The Experts below are selected from a list of 11547 Experts worldwide ranked by ideXlab platform
Vladimir J Kefalov - One of the best experts on this subject based on the ideXlab platform.
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circadian and light driven regulation of rod Dark Adaptation
Scientific Reports, 2015Co-Authors: Yunlu Xue, Susan Q Shen, Joseph C Corbo, Vladimir J KefalovAbstract:Continuous visual perception and the Dark Adaptation of vertebrate photoreceptors after bright light exposure require recycling of their visual chromophore through a series of reactions in the retinal pigmented epithelium (RPE visual cycle). Light-driven chromophore consumption by photoreceptors is greater in daytime vs. nighttime, suggesting that correspondingly higher activity of the visual cycle may be required. However, as rod photoreceptors are saturated in bright light, the continuous turnover of their chromophore by the visual cycle throughout the day would not contribute to vision. Whether the recycling of chromophore that drives rod Dark Adaptation is regulated by the circadian clock and light exposure is unknown. Here, we demonstrate that mouse rod Dark Adaptation is slower during the day or after light pre-exposure. This surprising daytime suppression of the RPE visual cycle was accompanied by light-driven reduction in expression of Rpe65, a key enzyme of the RPE visual cycle. Notably, only rods in melatonin-proficient mice were affected by this daily visual cycle modulation. Our results demonstrate that the circadian clock and light exposure regulate the recycling of chromophore in the RPE visual cycle. This daily melatonin-driven modulation of rod Dark Adaptation could potentially protect the retina from light-induced damage during the day.
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chromophore supply rate limits mammalian photoreceptor Dark Adaptation
The Journal of Neuroscience, 2014Co-Authors: Jinshan Wang, Soile Nymark, Rikard Frederiksen, Maureen E Estevez, Susan Q Shen, Joseph C Corbo, Carter M Cornwall, Vladimir J KefalovAbstract:Efficient regeneration of visual pigment following its destruction by light is critical for the function of mammalian photoreceptors. Here, we show that misexpression of a subset of cone genes in the rd7 mouse hybrid rods enables them to access the normally cone-specific retina visual cycle. The rapid supply of chromophore by the retina visual cycle dramatically accelerated the mouse rod Dark Adaptation. At the same time, the competition between rods and cones for retina-derived chromophore slowed cone Dark Adaptation, indicating that the cone specificity of the retina visual cycle is key for rapid cone Dark Adaptation. Our findings demonstrate that mammalian photoreceptor Dark Adaptation is dominated by the supply of chromophore. Misexpression of cone genes in rods may represent a novel approach to treating visual disorders associated with mutations of visual cycle proteins or with reduced retinal pigment epithelium function due to aging.
Joseph C Corbo - One of the best experts on this subject based on the ideXlab platform.
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circadian and light driven regulation of rod Dark Adaptation
Scientific Reports, 2015Co-Authors: Yunlu Xue, Susan Q Shen, Joseph C Corbo, Vladimir J KefalovAbstract:Continuous visual perception and the Dark Adaptation of vertebrate photoreceptors after bright light exposure require recycling of their visual chromophore through a series of reactions in the retinal pigmented epithelium (RPE visual cycle). Light-driven chromophore consumption by photoreceptors is greater in daytime vs. nighttime, suggesting that correspondingly higher activity of the visual cycle may be required. However, as rod photoreceptors are saturated in bright light, the continuous turnover of their chromophore by the visual cycle throughout the day would not contribute to vision. Whether the recycling of chromophore that drives rod Dark Adaptation is regulated by the circadian clock and light exposure is unknown. Here, we demonstrate that mouse rod Dark Adaptation is slower during the day or after light pre-exposure. This surprising daytime suppression of the RPE visual cycle was accompanied by light-driven reduction in expression of Rpe65, a key enzyme of the RPE visual cycle. Notably, only rods in melatonin-proficient mice were affected by this daily visual cycle modulation. Our results demonstrate that the circadian clock and light exposure regulate the recycling of chromophore in the RPE visual cycle. This daily melatonin-driven modulation of rod Dark Adaptation could potentially protect the retina from light-induced damage during the day.
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chromophore supply rate limits mammalian photoreceptor Dark Adaptation
The Journal of Neuroscience, 2014Co-Authors: Jinshan Wang, Soile Nymark, Rikard Frederiksen, Maureen E Estevez, Susan Q Shen, Joseph C Corbo, Carter M Cornwall, Vladimir J KefalovAbstract:Efficient regeneration of visual pigment following its destruction by light is critical for the function of mammalian photoreceptors. Here, we show that misexpression of a subset of cone genes in the rd7 mouse hybrid rods enables them to access the normally cone-specific retina visual cycle. The rapid supply of chromophore by the retina visual cycle dramatically accelerated the mouse rod Dark Adaptation. At the same time, the competition between rods and cones for retina-derived chromophore slowed cone Dark Adaptation, indicating that the cone specificity of the retina visual cycle is key for rapid cone Dark Adaptation. Our findings demonstrate that mammalian photoreceptor Dark Adaptation is dominated by the supply of chromophore. Misexpression of cone genes in rods may represent a novel approach to treating visual disorders associated with mutations of visual cycle proteins or with reduced retinal pigment epithelium function due to aging.
Susan Q Shen - One of the best experts on this subject based on the ideXlab platform.
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circadian and light driven regulation of rod Dark Adaptation
Scientific Reports, 2015Co-Authors: Yunlu Xue, Susan Q Shen, Joseph C Corbo, Vladimir J KefalovAbstract:Continuous visual perception and the Dark Adaptation of vertebrate photoreceptors after bright light exposure require recycling of their visual chromophore through a series of reactions in the retinal pigmented epithelium (RPE visual cycle). Light-driven chromophore consumption by photoreceptors is greater in daytime vs. nighttime, suggesting that correspondingly higher activity of the visual cycle may be required. However, as rod photoreceptors are saturated in bright light, the continuous turnover of their chromophore by the visual cycle throughout the day would not contribute to vision. Whether the recycling of chromophore that drives rod Dark Adaptation is regulated by the circadian clock and light exposure is unknown. Here, we demonstrate that mouse rod Dark Adaptation is slower during the day or after light pre-exposure. This surprising daytime suppression of the RPE visual cycle was accompanied by light-driven reduction in expression of Rpe65, a key enzyme of the RPE visual cycle. Notably, only rods in melatonin-proficient mice were affected by this daily visual cycle modulation. Our results demonstrate that the circadian clock and light exposure regulate the recycling of chromophore in the RPE visual cycle. This daily melatonin-driven modulation of rod Dark Adaptation could potentially protect the retina from light-induced damage during the day.
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chromophore supply rate limits mammalian photoreceptor Dark Adaptation
The Journal of Neuroscience, 2014Co-Authors: Jinshan Wang, Soile Nymark, Rikard Frederiksen, Maureen E Estevez, Susan Q Shen, Joseph C Corbo, Carter M Cornwall, Vladimir J KefalovAbstract:Efficient regeneration of visual pigment following its destruction by light is critical for the function of mammalian photoreceptors. Here, we show that misexpression of a subset of cone genes in the rd7 mouse hybrid rods enables them to access the normally cone-specific retina visual cycle. The rapid supply of chromophore by the retina visual cycle dramatically accelerated the mouse rod Dark Adaptation. At the same time, the competition between rods and cones for retina-derived chromophore slowed cone Dark Adaptation, indicating that the cone specificity of the retina visual cycle is key for rapid cone Dark Adaptation. Our findings demonstrate that mammalian photoreceptor Dark Adaptation is dominated by the supply of chromophore. Misexpression of cone genes in rods may represent a novel approach to treating visual disorders associated with mutations of visual cycle proteins or with reduced retinal pigment epithelium function due to aging.
Peter Charbel Issa - One of the best experts on this subject based on the ideXlab platform.
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impaired Dark Adaptation associated with a diseased bruch membrane in pseudoxanthoma elasticum
Retina-the Journal of Retinal and Vitreous Diseases, 2019Co-Authors: Kristina Hess, Frank G Holz, Martin Gliem, Johannes Birtel, Philipp L Muller, Doris Hendig, Colm Andrews, Ian J Murray, Peter Charbel IssaAbstract:PURPOSE To characterize Dark Adaptation in patients with pseudoxanthoma elasticum, a systemic disease leading to calcification of elastic tissue including the Bruch membrane. METHODS In this prospective case-control study, Dark Adaptation thresholds were measured using a Goldmann-Weekers Dark adaptometer. Additional assessments included best-corrected visual acuity testing, contrast sensitivity, low luminance deficit, and vision-related quality of life. RESULTS Dark Adaptation thresholds were significantly higher, and Adaptation periods were prolonged in patients with pseudoxanthoma elasticum (n = 35; 33 with 2 ABCC6 mutations) compared with controls (n = 35). The time to adapt 4 log units (20.6 ± 8.6 vs. 8.0 ± 1.3 minutes) and the mean Dark Adaptation threshold after 15 minutes (3.5 ± 1.1 vs. 1.8 ± 0.2 log units) were significantly different between patients and controls (both P < 0.001). Low luminance deficits (12.3 ± 6.4 vs. 6.1 ± 4.3 ETDRS letters), contrast sensitivity (1.4 ± 0.3 vs. 1.9 ± 0.1), and low luminance-related quality of life (LLQ score: 1,286 ± 355 vs. 2,167 ± 68) were also significantly worse in patients with pseudoxanthoma elasticum (all, P < 0.001). Two patients were treated with high-dose vitamin A which partially reversed impaired Dark Adaptation. CONCLUSION Patients with pseudoxanthoma elasticum often have impaired Dark Adaptation. Positive effects of vitamin A supplementation may indicate restricted retinal access of vitamin A through the Bruch membrane as one possible underlying pathogenic factor.
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Dark Adaptation in macular telangiectasia type 2
Retina-the Journal of Retinal and Vitreous Diseases, 2019Co-Authors: Simone Tzaridis, Kristina Hess, Tjebo F C Heeren, Jennifer Nadal, Clarissa Mai, Philipp Herrmann, Peter Charbel Issa, Frank G HolzAbstract:PURPOSE To evaluate Dark Adaptation (DA) in patients with macular telangiectasia Type 2 (MacTel). METHODS After a local photobleach (4 × 4° size, 83% bleach), DA was measured using a test stimulus (2° diameter) projected at 5° eccentricity horizontal from the foveal center within the temporal parafovea. Cone plateau, rod intercept time, and rod recovery rate (S2) were calculated from the resulting DA curves. Findings were correlated with disease stages (according to Gass and Blodi), the area of ellipsoid zone loss in optical coherence tomography, and macular pigment loss ("MP-Classes 1-3"). RESULTS Fifty-nine eyes of 59 patients were compared with 18 eyes of 18 healthy controls. Dark Adaptation was significantly impaired in patients with MacTel. Although differences were most pronounced for parameters indicating rod-mediated recovery, cone-mediated recovery was also decreased, yet to a lesser extent. Dark Adaptation parameters were only weakly associated with disease stages and ellipsoid zone loss. A better association was found between rod-mediated recovery (S2 and rod intercept time) and macular pigment loss (Kendall's tau for rod intercept time: 0.69 and S2: -0.51; both P < 0.0001). CONCLUSION Dark Adaptation is significantly impaired in patients with MacTel. Our results indicate an association of reduced macular pigment and rod dysfunction in MacTel.
Yunlu Xue - One of the best experts on this subject based on the ideXlab platform.
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circadian and light driven regulation of rod Dark Adaptation
Scientific Reports, 2015Co-Authors: Yunlu Xue, Susan Q Shen, Joseph C Corbo, Vladimir J KefalovAbstract:Continuous visual perception and the Dark Adaptation of vertebrate photoreceptors after bright light exposure require recycling of their visual chromophore through a series of reactions in the retinal pigmented epithelium (RPE visual cycle). Light-driven chromophore consumption by photoreceptors is greater in daytime vs. nighttime, suggesting that correspondingly higher activity of the visual cycle may be required. However, as rod photoreceptors are saturated in bright light, the continuous turnover of their chromophore by the visual cycle throughout the day would not contribute to vision. Whether the recycling of chromophore that drives rod Dark Adaptation is regulated by the circadian clock and light exposure is unknown. Here, we demonstrate that mouse rod Dark Adaptation is slower during the day or after light pre-exposure. This surprising daytime suppression of the RPE visual cycle was accompanied by light-driven reduction in expression of Rpe65, a key enzyme of the RPE visual cycle. Notably, only rods in melatonin-proficient mice were affected by this daily visual cycle modulation. Our results demonstrate that the circadian clock and light exposure regulate the recycling of chromophore in the RPE visual cycle. This daily melatonin-driven modulation of rod Dark Adaptation could potentially protect the retina from light-induced damage during the day.
