摘要:

Purpose. Proliferative vitreoretinopathy is a serious complication of retinal detachment surgery in which retinal pigment epithelial cells abnormally proliferate within the vitreous cavity and under the retinal surface. Octreotide acetate, a somatostatin analog, has been shown to inhibit the cellular proliferation of a variety of cell types. The aim of this study was to investigate the effect of octreotide acetate on the growth of rabbit retinal pigment epithelial cells in culture.Methods. Retinal pigment epithelial cells were isolated from rabbits and maintained in culture. Cells were exposed to standard media or media supplemented with octreotide acetate 10-4M to 10-12M for five days. Each concentration of octreotide acetate was tested in quadruplicate.Results. Exposure of rabbit retinal pigment epithelial cells to octreotide acetate significantly inhibited proliferation with a peak effect at 10-8M. The effect of octreotide is biphasic with higher and lower concentrations having less effect than 10-8M.Conclusions. This study suggests that octreotide acetate may be useful in the treatment of proliferative vitreoretinopathy; however, the optimum therapeutic dose range for this drug may be narrow. Curr. Eye Res. 15: 909–913, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017634

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose. We recently found that continuous light exposure at a moderate intensity triggered apoptosis of photoreceptor cells. Since intermittent light exposure is known to cause more severe retinal damage than is continuous light exposure, we sought to determine if intermittent light exposure also triggered apoptosis of photoreceptor cells.Methods. Lewis albino rats were reared, for 2 weeks, in cyclic light and dark adapted for 24 hr before light exposure. Rats were exposed to intermittent light or continuous light for 6 or 9 hr, respectively. Light-exposed rats were killed by lethal injection at three timepoints: immediately after light exposure, after 6 hr of dark recovery following light exposure and after 24 hr of dark recovery following light exposure. Retinal damage after light exposure was evaluated by morphology, morphometry, the terminal transferase-mediated biotin dUTP nick end labeling (TUNEL) technique for identification of nicked/cleaved nuclear DNA and agarose gel electrophoresis of retinal DNA.Results. Evaluation of morphology confirmed that intermittent light exposure caused more photoreceptor cell damage than did continuous light exposure of the same duration and intensity. The TUNEL technique showed that photoreceptor nuclei contained nicked or cleaved DNA after either intermittent or continuous light exposure, although more TUNEL-positive nuclei were observed after intermittent exposure. Agarose gel electrophoresis of retinal DNA showed internucleosomal DNA fragmentation, which is associated with apoptosis in samples from intermittent light exposure.Conclusions. These data demonstrated that intermittent light exposure triggered apoptosis in more photoreceptor cells than did continuous light exposure of the same intensity and duration. Curr. Eye Res. 15: 914–922, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017635

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

PurposeTo characterise changes in intravitreal growth factor profiles following retinal photocoagulation in the miniature pig.MethodsMiniature pig eyes underwent scatter photocoagulation by either diode infrared or emerald green laser. Animals were sacrificed at various times (up to 42 days) post-laser. The eyes were then removed and vitreous samples analysed for basic fibroblast growth factor, insulin-like growth factor-I and epidermal growth factor by radioimmunoassay, transforming growth factor-beta2 by ELISA and insulin-like growth factor binding proteins using Western ligand blotting.ResultsVitreous transforming growth factor-beta2 levels were decreased at 1 h post diode laser and at 4 and 7 days post emerald laser but returned to normal by 21 and 42 days respectively. Vitreous insulin-like growth factor-I levels increased at 4 and 7 days post diode and emerald laser respectively but returned to normal by 21 days. Insulin-like growth factor Western ligand blotting demonstrated that a 34 kDa insulin-like growth factor binding protein was predominant in the pig vitreous; the levels of this binding protein followed an identical trend to those observed for insulin-like growth factor-I. No changes in vitreous levels of either basic fibroblast growth factor or epidermal growth factor were observed following laser treatment.ConclusionsOur results demonstrate a significant shift in the balance of intravitreal growth factors following retinal laser photo-coagulation. Such changes may be pertinent to the regression of preretinal new vessels after laser photocoagulation. Curr. Eye Res. 15: 923–931, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017636

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

PurposeA conventional criticism of animal models of retinopathy of prematurity (ROP) concerns the common occurrence of rapid spontaneous resolution of retinal vascular sequelae. The purpose of this study was to determine whether animals subjected to a novel variable oxygen exposure protocol would undergo the rapid spontaneous resolution of retinal vascular pathology that is typical of past models.MethodsNewborn rats were exposed to an oxygen environment that alternated between 50% and 10% every 24 h for 14 days and then removed to room air, or were raised from birth in room air as controls. To determine early retinal vascular growth rate, both exposed and non-exposed rats were sacrificed between 3 and 28 days of age, after which eyes were enucleated and retinas dissected and stained for adenosine diphosphatase (ADPase) activity to demonstrate the vasculature. Rats were maintained in room air for 2 to 18 weeks after the variable oxygen exposure period for assessment of long-term retinal vascular abnormalities by ADPase histochemistry.ResultsThe retinal vasculature of oxygen-exposed rats was significantly different from that of room air-raised rats with respect to capillary density, branching frequency, and bifurcation angle. These differences were restricted to the area that was vascularized after removal to room air (the peripheral-most 25% of the retinal area), and they persisted for the duration of the study.ConclusionsWe have developed a rat model of ROP using an exposure protocol designed to create systemic oxygen levels that approximate those of premature infants. This model does not demonstrate the complete resolution of vessel abnormalities that historically has limited animal models of ROP. Curr. Eye Res. 15: 932–937, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017637

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

PurposeTo show the distribution of an anticoagulant factor, thrombomodulin, in a rabbit eye.MethodsImmunohistochemical staining using polyclonal anti-rabbit thrombomodulin antibody was performed with the excised eyes of pigmented adult rabbits. Streptavidin-biotin method was used to obtain intense staining.ResultsThe endothelium of the chorioretinal vessels showed positive linear staining. The ciliary non-pigmented epithelium showed granular staining, while the pigmented epithelium stained negatively. The positive staining was also detected in the trabecular plexus endothelium. The vascular endothelium of the ciliary body stained weakly.ConclusionsIt is suggested that thrombomodulin in the vessel walls and the aqueous drainage apparatus works to maintain normal blood fluidity and aqueous outflow. The role of non-vascular thrombomodulin in the ciliary non-pigmented epithelium is unclear. Curr. Eye Res. 15: 938–942, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017638

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

PurposeTo examine ocular actions by rilmenidine, an imidazoline1and alpha2adrenoceptor agonist.MethodsIntraocular pressure was measured in normal and sympathetically denervated rabbits by pneumatonometry. Electrically stimulated3H-norepinephrine release from sympathetic nerves was determined in isolated, perfused rabbit iris-ciliary bodies. cAMP levels were evaluated in rabbit iris-ciliary bodies by radioimmunoassay. Ca2+concentrations were measured in rabbit transformed nonpigmented ciliary epithelial cells by fluorescence ratio microscopy.ResultsTopical, unilateral administration of rilmenidine produced hypotensive responses in normal rabbits which were antagonized by either bilaterally administered efaroxan, an imidazoline receptor antagonist or rauwolscine, an alpha2 receptor antagonist. Sympathectomy also eliminated the ocular hypotensive response. Rilmenidine (0.001, 0.01, 0.1, 1.µM) caused 5±1%, 18±5%, 35±10%, and 48±9% inhibition, respectively, of3H-norepinephrine overflow whereas 10µM efaroxan or rauwolscine caused enhancement of norepinephrine release by 102±23% or 86±25%, respectively. Furthermore, pretreatment with efaroxan or rauwolscine partially antagonized the inhibition of norepinephrine release induced by rilmenidine. In other experiments, rilmenidine (1µM) inhibited isoproterenolstimulated cAMP accumulation in rabbit iris-ciliary bodies by 43±9% which was antagonized by 10µM efaroxan or rauwolscine. Rilmenidine induced large increases in [Ca2+]; in rabbit nonpigmented ciliary epithelial cells which were effectively antagonized by efaroxan or rauwolscine.ConclusionsThesein vivoandin vitrodata suggest that the ocular hypotensive activity induced by rilmenidine is due, in part, to suppression of sympathetic neuroeffector function in the rabbit ciliary body and that alpha2 adrenergic receptors and/or imidazolinel receptors are involved. Curr. Eye Res. 15: 943–950, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017639

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

PurposeTo localize proline in the rat retina.MethodWe prepared antibodies raised against proline coupled to bovine serum albumin (BSA) with glutaraldehyde. To confirm the specificity of the antiserum, crossreactivity with other amino acids was determined using an immunodot procedure. Rat eyes were enucleated on postnatal day 21. Immunohistochemistry was performed on semi-thin sections using gold-labelled secondary antibodies and a silver-enhancement technique.ResultsImmunodots revealed that the antiserum was specific for proline. Amino acids from retinal extracts were separated on gel, transferred to BSA-glutaraldehyde treated filters, and stained with antibodies to determine if our antibody reacted only with proline. Staining was most intense on postnatal day 21 and disappeared in the adult retina. In addition to Muller cells, horizontal cells, amacrine cells, and some cells in the ganglion cell layer were labelled.ConclusionsAntibodies raised against proline revealed a transient immunoreactivity in young rat neurons. Our findings strongly indicate that the retina may express a high level of proline in the developmental stages. This result may provide a clue for clarifying the role of proline in the retina. Curr. Eye Res. 15: 951–957, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017640

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

PurposeTo evaluate possible changes in the distribution ofγ-aminobutyric acid (GABA) in diabetic rat retinas.MethodsGABA distributions in the normal control and diabetic rat retinas were determined by a quantitative immunogold electron microscopic immunocytochemistry with anti-GABA antibody. GABA immunoreactivities (GABA-IR) in the retinas were visualized as bound gold colloidal particles in electron microscopy, and the average densities were calculated in each layer or in each kind of cells. The amounts of GABA-IR were statistically compared between normal control and diabetic rat retinas.ResultsIn the normal control rat retinas, the amounts of GABAIR was most abundant in the inner portion of the inner nuclear layer, followed by the inner plexiform layer. GABA-IR in amacrine cells ranged from the background level to the highest throughout the retina. Although the distribution pattern of GABA-IR in the diabetic rat retinas was similar to that of the normal control, GABA-IR increased significantly in the inner segment, the outer nuclear layer, and the outer plexiform layer (P<0.05, by the analysis of variance), and in Müller cells (P<0.001, by Mann-Whitney's U-test) of the diabetic rat retinas. However, pathologic accumulation of GABA-IR was not demonstrated in amacrine cells of the diabetic rat retinas.ConclusionsThese results supported the accumulation of GABA in diabetic rat retinal Müller cells evidenced by light microscopic itnmunocytochemistry previously. It was suggested that GABA accumulation represents one of the functional deterioration of Müller cells in diabetic rat retinas. Curr. Eye Res. 15: 958–964, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017641

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

PurposeDeposition of abnormal sub-epithelial matrix and posterior collagenous layer by epithelium and endothelium, respectively, in Fuchs' dystrophy gives us the opportunity to determine if these tissues synthesizeβig-h3.MethodsImmunohisto-/immunocytochemistry of corneas were conducted with rabbit anti-humanβig-h3 and monoclonal anti-human type VI collagen. Labeled sense and anti-senseβig-h3 oligonucleotide probes were used forin situhybridization.Resultsβig-h3-specific fluorescence was found just beneath detached epithelium in the sub-epithelial matrix, abnormal Descemet's membrane and posterior collagenous layer. Type VI collagen co-localized withβig-h3 within abnormal sub-epithelial matrix and corneal stroma adjacent to Descemet's membrane.βig-h3 mRNA was detected in corneal epithelium of dystrophic corneas.ConclusionsExpression ofβig-h3 in sub-epithelial matrix and posterior collagenous layer of Fuchs' dystrophy is consistent with the synthesis of new extracellular matrices by epithelial and endothelial tissues.βig-h3 mRNA in corneal epithelium further supports an epithelial source of this protein. Endothelial synthesis ofβig-h3 is based on circumstantial evidence due to cell loss during surgical and histological procedures. Co-localization ofβig-h3 with type VI collagen in abnormal sub-epithelial matrix and at the stromal/Descemet's membrane interface suggest this collagen in association withβig-h3 interacts with these tissues and anchors them to the adjacent stroma. Curr. Eye Res. 15: 965–972, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017642

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

PurposeTo compare the supporting mechanism between the serum-free and the fibroblast-cocultured single-cell clonal culture systems.MethodsClonal growth, measured by colony forming efficiency (CFE) and size, was compared between rabbit corneal and limbal epithelial cells in a previously-established serum-free MCDB medium supplemented with growth factors, and in a coculture system with a feeder layer of mitomycin C-treated mouse 3T3 fibroblasts grown in the MCDB or DMEM medium plus 20% fetal bovine serum (FBS).ResultsLimbal epithelial cells in the serum-free MCDB medium had a significantly lower CFE than corneal epithelial cells (p<0.001), suggesting that this system promoted more clonal growth of corneal progenitor cells. In contrast, with cocultured 3T3 fibroblasts limbal CFE was significantly increased (p<0.001), while corneal CFE was not changed, indicating that the 3T3 system promoted more clonal growth of limbal progenitor cells. Addition of 20% FBS in the MCDB medium cocultured with 3T3 fibroblasts significantly promoted both limbal and corneal CFEs (p<0.001). For both cultures, switching the serum-containing MCDB medium to the serum-containing DMEM medium produced clonal growth only with cocultured fibroblasts. This epithelial growth-promoting activity was not present on the cell surface or in the extracellular matrix, but present in pre-centrifuged and prefiltered 3T3 fibroblast-conditioned media. Both growth-promoting and anti-apoptotic activities were present in fibroblast-derived serum-free conditioned media. In the presence of this anti-apoptotic activity, serum addition promoted clonal growth, and the expression of cornea-type K3 keratin in limbal colonies was negative using AE-5 monoclonal antibody.ConclusionsFurther purification and characterization of this fibroblast-derived anti-apoptotic survival factor will facilitate understanding of the mechanism by which epithelial stem cells are regulated via epithelial-mesenchymal interactions. Curr. Eye Res. 15: 973–984, 1996.

ISSN:0271-3683    

DOI:10.3109/02713689609017643

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor