Trans-differentiation of iris pigmented epithelial cells of Euphlyctis cyanophlyctis tadpoles into lens in vitro.

Meshed pigmented iris epithelium along with neural retina of tadpoles of the frog Euphlyctis cyanophlyctis were found to undergo dedifferentiation and subsequently transdifferentiate into lens in culture medium. During lag period, depigmentation (dedifferentiation) occurred in many cells. When culture became confluent 3-4 weeks after seeding tiny lens like structures differentiated from foci of cultured pigmented iris epithelium cells. The percentage of lens formation was higher in vitamin A treated cases. The culture system appears to be a suitable for investigating the changes occurred during trans-differentiation of pigmented epithelial cells into lens.

Retinal pigment epithelial atrophy following indocyanine green dye-assisted surgery for serous macular detachment.

To report subretinal migration of indocyanine green dye (ICG) and subsequent retinal pigment epithelial (RPE) atrophy during macular surgery for serous macular detachment. A 65-year-old woman presented with residual epiretinal membrane and serous detachment of the macula following vitreoretinal surgery for epiretinal membrane. She underwent resurgery with ICG-assisted internal limiting membrane peeling and intraocular tamponade. Intraoperatively a large area of subretinal ICG was seen with subsequent RPE mottling and atrophy of the macula in the area involved during follow-up. This case demonstrates that subretinal migration of ICG is possible and can be toxic to RPE.

Photodynamic Therapy Treatment for Eyes with Drusenoid Pigment Epithelium Detachment

We report the clinical course of photodynamic therapy (PDT) in a patient with drusenoid pigment epithelium detachment (PED). A patient with drusenoid PED underwent PDT follow-up was carried out at one week, one month, three months, six months and one year after treatment. Fundus exam, optical coherence tomography (OCT) and fluorescein angiography were performed. After the PDT, drusen and PED were gradually diminished over one year. However, pure serous PED eventually developed at the same location of the drusenoid PED. The results of the PDT, on drusenoid PED, were initially effective, but not completely successful. Therefore, PDT may be considered as an alternative treatment option for drusenoid PED.

Delay of Photoreceptor Cell Degeneration in rd Mice by Systemically Administered Phenyl-N-tert-butylnitrone

PURPOSE: To study the effect of systemic administration of phenyl-N-tert-butylnitrone (PBN) on the degeneration of photoreceptor cells in rd mice. METHODS: PBN was injected intraperitoneally into FVB/rd mice on postnatal days (P) 5 to 14 (group A), and P10 to 18 (group B). At days P14, 16, 18, 20 and 27, morphological changes and apoptosis were analyzed by staining with hematoxylin and eosin or DAPI. The effect of PBN on apoptosis was analyzed in retinal pigment epithelial (RPE) cells by the measurement of caspase-3 activity. RESULTS: In control and group B mice, the outer nuclear layer (ONL) of the retina was composed of 8-10 rows at P12, and rapidly decreased to one row at P18. In group A mice, the ONL was preserved with 5-7 rows at P18, and decreased to one row at P22. PBN inhibited caspase-3 activity in cultured RPE cells. CONCLUSIONS: PBN delayed, but did not block, the degeneration of photoreceptor cells in rd mice. PBN may exert its inhibitory effect during the early phase of photoreceptor cell degeneration.

The Effects of Glucose on the Expression of MMP and TIMP in Cultured Retinal Pigment Epithelial Cells

This study evaluated the effects of glucose in human retinal pigment epithelial (RPE) cells to investigate the cause of diabetic retinal complications. Human RPE cells were cultured in media containing 5.5 mM, 11.0 mM, and 16.5 mM D-glucose. The present study performed proliferation and migration assays, and conducted western blotting for the protein expression, as well as RT-PCR for the mRNA expression, of MMP-2 and -9, and TIMP-1 and -2. The results of the western blotting analysis showed that increasing glucose concentration significantly increased the expression of MMP-2 and -9, but significantly decreased the expression of TIMP-1 and -2. Moreover, the RT-PCR results indicated significant increases in the mRNA expression of MMP-2 and -9, as well as of TIMP-1 and -2, by raising glucose concentration. This study provides fundamental data for future research on the mechanism of retinal complication in diabetic patients.

Hydrogen Peroxide-Induced Cell Death in a Human Retinal Pigment Epithelial Cell Line, ARPE-19

The loss of retinal pigment epithelium (RPE) with aging is related to age-related macular degeneration (AMD). This study was conducted to investigate the mechanism of hydrogen peroxide (H2O2) induced cell death in a human retinal pigment epithelial cell line, ARPE-19. Hydrogen peroxide was added at different concentrations to ARPE-19 cells and cultured. The cytotoxicity was assayed by mitochondrial function using 3- (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyl tetrazolium bromide (MTT) testing. The patterns of cell damage were assessed using an acridine orange-ethidium bromide differential staining method, in situ end labeling (ISEL) assay and transmission electron microscopy (TEM). Catalase, a major antioxidant, was used to prevent cell death. The cleavage of procaspase 3 and poly (ADP-ribose) polymerase (PARP) was determined by western blot analysis. Hydrogen peroxide significantly induced cell death in ARPE-19 cells, whereas pretreatment of the cells with catalase prevented cell death. Application of the ISEL assay and acridine orange/ethidium bromide staining demonstrated that the H2O2-induced cell death occurred by an apoptotic mechanism at lower concentrations of H2O2 (400, 500, 600 microM), whereas higher concentrations of H2O2 induced necrosis rather than apoptosis. Caspase 3 was associated with the apoptotic pathway in human RPE cell death. Western blot analysis confirmed caspase 3 activation and cleavage of substrate proteins in ARPE-19 cells treated with an H2O2 concentration of 600 microM. These results indicate that treatment with H2O2 induces apoptotic and necrotic cell death in ARPE-19, and that caspase 3 is associated with apoptotic cell death. Therefore, H2O2 may induce the destruction of RPE cells in AMD by the combined effects of apoptosis and necrosis.

Efeito do TGF-Beta2 e do TNF-alfa na cicatrizaçäo do epitélio pigmentado da retina humana: estudo in vitro / TGF-beta2 and TNF-alfa effects on human RPE wound healing

Proposiçäo: determinar o efeito do fator de necrose tumoral (TNF-alfa) e do fator de transformaçäo do crescimento beta 2 (TGF-Beta2) na migraçäo e proliferaçäo do epitélio pigmentado da retina (EPR) em um sistema simplificado de cicatrizaçäo invitro. Métodos: culturas confluentes e subconfluentes de células do EPR humano foram desnudadas centralmente em 2mm de largura com uma lâmina cortante. As culturas foram observadas na presença de RGF-B2 (10ng/ml), TNF-alfa (10ng/ml) ou meio de cultura para células (DMEM), após 24, 48, 72 e 96 horas. A migraçäo foi acessada por contagem do número do número de células na regiäo desnuda. A proliferaçäo foi acessada pela contagem da porcentagem de células positivas por imunohistoquímica para o antígeno ki-67 (relacionado à proliferaçäo celular) na regiäo desnuda e na margem da lesäo. Resultados: as culturas controles apresentaram cicatrizaçäo após 72h em culturas confluentes e após 96h em culturas subconfluentes..

Efeitos do uso do colirio de mitomicina C na superficie ocular de coelhos / Effects of use of mitomycin C on ocular surface in rabbits eyes

Proposito: Investigar os efeitos do uso topico de mitomicina C (MMC), na contagem de celulas caliciformes e no tipo de infiltrado celular inflamatorio, na conjuntiva ocular de coelhos. Metodos: coelhos de raca California receberam duas gotas de MMC (0,2mg/ml) quatro vezes por dia (n=15) ou agua destilada (n=5) por 14 dias. Exames biomicroscopicos foram realizados durante 25 dias. Especimens de conjuntiva para exame histopatologico foram obtidos apos a suspensao do uso de MMC nos dias 1 (n=5), 36 (n=5) e 86 (n=5) e foram processados para microscopia de luz corados com HE e PAS. A contagem de celulas caliciformes PAS-positiva foi realizada em campos de 400 aumentos em cada amostra. Resultados: Hiperemia conjuntival foi observada no quarto dia de instilacao de MMC e persistiu por 7 dias apos a suspensao da droga.

Mecanismos de la secreción del humor acuoso y su modulación por drogas / Aqueous humor secretion mechanisms and it modulation by drugs

Recordemos que el epitelio ciliar consta de dos cepas de células, pigmentadas y no pigmentadas; nuestro concepto es que existe un Sincitium funcional (recordemos que el Sincitium se define como citoplasma con varios núcleos sin límites celulares definidos), esto se refiere a que la membrana basal lateral de las células pigmentadas tiene todos los transportadores que necesita para llevar hacia arriba el cloruro de sodio y luego en consecuencia el agua. Esta membrana tiene el importante intercambio de Na + - K + y obviamente tiene un canal de cloruro y también una etapa de salida de bicarbonato. Nosotros pensamos que esta etapa de salida también puede ser modulada por los inhibidores de la anhidrasa carbónica. Recientemente se mostró en imágenes de video que este concepto es verdadero en el epitelio completo donde ambas cepas de células están juntas; se demostró que los electrolitos son llevados hacia arriba, al interior de la célula, desde las pigmentadas hacia las no pigmentadas y en ellas a la etapa de salida. Por lo tanto hemos visto como el mecanismo del humor acuoso es muy complejo, su secreción comprende apareamiento de transportadores y canales entre células pigmentadas y no pigmentadas y las dos capas de células son funcionalmente una, un Sincitium. Es importante el flujo constante del humor acuoso a través de las cámaras del ojo para una función visual normal. Es necesario un globo ocular formado por una presión intraocular adecuada para mantener la eficacia óptica. Además, el humor acuoso aporta los sustratos necesarios para la función metabólica normal de los tejidos oculares avasculares a los cuales bañan particularmente cristalino, córnea y red trabecular; este flujo de humor acuoso se encarga además de remover los desperdicios metabólicos. Es también un medio para que el iris responda a la luz...