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.
Article: Nitric oxide synthase induction and cytotoxic nitrogen-related oxidant formation in conjunctival epithelium of dry eye (Sjögren's syndrome).[show abstract] [hide abstract]
ABSTRACT: Until now, the expression and possible role of nitric oxide and nitrogen related oxidants in the human dry eye have not been investigated. Therefore, we examined immunohistochemically nitric oxide synthase isomers (NOS), enzymes generated nitric oxide, nitrotyrosine, a cytotoxic byproduct of nitric oxide and malondialdehyde, a byproduct of lipid peroxidation, in conjunctival epithelium of patients with dry eye, Sjögren's syndrome (SS). Moreover, in conjunctival epithelium of patients with dry eye (SS) the immunohistochemical staining of some pro-inflammatory cytokines was demonstrated: mature interleukin-1 beta (IL-1beta), interleukin 6 (IL-6), interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha). Conjunctival epithelial cells were obtained by the method of impression cytology. Normal eyes served as controls. In contrast to the normal eyes where endothelial nitric oxide synthase (NOS3) as well as inducible nitric oxide synthase (NOS2) were only slightly expressed in conjunctival epithelium, in dry eye both NOS (mainly NOS2) were gradually expressed along the severity of dry eye symptoms which was in accord with pro-inflammatory cytokine immunodetection (IL-1beta, IL-6, IL-8, TNF-alpha) in dry eye conjunctival cytology samples. This was in contrast to normal eyes where the staining of pro-inflammatory cytokines was weak or completely absent. Peroxynitrite formation (demonstrated by nitrotyrosine residues) and lipid peroxidation (evaluated by increased malondialdehyde staining) were also found in conjunctival epithelium of dry eye with highly pronounced symptoms of dryness. In conclusion, results point to the suggestion that reactive nitrogen species are involved in the pathogenesis or self-propagation of autoimmune dry eye (SS).Nitric Oxide 09/2007; 17(1):10-7. · 3.55 Impact Factor
Article: Homocysteine and nitric oxide levels in plasma of patients with pseudoexfoliation syndrome, pseudoexfoliation glaucoma, and primary open-angle glaucoma.[show abstract] [hide abstract]
ABSTRACT: To evaluate plasma total homocysteine (tHcy) and nitric oxide (NO) marker levels in patients with pseudoexfoliation syndrome (PXS), pseudoexfoliation glaucoma (PXG), primary open-angle glaucoma (POAG), and normal controls. This cross-sectional, prospective study involved 19 patients with POAG, 18 with PXS, 22 with PXG, and 20 control subjects. Fasting tHcy levels of all study participants were determined using a fluorescence polarization immunoassay method. Quantitation of total nitrate was based on the Griess reaction, in which a chromophore with a strong absorbance at 545 nm is formed by reaction of nitrite with a mixture of naphthylethylenediamine and sulphanilamide. The mean plasma homocysteine level was statistically significantly elevated in the PXS (p=0.033) and the PXG (p=0.023) groups but not in the POAG group (p=0.996) when compared with the control group. Multiple logistic regression analyses comparing the various patient groups with the single control group indicated that elevation in plasma homocysteine concentration was a significant risk factor for PXS (odds ratio per 1 micromol/l increase in homocysteine concentration=2.05, 95% CI=1.19-3.52) and PXG (odds ratio per 1 micromol/l increase in homocysteine concentration=1.36, 95% CI=1.00-1.85) but was not a significant risk factor for POAG (odds ratio per 1 micromol/l increase in homocysteine concentration=0.99, 95% CI=0.78-1.26). NO markers levels were found to be slightly higher in PXS and PXG patients than control and POAG patients but the differences were not statistically significant (p=0.151). Multiple logistic regression analyses comparing the various patient groups with the single control group indicated that elevation in NO marker concentration was not a significant risk factor for PXS (odds ratio per 1 micromol/l increase in NO concentration=1.00, 95% CI=0.99-1.01), PXG (odds ratio per 1 micromol/l increase in NO concentration=1.00, 95% CI=0.99-1.00) and POAG (odds ratio per 1 micromol/l increase in NO concentration=0.99, 95% CI=0.99-1.00). No statistically significant correlations were observed between plasma tHcy and NO markers in study groups (p>0.05). Elevated levels of homocysteine in pseudoexfoliation patients with and without glaucoma may partly explain the increased risk of vascular disease among patients with pseudoexfoliation. No significant difference was found in plasma NO markers among the POAG, PXS, PXG, and the control subjects.Albrecht von Graæes Archiv für Ophthalmologie 08/2005; 243(7):677-83. · 2.17 Impact Factor