The Effects of Hyperbaric Oxygen on the Crystallins of Cultured Rabbit Lenses: a Possible Catalytic Role for Copper

Padgaonkar, Vanita A.; Leverenz, Victor R.; Fowler, Karen E.; Reddy, Venkat N.; Giblin, Frank J.

doi:10.1006/exer.2000.0887

Cited by 32 publications

(23 citation statements)

References 77 publications

(89 reference statements)

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“…Previous reports on treatment of cultured lenses with HBO demonstrated significant oxidation of the reduced form of glutathione, 14 formation of oxidized proteins, and modification of certain susceptible enzymes, with effects being initiated primarily in the nuclear region of the lens. [15][16][17] These observations may support oxidative stress as a possible factor in senile cataract formation. Because hyperbaric conditions induce very high oxygen partial pressure, exposing lenses in tissue culture to HBO permits the study of lenticular oxidative damage.…”

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confidence: 69%

Lenticular Oxygen Toxicity

Schaal

Beiran

Rubinstein

et al. 2003

Invest. Ophthalmol. Vis. Sci.

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High oxygen load has a toxic effect on bovine lenses in organ culture. These effects appear to be cumulative: the higher the oxygen partial pressure and the greater the number of exposures, the more severe the changes observed in the lenses. Changes marking toxicity follow the route of oxygen diffusion into the lens, from the periphery to the center. Cautious interpretation of the results may indicate a role of oxygen (and/or its derivatives) in human cataract formation.

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confidence: 69%

Lenticular Oxygen Toxicity

Schaal

Beiran

Rubinstein

et al. 2003

Invest. Ophthalmol. Vis. Sci.

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“…67 ␣-Crystallin has been shown to decrease the amount of light-scattering and thiol oxidation of other crystallins induced by various conditions of oxidative stress in vitro, 68 and rabbit lenses treated with HBO in vitro have exhibited an apparent chaperone-like function for ␣-crystallin in the lens nucleus. 69 In the aging bovine lens, ␣-crystallin present in the HMW fraction has been shown to bind ␤-and ␥-crystallins in the central region of the supramolecular complex. 70 Nearly one half of the experimental nuclear WI protein dissolved in guanidine was found to consist of 150-to 1000-kDa proteins that were not present in the control (Fig.…”

Section: Discussionmentioning

confidence: 99%

Aggregation of Lens Crystallins in an In Vivo Hyperbaric Oxygen Guinea Pig Model of Nuclear Cataract: Dynamic Light-Scattering and HPLC Analysis

Simpanya

Ansari

Suh

et al. 2005

Invest. Ophthalmol. Vis. Sci.

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“…To understand the role of oxygen tension in the formation of allysine and 2-AAA, rabbits were exposed to hyperbaric oxygen for 48 h, as previously described (23). Lenses were processed with the same protocol as for human lenses and separated into cortical and nuclear water-soluble and -insoluble fractions.…”

Section: Resultsmentioning

confidence: 99%

“…Rabbit Lens Hyperbaric Treatment and Protein PreparationNew Zealand White rabbit lenses (n ϭ 6 per group) were treated with 50 atm 100% O 2 or normal atm air in HEPES TC-199 buffer for 48 h as described previously (23). After hyperbaric O 2 treatment, each rabbit lens was frozen immediately and dissected into cortex (C) and nuclear (N) fractions.…”

Section: Ages Determination By Gs/ms and Lc-ms/ms-amountsmentioning

confidence: 99%

Mechanism of Lysine Oxidation in Human Lens Crystallins during Aging and in Diabetes

Fan

Zhang

Theves

et al. 2009

Journal of Biological Chemistry

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Oxidative mechanisms during nuclear sclerosis of the lens are poorly understood, in particular metal-catalyzed oxidation. The lysyl oxidation product adipic semialdehyde (allysine, ALL) and its oxidized end-product 2-aminoadipic acid (2-AAA) were determined as a function of age and presence of diabetes. Surprisingly, whereas both ALL and 2-AAA increased with age and strongly correlated with cataract grade and protein absorbance at 350 nm, only ALL formation but not 2-AAA was increased by diabetes. To clarify the mechanism of oxidation, rabbit lenses were treated with hyperbaric oxygen (HBO) for 48 h, and proteins were analyzed by gas and liquid chromatography mass spectrometry for ALL, 2-AAA, and multiple glycation products. Upon exposure to HBO, rabbit lenses were swollen, and nuclei were yellow. Protein-bound ALL increased 8-fold in the nuclear protein fractions versus controls. A dramatic increase in methylglyoxal hydroimidazolone and carboxyethyl-lysine but no increase of 2-AAA occurred, suggesting more drastic conditions are needed to oxidize ALL into 2-AAA. Indeed the latter formed only upon depletion of glutathione and was catalyzed by H 2 O 2 . Neither carboxymethyl-lysine nor glyoxal hydroimidazolone, two markers of glyco-/lipoxidation, nor markers of lenticular glycemia (fructose-lysine, glucospane) were elevated by HBO, excluding significant lipid peroxidation and glucose involvement. The findings strongly implicate dicarbonyl/metal catalyzed oxidation of lysine to allysine, whereby low GSH combined with ascorbate-derived H 2 O 2 likely contributes toward 2-AAA formation, since virtually no 2-AAA formed in the presence of methylglyoxal instead of ascorbate. An important translational conclusion is that chelating agents might help delay nuclear sclerosis.The aging human lens accumulates a number of postsynthetic protein modifications that are thought to predispose lens crystallins toward aggregation and cataractogenesis. These include glycation by sugars, ascorbic acid, and oxoaldehydes, 3-hydroxy-kynurenination, oxidation, and photooxidation, deamidation, deamination, and protein truncation (reviewed in Ref. 1). Among the oxidative mechanisms, those involving formation of protein disulfides and mixed disulfides with glutathione or cysteine are well understood (2). Similarly, the presence of methionine sulfoxide in human lens crystallins has been known for several years (3, 4). In recent years, however, considerable interest has focused on the formation of so-called protein carbonyls as markers of oxidative stress in biology. Stadtman and co-workers (5) demonstrated that proteins incubated in the presence of redox active metals, such as Cu(II) and Fe(III), with hydrogen peroxide or ascorbic acid, underwent metal-catalyzed oxidation (MCO), 3 whereby histidine, proline, lysine, and arginine are preferentially oxidized. Lysine residues are oxidized into allysine (adipic semialdehyde) (Fig. 1), while proline and arginine residues into glutamic semialdehyde (6, 7). These "protein carbonyls" have been immuno...

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The Effects of Hyperbaric Oxygen on the Crystallins of Cultured Rabbit Lenses: a Possible Catalytic Role for Copper

Cited by 32 publications

References 77 publications

Lenticular Oxygen Toxicity

Lenticular Oxygen Toxicity

Aggregation of Lens Crystallins in an In Vivo Hyperbaric Oxygen Guinea Pig Model of Nuclear Cataract: Dynamic Light-Scattering and HPLC Analysis

Mechanism of Lysine Oxidation in Human Lens Crystallins during Aging and in Diabetes

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