Ultraviolet Light-induced Changes in the Glucose-6-Phosphate Dehydrogenase Activity of Porcine Corneas

Tsubai, Toshio; Matsuo, Mitsuyoshi

doi:10.1097/00003226-200207000-00011

Cited by 25 publications

(21 citation statements)

References 18 publications

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“…The process of neutralisation of reactive oxygen species by ascorbate and the employment of GSH and NADPH is well described by Rose et al [30], but the severe decrease in the levels of both antioxidants suggests impairment of this process. This would be in agreement with a previous study of Tsubai et al [37], where a large dose of UVC resulted in damage to the pentose phosphate pathway and disturbance in homeostasis of redox balances such as GSH/GSSG.…”

Section: Discussionsupporting

confidence: 94%

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The effect of single and repeated UVB radiation on rabbit cornea

Fris

Tessem

Čejková

et al. 2006

Graefe's Arch Clin Exp Ophthalmol

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Section: Discussionsupporting

confidence: 94%

“…The tissue is thus exposed to oxidative stress and the biochemical status of the cell is severely affected [4,37]. Moreover, as an additional harmful effect of UVB radiation, apoptosis has been frequently observed [24,25].…”

Section: Discussionmentioning

confidence: 99%

The effect of single and repeated UVB radiation on rabbit cornea

Fris

Tessem

Čejková

et al. 2006

Graefe's Arch Clin Exp Ophthalmol

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“…Concurrent with this observation, UVA-absorption was shown by us to be increased to 95% 4 in the cornea after riboflavin treatment compared to 25-35% without riboflavin. 17 Riboflavin (vitamin B 2 ) alone produced no cell damage as is also known from other experiments 20 and is not surprising because riboflavin is also present in the retina, liver, and heart, being an essential element in normal nutrition. 21 In terms of the clinical problems of keratocyte loss, only long-term imbalances of the keratocyte reconstitution bear a risk for corneal thinning.…”

mentioning

confidence: 61%

“…While ultraviolet C (UVC) (100-290 nm) is completely absorbed at the corneal surface and 80% of ultraviolet B (UVB) (290-315 nm) in the corneal epithelium, 25-34% of UVA (315-400 nm) is absorbed in the stroma. 17 Accordingly, massive keratocyte damage was observed especially in the anterior portion of the rabbit cornea following exposure to UVA-irradiation at 350 nm. 18,19 In the present in vitro study, the cytotoxic irradiance level after combined riboflavin/UVA-treatment was about 10-fold lower than that after treatment with UVA alone because the cytotoxic effect, which is due to the oxidant effect of UVA-light, is multiplied by the photosensitizer riboflavin due to increased UVAabsorption.…”

mentioning

confidence: 99%

Keratocyte cytotoxicity of riboflavin/UVA-treatment in vitro

Wollensak

Spoerl

Reber

et al. 2004

Eye

240

183

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Purpose Collagen crosslinking using ultraviolet-A (UVA) -irradiation combined with the photosensitizer riboflavin is a new technique for treating progressive keratoconus. It has been shown to increase effectively the biomechanical strength of the cornea and to stop or even reverse the progression of keratoconus. As part of a safety evaluation, the present study was undertaken to investigate in vitro the possible cytotoxic effect of combined riboflavin/UVA-treatment on corneal keratocytes and to compare it to UVA-irradiation alone. Methods Cell cultures established from porcine keratocytes were treated with 0.025% riboflavin solution and various UVA (370 nm)-irradiances ranging from 0.4 to 1.0 mW/cm 2 and with UVA alone between 2 and 9 mW/cm 2 for 30 min. The cell cultures were evaluated for cell death 24 h after irradiation using trypanblue and Yopro-fluorescence staining. Results An abrupt cytotoxic irradiance level was found at 0.5 mW/cm 2 for keratocytes after UVA-irradiation combined with the photosensitizer riboflavin, which is 10-fold lower than the cytotoxic irradiance of 5 mW/ cm 2 after UVA-irradiation alone. Conclusions A cytotoxic effect of combined riboflavin/UVA-treatment on keratocytes is to be expected at 0.5 mW/cm 2 , which is reached in the clinical setting in human corneas down to a depth of 300 mm using the standard surface UVA-irradiance of 3 mW/cm 2 .

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“…Normally, the human corneal stroma absorbs 32% of the UVA light. After riboflavin application, UVA absorption in the stroma increases to 95% 27, 39. The reason for the high absorption rate is that the wavelength range of UVA llight (315‐400 nm) corresponds to one of the riboflavin absorption maxima (ie, 370 nm) 26.…”

Section: Discussionmentioning

confidence: 99%

UV light crosslinking regresses mature corneal blood and lymphatic vessels and promotes subsequent high-risk corneal transplant survival

Hou

Tóth

et al. 2018

American Journal of Transplantation

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Immunologic graft rejection is the main complication after corneal transplant into pathologically prevascularized so‐called high‐risk eyes. The aim of this study was to evaluate whether ultraviolet (UV) light crosslinking can regress pathologic corneal blood and lymphatic vessels and thereby improve subsequent graft survival. Using the murine model of suture‐induced corneal neovascularization, we found that corneal crosslinking with UVA light and riboflavin regressed both preexisting blood and lymphatic vessels significantly via induction of apoptosis in vascular endothelial cells. In addition, macrophages and CD45+ cell counts were significantly reduced. Consistently, corneal crosslinking reduced keratocyte density and corneal thickness without affecting corneal nonvascular endothelial cells, iris, and lens depending on the crosslinking duration. Furthermore, using the murine model of corneal transplant, long‐term graft survival was significantly promoted (P < .05) and CD4+ CD25+FoxP3+ T regulatory cells were upregulated (P < .01) in high‐risk eyes preoperatively treated with crosslinking. Our results suggest UV light crosslinking as a novel method to regress both pathologic corneal blood and lymphatic vessels and to reduce CD45+ inflammatory cells. Furthermore, this study demonstrates for the first time that preoperative corneal crosslinking in prevascularized high‐risk eyes can significantly improve subsequent graft survival and may become a promising novel therapy in the clinic.

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Ultraviolet Light-induced Changes in the Glucose-6-Phosphate Dehydrogenase Activity of Porcine Corneas

Cited by 25 publications

References 18 publications

The effect of single and repeated UVB radiation on rabbit cornea

The effect of single and repeated UVB radiation on rabbit cornea

Keratocyte cytotoxicity of riboflavin/UVA-treatment in vitro

UV light crosslinking regresses mature corneal blood and lymphatic vessels and promotes subsequent high-risk corneal transplant survival

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