Phototoxicity of the Eye

Sarna, Tadeusz; Różanowska, Malgorzata Barbara

doi:10.1007/978-1-4899-1313-5_8

Cited by 7 publications

(4 citation statements)

References 103 publications

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“…Indeed, so‐called solar retinopathy is a frequently diagnosed acute retinal damage that can occur after gazing at the sun with unprotected naked eye (4–6). In contrast, chronic phototoxicity of the retina is an actinic damage that may result form repetitive exposure to sub‐threshold levels of short‐wavelength visible light (7,8). It has been postulated that this type of retinal damage might be involved in development of age‐related macular degeneration (AMD) (9–11).…”

Section: Introductionmentioning

confidence: 99%

Sub‐lethal Photodynamic Damage to ARPE‐19 Cells Transiently Inhibits Their Phagocytic Activity^†

Olchawa

Szewczyk

Zaręba

et al. 2010

Photochem & Photobiology

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Efficient phagocytosis of photoreceptor outer segments (POS) membranes by retinal pigment epithelium (RPE) plays a key role in biological renewal of these highly peroxidizable structures. Here, we tested whether photodynamic treatment, mediated by merocyanine 540 (MC 540), rose Bengal or a zinc-substituted chlorophyllide inhibited phagocytic activity of ARPE-19 cells in vitro. Specific phagocytosis of fluorescein-5-isothiocyanate-labeled POS isolated from cow retinas and nonspecific phagocytosis of fluorescent polystyrene beads were measured by flow cytometry. Photodynamic treatment, mediated by all three photosensitizers with sub-threshold doses, induced significant inhibition of the cell-specific phagocytosis. The nonspecific phagocytosis was inhibited by photodynamic treatment mediated only by MC 540. The inhibition of phagocytosis was a reversible phenomenon and after 24 h, the photodynamically treated cells exhibited phagocytic activity that was comparable with that of untreated cells. This study provides proof of principle that sub-threshold photodynamic treatment of ARPE-19 cells with appropriate photosensitizers is a convenient experimental approach for in vitro study of the effects of oxidative stress on specific phagocytic activity of RPE cells. We postulate that oxidative damage to key components of the cell phagocytic machinery may be responsible for severe impairment of its activity, which can lead to retinal degeneration.

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Section: Introductionmentioning

confidence: 99%

Sub‐lethal Photodynamic Damage to ARPE‐19 Cells Transiently Inhibits Their Phagocytic Activity^†

Olchawa

Szewczyk

Zaręba

et al. 2010

Photochem & Photobiology

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“…One important physicochemical property of melanin is its affinity to bind metal cations (Bruenger et al., 1967; Enochs et al., 1994; Kokkinou et al., 2004; Korytowski and Sarna, 1990b; Larsson and Tjälve, 1979; Sarna, 1992; Sarna and Rozanowska, 1994; Sarna and Swartz, 1998; Sarna et al., 1980). Although sequestration of metal ions by melanin may be viewed as an efficient protective mechanism, an excessive accumulation of redox active metal ions in the pigmented tissues could increase the risk of oxidative stress and pathological conditions.…”

Section: Introductionmentioning

confidence: 99%

Melanin in human irides of different color and age of donors

Wielgus

Sarna

2005

Pigment Cell Research

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Melanin is the main chromophore of the human iris. This pigment is considered to be the most important factor that determines the color of the irides. Previous studies based mainly on chemical degradation methods showed that brown irides contain more melanin than blue ones. In our study, we used electron spin resonance (ESR) spectroscopy to detect and characterize melanin free radical centers and associated iron in human irides. Based on this method, we determined the amount of melanin in the irides and the relative content of iron in iridial melanin as a function of their color, shade, and the age of their donors. Chemical degradation of iridial homogenates enabled us to characterize the structure of eumelanin and determine the content of pheomelanin present in human and bovine irides. The ESR amplitude, the normalized intensity obtained by double integration of the ESR signal of melanin, and the content of the pigment in the irides depended on color and shade of the eyes being 40% higher in the brown group of the irides compared with all other groups. On the other hand, the relative iron content normalized to the melanin content in light blue irides showed a small decrease with age of donors. Melanin in human and bovine irides was mostly composed of eumelanin, and pheomelanin content was of the order of a few percent. Although some differences in the structure of eumelanin present in the human and bovine irides are possible, the results obtained in this study suggest that human irides contain eumelanin with very similar chemical properties.

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“…Allthough biological functions of ocular melanin have not been unambiguously determined‚ a growing body of experimental evidence and epidemiological data suggest that both the iridial (uveal) and RPE melanin may have important photoprotective and antioxidant properties (Sarna‚ 1992;Sarna and 1994). Clearly‚ ocular pigmentation‚ particularly in the uveal tract‚ protects the retina from overexposure by absorbing and scattering the impinging light.…”

Section: Ocular Melaninmentioning

confidence: 98%

Free Radicals and Medicine

Swartz

Mason

Hogg

et al. 2005

Biomedical EPR, Part A: Free Radicals, Metals, Medicine, and Physiology

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Abstract:EPR has been employed in attempts to understand the basis of specific pathophysiologies in which free radicals have a postulated role. Examples described include pulmonary free radical damage‚ free radicals and sickle cell disease‚ free radicals in amyotrophic lateral sclerosis‚ melanin and free radicals and the potential role of oxidative stress in the induction of cancer. The final section of the chapter describes the use of NMR as the spectroscopic measure of spin-trapped radicals‚ after they have reacted further to form diamagnetic species.

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Phototoxicity of the Eye

Cited by 7 publications

References 103 publications

Sub‐lethal Photodynamic Damage to ARPE‐19 Cells Transiently Inhibits Their Phagocytic Activity^†

Sub‐lethal Photodynamic Damage to ARPE‐19 Cells Transiently Inhibits Their Phagocytic Activity^†

Melanin in human irides of different color and age of donors

Free Radicals and Medicine

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Phototoxicity of the Eye

Cited by 7 publications

References 103 publications

Sub‐lethal Photodynamic Damage to ARPE‐19 Cells Transiently Inhibits Their Phagocytic Activity†

Sub‐lethal Photodynamic Damage to ARPE‐19 Cells Transiently Inhibits Their Phagocytic Activity†

Melanin in human irides of different color and age of donors

Free Radicals and Medicine

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Product

Resources

About

Sub‐lethal Photodynamic Damage to ARPE‐19 Cells Transiently Inhibits Their Phagocytic Activity^†

Sub‐lethal Photodynamic Damage to ARPE‐19 Cells Transiently Inhibits Their Phagocytic Activity^†