The Effect of UVA Light on the Anaerobic Oxidation of Ascorbic Acid and the Glycation of Lens Proteins

Ortwerth, B.J.; Chemoganskiy, Vitaliy; Mossine, Valeri V.; Olesen, P.R.

doi:10.1167/iovs.02-0857

Cited by 17 publications

(12 citation statements)

References 26 publications

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“…Renal tubular acidosis is also found to be associated with lens epithelial abnormalities [26,28]. Oxidative stress in patients with CKD may induce carbamylation of lens proteins; advanced glycation end products under oxidative stress may cause yellowing of the lens and generation of oxygen-free radicals that lead to cataract [8,11,29,30]. Vitamin D deficiency may affect the calcium metabolism of the lens epithelial cells, causing lens tissue cloudy and distorted with calcium deposition [12,13,31.]…”

Section: Discussionmentioning

confidence: 99%

Association between Chronic Kidney Disease and Risk of Cataract: A Nationwide Retrospective Cohort Study

Liu

Hung²,

Lee³

et al. 2017

Am J Nephrol

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Background: Previous studies have established a relationship between chronic kidney disease (CKD) and cataract, but the relationship between the severity of renal impairment and risk of cataract is uncertain. This study investigates the relationship between the severity of renal disease and cataract in a nationwide sample from Taiwan. Methods: The cohort from 1-million National Health Insurance beneficiaries from Taiwan was retrospectively analyzed. All adult beneficiaries were followed from January 1, 2005 until December 31, 2013, to identify patients who underwent cataract surgeries. On the basis of the ambulatory care records, those diagnosed with CKD (ICD-9-CM code: 585) during the follow-up period were enrolled as CKD patients after careful evaluation. Each patient with CKD was age- and gender-matched with 4 individuals who did not have CKD. Cox regression models were applied to compare the hazard of cataract surgery in individuals with and without CKD. Subgroup analysis was used to compare patients with end-stage renal disease (ESRD) with age- and gender-matched non-CKD individuals. ESRD was defined by CKD patients who need regular renal replacement therapy. The same method was applied to evaluate hazard ratios (HRs). Results: After age and gender matching, there were 11,881 patients in the CKD group and 47,524 in the non-CKD group. After control for possible confounding, the adjusted HR (aHR) of cataract was 1.84 (95% CI 1.73-1.95) for the CKD group. Subgroup analysis of patients with ESRD (n = 3,209) and non-CKD individuals (n = 12,836), with matching done on the basis of age and gender, indicated an aHR of cataract was 2.33 (95% CI 2.10-2.59) for the ESRD group. Conclusions: This study indicates a relationship between CKD and cataract, and suggests that the risk for cataract increases with the severity of renal impairment.

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Section: Discussionmentioning

confidence: 99%

Association between Chronic Kidney Disease and Risk of Cataract: A Nationwide Retrospective Cohort Study

Liu

Hung²,

Lee³

et al. 2017

Am J Nephrol

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“…The dosage of UVA light that we used (60 mW cm −2 or 432 J cm −2 for a 2‐h exposure time) in our experiments is similar to what has been used previously , but is higher than what is typically encountered in the middle of a sunny day. For example, about 10 mW cm −2 of UV solar radiation was estimated to reach the surface of the earth at 40°N latitude (central US) .…”

Section: Resultsmentioning

confidence: 99%

UVA Light‐mediated Ascorbate Oxidation in Human Lenses

Rakete

Nagaraj

2017

Photochem & Photobiology

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Whether ascorbate oxidation is promoted by UVA light in human lenses and whether this process is influenced by age and GSH levels are not known. In this study, we used paired lenses from human donors. One lens of each pair was exposed to UVA light whereas the other lens was kept in the dark for the same period of time as the control. Using LC-MS/MS analyses, we found that older lenses (41 to 73 years) were more susceptible to UVA-induced ascorbate oxidation than younger lenses (18 to 40 years). Approximately 36% of the ascorbate (relative to control) was oxidized in older lenses compared to ~16% in younger lenses. Furthermore, lenses with higher levels of GSH were less susceptible to UVA-induced ascorbate oxidation compared to those with lower levels, and this effect was not dependent on age. The oxidation of ascorbate led to elevated levels of reactive α-dicarbonyl compounds. In summary, our study showed that UVA light exposure leads to ascorbate oxidation in human lenses and that such oxidation is more pronounced in aged lenses and is inversely related to GSH levels. Our findings suggest that UVA light exposure could lead to protein aggregation through ASC oxidation in human lenses.

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“…It was shown that the products of ascorbate photooxidation results in the glyco sylation of lens proteins. 59 In the case of nitroxyl radicals, the quenching proceeds via the physical mechanism with out the formation of chemical reaction products.…”

Section: Resultsmentioning

confidence: 99%

Antioxidative properties of nitroxyl radicals and hydroxyamines in reactions with triplet and deaminated kynurenine

et al. 2010

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The reactions of triplet kynurenine and 4 (2 aminophenyl) 4 oxocrotonic acid, formed upon the thermal decomposition of kynurenine, with nitroxyl radicals and cyclic N hydr oxylamines were studied. Nitroxyl radicals were found to quench efficiently the triplet state of kynurenine (rate constant 3-6•10 8 L mol -1 s -1 ). The quenching proceeds via the spin exchange mechanism and affords no new products. Neither nitroxyl radicals, nor hydroxy lamines react with 4 (2 aminophenyl) 4 oxocrotonic acid under conditions similar to phy siological.

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The Effect of UVA Light on the Anaerobic Oxidation of Ascorbic Acid and the Glycation of Lens Proteins

Cited by 17 publications

References 26 publications

Association between Chronic Kidney Disease and Risk of Cataract: A Nationwide Retrospective Cohort Study

Association between Chronic Kidney Disease and Risk of Cataract: A Nationwide Retrospective Cohort Study

UVA Light‐mediated Ascorbate Oxidation in Human Lenses

Antioxidative properties of nitroxyl radicals and hydroxyamines in reactions with triplet and deaminated kynurenine

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