Masao Nagata

Ultrastructure of Posterior Subcapsular Cataract in Human Lens

In 20 eyes with posterior subcapsular cataract, ultrastructural changes were observed in the capsule and the subcapsular cortex. In 13 eyes, lens fibers of the subcapsular cortex were markedly swollen and liquefied, and contained granules of various sizes. In 4 eyes, various vacuoles or wide separations of the cell membrane were seen. In 3 eyes, the lens fibers became narrow and showed high electron density. The structure of human posterior subcapsular cataract affects the operation for posterior subcapsular cataract. In 1 case of posterior subcapsular cataract, a lamellar structure containing fine fibrils was observed in the deep layer of the posterior capsule and the epithelial cells which had a long nucleus and poor cytoplasm were scattered just under the posterior capsule. It is considered that these changes in the cells indicated a reduction of cellular function.

Lens Epithelial Cell Damage and Apoptosis in Atopic Cataract. Histopathological and Immunohistochemical Studies.

PURPOSE To elucidate the relationship between damage of lens epithelial cells and apoptotic cell death in patients with atopic cataract. METHODS Histopathological and immunohistochemical studies were carried out using anterior lens capsules obtained at surgery from 13 patients with atopic cataract and from 25 patients with senile cataract. RESULTS No specific histopathological findings were found in the lens epithelial cells in atopic cases. However, the frequency and severity of histopathological findings such as flattening, nuclear pyknosis, and loss of cells were more frequent and more severe in atopic cases than in senile cases. The terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labelling (TUNEL) method revealed that the mean ratio of cells containing fragmented DNA to whole epithelial cells was almost the same in both atopic and senile cases. However, the mean ratio of Bax-positive cells was significantly higher in atopic cases (mean +/- standard deviation, 29.1 +/- 35.0%) than in senile cases (2.7 +/- 7.0%) (p < 0.05). The mean ratio of Bcl-2-positive cells was significantly lower in atopic cases (1.4 +/- 3.4%) than in senile cases (44.3 +/- 35.7%) (p < 0.05). CONCLUSION These results suggest that apoptotic cell death may play an important role in the development of lens epithelial cell damage in atopic cataract.

Expression of stress-response protein 60 in iritis associated with experimental autoimmune encephalomyelitis

PURPOSE To study the expression of stress-response proteins in the inflamed iris of rats with experimental autoimmune encephalomyelitis (EAE). METHODS EAE was induced in Lewis rats by immunization with homogenized spinal cord of the guinea pig emulsified in complete Freunds adjuvant (CFA) (group EAE). Control rats included those immunized with only CFA (group CFA) and those that were untreated (group Normal). Immunohistochemical study for the localization of stress-response protein (srp) 27, srp 60, srp 72, ubiquitin, and alphaB-crystallin was performed. RESULTS All rats in group EAE developed iritis, whereas none of the rats in group CFA and group Normal developed iritis. No expression of ubiquitin, alphaB-crystallin, srp 27, srp 60, or srp 72 was seen in the epithelium of the iris in group CFA rats. In the eyes of rats in group EAE, srp 60 was expressed in the epithelium of the iris in 20 of 22 (90.9%), ubiquitin in 4 of 22 (18.2%), and alphaB-crystallin in 3 of 22 (13.6%). In the group Normal rats, only ubiquitin was expressed in the epithelium of the iris in 1 of 6 (16.7%) eyes examined. CONCLUSIONS These results suggest that srp 60 may be a potential uveitogenic antigen in the iris in EAE.

Expression of stress-response protein 60 in lens epithelial cells in atopic cataract.

PURPOSE To clarify the pathogenesis of atopic cataract, especially to determine if there is any relationship between autoimmunity and atopic cataract. METHODS We investigated the lens epithelia obtained at surgery from 12 patients (12 eyes) with atopic cataract: from 8 patients (8 eyes) with nonatopic cataract (5 with senile cataract, 2 with juvenile cataract, and one with secondary cataract due to anterior uveitis); and from 4 autopsy eyes as controls. RESULTS Histopathological findings in the lens epithelial cells from atopic and nonatopic cataract patients were essentially the same: atrophy of the cells, presence of the superimposed cells, migration of cells into the lens cortex, cytoplasmic vacuolation, and loss of cells. In an immunohistochemical study, the expression of stress-response protein 60 (srp 60), srp 27, and srp 72 was examined in the lens epithelial cells. In atopic cataract specimens, 71%-87% of the lens epithelial cells were stained with the antibody against srp 60, but the cells in nonatopic cataract and control specimens were not stained. CONCLUSIONS Srp 27 and srp 72 were not expressed in any observed epithelial cells. The expression of srp 60 may reflect a protective mechanism of the epithelial cells against injury triggered by immunorelated agents. These findings suggest that the pathogenesis of degeneration of the lens epithelial cells in patients with atopic cataract may be related to autoimmunity.

Ultrastructure of the basal surface of the rat corneal epithelium

Basal surfaces of the rat corneal epithelium were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The epithelium was dissociated from the underlying stroma by dissolving the basal lamina with NaOH, and its basal surface was observed by SEM. Depressions, produced by the indentations of the plasma membrane, were present on the basal cell surfaces in rats which were 15 and 18 months old. TEM observations clarified that electron-dense deposits, presumably containing calcium, were located in the depressions. These depressions also accompanied the thickened basal lamina.