Shigeki Fujisawa

Rebamipide increases the amount of mucin-like substances on the conjunctiva and cornea in the n-acetylcysteine-treated in vivo model

Purpose: Rebamipide increases the amount of mucin-like substances in the stomach. We aimed to determine the effects of rebamipide on the amount of mucin-like substances in the conjunctiva and cornea of N-acetylcysteine-treated eyes. Furthermore, we attempted to evaluate the effects of rebamipide on the wound healing of N-acetylcysteine-treated eyes. Methods: The model was created by instilling 10% N-acetylcysteine solutions into rabbit eyes. Rebamipide was then applied on the day following the completion of N-acetylcysteine treatment. The amount of mucin-like substances on the conjunctiva and cornea was measured using the Alcian-blue binding method. The degree of damage was evaluated using scores based on the areas and densities of the cornea and conjunctival after staining using a rose Bengal solution under blind conditions. Results: Rebamipide increased the level of mucin-like substances on the conjunctiva of N-acetylcysteine-treated eyes when instilled at concentrations of 0.3% or higher, and 1% rebamipide increased the amount of mucin-like substances covering the cornea. Moreover, 1% rebamipide improved the rose Bengal scores of the cornea and conjunctiva in N-acetylcysteine-treated eyes. Conclusions: Rebamipide increased mucin-like substances on the cornea and conjunctiva of N-acetylcysteine-treated eyes. In accordance with the mucin-increasing effects, rebamipide improved the rose Bengal scores for the cornea and conjunctiva of N-acetylcysteine-treated eyes. However, the relevance of these findings to dry eyes is unclear because it is not known whether the change in mucus expression in the N-acetylcysteine model is similar to what occurs in aqueous tear deficiency. Consequently, it may be worth trying on an animal model of keratoconjunctivitis sicca.

Rebamipide Increases Mucin-Like Substance Contents and Periodic Acid Schiff Reagent-Positive Cells Density in Normal Rabbits

PURPOSE The effects of rebamipide on the number of periodic acid Schiff reagent (PAS)-positive cells in the conjunctiva, the mucin content in the cornea and conjunctiva of normal rabbits, and desiccation-induced corneal damage in vivo were examined. METHODS Rebamipide (0.1%-3%) was applied 6 times a day for 14 days, and the PAS-positive cell count in the bulbar conjunctiva was measured by impression cytology. The amount of conjunctival and corneal mucin-like substances was measured by Alcian blue binding. The corneal damage model was created by desiccation from air flow at room temperature. The level of corneal damage was determined by scoring the area stained with rose bengal and fluorescein dye. RESULTS Rebamipide increased the number of PAS-positive cells in the conjunctiva when instilled at concentrations of 0.3% or higher, and 1% rebamipide increased the amount of mucin-like substances of the conjunctiva and cornea. Moreover, 1% rebamipide was also found to lower the rose bengal scores of the cornea in the corneal damage model by desiccation. CONCLUSIONS Rebamipide is a possible candidate drug for treatment of cornea and conjunctival epithelial damage due to its mucin-like substance increasing action, for instance, in the treatment of dry eye disease.

Carteolol Hydrochloride Protects Human Corneal Epithelial Cells From Uvb-induced Damage In Vitro

Purpose: To investigate whether carteolol hydrochloride has protective effects against ultraviolet B (UVB)-induced damage in human corneal epithelial cells (HCECs). Methods: Cultured HCECs were exposed to a single dose of UVB 300 mJ/cm2, and the cell viability was measured 12 hours after the UVB irradiation using a cell-counting kit. Test samples at 0.01-1.0 mmol/L (carteolol hydrochloride, timolol maleate, betaxolol hydrochloride, levobunolol hydrochloride, or nipradilol) were added to the HCECs before, during, or after UVB irradiation. UV absorption spectra for each drug sample were determined using a spectrophotometer. Hydrogen peroxide (H2O2) and carteolol hydrochloride were simultaneously added to the HCECs for 10 minutes, and the cell viability was measured 12 hours later. The ability of carteolol hydrochloride to scavenge superoxide anion (O2−) and singlet oxygen (1O2) was investigated using the MCLA chemiluminescence method. Results: UVB irradiation decreased the number of viable HCECs in a dose-dependent manner. Carteolol hydrochloride at 1 mmol/L attenuated the UVB-induced cell damage when added before, during, or after UVB irradiation (P < 0.01). Levobunolol hydrochloride at 1 mmol/L (P < 0.01) added during or after irradiation and timolol maleate at 0.1 mmol/L or higher (P < 0.05) added during irradiation attenuated the UVB-induced cell damage. Betaxolol hydrochloride and nipradilol had no effect. The UV absorption spectra of timolol maleate and levobunolol hydrochloride overlapped with the UVB wavelength spectrum, while carteolol hydrochloride, betaxolol hydrochloride, and nipradilol showed a partial overlap. Carteolol hydrochloride at 1 mmol/L (P < 0.05) significantly inhibited H2O2-induced cell damage and was able to scavenge O2− (EC50 value: 48 mmol/L). Conclusions: These data strongly suggest that carteolol hydrochloride has a protective action against UVB-induced HCEC damage, and its radical scavenging ability may be an important basis for this effect.

Effects of Carteolol Hydrochloride on the In Vitro Production of LPS-Induced Proinflammatory Cytokines by Murine Macrophage

We investigated whether carteolol hydrochloride, which has intrinsic sympathomimetic activity (ISA), inhibits the production of proinflammatory cytokines using mouse macrophages (MPs) and peripheral-blood mononuclear cells (PBMCs). MPs and PBMCs were collected from BALB/C strain mice, treated simultaneously with lipopolysaccharide (LPS) and test agents (carteolol hydrochloride, timolol maleate, betaxolol hydrochloride, levobunolol hydrochloride, or nipradilol) in medium, and incubated in a CO2 incubator. TNF-alpha and IL-6 in medium were measured by ELISA. Carteolol hydrochloride significantly inhibited the production of TNF-alpha and IL-6 by MPs at 10(-5) M and higher (p < 0.01) or PBMCs at 10(-6) M and higher (p < 0.01) compared to the controls, while the other test agents had no inhibitory effect. Carteolol hydrochloride inhibited the production of proinflammatory cytokines by inflammatory cells, raising the possibility that this intraocular hypotensive drug may be expected to have anti-inflammatory effects in patients with increased intraocular tension and postoperative inflammation.

Effect of Continuous Intravenous Infusion of Carteolol Chloride on Tissue Blood Flow in Rabbit Optic Nerve Head

PURPOSE To investigate the effect of an intravenous infusion of carteolol on tissue blood flow in the optic nerve head (ONH) of rabbits. METHODS Rabbits received either a 3-week topical instillation, or a single intravenous injection (10, 20, 30 microg/kg) or a continuous intravenous injection (2.5, 5, 20, 40, 80 microg/kg per hour) of carteolol. The plasma carteolol level was determined by the gas chromatography negative-ion chemical ionization mass spectrometric method. The ONH blood flow was determined by the hydrogen clearance method. RESULTS The plasma level of carteolol after a 3-week instillation was 5.55 ng/mL, and a continuous intravenous injection (5 microg/kg per hour) led to approximately the same plasma level. The continuous intravenous infusion of 5 microg/kg per hour of carteolol significantly increased the ONH blood flow compared to the controls from 30 minutes to 2 hours after the beginning of the infusion (n = 10). The mean blood pressure and intraocular pressure (n = 6) were not significantly changed during the continuous intravenous infusion of carteolol. CONCLUSIONS These results suggest that the plasma carteolol level in rabbits after long-term instillation can increase the ONH blood flow. We conclude that the increase resulted from a reduction in the vascular resistance in the ONH.