Search results for "RETINAL PIGMENT"

Primary Cilium Mediated Retinal Pigment Epithelium Maturation is Retarded in Ciliopathy Patient Cells

2018

Primary cilia are sensory organelles that protrude from the cell membrane. Cilia defects cause ciliopathy disorders with retinal degeneration as a prominent phenotype. Here, we demonstrate that the retinal pigment epithelium (RPE), essential for photoreceptor development and function, requires a functional primary cilium for complete maturation, and RPE maturation defects in ciliopathies precede photoreceptor development. Pharmacologically enhanced ciliogenesis in wildtype induced pluripotent stem cells (iPSCs)-RPE leads to fully-mature and functional cells. Whereas, ciliopathy patient-derived iPSCs-RPE and wildtype iPSC-RPE with a knockdown of ciliary-trafficking protein remain immature, w…

2021

Primary cilia are sensory organelles vital for developmental and physiological processes. Their dysfunction causes a range of phenotypes including retinopathies. Although primary cilia have been described in the retinal pigment epithelium (RPE), little is known about their contribution to biological processes within this tissue. Ciliary proteins are increasingly being identified in non-ciliary locations and might carry out additional functions, disruption of which possibly contributes to pathology. The RPE is essential for maintaining photoreceptor cells and visual function. We demonstrate that upon loss of Bbs8, predominantly thought to be a ciliary gene, the RPE shows changes in gene and …

Retinol and retinyl esters in pigment epithelium of rats with inherited retinal degeneration

1976

A comparative study of the retinol and retinyl ester concentrations was performed in the retinal pigment epithelium of the normal and affected rats. Our findings indicate that in dystrophic rat retinol content increases, whereas the amount of retinyl esters is always lower than normal. An hypothesis can be made on the deficiency of enzymic activities which regulate retinol retinol and retinyl esters levels in the pigment epithelium.

Combination of Resveratrol with omega-3 fatty acids synergize to counteract VEGF-R pathway in sick retinal pigment epithelium cells mimicking AMD

2015

Purpose The aim of this work is to assess whether RSV (Resveratrol) can act synergistically with omega-3 fatty acids to modulate VEGF (Vascular Endothelial Growth Factor) signaling pathway in order to identify a new and more effective therapy for the treatment of AMD (Age-Related Macular Degeneration). Methods In this study, undifferentiated and differentiated human retinal pigment epithelial cells (ARPE-19) were used. The cells were treated with an omega-3/RSV preparation (Resvega®), or a RSV-free formulation or RSV alone for 24 h. The expression of key proteins in VEGF signaling pathway was evaluated by Western Blotting. Results We observed that the combination omega-3/RSV preparation (Re…

Ocular Drug Delivery Systems per la veicolazione di molecole bioattive al segmento posteriore dell'occhio

Assessment of the toxicity of cholesterol oxides on retinal pigment epithelial cultured cells

2006

International audience; Purpose: Among the retinal lipid deposits found in AMD (age related macular degeneration), esterified and unesterified cholesterol have been identified. Cholesterol that accumulates in Bruch's membrane could be oxidized and lead to cholesterol oxides known as oxysterols. These compounds have cytotoxic activities on many vascular cell types, and we conducted this study to evaluate the cytotoxics effects of oxysterols on retinal pigment epithelial (RPE) cells. Methods: Human RPE cells (ARPE–19) were cultured and treated by 7–ketocholesterol (7–keto), 7–betahydroxycholesterol (7–beta) and 25–hydroxycholesterol (25–OH). ARPE–19 cells viability was determined with MTT ana…

Gap junctions and connexin hemichannels both contribute to the electrical properties of retinal pigment epithelium.

2022

Gap junctions are intercellular channels that permit the transfer of ions and small molecules between adjacent cells. These cellular junctions are particularly dense in the retinal pigment epithelium (RPE), and their contribution to many retinal diseases has been recognized. While gap junctions have been implicated in several aspects of RPE physiology, their role in shaping the electrical properties of these cells has not been characterized in mammals. The role of gap junctions in the electrical properties of the RPE is particularly important considering the growing appreciation of RPE as excitable cells containing various voltage-gated channels. We used a whole-cell patch clamp to measure …

Electrofunctional features of the tilted disc syndrome.

1986

The ERG, EOG and VEPs of 15 patients with tilted disc syndrome were studied. The ERG showed abnormal amplitudes in about 1/4 of the eyes and the EOG values were pathological in 3 patients. It is probable that the abnormality of the inferior-nasal portion of the retina and retinal pigment epithelium seen in the tilted disc syndrome causes the changes in the ERG and EOG. Pattern VEPs latency was delayed in most patients. This finding is probably due to the poor focusing of the light in the retina.

Pigment patterns in mutants affecting the biosynthesis of pteridines and xanthommatin in Drosophila melanogaster.

1986

Eye-color mutants of Drosophila melanogaster have been analyzed for their pigment content and related metabolites. Xanthommatin and dihydroxanthommatin (pigments causing brown eye color) were measured after selective extraction in acidified butanol. Pteridines (pigments causing red eye color) were quantitated after separation of 28 spots by thin-layer chromatography, most of which are pteridines and a few of which are fluorescent metabolites from the xanthommatin pathway. Pigment patterns have been studied in 45 loci. The pteridine pathway ramifies into two double branches giving rise to isoxanthopterin, “drosopterins,” and biopterin as final products. The regulatory relationship among the …

Glaucomatous Maculopathy: Thickness Differences on Inner and Outer Macular Layers between Ocular Hypertension and Early Primary Open-Angle Glaucoma U…

2020

The purpose of this study was to compare the thickness of all inner and outer macular layers between ocular hypertension (OHT) and early primary open-angle glaucoma (POAG) using spectral domain optical coherence tomography (SD-OCT) 8 × 8 posterior pole algorithm (8 × 8 PPA). Fifty-seven eyes of 57 OHT individuals and fifty-seven eyes of 57 early POAG patients were included. The thickness of macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform and nuclear layer, photoreceptor layer (PRL) and retinal pigment epithelium were obtained in 64 cells for each macular layer and mean thickness of superior and inf…