[Reduction of lipid peroxidation and apoptosis in corneal endothelial cells by vitamin A].
ABSTRACT The goal of this study was to determine the effects of lipid peroxidation-mediated toxicity of iron ions on corneal endothelial cells leading to apoptosis.
Murine corneal endothelial cells were maintained in tissue culture medium supplemented with free iron ions, known to lead to increased lipid peroxidation. Retinoic acid in the cell supernatant and cytoplasm of these cells was determined using HPLC. The rate of apoptosis was assessed by quantification of caspase-3-like activity. The lipid peroxidation was measured using the malondialdehyde method. Supplementation of retinoic acid was tested in the setting of apoptosis.
Free iron ions led to a rapid loss of retinoic acid in the supernatant and the corneal endothelial cells. This was correlated with rising levels of malondialdehyde following oxidative stress and increased apoptosis. Supplementation of retinoic acid alone significantly reduced oxidative stress and apoptosis in the respective cells.
In this study the authors present a novel in vitro model to test the direct influence of pro-oxidative species on corneal endothelial cells. The authors also prove that supplementing corneal endothelial cells with retinoic acid sufficiently prevents free radical injury and apoptosis.
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ABSTRACT: To determine the potential role of apoptosis in the noninflammatory degeneration characteristic of keratoconus. Four normal corneas and 16 keratoconus corneas were obtained as archival specimens. Tissues were examined histopathologically for TUNEL immunoreactivity to detect the presence of DNA fragmentation. Tissues were also subjected to single-stranded DNA (ssDNA) analysis, a more apoptosis-specific stain. Normal corneas exhibited fewer than five TUNEL-positive epithelial cells per section, these being very lightly stained. All 16 keratoconus corneas demonstrated extensive, intense TUNEL staining in at least one layer. Fifteen of 16 exhibited staining in the epithelial layer, 11 of 16 in the stromal layer, and 13 of 16 in the endothelial layer, whereas 10 of 16 keratoconus cases demonstrated TUNEL immunoreactivity in all three layers. The ssDNA stain was also positive and evident in all three layers of the cornea, although to a lesser degree than the TUNEL assay. The noninflammatory nature of keratoconus, coupled with the TUNEL in situ results, suggests apoptosis as a mode of cell death in this degenerative disease.Cornea 04/2002; 21(2):206-9. · 1.75 Impact Factor
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ABSTRACT: Oxidized low-density lipoprotein (LDL) is implicated in atherogenesis, but the mechanisms that oxidize LDL in the human artery wall have proven difficult to identify. A powerful investigative approach is mass spectrometric quantification of the oxidized amino acids that are left in proteins by specific oxidation reactions. Comparison of these molecular fingerprints in biological samples with those produced in proteins by various in vitro oxidation systems can indicate which biochemical pathway has created damage in vivo. For example, the pattern of oxidized amino acids in proteins isolated from atherosclerotic lesions implicates reactive intermediates generated by myeloperoxidase, a major phagocyte enzyme. These intermediates include hypochlorous acid, tyrosyl radical, and reactive nitrogen species, each of which generates a different pattern of stable end products. Despite this strong evidence that myeloperoxidase promotes LDL oxidation in vivo, the antioxidant that has been tested most extensively in clinical trials, vitamin E, fails to inhibit myeloperoxidase pathways in vitro. Because the utility of an antioxidant depends critically on the nature of the pathway that inflicts tissue damage, interventions that specifically inhibit myeloperoxidase or other physiologically relevant pathways would be more logical candidates for the prevention of cardiovascular disease. Moreover, levels of oxidized amino acids in urine and plasma might reflect those in tissues and therefore identify individuals with high levels of oxidative stress. Trials with such subjects would seem more likely to uncover effective antioxidant therapies than trials involving the general population.Free Radical Biology and Medicine 07/2002; 32(11):1090-101. · 5.27 Impact Factor
Article: Corneal allograft rejection.British Journal of Ophthalmology 09/1994; 78(8):649-52. · 2.73 Impact Factor