Dietary zerumbone prevents mouse cornea from UVB-induced photokeratitis through inhibition of NF-kappaB, iNOS, and TNF-alpha expression and reduction of MDA accumulation.
(18/24)
PURPOSE: Ultraviolet B (UVB) irradiation activates nuclear factor-kappa B (NF-kappaB) and inducible nitric oxide synthase (iNOS) in the cornea, resulting in inflammatory responses and malondialdehyde (MDA) accumulation. This study aims to determine the effect of zerumbone, a potent NF-kappaB inhibitor and inflammation modulators, on UVB-induced corneal damages in a mouse model. METHODS: Fifty female imprinting control region (ICR) mice were randomly divided into five groups. The mice were anaesthetized with their ocular surfaces exposed to UVB light (0.72J/cm(2)/daily), followed by daily dietary zerumbone supplements at 0, 1, 10, and 100 mg/kg of bodyweight. Mice without zerumbone supplements were used as treatment controls and mice without UVB irradiation as blank controls. Corneal surface damages were graded according to smoothness, opacity, and the extent of lissamine green staining. Histopathological changes were also examined, along with the expression of NF-kappaB, iNOS, and tumor necrosis factor-alpha (TNF-alpha). MDA accumulation and the levels of two antioxidant enzymes, glutathione (GSH) and GSH reductase (GR) were also examined. RESULTS: UVB irradiation caused significant damages to cornea, including sustained inflammation, apparent corneal ulcer, and severe epithelial exfoliation, leading to thinning of corneal epithelial layer, and infiltration of polymorphonuclear leukocytes. NF-kappaB expression was highly activated with nuclear translocation. The expression of iNOS and TNF-alpha were increased. MDA accumulation was also increased in both the corneal epithelial layer and the stroma. With dietary zerumbone, corneal damages were ameliorated in a dose-dependent manner. NF-kappaB activation and its nuclear translocation were blocked with decreased expression of iNOS and TNF-alpha. Infiltration of polymorphonuclear leukocytes was also blocked by dietary zerumbone. Besides, MDA accumulation was reduced with concomitant increase of GSH and GR levels. CONCLUSIONS: Dietary zerumbone prevents UVB-induced corneal damages by inhibition of NF-kappaB, iNOS, and TNF-alpha, with concomitant reduction of MDA accumulation and increase of GSH and GR levels in the mouse model. Results of this study suggest that dietary zerumbone may be used as a prophylactic agent against UVB-induced photokeratitis. (+info)
Optimizing evaluation of Lissamine Green parameters for ocular surface staining.
(19/24)
Arbuscular mycorrhizal symbiosis increases relative apoplastic water flow in roots of the host plant under both well-watered and drought stress conditions.
(20/24)
Protective effects of Dunaliella salina - a carotenoids-rich alga - against ultraviolet B-induced corneal oxidative damage in mice.
(21/24)
PURPOSE: Ultraviolet B (UVB) radiation from sunlight is known to be a risk factor for human corneal damage. The purpose of this study was to investigate the protective effects of Dunaliella salina (D. salina) on UVB radiation-induced corneal oxidative damage in male imprinting control region (ICR) mice. METHODS: Corneal oxidative damage was induced by exposure to UVB radiation at 560 muW/cm(2). Animals were orally administered (gavage) D. salina at doses of 0, 123, and 615 mg/kg bodyweight/day for eight days. Corneal surface damages were graded according to smoothness and the extent of lissamine green staining. Corneal glutathione (GSH) and malondialdehyde (MDA) levels, as well as the activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GSH-Px), and glutathione reductase (GSH-Rd) in cornea were measured to monitor corneal injury. RESULTS: UVB irradiation caused significant damage to the corneas, including apparent corneal ulcer and severe epithelial exfoliation, leading to decrease in the activities of SOD, catalase, GSH-Px, GSH-Rd, and GSH content in cornea, whereas there was increased corneal MDA content as compared with the control group. Treatment with D. salina could significantly (p<0.05) ameliorate corneal damage and increase the activities of SOD, catalase, GSH-Px, GSH-Rd, and GSH content, and decrease the MDA content in corneas when compared with the UVB-treated group. CONCLUSIONS: The studies demonstrate that D. salina exhibits potent protective effects on UVB radiation-induced corneal oxidative damage in mice, likely due to both the increase of antioxidant enzyme activity and the inhibition of lipid peroxidation. (+info)
Factors predicting the ocular surface response to desiccating environmental stress.
(22/24)
Staining characteristics and antiviral activity of sulforhodamine B and lissamine green B.
(23/24)
PURPOSE: Fluorescein and rose bengal are dyes used routinely in the examination of the ocular surface. As part of an ongoing search for a superior ophthalmic dye with optimal specificity and sensitivity and a lack of interference with subsequent viral cultures, and as part of studies that use chemical dyes to understand better the pathophysiology of ocular surface disorders, the staining characteristics and antiviral activity of sulforhodamine B and lissamine green B were investigated. METHODS: Staining of rabbit corneal epithelial cell cultures by sulforhodamine B and lissamine green B was compared to that of fluorescein and rose bengal. Diffusion of each dye through a collagen gel was measured. Uptake of lissamine green B by herpes simplex virus type 1 (HSV-1)-infected Vero cell cultures was compared at several times postinfection. The effect of sulforhodamine B and lissamine green B on HSV-1 plaque formation in Vero cells was determined. The cellular toxicity of sulforhodamine B and lissamine green B in vitro was examined by a quantitative 14C-amino acid uptake assay and by a qualitative cell viability assay. Finally, the effect of sulforhodamine B and lissamine green B on viral replication was compared in vivo with that of rose bengal in a rabbit model of herpetic epithelial keratitis. RESULTS: Rose bengal vividly stained cell monolayers of explant cultures of rabbit corneal epithelium. By light microscopy, sulforhodamine B and lissamine green B, like fluorescein, did not stain the epithelial cells, but did stain the corneal explant stroma. Pretreatment of epithelial cells with 0.25% trypsin for 5 minutes failed to induce dye uptake; however, pretreatment with 0.5% Triton X-100 for 5 minutes resulted in nuclear staining by lissamine green B, but not sulforhodamine B. When added to a collagen gel, the relative diffusion rate was fluorescein > lissamine green B > sulforhodamine B > rose bengal. By spectrophotometric analysis, HSV-1-infected and uninfected Vero cells bound equivalent amounts of lissamine green B until late in infection, when infected cells took up more dye (P < 0.001). A direct neutralization assay showed that 0.06% lissamine green B or 0.5% sulforhodamine B reduced HSV-1 plaque formation in Vero cells by greater than 50%, when present at the time of viral adsorption. By a quantitative 14C-amino acid uptake assay, lissamine green B was toxic to Vero cells in a dose-dependent manner, whereas sulforhodamine B was relatively nontoxic at the concentrations tested. By a cell viability assay, however, neither dye showed significant cellular toxicity. In a rabbit model of herpetic epithelial keratitis, rose bengal significantly reduced viral replication and recovery, whereas sulforhodamine B and lissamine green B had no effect. CONCLUSIONS: Neither sulforhodamine B nor lissamine green B stain healthy, normal cells. Lissamine green B stains membrane-damaged epithelial cells, but sulforhodamine B does not. Both sulforhodamine B and lissamine green B stain corneal stroma. Lissamine green B inhibits HSV-1 plaque formation at low concentrations of dye in vitro, which correlates with suppression of cellular metabolism as demonstrated by a 14C-amino acid uptake assay, but does not affect cell viability. Neither sulforhodamine B nor lissamine green B inhibit viral replication or recovery in vivo. (+info)
Measurement of cytosolic Ca2+ concentration in Limulus ventral photoreceptors using fluorescent dyes.
(24/24)
Several Ca-sensitive fluorescent dyes (fura-2, mag-fura-2 and Calcium Green-5N) were used to measure intracellular calcium ion concentration, Cai, accompanying light-induced excitation of Limulus ventral nerve photoreceptors. A ratiometric procedure was developed for quantification of Calcium Green-5N fluorescence. A mixture of Calcium Green-5N and a Ca-insensitive dye, ANTS, was injected in the cell and the fluorescence intensities of both dyes were used to calculate the spatial average of Cai within the light-sensitive R lobe of the photoreceptor. In dark-adapted photoreceptors, the initial Cai was 0.40 +/- 0.22 microM (SD, n = 7) as measured with fura-2. Cai peaked in the light-sensitive R lobe at 700-900 ms after the onset of an intense measuring light step, when the spatial average of Cai within the R lobe reached 68 +/- 14 and 62 +/- 37 microM (SD, n = 5) as measured with mag-fura-2 and Calcium Green-5N, respectively. The rate of Cai rise was calculated to be approximately 350 microM/s under the measuring conditions. The resting level of Mg2+ was estimated to be 1.9 +/- 0.9 mM, calculated from mag-fura-2 measurements. To investigate the effect of adapting light on the initial Cai level in the R lobe, a 1-min step of 420 nm background light was applied before each measurement. The first significant (P < 0.05) change in the initial level of Cai occurred even at the lowest adapting light intensity, which delivered approximately 3 x 10(3) effective photons/s. The relative sensitivity of the light-adapted photoreceptors was linearly related to the relative Cai on a double log plot with slope between -4.3 and -5.3. We were unable to detect a Cai rise preceding the light-activated receptor potential. The Cai rise, measured with Calcium Green-5N, lagged 14 +/- 5 ms (SD, n = 32) behind the onset of the receptor potential at room temperature in normal ASW. In the absence of extracellular Ca2+ and at 10 degrees C, this lag increased to 44 +/- 12 ms (SD, n = 17). (+info)