Significant variation of the elevated nitric oxide levels in aqueous humor from patients with different types of glaucoma.
ABSTRACT Though several studies have shown that the biochemical function of nitric oxide (NO) in the eye might play an important role in the regulation of intraocular pressure (IOP), local control of ocular blood flow and loss of retinal ganglion cells by apoptosis, it is unclear whether the role of NO is similar in the pathogenesis of different kinds of glaucoma: primary open-angle glaucoma (POAG), chronic closed-angle glaucoma (CCAG) and neovascular glaucoma (NVG). To further explore this issue, we measured the concentrations of NO in aqueous humor and plasma samples from patients with POAG (n = 31), CCAG (n = 76), NVG (n = 8) and cataract (n = 30). All of the NVG patients suffered from severe proliferative diabetic retinopathy, while other patients were free of any other systemic disease. The NO levels in both aqueous humor and plasma samples were assessed by chemiluminescence assay. We found that the NO levels in aqueous humor samples were greatly varied in patients with POAG (36.2 +/- 3.3 microM), CCAG (47.7 +/- 3.4 microM) and NVG (65.8 +/- 5.4 microM), and all of them were significantly higher than in cataract patients (27.0 +/- 2.9 microM p < 0.05). Except NVG patients whose NO levels in plasma samples were highest (24.1 +/- 3.5 microM) among all groups, the plasma NO levels were not significantly different between the other glaucoma patients and the cataract patients. We therefore concluded that significant variation of the elevated NO levels in aqueous humor samples from the patients with different types of glaucoma may reflect their differences in the pathogenesis.
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ABSTRACT: Trehalose, a nonreducing disaccharide of glucose, produced and stored in many lower and higher organisms, although not in mammals, is synthetized as a stress responsive factor when cells are exposed to various environmental stress conditions. Recently, trehalose has been implicated in various situations in mammals. The aim of this paper was to examine whether trehalose might decrease the damage of the rabbit cornea evoked by UVB rays. During irradiation with UVB rays, consisiting of a daily dose of 0.5 J/cm2 for four days, trehalose was applied in eye drops on the right eye and buffered saline on the left eye. One day after the end of irradiation the animals were sacrificed and the corneas examined spectrophotometrically for light absorption. Another group of corneas similarly treated were examined morphologically and immunohistochemically. Corneal thickness (hydration) was measured using a Pachymeter. The results show that compared to buffered saline, trehalose treated corneas displayed fewer corneal disturbances during UVB irradiation. The increases in corneal hydration and light absorption were less pronounced and intracorneal inflammation and corneal neovascularization were suppressed. Nitric oxide synthases that generate nitric oxide were less expressed in the cornea, and formation of cytotoxic peroxynitrite (demonstrated by nitrotyrosine residues) was decreased. The expression of the antioxidant aldehyde dehydrogenase3A1 was less inhibited in the corneal epithelium, and apoptotic corneal epithelial cell death (detected by immunostaining for active caspase-3) was greatly diminished. In conclusion, trehalose reduced UVB-induced damage caused by reactive oxygen and nitrogen species and decreased changes in the corneal optics.Histology and histopathology 11/2010; 25(11):1403-16. · 2.24 Impact Factor
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ABSTRACT: Glaucoma, the second leading cause of blindness, is characterized by changes in the optic disc and visual field defects. The elevated intraocular pressure was considered the prime factor responsible for the glaucomatous optic neuropathy involving death of retinal ganglion cells and their axons. Extensive investigations into the pathophysiology of glaucoma now reveal the role of multiple factors in the development of retinal ganglion cell death. A better understanding of the pathophysiological mechanisms involved in the onset and progression of glaucomatous optic neuropathy is crucial in the development of better therapeutic options. This review is an effort to summarize the current concepts in the pathophysiology of glaucoma so that newer therapeutic targets can be recognized. The literature available in the National Medical Library and online Pubmed search engine was used for literature review.Indian Journal of Ophthalmology 03/2009; 57(4):257-66. DOI:10.4103/0301-4738.53049 · 0.93 Impact Factor
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ABSTRACT: Irradiation of the cornea with UVB rays leads to its oxidative damage, swelling and increased light absorption. We investigated changes in the corneal optics (evaluated by changes of corneal hydration and light absorption) and microscopical disturbances of corneas irradiated with UVB rays as influenced by eye drops containing actinoquinol with hyaluronic acid. Rabbit corneas were irradiated with a daily dose of 0.5 or 1.01 J cm(-2) of UVB rays (312 nm) for 4 days. During irradiation, the eye drops were applied on the right eye and buffered saline (or hyaluronic acid) on the left eye. On day 5 the rabbits were sacrificed and the corneas examined spectrophotometrically for light absorption. The corneal thickness (hydration) was measured using a pachymeter. Corneas of some other rabbits were examined immunohistochemically. After buffered saline treatment UVB rays evoked changes in the corneal optics and induced oxidative damage of the corneas. After actinoquinol-hyaluronic acid application, these changes were diminished. Hyaluronic acid alone was less effective. In conclusion, actinoquinol-hyaluronic acid eye drops decreased changes in corneal optics and suppressed oxidative damage in the UVB-irradiated cornea. However, the effective corneal protection by these eye drops was limited to the lower UVB dose.Photochemistry and Photobiology 11/2010; 86(6):1294-306. DOI:10.1111/j.1751-1097.2010.00796.x · 2.68 Impact Factor