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RISS 인기검색어
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- 주제어 : 렌즈 상피세포 (검색결과 4 건)
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이성민 관동대학교 일반대학원 2009 국내석사
A cataract is an opacity that develops in the crystalline lens of the eye or in its envelope; it varies in degree from slight to completely opaque, obstructing the passage of light. The lens epithelium covers the anterior surface of the lens. Epithelial cells near the lens equator divide and differentiate into lens fibers. This process continues at a constant, slow rate throughout adult life, resulting in steady growth of the lens fiber mass.1The mitotically quiescent central region of the epithelium is thought to protect the underlying fibers from various insults, to transportions to and from the deeper layers of the lens, and perhaps to provide nutrients to elongating lens fibers. 2 Damage to the lens epithelium has been the focus of investigators in the identification of causes of cataract formation.3 Apoptosis, also known as programmed cell death, is a form of cell death that serves to eliminate dying cells in proliferating or differentiating cell populations. Thus, apoptosis plays a crucial role in normal development and tissue homeostasis. 4,5 Previous studies have shown that apoptosis of lens epithelial cells plays ani mportant role in the development of several types of cataract.6-8 These studies have suggested that apoptosis of lens epithelial cells appears as a common cellular mechanism mediating stress-induced noncongenital cataractogenesis.9,10 Apoptosis can be detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, a measure of DNA fragmentation in tissue sections, and by observation of a DNA ladder, a measure of fragmentation in DNA extracted from cells or tissues.11,12 In human cataract research, TUNEL-positive cells indicate apoptotic cell death in the lens epithelium.1,13 Another important characteristic of apoptosis is caspase activation. Caspase-3 is one of the most widely studied caspases, and it is a key executor of apoptosis.14 In addition to caspases, Bcl-2 family proteins also play a pivotal role in the regulation of apoptosis. The Bcl-2 family is classified into anti-apoptotic and pro-apoptotic proteins according to function. The balance between pro-apoptotic and anti-apoptotic Bcl-2 family members determines the mitochondrial response to apoptotic stimuli.15 Catechin is a naturally occurring polyphenolic compound found abundantly in green tea. Polyphenolic compounds include (-)-epgallocathechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG), and (-)-epicatechin (EC), and these are the main constituents of catechin.16 Previous studies have shown that catechin has diverse health benefits, including anti-oxidant, anti-hyperglycemic, anti-cancer, and anti-apoptosis effects.17-20 Catechin has also been reported to exert a protective effect on UV radiation-induced epithelial cell damage of the retina21 and lens.22 The functional roles of catechin have been well documented. However, its effects on the lens epithelium following cataract formation are not well known. Although great advances have been made in surgical treatment, the incidence of cataracts in developing countries is so high that it overwhelms the capacity of surgical intervention. Thus, we investigated the effect of catechin on apoptosis in the lens epithelium following cataract formation in rats. In this study, we performed TUNEL assay, Western-blot for Bcl-2 and Bax, and immunohistochemistry for caspase-3.
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역기하렌즈 ; 근시교정효과 및 각막상피세포와 기질에 미치는 영향
Orthokeratology is the technique of fitting reverse geometry lenses in order to change the corneal curvature as a way of improving myopia. This study is designed to evaluate the level of myopia correction and safety of Ortho-K LK^(TM) lenses and the effect of reverse geometry lens to corneal epithelium and stroma. A through and retrospective analysis was performed on 17 patients (34 eyes), who were wearing Ortho-K LK^(TM) lenses. In order to track the changes in the level of uncorrected visual acuity, spherical equivalent, astigmatism, and corneal endothelial cell count, we performed a periodical analysis, before the fitting and after the fitting, based on 1 week, 2 week, 1 month, 3 month and 6 month-term. The reverse geometry lenses were fitted to the right eyes of 15 rabbits and RGP lenses to the other 15 rabbits to compare the effects of reverse geometry lenses to cornea epithelium and stroma. Rabbits were sacrificed on the day of the first, third, seventh, tenth and fourteenth days after lens fitting. The thickness of the cornea was measured by microscope and microscale and the ratio of right and left corneal thickness was also considered in order to eliminate the deviation of difference in the individual cornea. In addition, to prove the migration and redistribution of corneal epithelial cells, we observed the filamentous actin in corneal epithelium after immunofluorescent stain, using NBD phallacidin. A significant progress developed that the uncorrected visual acuity and spherical equivalent improved in a week and it persisted in 6 months. But, no significant changes were found in the amount of astigmatism and corneal endothelial cell density. However, the visual acuity had been decreased in 3 to 6 months after the fitting, therefore we assumed that there must be another reason beyond the patients' compliance. The most common examples among the known complications were the decenteration of lenses, corneal erosion and corneal iron deposit. However, there were no such serious complications as to stop lens weanng. Furthermore, no consistent changes in the thickness of corneal epithelium and stroma at center and periphery were found, which can be explained by the severe corneal edema due to the persistent lens fitting and decenteration of lenses in the cornea of the rabbits. We did observe the positive NBD phallacidin immunofluorescent stain in both of the groups with the reverse geometry lenses and RGP lenses. But, on the cornea with the reverse geometry lenses showed a stronger reaction. Thus, we concluded that the migration of corneal epithelium under the effect of reverse geometry lenses changed the anterior corneal curvature.
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