Microscopic Analysis of the Water/Glycerol/EO30PS System in Bulk and on a Solid Substrate

Surfactant systems are often employed in cosmetic formulations where they dry on skin as a surface, thereby becoming increasingly concentrated systems. To better understand this drying process, we focused on the difference of self-assembled structures of the water/glycerol/polyoxyethylene (30) phytosteryl ether (EO30PS) system in bulk and on a solid substrate because the interaction between the substrate and the surfactant may have a substantial effect on the self-assembly, which may be related to the bulk structure but in detail may also differ strongly from the bulk situation. In bulk, small-angle neutron scattering (SANS) experiments showed that with increasing loss of water, the degree of ordering increases but changes of the aggregate structure are rather small. The results indicate that ellipsoidal micelles of EO30PS are densely packed and simply become more ordered in bulk during the drying process. On the other hand, neutron reflectometry revealed that EO30PS molecules adsorb onto a Si surface in the form of bilayers and analysis indicates that at a high concentration (c = 20 wt %), there are on average two bilayers (a double bilayer) on the Si substrate. The adsorbed membrane structure of EO30PS is rather thin with respect to its hydrophobic part, indicating tilted molecules, containing only some solvent, and being not highly ordered. These experimental results then allow for a much deeper understanding of the structural properties of practical formulations as they are applied, for instance, in cosmetic lotions.

Novel O/W Emulsions by Utilizing a Vesicle/Disc Transformation of Polyether Modified Silicone

Emulsification is an important technology in the field of cosmetics and household products. Emulsions are in non-equilibrium state; therefore, the products vary depending on the preparation process, and their state changes with time. Furthermore, it is known empirically that different types of oils have different emulsification properties (preparation and stability). For these reasons, the variables in emulsification research are numerous and complicated to analyze. As a result, many industrial applications have had to rely on empirical rules. In this study, emulsions with a lamellar liquid crystalline phase as an adsorption layer at the emulsion interface were investigated. The characteristics of O/W emulsions formed with the excess solvent phases (aqueous and oil phases) separated from the lamellar liquid crystalline phase were investigated based on the phase equilibrium of the ternary system.As a result, it was found that by agitating the aqueous phase containing dispersed vesicles of emulsifier (polyether modified silicone) together with the oil phase, an emulsion with a uniform interfacial membrane of lamellar liquid crystalline phase could be obtained. The emulsions prepared by this method were found to have good stability against coalescence. The process of transformation from vesicles to the uniform liquid crystal interfacial membrane during the emulsification process was clarified by a freeze-fracture transmission electron micrograph and the calculation of interfacial membrane thickness based on precise particle size analysis. Furthermore, the emulsification properties of polyether-modified silicones were clarified using polar oils and silicone oils, which are a combination of high/low and low/high compatibility with hydrophilic (polyethylene glycol) and lipophilic (polydimethylsiloxane) groups of polyether modified silicone, respectively. It is expected that this research will lead to the evolution of various functionalities in products in the fields of cosmetics, household products, food, pharmaceuticals, paint and others.

Promotion of glyoxylic acid penetration into human hair by glycolic acid

OBJECTIVE

Glyoxylic acid (GA) is widely used as a straight perming agent for hair care products, however, advanced GA penetration-enhancing agents are desired due to the peculiar odour and hair colour fading caused by the continuous use of GA products. Hence, it is important to develop a penetration-enhancing agent that helps minimize the GA concentration. We have found that the combined use of GA and glycolic acid (GCA) has a strong hair straightening effect.

METHODS

Straightening hair test was carried out to the evaluation of the effect of additives. Liquid chromatography-mass spectrometry (LC/MS) was performed to quantify the GA penetration amount into human hair. Attenuated total reflection (ATR) Fourier transform-infrared spectroscopy (FT-IR) and FT-IR microscope were implemented to estimate the localization of GA in the hair.

RESULTS

Straightening hair tests indicated that the hair straightening effect by GA was enhanced by the presence of GCA. LC/MS results showed that the addition of GCA enhanced the amount of GA that penetrated human hair by about four times. ATR FT-IR and FT-IR microscope measurements indicated that GA was localized more in the innermost region of hair (medulla) than the cortex and cuticle. The GA accumulated in the medulla disappeared after a hair straightener treatment at 180°C due to the chemical reaction.

CONCLUSIONS

The GA penetration-enhancing effect of GCA is worth investigating to reduce the GA concentration in products for more comfortable use.

Control of Lipid Self-Assembled Structures & Assessment of Lipid Membrane Fluidity by Fluorescence Spectroscopy

It is well known that lipids form various kinds of self-assembled structures. First, lipid nanoparticles dispersed with hydroxy propyl methyl cellulose acetate succinate (HPMCAS) were introduced. The influence of polymers on the lipid self-assembled structures was evaluated by small and wide angle X-ray scattering (SWAXS). Self-assembled structures containing higher alcohols have attracted much attention in the cosmetic industry. The α-form hydrated crystalline phase (often called α-gel) is one of the hydrated crystalline phases which can be exhibited by surfactants and higher alcohols. As surfactants in this study, an ionic complex or a silicone type were used. This review also reports the lipid membrane fluidity by using fluorescence spectroscopy.

Novel Cubosome System Resistant to Lipid Removal by Serum Albumin

Cubosomes are lipidic nanoparticles containing bicontinuous cubic structures. Their unique architecture and potential as drug delivery vehicles have attracted researchers' attention. However, cubosome systems that are more robust in the presence of plasma components are being sought after for applications in intravenous administration. In this study, we prepared cubosomes consisting of 1,2-dioleoyl-sn-glycero-3-hexylphosphocholine (hexyl-DOPC) and compared their interaction with bovine serum albumin (BSA), the most abundant protein in plasma, with that of conventional cubosome systems consisting of several bicontinuous cubic phase-forming lipids, including 1-monoolein (MO), 1-O-(5,9,13,17-tetramethyloctadecanoyl)erythritol (EROCO C22), or 1-O-(5,9,13,17-tetramethyloctadecyl)-β-D-xylopyranoside (β-XP). The average number of lipids bound to each BSA molecule was between 1.2-4.0 for MO, EROCO C22, and β-XP. On the other hand, hexyl-DOPC exhibited negligible binding to BSA. This result suggests that hexyl-DOPC, which was shown to resist removal from particles by BSA, can be used as a new lipid component of cubosomes, and has higher plasma stability than the other cubic phase-forming lipids.

Physicochemical Properties of α-Form Hydrated Crystalline Phase of 3-(10-Carboxydecyl)-1,1,1,3,5,5,5-heptamethyl Trisiloxane/Higher alcohol/Polyoxyethylene (5 mol) Glyceryl monostearate/Water System

The α-form hydrated crystalline phase (often called as an α-gel) is one of the hydrated crystalline phases which can be exhibited by surfactants and lipids. In this study, a novel system of an α-form hydrated crystal was developed, composed of 3-(10-carboxydecyl)-1,1,1,3,5,5,5-heptamethyl trisiloxane (CDTS), polyoxyethylene (5 mol) glyceryl monostearate (GMS-5), higher alcohol. This is the first report to indicate that a silicone surfactant can form an α-form hydrated crystal. The physicochemical properties of this system were characterized by small and wide angle X-ray scattering (SWAXS), differential scanning calorimetry (DSC), and diffusion-ordered NMR spectroscopy (DOSY) experiments. SWAXS and DSC measurements revealed that a plurality of crystalline phases coexist in the CDTS/higher alcohol/water ternary system. By adding GMS-5 to the ternary system, however, a wide region of a single α-form hydrated crystalline phase was obtained. The self-diffusion coefficients (D_sel) from the NMR measurements suggested that all of the CDTS, GMS-5, and higher alcohol molecules were incorporated into the same α-form hydrated crystals.

Treatment with Bifemelane for Optic Nerve Damage following High Intraocular Pressure in Rat Eyes

This study found that pretreatment with 4-(o-benzylphenoxy)-N- methylbuty-lamine hydrochloride (bifemelane hydrochloride, Celeport) reduced ischemia-reperfusion injury in rat eyes. Bifemelane (25 mg/kg) was injected intraperitoneally 30 minutes before an ischemic insult, then acute ischemia of the retina and optic disc was induced by increasing intraocular pressure to 110 mmHg for 45 minutes. After one week, the axonal count of the optic nerve was investigated using electron microscopy. The control group consisted of vehicle-treated eyes which received normal saline. The axon count was 93.4 +/- 7.9 for the bifemelane treated group, and 79.2 +/- 6.4 for the controls. The axon count in the treated group was significantly higher. These results suggest that bifemelane, which prevents cerebral nerve cell damage from ischemia, can reduce ischemic retinal nerve cell injury.

Effect of Dialkyl Ammonium Cationic Surfactants on the Microfluidity of Membranes Containing Raft Domains

It has been reported that a lot of receptors localize in lipid raft domains and that the microfluidity of these domains regulates the activation of these receptors. In this study, we focused on the lipid raft and in order to evaluate the physicochemical effects of surfactants on microfluidity of lipid membranes, we used liposomes comprising of egg-yolk L-α-phosphatidylcholine, egg-yolk sphingomyelin, and cholesterol as a model of cell membranes containing raft domains. The microfluidity of the domains was characterized by fluorescence spectrometry using 1,6-diphenyl-1,3,5-hexatriene and 2-dimethylamino-6-lauroylnaphthalene. Among several surfactants, dialkylammonium-type cationic surfactants most efficiently increased the microfluidity. It is therefore concluded that (1) the electrostatic interaction between the cationic surfactant and eggPC/eggSM/cholesterol liposome could be important, (2) surfactants with alkyl chains more effectively inserted into membranes than those with acyl chains, and (3) cationic surfactants with lower T_m values have a greater ability to increase the fluidity.

Useful modified cellulose polymers as new emulsifiers of cubosomes

This report introduces modified cellulose polymers as new emulsifiers of cubosomes. We prepared novel nanoparticles containing cubic-phase-forming lipids using hydroxypropyl methylcellulose acetate succinate (HPMCAS). Small-angle X-ray scattering showed a much lower incorporation of HPMCAS into the cubic structure of monoolein than did a conventional emulsifier, Pluronic F127, which is known to modify the cubic structure. Cubosomes prepared with HPMCAS showed roughly equal stability as nanoparticles with Pluronic F127. These results suggest that HPMCAS can be a novel emulsifier of cubosomes, which brings about no internal structure modification.

Expression of cytokines and transcription factors in photocoagulated human retinal pigment epithelial cells

BACKGROUND

It has been shown that scatter photocoagulation induces regression of retinal neovascularization, but the mechanism for this effect is not completely understood. The main focus of our research is to determine the mechanism for the beneficial effects of photocoagulation. In the present study, we quantified the expression of growth factors and transcription factors that inhibit or induce angiogenesis in photocoagulated human retinal pigment epithelial (RPE) cells in vitro.

METHODS

RPE cells were grown to confluence, and RNA was isolated from the RPE cells with or without photocoagulation. The following growth factors, their receptors and transcription factors were examined by reverse transcription polymerase chain reaction (RT-PCR): transforming growth factor (TGF)-beta 1, basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), kinase insert domain-containing receptor (KDR/flk-1), hypoxia-inducible factor (HIF)-1, ETS-1, nuclear factor kappa B (NF-kappa B), interleukin-8 (IL-8).

RESULTS

Laser photocoagulation increased the expression of TGF-beta 1. Expression of angiogenic factors bFGF, VEGF, IL-8 and their transcription factor, ETS1, was also increased. However, the up-regulation of these factors was observed early (6 h) after photocoagulation. Seventy-two hours after photocoagulation, when RPE cells were repaired, the expression of VEGF, IL-8, ETS-1, and NF-kappa B was decreased to the levels before photocoagulation.

CONCLUSIONS

These results suggest that TGF-beta produced by photocoagulated RPE cells and the down-regulation of angiogenic factors in repaired RPE cells, in all likelihood, play an important role in the processes that occur after laser photocoagulation.

Comparative study of experimental choroidal neovascularization by optical coherence tomography and histopathology

PURPOSE

To study the development, progression, and regression of experimental choroidal neovascularization (CNV) by correlating the cross-sectional images from sequential optical coherence tomography (OCT) with histopathologic sections of the same retinal regions.

METHODS

Laser photocoagulation was performed in the posterior pole of the eye of 4 rhesus monkeys to induce CNV. Funduscopy, fluorescein angiography (FAG), and OCT were performed on day 1 and weekly for 13 weeks. Histological serial sections of CNV tissue were compared to corresponding OCT images.

RESULTS

In the developmental stage of CNV, the CNV was observed by OCT as a nodular high reflex area continuing from the highly reflective retinal pigment epithelium (RPE). Histopathological studies showed that the CNV was composed of tightly packed proliferated RPE and immature vascular endothelial cells. In the active stage, OCT revealed a thick multi-layered high reflex area under the sensory retina. This high reflex area corresponded with the CNV membrane that consisted of newly formed blood vessels with wide vascular lumens and proliferated spindle-shaped RPE cells. In the regressive stage, OCT revealed a dome-like, white-colored highly reflective layer continuing from the RPE layer with moderate reflection beneath the layer. Histopathologically, the neovascular tissue was enveloped by mono-layered, cuboidal-shaped RPE cells with melanin granules.

CONCLUSION

Optical coherence tomography images clearly demonstrated the positional relationship between the CNV and the RPE. Optical coherence tomography imaging provides information on the CNV which complements conventional examinations by funduscopy and FAG.

Enhancement of dedifferentiation and myoid differentiation of retinal pigment epithelial cells by platelet derived growth factor

AIMS

To clarify factor(s) involved in morphological dedifferentiation of retinal pigment epithelial (RPE) cells in vitro from mitotically quiescent hexagonal cells to flattened cells that lack epithelial characteristics and concurrent myoid differentiation.

METHODS

RPE cells which retained their differentiated hexagonal morphology were isolated from bovine eyes by mechanical pipetting. Dedifferentiation and myoid differentiation of RPE cells were examined by microscopic observation and immunohistochemical analysis using antibodies against cytokeratin, an epithelial marker, and alpha smooth muscle actin, a marker of myoid differentiation. The contractile ability of RPE cells was evaluated by collagen gel contraction assay.

RESULTS

Platelet derived growth factor (PDGF) enhanced morphological changes in the RPE from hexagonal-shaped cells to flattened cells. Coincident with this morphological alteration, the expression of cytokeratin in RPE cells decreased and expression of alpha smooth muscle actin began and was increased in a time dependent manner. These alterations were completely blocked by collagen synthesis inhibitors. Interleukin 1beta, transforming growth factor beta1, insulin-like growth factor I, and basic fibroblast growth factor had little or no effect on the dedifferentiation. PDGF also potentiated the RPE induced collagen gel contraction.

CONCLUSIONS

These results demonstrate that PDGF enhanced the dedifferentiation of RPE cells, the initial step of proliferative vitreoretinopathy (PVR), as well as myoid differentiation and collagen gel contraction. PDGF may have a versatile role in the pathogenesis of PVR involving collagen synthesis.

The second eye of Japanese patients with unilateral exudative age related macular degeneration

AIM

To clarify the incidence of choroidal neovascularisation (CNV) and predisposing findings for development of CNV in the second eye of Japanese patients with unilateral exudative age related macular degeneration (AMD).

METHODS

The second eyes of unilaterally affected patients with exudative (neovascular) AMD treated in our clinic during the past 10 years (1988-97) were carefully followed up for more than a year. Evidence of CNV was confirmed by fluorescein and indocyanine green angiography. Macular lesions in patients, in whom CNV developed in the second eye, were retrospectively evaluated from patient records.

RESULTS

170 patients met the criteria. The average follow up period was 47 months (range 12-108 months). All patients were Japanese. CNV developed in the second eye in 12 (7%) of 170 patients, 30.3 months on average after the first examination. Cumulative incidence of developing CNV in the second eye using Kaplan-Meier life table analysis was: 0.6% by 1 year, 5.6% by 3 years, and 12.3% by 5 years, and was relatively low compared with that in white patients. CNV developed most frequently from serous pigment epithelial detachment (PED) in the macula (58%). Soft drusen were not prevalent and risk of developing CNV was not very high (18%).

CONCLUSION

It was confirmed that there were some differences in the incidence and predisposing findings for CNV developing in AMD among Japanese and other Asian patients compared with those in white people. It is important to recognise these differences between the two populations to understand the pathogenesis and epidemiology of AMD.

Occult retinal pigment epithelial detachment in hyperviscosity syndrome

We document and evaluate a serous retinal detachment in a patient with hyperviscocity syndrome. Optical coherence tomographic images of the serous retinal detachment in a patient with hyperviscocity syndrome were correlated with slit-lamp biomicroscopic findings, fundus photographs, fluorescein angiograms, and indocyanine green angiograms. Fluorescein angiography demonstrated venous and capillary bed abnormalities but no leakage or pooling of fluorescein corresponding to the retinal pigment epithelial detachment (PED) beneath the serous retinal detachment. Indocyanine green angiogram disclosed a delay of intrachoroidal circulation. Optical coherence tomography (OCT) revealed a large retinal pigment epithelial detachment beneath the serous retinal detachment. The occult retinal PED beneath the neurosensory retinal detachment was detected only by OCT in a patient with hyperviscosity syndrome. We suggest that gamma globulin, which is the hyperviscosity material, accumulated in the subretinal pigment epithelial space and blocked the leakage or pooling of fluorescein corresponding to the retinal pigment epithelial detachment.

Optical coherence tomographic findings of idiopathic polypoidal choroidal vasculopathy

BACKGROUND AND OBJECTIVE

To identify the histological level of abnormal vessels associated with idiopathic polypoidal choroidal vasculopathy (IPCV), we examined IPCV with Optical Coherence Tomography (OCT).

PATIENTS AND METHODS

Fourteen patients diagnosed with IPCV were examined with Indocyanine green (ICG) angiography and OCT.

RESULTS

ICG angiography demonstrated branching vascular networks with polypoidal dilatations at the terminals beneath the retinal pigment epithelium (RPE). OCT showed dome-like elevation of the RPE, and moderate reflex or nodular appearance were seen beneath the RPE.

CONCLUSION

The abnormal vessel associated with IPCV is supposed to be choroidal neovascularization with polypoidal dilatations at the terminals between Bruch's membrane and RPE. We consider that this disease is a peculiar form of age-related macular degeneration.

[Ciliochoroidal detachment following scleral buckling surgery for rhegmatogenous retinal detachment]

PURPOSE AND METHODS

We observed the peripheral choroid; ciliary body, and depth of the anterior chamber by ultrasound biomicroscopy (UBM) in 31 eyes with rhegmatogenous retinal detachment before and after scleral buckling surgery. Scleral encircling was performed in 11 eyes and segmental scleral buckling in 20 eyes.

RESULTS

With UBM, ciliochoroidal detachment was detected in all eyes (100%) following scleral encircling and in 8 eyes (40.0%) following segmental scleral buckling. After scleral encircling procedure, the eyes with preoperatively bullous and wide retinal detachment showed a severe ciliochoroidal detachment and edema of the ciliary body. Shallowing of the anterior camber occurred in all 11 eyes (100%) after scleral encircling and in 12 of 20 eyes (60.0%) after segmental scleral buckling. Marked shallowing with closure of the angle and elevated intraocular pressure occurred in 2 eyes.

CONCLUSION

The results showed that careful postoperative examinations for the anterior segments, chamber angle, and intraocular pressure are necessary with slit-lamp examination and applanation tonometry after scleral buckling surgery.

Uveal effusion syndrome: clinical features, surgical treatment, histologic examination of the sclera, and pathophysiology

PURPOSE

To clarify clinical features and pathophysiology and to evaluate surgical outcome of subscleral sclerectomy for primary uveal effusion syndrome.

DESIGN

Prospective, consecutive noncomparative case series.

PARTICIPANTS

Nineteen eyes of 16 patients diagnosed with uveal effusion syndrome treated in our clinic between 1989 and 1998.

METHODS

Patients were examined by routine ophthalmologic examinations, fluorescein and indocyanine green angiography; measurement of the axial length of the eyeball; magnetic resonance imaging; and echography. Subscleral sclerectomy (sclerectomy under the scleral flap) was performed at the equator on all patients. Histologic examination of excised sclera was carried out on all samples. Patients were followed for outcome over time.

MAIN OUTCOME MEASURES

Reattachment of the choroid and retina with resolution of the serous fluid.

RESULTS

Three subgroups were identified: In type 1, nanophthalmic eye; the eyeball is small (average axial length 16 mm) and high hypermetropic (average +16 diopters); in type 2, the eyeball size is normal (average axial length 21 mm) with small refractive error; and in type 3, the eyeball size is normal. Histologically, types 1 and 2 demonstrated abnormal sclera with disorganization of collagen fiber bundles and deposits of proteoglycans in the matrix, whereas type 3 showed normal sclera. Subscleral sclerectomy was effective for types 1 and 2, inducing postoperative resolution of the subretinal fluid. However, type 3 eyes were not helped by this technique.

CONCLUSIONS

Primary uveal effusion syndrome is caused by abnormalities of the sclera and increased resistance to transscleral fluid outflow as subscleral sclerectomy is an effective treatment in types 1 and 2 only, correct preoperative classification is essential for early surgical management.

In vivo gene transfer into choroidal neovascularization by the HVJ liposome method

PURPOSE

To evaluate the efficacy of the HVJ liposome method for gene transfer in rats with experimentally induced choroidal neovascularization.

METHODS

Plasmid DNA containing the LacZ reporter gene, or fluorescein isothiocyanate (FITC)-labeled double-stranded phosphorothioate oligodeoxynucleotides (S-ODNs), was encapsulated in liposomes. The liposomes were coated with the envelope of inactivated hemagglutinating virus of Japan (HVJ). Intense laser burns were applied to the posterior pole of the retina of pigmented rats to induce choroidal neovascularization. Following photocoagulation, HVJ liposome suspension was injected into the vitreous. On days 3, 7, 14, and 28 after injection, the eyes were removed and fixed. The eyes injected with LacZ gene were reacted with X-gal, frozen, and cut into thin sections. The sections were examined for the expression of the LacZ gene by light microscopy. The enucleated eyes injected with double-stranded S-ODNs were frozen, cut into thin sections, and examined a confocal scanning laser microscope for FITC labeling. Eyes without injection of HVJ liposomes served as controls.

RESULTS

Expression of LacZ genes (beta-galactosidase activity), or localization of FITC labeling, was observed mainly in the laser-induced choroidal neovascular tissue from 3 to 28 days after the intravitreal injection of HVJ liposome.

CONCLUSIONS

We conclude that the HVJ liposome method achieved effective gene transfer into choroidal neovascular tissue. Thus, this method can be used as a nonviral gene therapy system for the treatment of choroidal neovascularization in vivo.

[Effects of corticosteroid on porcine retinal pigment epithelial cells in culture--2. Effects on phagocytosis and lysosomal activity]

PURPOSE

The effects of a corticosteoid on the phagocytosis and lysosomal activity of cultured porcine retinal pigment epithelium (RPE) cells were investigated.

METHODS

After exposing cultured RPE cells to various concentrations (10, 50, 100, 500, 1,000 nM) of betamethasone sodium phosphate (betamethasone), the cells were incubated with latex microspheres for 6 hours.

RESULTS

The number of latex microspheres phagocytized by the cultured RPE cells was inhibited by 50 nM betamethasone within 24 hours. Ten-nM betamethasone did not inhibit the proliferation of cultured RPE cells, but ingestion of latex microspheres by the cells was inhibited after 3 days. Lysosomal activity (acid phosphatase, beta-glucuronidase) of RPE cells was inhibited by a high concentration (500 nM) of betametasone.

CONCLUSION

These results suggest that corticosteroid inhibits the phagocytosis and lysosomal activity of cultured RPE cells.

Histopathological findings of X-linked retinoschisis with neovascular glaucoma

BACKGROUND

X-linked retinoschisis (XLRS) is rarely complicated by neovascular glaucoma. Only a few reports of XLRS histopathological findings with neovascular glaucoma have been published.

METHODS

A 41-year-old man with XLRS complicated by neovascular glaucoma in his left eye was examined with electroretinography, B-scan, ultrasound biomicroscopy and computed tomography. He was examined by ophthalmoscopy and fluorescein angiography in the other eye. An enucleation was performed in his left eye due to uncontrollable high intraocular pressure and persistent ocular pain. We examined the enucleated eye histopathologically.

RESULTS

Examination of the enucleated eye showed nuclear sclerosis of the lens, pigmented retrolental membrane and retinoschisis which separated the inner layer of the retina and made a large space in the vitreous cavity without any apparent detachment of the outer layers of the retina. Sclerotic vessels were present histopathologically in both the inner and outer layers of the retina. There was a peripheral anterior synechia, ectropion uveae and a fibrovascular membrane, which contained many lumina of neovascularization, indicating marked rubeosis iridis. Small cystic spaces were observed in both the schitic retina in the peripheral region and the foveal schisis at the outer layer of the retina. The photoreceptor cells had become markedly atrophied and multiple regions of calcification were observed. The optic nerve showed severe atrophy with gliosis, but the central retinal artery and vein were still open within the nerve.

CONCLUSIONS

These histopathological findings suggest that rubeosis iridis may have developed secondarily to retinal ischemia due to occlusion of the retinal blood vessels.

Heterogeneity in ornithine cytotoxicity of bovine retinal pigment epithelial cells in primary culture

Gyrate atrophy of the choroid and retina is a chorioretinal degeneration caused by hyperornithinemia and a deficiency of ornithine-delta-aminotransferase (OAT). We recently showed that ornithine exhibits cytotoxicity to human retinal pigment epithelial (RPE) cell lines treated with the OAT inhibitor, 5-fluoromethylornithine (5-FMOrn), and suggested that this system may be an in vitro model of gyrate atrophy. In the present study, in order to apply this system to primary cultured RPE cells, we freshly prepared RPE cells from bovine eyes and studied the effect of ornithine on cell damage. Two phenotypes, epithelioid and fusiform, which coexisted in the primary culture and epithelioid phenotype cells, but not fusiform ones, were severely damaged and partially detached from the substrate by 10 m m ornithine and 0.5 m m 5-FMOrn. Neither ornithine nor 5-FMOrn alone exhibited such cytotoxicity to both phenotypes of RPE cells. Proline significantly prevented the ornithine-induced cytotoxicity. Epithelioid and fusiform phenotypes isolated from the primary culture showed different distribution of actin filaments. A combination of ornithine and 5-FMOrn time-dependently inhibited [(3)H]thymidine incorporation in the epithelioid, but not fusiform, cells. Proline prevented the inhibition of [(3)H]thymidine incorporation by ornithine in 5-FMOrn-treated epithelioid cells. Furthermore, l -azetidine-2-carboxylic acid, a collagen synthesis inhibitor, reduced [(3)H]thymidine incorporation in epithelioid, but not fusiform, cells, which was reversed by proline. These results demonstrate that the epithelioid phenotype of bovine RPE cells becomes susceptible to ornithine following inactivation of OAT. The phenotypic cells and its prevention by proline may provide insight into biochemical triggers that induce gyrate atrophy.

Changes in choriocapillaris and retinal pigment epithelium in age-related macular degeneration

Retinal pigment epithelial cells (RPE) and the choriocapillaris are on opposite sides of Bruch's membrane and control transport in and out of the retina. In age-related macular degeneration (AMD), they may also be responsible for deposition of material in and on Bruch's membrane and the formation or regression of choroidal neovascularization (CNV). Indocyanine green (ICG) angiography can be used to visualize the choroidal vasculature and CNV. Filling of the choriocapillaris with ICG was delayed in subjects older than 50 years of age, and areas of hypofluorescence were observed in maculas of AMD subjects, often associated with CNV. Laser Doppler flowmetry of the choriocapillaris in the macula demonstrated that choroidal blood flow and volume are reduced in subjects older than 46 years of age and further decreased in subjects with AMD. The human choriocapillaris can be histologically studied in two dimensions by incubating the tissue for alkaline phosphatase activity, flat-embedding it in transparent polymer and sectioning it. Using this technique, choriocapillaris dropout was found to be associated with deposition of material in Bruch's membrane in diabetic subjects. When RPE are removed from Bruch's membrane, the choriocapillaris degenerates; the regeneration of choriocapillaris can be blocked by Genistein, a tyrosine kinase inhibitor. Finally, RPE cells may produce substances that both stimulate the formation and regression of CNV in animal models. These studies suggest that there may be a reduction in choriocapillaris flow in AMD, and this loss of choriocapillaris can be associated with the Bruch's membrane deposits that are hallmarks of AMD. Furthermore, RPE may stimulate the formation and regression of CNV and RPE loss can result in loss of choriocapillaris.

Transfection of basic fibroblast growth factor (bFGF) gene or bFGF antisense fene into human retinal pigment epithelial cells

BACKGROUND

Transplantation of RPE cells offers a potential of restoring retinal pigment epithelium (RPE) function and has been shown to be effective in the dystrophic RCS rat model. Recently, RPE transplantation was attempted in patients with age-related macular degeneration. Basic fibroblast growth factor (bFGF) plays important roles in maintaining normal retinal function. The purpose of this study was to introduce bFGF sense or antisense cDNA into human RPE cells to alter the expression of bFGF.

METHODS

Human bFGF sense cDNA or antisense cDNA was inserted into the pBK-CMV vector. For stable gene expression, we introduced the plasmids into RPE cells using the electroporation method. Following electroporation, transfected RPE cells were cultured and resistant cells were selected in the presence of antibiotic G418. We analyzed the expression of the transfected genes in the cloned RPE cells by polymerase chain reaction (PCR) and by reverse transcription (RT)-PCR.

RESULTS

Cloned RPE cells in which the bFGF sense or antisense cDNA had been efficiently transfected were established. PCR and RT-PCR analysis demonstrated not only the presence but also the expression of bFGF sense or antisense cDNA in the transfected RPE cells.

CONCLUSIONS

Human bFGF sense cDNA or antisense cDNA can be efficiently introduced into cultured RPE cells by the electroporation method. The successful expression of the genes into RPE cells demonstrated that this technique can be used to regulate bFGF expression and thus increase the scope of RPE transplantation for the treatment of retinal diseases.

Idiopathic polypoidal choroidal vasculopathy in Japanese patients

OBJECTIVE

To describe the vascular nature and clinical features of idiopathic polypoidal choroidal vasculopathy in Japanese patients.

METHODS

Patients thought to have idiopathic polypoidal choroidal vasculopathy were examined with binocular ophthalmoscopy, slitlamp biomicroscopy with a contact lens, fluorescein angiography, and indocyanine green angiography.

RESULTS

From January 1993 to December 1997, 35 eyes in 32 patients were diagnosed as having idiopathic polypoidal choroidal vasculopathy. Men were predominantly affected (22 patients [69%]). Most patients were unilaterally involved (29 patients [91%]) and elderly, with a mean age of 65.7 years (range, 44-82 years). Ocular manifestations were relatively mild, with serous or hemorrhagic detachments of the retinal pigment epithelium and neurosensory retina in the posterior pole. Most patients had a favorable course, although some experienced recurrence, and a few eyes developed disciform scarring. In all patients, indocyanine green angiograms demonstrated branching vascular networks with polypoidal dilations at terminals of the network beneath the retinal pigment epithelium. These lesions were mostly in the macula (33 eyes [94%]), with a few in the peripapillary area.

CONCLUSIONS

Idiopathic polypoidal choroidal vasculopathy in Japanese patients differs from that in American patients. It seems that this disorder occurs in elderly Japanese patients and should be treated as a distinct clinical entity. It is probably a peculiar form of choroidal neovascularization beneath the retinal pigment epithelium. We propose the term "polypoidal choroidal neovascularization" for this disorder.

[Histological proof of indocyanine green angiography--healthy eyes]

PURPOSE

To determine the histological localization of indocyanine green (ICG) in the healthy rat eye and to correlate this with ICG angiographic findings.

METHODS

After intravenous ICG dye injection, the rat eyes were enucleated and processed by freeze-substitution fixation with acetone. The tissue sections were stimulated with an 805-nm diode laser and observed with an infrared microscope with an intensified charge coupled device camera. The histological examinations of ICG localization were correlated with the ICG angiographic images.

RESULTS

ICG dye did not leak from the retinal and iris vessels. However, in the choroid, extravasation of ICG from the choriocapillaris was observed. The extravascular ICG from the choriocapillaris slowly diffused to the choroidal stroma but did not diffuse to the neurosensory retina through the retinal pigment epithelium.

CONCLUSIONS

Change in the localization of ICG in ocular tissue was demonstrated in the ICG angiographic findings. These results help to interpret clinical ICG angiographic findings.

[Angiographic findings and histological localization of indocyanine green in N-methyl-N-nitrosourea induced retinal degeneration in rats]

PURPOSE

We used N-methyl-N-nitrosourea (MNU) to induce chorioretinopathy as a model of retinitis pigmentosa, and compared the histological localization of indocyanine green (ICG) with ICG angiographic features.

METHODS

Brown-Norway pigmented rats received a single intraperitoneal injection of MNU (75 mg/kg body weight). At 3 and 21 days after treatment, we compared ICG angiographic findings with histological localization of ICG in the retina and choroid. Histological localization of ICG was observed with an infrared light microscope.

RESULTS

3 days after treatment, destruction of the photoreceptor cells and photoreceptor segments had developed, and the retinal pigment epithelial cells (RPEs) were also damaged. In ICG angiography, diffuse hyperfluorescence was evident. In histological localization of ICG, RPEs were stained by ICG, and ICG was seen in the sensory retina through the damaged RPEs. At 21 days after treatment, the inner nuclear layer directly contact with the choroid. The photoreceptor cells, RPEs and choriocapillaris had disappeared. In ICG angiography, hypofluorescence was seen in the chorioretinal atrophic area. In histological localization of ICG, there was no ICG in the atrophic area, but ICG leaked from the remaining choriocapillaris into the neighboring sensory retina.

CONCLUSION

These results support the precise interpretation of ICG angiographic findings in clinical use.

[Effects of corticosteroid on porcine retinal pigment epithelial cells in culture--1. Inhibitory effect on cell proliferation]

PURPOSE

Proliferation is an important function of the retinal pigment epithelial (RPE) cells. The effect of a corticosteroid on the proliferation of cultured porcine RPE cells was investigated.

METHODS

After administration of various concentrations (10-1,000 nM) of betamethasone sodium phosphate (betamethasone), we counted RPE cell numbers at 1, 3, 6, 9, and 14 days.

RESULTS

Betamethasone administration resulted in a dose-dependent decrease in RPE cell proliferation. The proliferation of the cultured RPE cells was significantly inhibited by betamethasone, at a dose of 300 nM in 9 days. Ten-nM betamethasone neither inhibited nor promoted the RPE cell proliferation in culture.

CONCLUSIONS

These results suggest that corticosteroids inhibit proliferation of cultured porcine RPE cells.

[Vascular endothelial growth factor promotes experimental choroidal neovascularization in monkey eyes]

PURPOSE

To evaluate the effect of vascular endothelial growth factor (VEGF) on experimental choroidal neovascularization (CNV) in monkey eyes through clinical, morphometric, and histological observations.

METHOD

CNV was induced in both eyes of 6 rhesus monkeys by intense photocoagulation by red krypton laser. Immediately after photocoagulation, 2.5 micrograms of exogenous human VEGF was injected into the vitreous of the left eye in each animal. The right eyes served as controls. The eyes were enucleated 3 days to 12 weeks after photocoagulation and were examined by light and electron microscopy.

RESULTS

VEGF-treated eyes developed remarkable serous retinal detachment around the sites of photocoagulation with manifest CNV one week after photocoagulation. Although there was no difference in the incidence of CNV between the treated and control eyes, the treated eyes showed more intense leakage of fluorescein from the CNVs for up to 4 weeks after treatment. Morphometrically, the CNVs were significantly larger and continued to grow longer in the treated than in the control eyes after one week of photocoagulation. Histologically, newly formed vessels with a distinct lumen were present in the treated eyes after 3 days of photocoagulation.

CONCLUSION

Intravitreal injection of human VEGF promotes experimental choroidal neovascularization in monkey eyes.

[Effects of local administration of interferon-beta on proliferation of the retinal pigment epithelium]

PURPOSE

We demonstrated effects of local administration of human interferon (IFN)-beta on the repair process of the rabbit retinal pigment epithelium (RPE).

MATERIAL AND METHODS

We used adult pigmented rabbits in this experiment. We measured IFN-beta levels in the ocular tissues after sub-Tenon administration of human IFN-beta by means of enzyme-linked immunosorbent assay (ELISA) methods. Laser photocoagulation in moderate intensity was applied after IFN administration. The repair process of the RPE in laser lesion sites was examined histopathologically.

RESULTS

Locally administrated IFN spread by diffusion into the intraocular tissues. The highest IFN level was detected in the choroid. In eyes treated with IFN, RPE cells proliferated vigorously to the center of the photocoagulated lesions on early stages after laser photocoagulation. Proliferation of RPE cells after laser photocoagulation was remarkable in eyes treated with large amounts of IFN.

CONCLUSION

It was demonstrated histopathologically that sub-Tenon administration of IFN-beta promoted proliferation of RPE cells during the repair process after laser photocoagulation.

Phosphorothioate oligonucleotides induction into experimental choroidal neovascularization by HVJ-liposome system

PURPOSE

The purpose of this study was to determine whether the inactivated hemagglutinating virus of Japan (HVJ)-liposome method can induce phosphorothioate oligonucleotides effectively into an experimentally-induced choroidal neovascularization of rats. We also examined whether antisense phosphorothioate oligonucleotides against VEGF could be induced into choroidal neovascularization as a therapeutic agent by the HVJ-liposome method.

METHODS

The experiments were conducted on a rat model of choroidal neovascularization. FITC-labeled phosphorothioate oligonucleotides were coencapsulated in liposomes. The liposomes were coated with the envelope of inactivated HVJ and injected into the vitreous cavity following photocoagulation of pigmented rat eyes. The eyes were removed following injection, fixed, frozen and cut into thin sections. Induction of oligonucleotides was observed under a laser confocal scanning microscope for fluorescence and the development of choroidal neovascularization was evaluated histopathologically.

RESULTS

Phosphorothioate oligonucleotides were effectively induced into ganglion cells and into the cells of the choroidal neovascularization induced by laser photocoagulation. Highly effective induction of oligos was observed 3 to 14 days after intravitreal injection of HVJ-liposomes after which the level decreased. Antisense oligonucleotides against VEGF were induced specifically into cells in the choroidal neovascularization, however neovascularization was still observed.

CONCLUSIONS

Phosphorothioate oligonucleotides can be effectively induced into ganglion cells, and specifically into cells in choroidal neovascularization. Although antisense oligonucleotides against VEGF failed to prevent choroidal neovascularization, the HVJ-liposome method provided a highly effective means of inducing antisense oligos for in vivo antisense therapy.

Natriuretic peptide receptors, NPR-A and NPR-B, in cultured rabbit retinal pigment epithelium cells

We tried to detect natriuretic peptide (NP) receptor (NPR-A and NPR-B) mRNAs in cultured rabbit retinal pigment epithelium (RPE) cells and examined the regulation of their expression in relation to subretinal fluid absorption or RPE cell proliferation. RPE cells from 2-4 passages were grown to confluence on microporous membranes and analyzed for levels of expression of receptor mRNAs by quantitative RT-PCR and Northern blotting. The expression of NPR-B mRNA was approximately tenfold higher than that of NPR-A mRNA. The expression of NPR-A mRNA was not affected by treatments that may change subretinal fluid transport, while that of NPR-B mRNA was inhibited by transmitters involved in light- and dark-adaptation such as dopamine and melatonin. Expression of NPR-B mRNA was also suppressed by platelet-derived growth factor and transforming growth factor-beta. Furthermore, atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP), ligands for NPR-A and B, respectively, inhibited the proliferation of RPE cells, as analyzed by incorporation of [3H]thymidine. These findings suggest that ANP may be involved in constitutive absorption of subretinal fluid and that NPs form an important regulatory system of proliferation in RPE cells.

Expression of vascular endothelial growth factor and its receptor (KDR/flk-1) mRNA in experimental choroidal neovascularization

PURPOSE

Vascular endothelial growth factor (VEGF) is an angiogenic peptide that has been suggested to be important in the pathogenesis of choroidal neovascularization. We investigated the transcription of VEGF and its receptor KDR/flk-1 genes during the development of experimentally induced choroidal neovascularization.

METHODS

Rat VEGF or KDR cDNA was inserted in PGEM or pBluescript to prepare antisense or sense riboprobes. Multiple krypton laser burns were applied to the posterior pole of pigmented rat eyes according to a previously described protocol which produces choroidal neovascularization. At intervals of up to 4 weeks after photocoagulation, the eyes were removed and cut into thin sections. The sections were subjected to in situ hybridization with digoxigenin (DIG)-labeled single-strand rat VEGF and KDR cDNA riboprobes.

RESULTS

In normal adult rat retinas, VEGF and KDR mRNA expression was mainly observed in the ganglion cell and the inner nuclear layers. During the development of neovascularization, VEGF and KDR mRNAs were detected in retinal pigment epithelial-like cells, fibroblast-like cells and endothelial cells in neovascular lesions. The level of expression was strongest at 1 week after photocoagulation in lasered lesions, and decreased by 4 weeks after photocoagulation.

CONCLUSIONS

Our findings demonstrate that expression of VEGF and its receptor KDR may play a role in the formation of experimentally induced choroidal neovascularization. In this study, VEGF and its receptor were co-localized, suggesting that an autocrine and/or paracrine mechanism may be operative.

Indocyanine green angiography and pathophysiology of multifocal posterior pigment epitheliopathy

PURPOSE

To clarify the pathophysiology of multifocal posterior pigment epitheliopathy (MPPE), or bullous retinal detachment (RD)-an unusual manifestation of central serous chorioretinopathy (CSC)-we evaluated indocyanine green (ICG) angiographic findings of patients with MPPE.

METHODS

Indocyanine green angiography was performed on 45 eyes of 26 patients with MPPE in our clinic during a 4-year period and compared with clinical and fluorescein angiographic (FA) findings.

RESULTS

Ophthalmoscopically, in the posterior pole there were multiple yellowish-white retinal exudations, associated with flat, serous RD and bullous RD in the lower periphery. Fluorescein angiography demonstrated multiple massive leakages from the choroid into the subretinal space. These leakage sites corresponded to the retinal exudations. Indocyanine green angiography showed hyperfluorescence in the posterior pole of the choroid. The hyperfluorescence was first seen in the middle phase and became prominent in the late phase. This finding seems to be due to extravasation from the choriocapillaris. After laser photocoagulation of the leakage sites seen on FA, the leakages stopped and the retinal exudations and RD were resolved. Indocyanine green angiography, however, revealed hyperfluorescence in the posterior pole that was seen in active stage.

DISCUSSION AND CONCLUSION

These ICG angiographic findings for MPPE show that hyperpermeability of the choroidal vessels may be the primary causative lesion. This is followed by an intrastromal accumulation of the extravasated choroidal fluid, which may be subclinical. Involvement of the retinal pigment epithelium may be secondary, and then the disease becomes manifest with RD. In MPPE, a severe form of CSC, the retinal pigment epithelium is involved extensively and widely, and prognosis is unfavorable. We conclude that MPPE and CSC represent opposite ends of a common morbid spectrum.

Surgical outcome on combined procedures of lens extraction, intraocular lens implantation, and vitrectomy during removal of the epiretinal membrane

BACKGROUND AND OBJECTIVE

The authors evaluated the outcome of combined procedures of lens extraction, intraocular lens implantation, and vitrectomy during procedures for the removal of the epiretinal membrane, and attempt to clarify which factors affected the outcome of surgery.

PATIENTS AND METHODS

Surgery for the removal of the epiretinal membrane was performed and a 2-year follow-up program was maintained for 32 eyes at the authors' clinic during the past 5 years. The combined procedure was undertaken in 15 eyes, whereas a simple vitrectomy was performed in 17 eyes. Results were analyzed by postoperative ophthalmoscopic and slit-lamp examinations for visual acuity and complications.

RESULTS

Six months after surgery, visual acuity improved similarly in both groups. But, 2 years after surgery, 11 eyes (65%) that underwent a simple vitrectomy showed decreased visual acuity due to the advancement of cataracts. The postoperative visual acuity at 6 months correlated to preoperative visual acuity, and the advancement of cataracts tended to correlate inversely to the age of the patients. Major complications did not occur in any of the cases.

CONCLUSION

Earlier surgical management is better for treatment of the epiretinal membrane, and a combined procedure has advantages in cost reduction and is less troublesome, especially for elderly patients.

Expression of vascular endothelial growth factor and its receptor, KDR, following retinal ischemia-reperfusion injury in the rat

PURPOSE

There is considerable evidence that vascular endothelial growth factor (VEGF) mediates ocular neovascularization in retinal vascular diseases. We investigated the time-dependent changes in the expression of VEGF and its receptor KDR/ Flk in a transient retinal ischemia-reperfusion injury model.

METHODS

Transient retinal ischemia was induced by increasing the intraocular pressure in albino rats eyes for 45 min. In situ hybridization was used to identify the retinal cells synthesizing VEGF mRNA and KDR mRNA at various times following reperfusion. Immunohistochemical analysis was also carried out to detect VEGF immunoreactivity.

RESULTS

In the control, non-ischemic retinas, signals for VEGF mRNA and KDR mRNA were observed in the cells of the ganglion cell layer. Immunoreactivity to VEGF was also found in the nerve fiber layer, the ganglion cell layer, and the retinal pigment epithelial (RPE) cell layer. Immediately and 6 h after reperfusion, VEGF and KDR mRNA expression was markedly decreased, but recovered by 24 h to the levels observed in normal retinas. Immunoreactivity for VEGF was also decreased immediately and 6 h after reperfusion, and was detected in the endothelial cells of the retinal vessels after 24 h. Immunoreactivity to VEGF recovered by 48 h after reperfusion.

CONCLUSIONS

The hybridization pattern of VEGF and KDR mRNA in the ganglion cell layer strongly suggests that the ganglion cells are the major source of this growth factor. The decrease of VEGF mRNA, KDR/Flk mRNA and VEGF protein levels after ischemia and recovery after reperfusion suggest that transient hypoxia might mediate short-term down-regulation of VEGF and KDR mRNA.

Retinal degeneration induced by N-methyl-N-nitrosourea in Syrian golden hamsters

BACKGROUND

The sequential retinal changes in Syrian golden hamsters induced by N-methyl-N-nitrosourea (MNU) have not been studied.

METHODS

Female hamsters received a single intraperitoneal injection of 90 mg/kg MNU at 50 days of age, and the retina was examined light and electron microscopically, immunohistochemically and by the TdT-mediated dUTP-digoxigenin nick end labeling (TUNEL) method until 20 weeks after the treatment.

RESULTS

The retinal changes were as follows: (1) Photoreceptor apoptosis occurred 1 day after the treatment and resulted in photoreceptor loss at day 7. During the degeneration, Müller cell proliferation was conspicuous at day 5. (2) After the photoreceptor cell loss, migration of the pigment epithelial cells in all layers of the retina which were in contact with blood vessels occurred. Due to the Müller cell proliferation, gliosis was prominent at the later stage.

CONCLUSIONS

The MNU injection caused photoreceptor apoptosis followed by pigment epithelial cell migration around the blood vessels, accompanied by gliosis. The primary event and the course of this disease closely resemble those of retinitis pigmentosa in humans.

Granulocyte-macrophage colony-stimulating factor expressed in T cells mediates immunity against herpes simplex virus type 1 encephalitis

A model of herpes simplex virus type 1 (HSV-1) infection was developed in rats to study systemic immune responses elicited by intravitreous inoculation of the virus. HSV-1 inoculation led to distinct granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing memory T cells, which did not develop in rats inoculated with either HSV-1 intraperitoneally or inactivated HSV-1 intravitreously. On subsequent intraperitoneal viral boosting, systemic GM-CSF production was elicited as a secondary immune response that caused neutroeosinophilia. To examine the role of GM-CSF in anti-herpetic immunity, cytokine-producing and -nonproducing rats were intravitreously challenged with HSV-1, which causes lethal encephalitis. Only intravitreously primed rats were protected upon production of GM-CSF. Furthermore, pretreatment with recombinant GM-CSF protected unimmunized rats against the encephalitis. It is thus strongly suggested that the production of GM-CSF leads to anti-HSV-1 immunity against the transneuronal spread of challenged HSV-1 within the visual system.

Prevention of ornithine cytotoxicity by proline in human retinal pigment epithelial cells

PURPOSE

To investigate the relationship between ornithine-delta-aminotransferase (OAT) deficiency and ornithine accumulation and the specific degeneration of retinal pigment epithelial (RPE) cells in gyrate atrophy.

METHODS

Human RPE cells, human hepatoma cells, and human fibroblast cells were treated with 5-fluoromethylornithine (5-FMOrn), a specific irreversible inhibitor of OAT. Ornithine cytotoxicity was determined by using a [3H]thymidine incorporation assay and immunohistochemical staining for cytokeratin. The effects of various metabolites of ornithine and arginine, such as creatine, creatine phosphate, I-delta 1-pyrroline-5-carboxylic acid (L-P5C), and proline, which may be deficient in gyrate atrophy on RPE cell damage by ornithine, were determined by the same procedures.

RESULTS

When the human RPE cells, HepG2 hepatoma cells, and WI-38 fibroblast cells were treated with 0.5 mM 5-FMOrn for 30 minutes, which inactivated OAT, ornithine exhibited severe time- and dose-dependent inhibition of DNA synthesis in the human RPE cells but not in the HepG2 hepatoma cells or WI-38 fibroblast cells. The inhibition of DNA synthesis was accompanied by drastic changes in morphologic appearance, disorganization of the cytoskeleton, and cell death. Ornithine or 5-FMOrn alone did not exhibit such cytotoxicity to the RPE cells. Proline prevented the cytotoxicity of ornithine.

CONCLUSIONS

These findings suggest that an elevated level of ornithine combined with an increased sensitivity to ornithine as a result of OAT deficiency may be crucial to the specific RPE degeneration in gyrate atrophy. They suggest also that abnormalities of proline metabolism may be involved in the progress of gyrate atrophy.

Expression of basic fibroblast growth factor and its receptor mRNA in retinal tissue following ischemic injury in the rat

BACKGROUND

Our purpose was to determine the time-dependent changes of expression of basic fibroblast growth factor (bFGF) and its receptor in pressure-induced retinal ischemia in rats.

METHODS

Retinal ischemia was induced in Wistar rats by increasing the intraocular pressure to 110 mmHg for 45 min by cannulation into the eyes. At the end of the ischemic period, reperfusion of the retinal vasculature was confirmed. Localization of bFGF and FGF receptor-1 (FGF-R) mRNAs were evaluated by in situ hybridization at various times after reperfusion. The reverse-transcription polymerase chain reaction (RT-PCR) method was used to detect the expression of bFGF and FGF-R mRNA in the sensory retina.

RESULTS

In normal sensory retina, bFGF and FGF-R mRNAs were observed in the ganglion cell layer and inner nuclear layer. bFGF gene expression in the sensory retina increased within 24 h, particularly at 6-12 h. FGF-R gene expression increased earlier than that of bFGF. By RT-PCR, expression of bFGF gene reached a peak at 6-24 h, and FGF-R reached a peak at 3-12 h. These RT-PCR results are comparable to those of in situ hybridization.

CONCLUSIONS

These results demonstrate that transient retinal ischemia leads to the induction of bFGF mRNA synthesis, and suggest that bFGF has a protective role, e.g., a defense mechanism for the sensory retina.

Apoptosis of photoreceptor cells in ornithine-induced retinopathy

BACKGROUND

The intravitreal injection of ornithine produces selective damage to the retinal pigment epithelium (RPE) and results in a loss of RPE, choriocapillaris and photoreceptor cells. To elucidate the mechanism of secondary retinal atrophy, we investigated the presence of apoptotic cells in a rat model of ornithine-induced retinopathy.

METHODS

At 6 and 12 h and 1, 2, 4, 7, 14 and 28 days after an intravitreal injection of L-ornithine hydrochloride in rat eyes, we removed the eyes and subjected them to histopathological examination. We detected apoptotic cells by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate digoxigenin nick end labeling (TUNEL) assay, which stains the 3'-OH ends of fragmented DNA. We used electron microscopy to detect the apoptotic cells morphologically.

RESULTS

RPE cells were selectively damaged immediately after ornithine administration. TUNEL-positive photoreceptor cells appeared exclusively in the photoreceptor cell layer 12 h after ornithine administration. The number of TUNEL-positive cells increased throughout the 2 days following the injection, then decreased markedly. TUNEL-positive cells remained until 28 days, when the photoreceptor cells had disappeared. The ganglion cell layer, inner nuclear layer and damaged RPE cells were negative for TUNEL staining during all stages. The electron microscopic study also revealed the pyknotic nuclei of apoptotic photoreceptor cells.

CONCLUSION

An intravitreal injection of ornithine caused primary damage to the RPE, and subsequently some of the photoreceptor cells revealed apoptosis by TUNEL assay. These findings suggest the dysfunction of the RPE causes photoreceptor cell death according to the intrinsic program of an apoptotic mechanism.

Midkine expression in transient retinal ischemia in the rat

PURPOSE

Midkine (MK), a 13-kDa heparin-binding growth factor, is known to exert neurotrophic activities on various nerve cells including retinal cells. To initiate studies toward determining the physiological role of endogenous MK, we investigated the spatial and temporal expression profile of MK before and after intraocular pressure-induced retinal ischemia.

METHODS

Retinal ischemia was induced in Wistar strain rats by increasing the intraocular pressure to 110 mm Hg for 45 min via cannulation into the anterior chamber. The localization and abundance of the MK protein and mRNA were determined by the use of immunohistochemistry and in situ hybridization in the normal retina, as well as the retina after reperfusion. The protein expression profile was confirmed by Western blot analysis.

RESULTS

Immunohistochemical analysis showed that MK protein was expressed in the ganglion cell layer, the inner portion of the inner nuclear layer, and in the retinal pigment epithelium of the normal rat. MK expression transiently decreased 3 h to 2 days after reperfusion, and then dramatically increased to a level higher than normal after 7 to 28 days. The temporal expression profile of the MK protein was confirmed by Western blot analysis. In situ hybridization analysis gave results comparable to those obtained with immunohistochemistry.

CONCLUSIONS

MK was expressed in the neural cells of the retina in the normal state, but became more abundant after pressure-induced retinal ischemia. Thus, endogenous MK responds to ischemic treatment by an initial decrease in expression and then a period of expression above basal levels.

Time-course expression of vascular endothelial growth factor as related to the development of the retinochoroidal vasculature in rats

Growth factors involved in angiogenesis are critical to both the normal and pathological vascular development in the retina and choroid. In the present experiment, the relationship between the vascular endothelial growth factor (VEGF) expression and the retinochoroidal vasculogenesis in Sprague-Dawley rats was investigated using in situ hybridization and immunohistochemistry. It was found that VEGF was produced mainly by astrocytes and Muller cells in the neural retina, and this was correlated temporally and spatially with the retinal vasculogenesis. In addition, it was observed that, although the VEGF expression in the retinal pigment epithelium (RPE) decreased with increasing age, it persisted from the embryonic stage to adulthood. These findings indicate that the VEGF expression in RPE may play a role in the development of the choroidal vessels as well as in the maintenance of the normal structure and permeability of the choriocapillaris in adults.

Immunolocalization of transforming growth factor beta during wound repair in rat retina after laser photocoagulation

BACKGROUND

Scatter photocoagulation induces regression of retinal neovascularization, but the mechanism of its therapeutic effect is incompletely understood. To elucidate the mechanism of therapeutic effect of photocoagulation is the main focus of our research. We have already demonstrated basic fibroblast growth factor (bFGF) immunolocalization during retinal wound repair following laser photocoagulation. Transforming growth factor beta (TGF beta) reportedly inhibits endothelial cell growth and bFGF-induced cell proliferation in vitro. In the present study, we evaluated the immunohistochemical localization of TGF-beta 1 and -beta 2 during wound repair in the rat retina following laser photocoagulation.

METHODS

Krypton laser photocoagulation was performed on the eyes of pigmented rats. The eyes were then enucleated on day 1, 3, 7, 14, 28 or 56 following the photocoagulation and enrolled into the analysis of immunohistochemical localization of TGF-beta 1 and -beta 2.

RESULTS

Immunoreactivity for TGF-beta 1 and -beta 2 was present in the ganglion cell layer and photoreceptor outer segments of the normal adult rat retina. The cytoplasm of RPE cells at the photocoagulated lesion showed intense TGF-beta 1 and -beta 2 immunoreactivity on day 3 after laser photocoagulation. Macrophages that migrated into the lesion lacked positive staining for TGF-beta 1 and -beta 2. TGF-beta immunoreactivity in RPE cells continued to be upregulated for more than 1 month compared with that in normal RPE cells. Controls did not exhibit any positive staining.

CONCLUSION

An elevated expression of TGF-beta immunoreactivity for a longer period of time than bFGF was observed in RPE cells at the photocoagulated lesion in vivo. In the late phase of retinal wound repair, TGF-beta may inhibit cell proliferation induced by mitogens, introduce an end stage of cellular events, and induce extracellular matrix induction.

[Results of vitreous surgery for proliferative vitreoretinopathy]

During the past four years, we performed vitreous surgery on 73 eyes with rhegmatogenous retinal detachments complicated with severe proliferative vitreoretinopathy (PVR). We analyzed the surgical outcome of PVR according to the revised classification of PVR Grade C (1991). After a mean follow-up period of 19 months, the retinas were successfully reattached in 62 of 73 eyes (85%). The reattachment rate in the eyes with only posterior proliferation was high (96%), regardless of the extent of posterior proliferation. However, the reattachment rate in the eyes associated with anterior proliferation was markedly low (57%), depending on the extent of anterior proliferation. Among 62 eyes with successfully reattached retinas, 39 eyes (63%) had an improved postoperative visual acuity. These results demonstrated that the eyes with anterior PVR have a worse reattachment rate than the eyes with only posterior PVR. Using the revised classification of PVR, we were able to analyze the surgical outcome of PVR which could not be classified by the old classification.