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PubMed2006

Iris and trabecular meshwork pigment changes after posterior chamber phakic intraocular lens implantation.

PURPOSE: To evaluate the changes in laser iridotomies, intraocular pressure (IOP), angle structures, and pupil diameter after implantable contact lens (ICL) (Version 4 Staar Surgical) implantation in myopic Asian eyes. SETTING: Department of Ophthalmology, Chung-Ang University Yongsan Hospital, Seoul, Korea. METHODS: The ICL was implanted in 81 eyes of 43 patients with spherical equivalent greater than -6.00 diopters. Gonioscopy examination was performed 1 day after laser iridotomy and 6 and 12 months after ICL implantation. The changes in laser iridotomy sites, IOP, and pupil diameter were also evaluated. RESULTS: Ten eyes (12.3%) had occlusion or narrowing of the laser iridotomy sites. The angle width was more than 30 degrees in all cases preoperatively but narrowed to less than 20 degrees in 16 eyes (19.8%) 6 months postoperatively. The mean pigment, measured by the semiquantitative method (grade 0 to 4), was 2.03 in the inferior angle, 0.18 in the nasal angle, 0.12 in the temporal angle, and 0.00 in the superior angle 12 months postoperatively. The pigment in all quadrants increased temporally as a result of the laser iridotomy or iris rubbing by the ICL; however, the pigments absorbed gradually and decreased to values before laser iridotomy 12 months postoperatively. There was a temporary increase in IOP from the instillation of steroid eyedrops 1 week and 1 month postoperatively; IOP returned to the preoperative level and remained there 12 months postoperatively. There was a significant decrease in pupil diameter 1 and 3 months postoperatively; the diameter returned to the preoperative size at 6 and 12 months. Pigment dispersion syndrome and pigmentary glaucoma were not seen. CONCLUSION: Implantation of the ICL narrowed the angle width but did not increase trabecular pigmentation compared with values after laser iridotomy, indicating ICL implantation is safe regardless of the pigmentary changes in the trabecular meshwork.

Adult↗
PubMed1989

Eicosanoid production and glucocorticoid regulatory mechanisms in cultured human trabecular meshwork cells.

The techniques we developed to propagate HTM cells in serial cell culture have provided an opportunity to investigate the spectrum of endogenous PGs and other eicosanoids that are produced by these cells. PGE2 and PGF2 alpha were the major cyclooxygenase products detected by both radioimmunoassay and thin-layer chromatography. A small amount of 6-keto PGF1 alpha was also detected, indicating that these cells are able to produce prostacyclin. The observation of a substantial increase in the proportion of PGF2 alpha relative to PGE2 at later time periods after a media change suggests a metabolic conversion of PGE2 to PGF2 alpha by these cells. Bradykinin, thrombin, platelet activating factor, and serum were found to be effective stimulators of PG production by HTM cells, whereas calcium ionophore produced only a minor effect. Using high pressure liquid chromatography, elution profiles of radiolabeled metabolites of AA suggested the presence of certain lipoxygenase products, including LTB4, 12-HETE, 15-HETE, and a small amount of 5-HETE in HTM cells. The formation of these products was inhibited by both DEX and BW 755c, reinforcing the view that metabolic conversions of AA through the lipoxygenase pathway were possible in the trabecular meshwork. We also examined the effects of glucocorticoids on specific protein synthesis in the HTM cells, using 35S-methionine labeling and SDS-PAGE techniques. Short-term (1 day) DEX treatment revealed a major induction of a protein band at approximately 30 kDa. Longer treatments (1 to 3 weeks) resulted in major inductions at approximately 55 kDa inside the cells, with the presence of secreted forms (probably glycoproteins) between 55 and 72 kDa. The short-term DEX effect on protein synthesis a phospholipase inhibitor regulating eicosanoid production within the HTM. The longer-term induction may, on the other hand, be related more directly to the development of steroid glaucoma, based on our findings that the inductions of these proteins correlate with the observed time course and dose-dependence topical glucocorticoid effects on IOP. Continued in vitro and in vivo evaluations of the eicosanoid pathways in cultured HTM cells obtained from normal and glaucomatous human eyes may help to delineate their relationship to IOP regulation and the pathogenesis and treatment of glaucoma. Glucocorticoid-induced proteins may be key participants in the regulation of phospholipase activity and hence may represent a major control mechanism of the AA cascade.(ABSTRACT TRUNCATED AT 400 WORDS)

Cells, Cultured↗
PubMed1998

Novel trabecular meshwork inducible glucocorticoid response mutation in an eight-generation juvenile-onset primary open-angle glaucoma pedigree.

OBJECTIVE: This study aimed to update a large kindred with juvenile-onset primary open-angle glaucoma (POAG) first described in 1940 and to identify the underlying genetic cause of the disease. DESIGN: Molecular genetic study of a single kindred, including clinical examination, retrospective review of clinical and family history records, linkage analysis, and mutation screening. PARTICIPANTS: The retrospective review included 957 members of a single large family. The linkage study included 40 members of 1 branch of the family in which juvenile-onset POAG is segregating in an autosomal-dominant pattern. Mutation screening included 15 at-risk family members with juvenile-onset POAG, probands of 40 families with adult-onset POAG, probands of 11 additional unrelated juvenile-onset POAG families, and 43 unrelated normal control subjects. INTERVENTION: Clinical and family history records were obtained, ophthalmologic examinations were performed, and blood samples were drawn for use in genotyping. MAIN OUTCOME MEASURES: Allele sizes of microsatellite repeat genetic markers from the vicinity of the GLC1A glaucoma gene on chromosome 1q were assigned based on size fractionation of DNA fragments generated by polymerase chain reaction (PCR). Linkage was established by the method of lod scores. Mutations were identified by determination of the DNA sequence of PCR products amplified from the trabecular meshwork inducible glucocorticoid response (TIGR) gene. Glaucoma status for purposes of linkage and mutation analysis was based on a combination of ophthalmologic examination, clinical records, family history, and previously published information. For some individuals reported in the pedigree, but not included in the genotyping studies, less information was available as presented in the text and tables. RESULTS: Autosomal-dominant POAG was confirmed or reported for 78 members of an 8-generation family. Linkage analysis showed significant evidence for linkage of juvenile-onset POAG in one branch of the family to D1S452 (maximum lod score of 6.42 at a recombination fraction of 0.00) and other markers in the vicinity of the GLC1A gene on chromosome 1q. Screening of the TIGR gene identified a mutation that results in substitution of asparagine for isoleucine at codon 477 near the carboxyterminal end of the protein. CONCLUSIONS: The authors' findings strongly suggest that the juvenile-onset POAG locus in this family is the GLC1A locus and that the underlying cause of the disease is the IIe477Asn TIGR mutation that cosegregates with juvenile-onset POAG in one branch of this large family. Lack of samples from deceased individuals prevented the authors from determining whether reported adult-onset cases in this family could also be attributed to the IIe477Asn TIGR mutation. Absence of the IIe477Asn TIGR mutation from other juvenile- and adult-onset POAG families implies that this TIGR mutation is not a common cause of glaucoma.

Adolescent↗
PubMed1984

Trabecular meshwork cell culture in glaucoma research: evaluation of biological activity and structural properties of human trabecular cells in vitro.

The propagation of human trabecular cells in culture allows the study of the structural and functional properties of this distinct cell type under reproducible experimental conditions. Human trabecular cells can be effectively grown from dissected explants of trabecullar tissue, and the cultured cells can maintain the distinctive ultrastructural features of uncultured trabecular cells through at least five passages in vitro. The trabecular cell possesses a wide range of biochemical and structural properties that may be important for the maintenance of the aqueous outflow pathway. These properties include the growth of trabecular cells as an endothelial monolayer with a nonthrombogenic cell surface, the production of plasminogen activator, avid phagocytosis, and the ability to synthesize glycosaminoglycans, collagen, fibronectin, and other connective tissue elements. The presence of hyaluronidase and other lysosomal enzymes emphasizes that human trabecular cells are capable of metabolizing hyaluronic acid and other extracellular materials. Potential mechanisms of trabecular cell damage in vitro are examined by evaluating the effects of extended passage, peroxide exposure, and laser treatment on cellular morphology.

Adolescent↗
PubMed1996

[The study of the biological character on the culture of human trabecular meshwork cells in vitro].

PURPOSE: To establish the culture of human trabecular cells in vitro and to study their biological character. METHOD: The trabecular specimens from human eyes were cultured. The morphologic features of cultured cells were examined by light and electron microscopy, the immunohistochemical characteristics and the proliferative curve of the cultured cells were also investigated. RESULTS: The primary cells in culture are multiangular or irregular, and the confluent trabecular cells grow as a single cell layer. The junctions between trabecular cells observed most frequently are puncta adherens and gap junction. Trabecular cells showed apical villons projections and had a high density of various organelles. The trabecular cells were stained intensely with monoclone antibodies to fibronection and laminin and NSE. And it had negative reaction to monocolone antibodies to VIII factor. The cultured cells showed a longer doubling time. CONCLUSION: The culture of human trabecular cells in vitro was established. This was a key step to dissect the trabecular specimen accurately and carefully. According to the different cellular growth patterns and speed, morphologic and immunohistochemical characteristics from that of the near cells, the cultured human trabecular cells can been identified.

Cell Division↗
PubMed1979

Actin filaments in cells of human trabecular meshwork and Schlemm's canal.

With subfragment-one of myosin used as the histochemical marker, actin filament distribution was mapped in cells of the aqueous outflow pathway. In uveal, corneal-scleral and juxtacanalicular meshwork cells, bundles of actin filaments were present along the basal cytoplasm. Some of these bundles terminated at adhesion plaques. Juxtacanalicular meshwork cells contained, in addition to bundles, randomly oriented actin filaments at the end of cell extensions. Giant vacuoles in the inner wall of Schlemm's canal did not have actin filaments associated with their membranes; there were, however, intermediate filaments present along the membrane. Bundles of actin filaments were also found within the cells of both inner and external walls of Schlemm's canal. Cells of both the meshwork and inner wall of Schlemm's canal had actin filaments extending out into the cytoplasm from cell junctions. In all areas of the meshwork and especially in the area external to Schlemm's canal, cells were observed which had a cytoplasm, very rich in actin filaments. These cells had characteristics common to smooth muscle cells. The actin filaments of cells of the aqueous outflow pathway could have any or all of several functions. Bundles of filaments in the meshwork could contract to lift and separate trabecular sheets and/or, through their association with adhesion plaques, they could stabilize cells on their collagen substrate, thus acting as cytoskeletal struts. Randomly oriented actin filaments, noted particularly in cells of the juxtacanalicular meshwork, may play a role in phagocytosis. Actin filaments found in association with junctions may be important structures for maintaining cell-to-cell contacts. Lack of actin filaments around giant vacuoles in Schlemm's canal indicates that they do not play a role in shuttling aqueous across the endothelium of the canal. The significance of "actin-rich" cells in the meshwork and those external to Schlemm's canal is unknown.

Actins↗