Biomedical subjects
Chikako Katakami
Publications and source records attributed to Chikako Katakami.
[Effects of various eye drops on corneal wound healing after superficial keratectomy in rabbits].
PURPOSE: The effects of various eye drops on corneal wound healing, particularly in the subepithelial haze area, investigated histologically following superficial keratectomy in rabbits. MATERIAL AND METHODS: Mechanical superficial keratectomy was performed in rabbit eyes. Tranilast, betamethasone, hyaluronic acid and diclofenac eye drops were administered after the procedure. Physiological saline was used as a control. Corneas were excised 1, 2, 3, and 4 weeks after keratectomy, labeled with 3H-thymidine or 3H-proline, and subjected to autoradiography. RESULTS: In the control and diclofenac groups, corneal haze occurred three weeks after keratectomy. Histological examination revealed accumulation of proliferating keratocytes and active synthesis of collagen in the subepithelial area. In the tranilast and betamethasone groups, formation of corneal haze was reduced compared to the controls. The proliferation of keratocytes and the production of collagen in the corneal stroma were inhibited by these drugs. In the hyaluronic acid groups, corneal haze was decreased. In this group, although the proliferation of keratocytes was activated compared to the controls, abnormal accumulation of keratocytes in the subepithelial area was not detected. CONCLUSION: Tranilast and betamethasone decrease the formation of subepithelial haze by inhibiting keratocyte proliferation and synthesis of extracellular matrix in the corneal stroma. Hyaluronic acid, on the other hand, inhibits subepithelial haze by promoting physiologic wound healing.
Corneal disorders in KKAy mouse: a type 2 diabetes model.
PURPOSE: To observe the clinical and histopathological changes occurring in corneas of KKAy mice, a model of type 2 diabetes, and to elucidate the possible mechanisms involved in these changes. METHODS: Corneal epithelial cell proliferation was analyzed in KKAy and age-matched non-diabetic C57BL/6J control mice using (3)H-thymidine autoradiography. Clinical examination and histopathological analysis were also conducted on both types of mice. RESULTS: KKAy mice showed a significant elevation in blood glucose concentration and body weight compared to age-matched control mice. Fragile corneal epithelial cell attachment and subepithelial opacities were observed in the central area of the cornea of 10-week-old KKAy mice. Corneal epithelial cell proliferation decreased significantly in the 16-week-old KKAy mice. Histological study in the older KKAy mice groups revealed the presence of subepithelial deposits, widening of the intracellular spaces between corneal epithelial cells with poor adherence to the basement membrane (BM) and thickening of the BM itself. At the central area of the cornea, remnants of cell components with deposits and lacuna formation were observed, perhaps secondary to the continuous presence of poor adhesion and detachment of epithelial cells in the area. In the 50-week and older KKAy mice, thinning and atrophy of the corneal epithelial cell layer became more prominent at the central cornea with increases in deposition of materials, blood vessel invasion and activation of keratocytes. The deposits were stained black by von Kossa's method, indicating the presence of tissue calcium. Type IV collagen immunoreactivity was observed not only in the corneal and conjunctival BM but also between the stroma, particularly around the central cornea and in the walls of invading vessels. Laminin staining was intense at the BM around the central cornea, and in the walls of invading vessels along the stroma. Pyrraline, which is one of the major components of advanced glycation end products, was also present in the stroma, and around blood vessels. All these corneal changes were not observed with aging in the age-matched C57BL/6J mice. CONCLUSIONS: Our findings provide evidence of the existence of corneal disorders in KKAy mice. These observations may provide useful information for the explanation of the mechanisms involved in corneal disorders in non-insulin-dependent diabetes mellitus patients.
Effects of various eye drops on corneal wound healing after superficial keratectomy in rabbits.
PURPOSE: The effects of various eye drops on corneal wound healing, particularly in the subepithelial haze area, were investigated histologically following superficial keratectomy in rabbits. METHODS: Mechanical superficial keratectomy was performed in rabbit eyes. Tranilast, betamethasone, hyaluronic acid, and diclofenac eye drops were administered after the procedure. Physiological saline was used as a control. Corneas were excised 1, 2, 3, and 4 weeks after keratectomy, labeled with 3H-thymidine or 3H-proline, and subjected to autoradiography. RESULTS: In the control and diclofenac groups, corneal haze occurred 3 weeks after keratectomy. Histological examination revealed an accumulation of proliferating keratocytes and active synthesis of collagen in the subepithelial area. In the tranilast and betamethasone groups, formation of corneal haze was reduced compared to the controls. The proliferation of keratocytes and the production of collagen in the corneal stroma were inhibited by these drugs. In the hyaluronic acid group also, corneal haze was decreased. In this group, although the proliferation of keratocytes was activated compared to the controls, abnormal accumulation of keratocytes in the subepithelial area was not detected. CONCLUSIONS: Tranilast and betamethasone decrease the formation of subepithelial haze by inhibiting keratocyte proliferation and synthesis of extracellular matrix in the corneal stroma. Hyaluronic acid, on the other hand, inhibits subepithelial haze by promoting physiologic wound healing.