alta concentração de glicose. O tratamento com agentes químicos como a S-nitrosoglutationa (GSNO), ou naturais (cacau enriquecido com polifenol) atuaram em diferentes vias de inibição da iNOS, prevenindo o estresse nitrosativo. Para o estudo in vivo com o colírio de GSNO (artigo I) foram utilizados animais espontaneamente hipertensos (SHR) com 4 semanas de idade. O diabetes (DM) foi induzido por STZ. Após a confirmação do DM (48 horas), os animais foram divididos em 6 grupos: controles (CTs) veículo; GSNO 900nm e GSNO 10?m ou DMs veículo; GSNO 900nm e GSNO 10?m. O efeito do tratamento com colírio de GSNO foi dependente da presença ou ausência da condição do DM. Nos animais CT, o GSNO atuou como um agente nitrosativo e nos animais DM preveniu o aumento da expressão da iNOS, preservando a retina funcional. Os estudos in vitro, demonstraram que o efeito do GSNO foi deletério ou protetor dependente da concentração de glicose. Nas células ARPE-19 expostas a condições normais de glicose, o tratamento promoveu um aumento na produção de NO¿ sem aumentar a expressão de iNOS e nas células sob alta glicose induziu uma modificação pós-translacional de proteína, a S-glutationilação da iNOS prevenindo o estresse nitrosativo. No estudo do cacau (artigo II), foi avaliado in vitro (ARPE-19 exposta a alta concentração de glicose) o seu efeito protetor dependente da concentração de polifenóis. Para isso foram testadas duas formulações de cacau que diferiram somente na concentração de polifenol: 0,5% para o cacau com baixo teor de polifenol e 60,5% para o cacau com alto teor de polifenol. A epicatequina (EC), encontrada na concentração de 12% no cacau com alto teor de polifenol foi tão eficaz quanto o próprio e esteve envolvida no controle da expressão da iNOS através da estimulação do receptor ?-opióide (DOR) diminuindo os níveis de TNF-?. A modulação da iNOS, preveniu a S-nitrosilação da caveolina-1 (CAV-1) e diminuição da expressão das junções intercelulares claudina-1 e ocludina através da prevenção da interação CAV-1?junções. Em ambos os estudos, o alvo terapêutico foi a iNOS em duas diferentes modalidades: modificação pós-translacional de proteína e modulação do TNF-? via DOR no EPR em modelos experimentais de RD. Os tratamentos apresentados neste trabalho demonstraram a iNOS como alvo terapêutico e mostraram-se eficaz em conter danos funcionais e morfológicos promovidas pela situação de mimetismo do DM no EPR demonstrando o importante papel da iNOS no desenvolvimento da RD
Abstract: The pathogenesis of diabetic retinopathy (DR) is associated with nitrosative stress. Changes in outer blood-retinal barrier (BRB), formed by retinal pigment epithelium cells (RPE) are associated in the early stages of DR and can cause imbalance in the maintenance of photoreceptors and thereby cause changes on retinal neuronal cells. The nitrosative stress as a result of increased production of nitric oxide (NO) produced by overexpression of nitric oxide synthase (iNOS) was present in all layers of the retina and mainly in RPE cells in early in vivo experimental DR or in human RPE cell line (ARPE-19) exposed to high glucose condition. Therapy with chemical agents such as S-Nitrosoglutathione (GSNO) or natural compounds (enriched cocoa polyphenol) acted in different pathways of iNOS inhibition, preventing nitrosative stress. For the in vivo study with GSNO eye drops (article I), it were used spontaneously hypertensive rats (SHR) rats with 4 week old. Diabetes (DM) was induced by streptozotocin (STZ). After DM confirmation (48 hours), the animals were divided into 6 groups: controls (CTs) vehicle; GSNO 900nm and GSNO 10?m or DMs vehicle; GSNO 900nm e GSNO 10?m. The effects of treatments were dependent on glucose concentration. In CT animals, GSNO acted as a nitrosative agent and in DM rats prevented iNOS overexpression, preserving the retina function. In vitro study showed that GSNO protective or deleterious effects were dependent on the glucose concentration. In ARPE-19 cells exposed to normal glucose, the treatment promoted an increase of NO¿ production without increase iNOS expression and in cells under high glucose (HG) condition induced post-translational protein modification, S-glutationylation of iNOS, preventing nitrosative stress. In the study with cocoa (article II), it was evaluated its protective effect dependent on concentration of polyphenols in ARPE-19 cells under HG condition. For this study, the composition of cocoa was the same in both preparations with the only difference in the amounts of polyphenol, 0.5% for low polyphenol cocoa (LPC) and 60.5% for high polyphenol cocoa (HPC). Epicatechin (EC), found in 12% of HPC was similarly protective compare to HPC and it was involved in controlling iNOS expression by stimulation of the delta opioid receptor decreasing TNF- ? levels. The modulation of iNOS prevented S-nitrosylation of caveolin-1 (CAV-1) and decreased expression of claudin-1 and occluding tight junctions by preventing CAV-1/junctions interactions. The treatments presented here showed iNOS as a therapeutic target containing functional and morphological changes promoted by DM milieu in RPE showing the important role of iNOS in the development of DR
Doutorado
Clinica Medica
Doutora em Clínica Médica
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Valença, Andreia Barbosa. "Analysis of TIM2 deficiency in the mouse retina." Doctoral thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2019. http://hdl.handle.net/10400.5/18022.
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Tese de Doutoramento em Ciências Veterinárias, na especialidade de Ciências Biológicas e BiomédicasCareful control of iron availability in the retina is central to maintenance of iron homeostasis, as its imbalance is associated with oxidative stress and progress of several retinopathies, such as diabetic retinopathy. Ferritin, known for its role in iron storage and detoxification, has also been proposed as an iron-transporter and can be regarded as a potential deliverer of a considerable large amount of iron to the retina compared to transferrin, the classical ironcarrier protein. Ferritin can bind to scavenger receptor class A member 5 (Scara5) and T-cell immunoglobulin and mucin-domain 2 (TIM2) receptors and is likely endocytosed. In this study, the presence of TIM2, which remained unknown in the retina, was investigated. Although no human ortholog for mouse TIM2 has been identified, human TIM1 and mouse TIM2 have similar functions. Our results revealed for the first time the presence of TIM2 receptors in the mouse retina, mainly expressed in Müller cells, unveiling new aspects of retinal iron metabolism regarding the putative role of TIM2 in this tissue. A knockout mouse for this membrane receptor was generated in order to better understand TIM2 functions in the retina. TIM2 deficiency affected retinal iron metabolism. Iron-loaded ferritin accumulation, probably due to increased ferritin uptake mediated by Scara5, and increased iron uptake by transferrin receptor 1 (TfR1)- transferrin binding led to retinal iron overload. Consequently, increased vascular permeability and blood-retinal barrier (BRB) breakdown were observed, inducing edema of the central retina. Paracellular and transcellular transports were impaired with tight junction integrity loss and increased caveolae number. Two mechanisms seem to be involved in this process: association of iron and ferritin overload with vascular endothelial growth factor (VEGF) overexpression and oxidative stress triggered by reactive oxygen species (ROS) overproduction generated by retinal iron overload. Altogether, these results point to TIM2 as a new key player in iron homeostasis in the mouse retina, possibly modulating cellular iron levels, and a potential target for the treatment of diabetic macular edema.
RESUMO - Análise da deficiência de TIM2 na retina de murganho - A retina necessita especificamente de ferro, devido a este ser um co-factor essencial da enzima guanilato ciclase que assegura a síntese de monofosfato de guanosina cíclico, segundo mensageiro na cascata de fototransdução. Para além disso, a retina é particularmente dependente de ferro devido à contínua necessidade de síntese de membranas, para suprir a constante renovação dos segmentos externos dos fotorrecetores, que requer como co-factor este elemento. Porém, o desequilíbrio da homeostasia do ferro está associado ao dano oxidativo e ao desenvolvimento de várias situações de retinopatia, como por exemplo a retinopatia diabética. A retina é particularmente propensa a stress oxidativo e o excesso de ferro exacerba potencialmente esta situação, devido à participação do ferro na reação de Fenton, que gera a superprodução de espécies reativas de oxigénio que, por sua vez, desencadeiam stress oxidativo. Por conseguinte, a manutenção da homeostasia do ferro é crucial neste tecido. Contudo, mecanismos de regulação do ferro na retina ainda não são completamente conhecidos. A retina obtém ferro a partir da circulação sanguínea. No entanto, a barreira hemato-retiana isola a retina da circulação sanguínea, protegendo-a de potenciais estímulos nocivos. Assim, são necessários mecanismos específicos e rigorosamente regulados de absorção de ferro para atravessar esta barreira e importar a quantidade de ferro estritamente essencial para o normal funcionamento da retina. Classicamente, a transferrina foi estabelecida como a proteína transportadora de ferro na retina, sendo aceite que a transferrina sérica se liga ao seu recetor de membrana, recetor da transferrina 1, na superfície das células endoteliais e do epitélio pigmentar da retina. Após a endocitose deste complexo, o ferro é libertado no parênquima retiniano. Mais recentemente, a ferritina, considerada classicamente como uma proteína de armazenamento de ferro e destoxificação, foi também proposta como uma proteína transportadora deste elemento. A vantagem da ferritina sérica em relação à transferrina no transporte de ferro prende-se na capacidade da ferritina de incorporar ~ 4,500 átomos de ferro, ao passo que a transferrina apenas transporta 2 átomos de ferro, constituindo, assim, a ferritina uma fonte muito eficiente de ferro para os tecidos. A molécula da ferritina é composta por 24 subunidades de dois tipos: cadeia leve (L) e cadeia pesada (H) que se unem aos recetores Scara5 (scavenger receptor class A member 5) e TIM2 (T-cell immunoglobulin and mucin-domain 2), respetivamente. O nosso grupo identificou pela primeira vez a presença de recetores Scara5 na retina humana e do murganho. No entanto, até à data, a presença de recetores TIM2 na retina não foi reportada na bibliografia. O TIM2, uma proteína transmembranar do tipo 1, é um membro da família de genes portadores dos domínios mucina e imunoglobulina de células T e, para além de ser um recetor para a ferritina-H, está envolvido na regulação da resposta imunitária...
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Chapy, Hélène. "Identification fonctionnelle et moléculaire d'un transporteur de psychotropes et substances d'abus." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015PA05P603.
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Le système nerveux central est un organe privilégié et protégé, notamment grâce à l’existence des barrières histologiques entre le sang et les tissus nerveux. La barrière-hémato encéphalique (BHE) et la barrière hémato-rétinienne (BHR) séparent respectivement le parenchyme cérébral et la rétine des composés contenus dans l’espace vasculaire, grâce à l’expression de jonctions serrées et de transporteurs membranaires permettant une régulation spécifique des échanges entre le sang et le parenchyme nerveux. Ce travail a porté sur l’étude d’un nouveau transporteur de cations organiques mis en évidence fonctionnellement à la BHE de la souris. Ce transporteur appartenant très probablement à la superfamille des solute carrier (SLC), fonctionne comme un antiport proton. Actuellement, sa présence ne peut être démontrée que de façon fonctionnelle car son identité moléculaire est encore inconnue. Cet antiport proton constitue un nouvel acteur de la perméabilité cérébrale et ouvre une nouvelle voie d’accès au cerveau. Nous nous sommes tout d’abord attachés à approfondir les connaissances fonctionnelles de ce transporteur en étudiant de nouveaux substrats et tissus d’expression. Le transport cérébral de psychotropes a été étudié in vivo par la technique de perfusion carotidienne in situ chez la souris et in vitro grâce à une lignée de cellules endothéliales cérébrales humaines immortalisées (hCMEC/D3). Nous avons démontré que la haute perméabilité cérébrale de la cocaïne fait intervenir à la fois une diffusion passive et surtout une diffusion médiée par un antiport proton. La vitesse d’entrée des substances d’abus dans le cerveau est associée à un plus fort risque d’addiction et fait de ce transporteur un nouvel acteur critique de la régulation du passage cérébral. En effet, d’autres substances comme la nicotine et certaines amphétamines comme le MDPV et l'ecstasy sont également des substrats de cet antiport. Ce transporteur apparaît comme une cible pharmacologique potentielle dans la prise en charge de toxicomanies. Malgré la diversité chimique et pharmacologique d’interactions des composés avec cet antiport, les concentrations nécessaires pour l’inhiber dépassent celles retrouvées dans le sang. Pour aider l’identification d’inhibiteurs sélectifs et efficaces nous avons développé un modèle pharmacophorique d’inhibiteurs du transporteur à partir de données générées in vitro et de l’approche FLAPpharm. Ce modèle semble prédictif de nouveaux composés pouvant constituer de meilleurs inhibiteurs de ce transporteur. L’étude des échanges in vivo au niveau du tissu nerveux nous a menés à étudier l’impact de transporteurs ABC et de l’antiport-proton au niveau cérébral et rétinien à l’aide de substances spécifiques ou de substrats mixtes comme le vérapamil. L’antiport proton est fonctionnel au niveau de la BHR et transporte notamment la clonidine, le DPH et le vérapamil. Cependant, dans le cas d’un substrat mixte P-gp et SLC (ex : vérapamil), ce transport d’influx n’est visible à la BHE que lorsque la P-gp est neutralisée. Au contraire, à la BHR l’influx lié à cet SLC est visible naturellement. L’impact de la P-gp à la BHR étant 6.3-fois plus faible ce processus est probablement moins masqué. Cette étude illustre la difficulté actuelle de prédire l’impact fonctionnel d’un transporteur pour des substrats multi-spécifiques et l’existence d’une priorisation du transport. Enfin, nous avons essayé d’identifier l’antiport proton au niveau moléculaire par une méthode de photo-activation à l’aide d’un composé adapté. Cette méthode s’est avérée efficace pour fixer une molécule sur le transporteur, permettant par la suite de l’isoler plus facilement. En conclusion, ce travail a permis de mettre en évidence l’importance de l’antiport proton dans la distribution cérébrale de psychotropes et d’ouvrir de nouvelles perspectives dans l’addiction et la compréhension du transport de substrats multi-spécifiquesThe central nervous system is a privilege organ protected by histological barriers between the blood and the nervous tissue. The blood-brain barrier (BBB) and the blood-retinal barrier (BRB) separate cerebral parenchyma and retina from the circulating blood and both express tight junctions and membrane transporters, allowing a precise regulation of the exchanges between the blood and nervous tissues. We studied a new cationic transporter functionally evidenced at the mouse BBB. This molecularly unknown transporter belong to the solute carrier super family (SLC) and is a proton antiporter. It could constitute a new actor in the cerebral permeability and may be a new brain access pathway. First, we worked on the functional identification studying new substrates and new localization. Psychotropic brain transport was studied in vivo by brain in situ perfusion on mouse and in vitro with human immortalized endothelial cells (hCMEC/D3). We showed that cocaine brain entry depends on passive diffusion but also mainly on a proton antiporter. Brain entry rate of drugs of abuse is associated with modulation of addiction liability, making this transporter a new component of brain entry of cocaine, and also nicotine and some amphetamines such as ecstasy and MDPV. This proton antiporter appears to be a new potential target in addiction. Various chemical entities interact with this transporter; however concentrations used to inhibit the transporter are much higher than the one possibly found in the blood. In order to help find or design new selective and potent inhibitors, we developed a pharmacophore model of the proton antiporter inhibitors using in vitro data and the FLAPpharm approach. The model predicts well new possible inhibitors of this transporter. We also studied the impact of the ABC transporters and the proton antiporter at the BBB and the BRB using specific or multi-specific substrates such as verapamil. The proton antiporter is functionally expressed at the BRB and transports clonidine, DPH and verapamil. However, for the multi-specific (P-gp and SLC) compound verapamil, influx transport by the proton antiporter is visible at the BBB only when P-gp efflux is neutralized. On the contrary, at the BRB, the proton antiporter influx is always visible. This is certainly due to the lower impact (by 6.3 fold) of P-gp at the BRB compared to the BBB. These results show the difficulty to predict the functional impact of a transporter for multi-specific compounds and a probable transport prioritization. Finally we worked on the molecular identification of the proton antiporter using a photolabeling method. This work evidenced the importance of the proton antiporter in the brain distribution of psychotropic and drugs of abuse and opened toward new perspectives in addiction and transport comprehension
Books on the topic "Blood retinal barrier"
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The blood-brain and other neural barriers: Reviews and protocols. New York, N.Y: Humana Press, 2011.
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Biology and regulation of blood-tissue barriers. New York, N.Y: Springer Science+Business Media, 2012.
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Cheng, C. Yan. Biology and regulation of blood-tissue barriers. New York, N.Y: Springer Science+Business Media, 2012.
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Ocular drug delivery systems: Barriers and application of nanoparticulate systems. Boca Raton: CRC Press/Taylor & Francis, 2013.
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Nag, Sukriti. Blood-Brain and Other Neural Barriers: Reviews and Protocols. Humana Press, 2016.
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Cunha-Vaz, José. Blood-Retinal Barriers. Springer London, Limited, 2013.
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Cunha-Vaz, Jose G. The Blood-Retinal Barriers. Springer, 2013.
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Cunha-Vaz, José. The Blood-Retinal Barriers. Springer, 2014.
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Thassu, Deepak, and Gerald J. Chader. Ocular Drug Delivery Systems: Barriers and Application of Nanoparticulate Systems. Taylor & Francis Group, 2012.
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Thassu, Deepak, and Gerald J. Chader. Ocular Drug Delivery Systems: Barriers and Application of Nanoparticulate Systems. Taylor & Francis Group, 2012.
Find full textBook chapters on the topic "Blood retinal barrier"
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Hayreh, Sohan Singh. "The Blood-Retinal Barrier." In Ocular Vascular Occlusive Disorders, 165–71. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-12781-1_9.
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Kubo, Yoshiyuki, Shin-ichi Akanuma, and Ken-ichi Hosoya. "In Vivo Analysis to Study Transport Across the Blood-Retinal Barrier." In Blood-Brain Barrier, 249–65. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-8946-1_15.
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Hosoya, Ken-ichi, and Masanori Tachikawa. "The Inner Blood-Retinal Barrier." In Advances in Experimental Medicine and Biology, 85–104. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-4711-5_4.
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Hudson, Natalie, and Matthew Campbell. "Inner Blood-Retinal Barrier Regulation in Retinopathies." In Retinal Degenerative Diseases, 329–33. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-27378-1_54.
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Ishiko, Satoshi, Akitoshi Yoshida, and Norihiko Kitaya. "Blood-Retinal Barrier in Experimental Myopia." In Myopia Updates, 270–77. Tokyo: Springer Japan, 1998. http://dx.doi.org/10.1007/978-4-431-66959-3_49.
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Greenwood, John, Simon Bamforth, Yufei Wang, and Lesley Devine. "The Blood-Retinal Barrier in Immune-Mediated Diseases of the Retina." In New Concepts of a Blood—Brain Barrier, 315–26. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-1054-7_31.
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Greenwood, J. "Experimental Manipulation of the Blood-Brain ”and Blood-Retinal Barriers." In Physiology and Pharmacology of the Blood-Brain Barrier, 459–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-76894-1_19.
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Runkle, E. Aaron, and David A. Antonetti. "The Blood-Retinal Barrier: Structure and Functional Significance." In Methods in Molecular Biology, 133–48. Totowa, NJ: Humana Press, 2010. http://dx.doi.org/10.1007/978-1-60761-938-3_5.
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Liu, Li, and Xiaodong Liu. "Roles of Drug Transporters in Blood-Retinal Barrier." In Advances in Experimental Medicine and Biology, 467–504. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7647-4_10.
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Cunha-Vaz, J. G. "Blood—retinal barrier and new perspectives of management of retinal disease." In Documenta Ophthalmologica Proceedings Series, 5–11. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5137-5_2.
Full textConference papers on the topic "Blood retinal barrier"
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Schuschereba, Steven T., Jeremiah Brown, Bruce E. Stuck, and John Marshall. "Untoward effects of high-dose methylprednisolone therapy on blood-retinal barrier closure, retinal hole repair, and long-term scarring." In BiOS 2001 The International Symposium on Biomedical Optics, edited by Bruce E. Stuck and Michael Belkin. SPIE, 2001. http://dx.doi.org/10.1117/12.426715.
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Daley, Michael L., George A. Burghen, David Meyer, and Paul Maisky. "Racial Difference of Blue-Sensitive Mechanism." In Advances in Color Vision. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/acv.1992.fb9.
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Acquired loss of color vision is associated with diseases which produce vascular complications that affect the eye.1,2 In particular, the early loss of color vision associated with diabetes mellitus initially influences the blue-sensitive mechanism. Generally, as the disease progresses, loss of green vision becomes evident, and finally, red vision is involved.3 The patho-physiological mechanisms which produce the visual loss appear to be related to optical and neural changes within the eye.4,5 The optical loss may be caused by light scattering produced by plasma proteins which leak into the retina through an altered blood-retinal barrier.4,5
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Curcio, Christine A. "Aging and topography of human photoreceptors." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.wc1.
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Age-related decrements in acuity and contrast sensitivity are only partially explained by the combined effects of pupillary constriction and lens opacification. The notion of a neural origin for these visual deficits remains controversial. Limited quantitative data on photoreceptors in aging suggest disorganization of both rod and cone outer segments, displacement of nuclei, and outright cell loss, particularly in the fovea. The relationship of these phenomena to nonpathological changes in retinal supporting tissues which may impair transport of nutrients across the outer blood–retinal barrier is unclear. The effects of age-related point deletions in the photoreceptor mosaic on spatial sampling characteristics of the retina are unknown. Recent studies of photoreceptor distribution in human retina show that individual variability in foveal cone density is much greater than previously appreciated. The implications of this finding for aging studies are (1) sample size must take into account high variability; (2) anatomical data need to be viewed in relation to functional and clinical data from the same individual; (3) photoreceptor counts alone are probably not sufficiently sensitive to detect age-related cell loss, and some measure of mosaic disorder is likely to be more informative.
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Koester, Charles J., R. Theodore Smith, and Charles J. Campbell. "Deconvolution of ocular fluorophotometer data." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/oam.1985.thp1.
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Following the intravenous injection of fluorescein, the concentrations of fluorescein in the ocular aqueous and vitreous are measured to determine the integrity of the blood-retinal barrier. The fluorophotometer has an effective sampling volume formed by the intersection of the excitation beam and the fluorescence detection beam. As the sampling volume is scanned through the ocular media, it produces an instrument spread function that is convolved with the actual distribution of fluorescein. Provided that the spread function can be determined, it is possible to perform a deconvolution to recover an approximation to the original distribution. Several methods of deconvolution can be utilized. Factors that affect the results include sampling interval, alignment of the data, precise knowledge of the spread function, and noise. Simulations and model data demonstrate that substantial improvement can be achieved. With patient data, the principal advantage of deconvolution is the ability to assess fluorescein concentration close to the retina, a region that is otherwise obscured by the presence of strong fluorescence in the retina itself.
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Bungay, P. M., M. S. Roy, and R. F. Bonner. "New Scheme for Analyzing Vitreous Fluorophotometry (VFP) Scans." In Noninvasive Assessment of the Visual System. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/navs.1987.wc3.
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The shape of a VFP measurement scan depends in a very complicated way upon the condition of the blood-retinal barrier and a variety of other factors, such as the elapsed time after administration of the dye, the manner of dye administration, the character of the vitreous, optical properties of the eye, and the design of the instrument. Existing schemes for analyzing vitreous fluorophotometry scans suffer from deficiencies in the ways they do, or do not, take these influences into account. We report the development of new methodology for scan interpretation. Improvements over existing analysis schemes are discussed.