Cataract in atomic bomb survivors

PURPOSE

Ophthalmologic examinations were conducted on atomic bomb (A-bomb) survivors 55 years after exposure.

MATERIALS AND METHODS

A-bomb survivors who had been exposed before 13 years of age at the time of the bombings in 1945 or who had been examined in a previous study between 1978 and 1980. The examinations, conducted between June 2000 and September 2002, included slit-lamp examination, digital photography and a cataract grading system for three parts of the lens (nucleus, cortex and posterior subcapsule) as an outcome variable. Proportional odds logistic regression analysis was conducted using the lowest grading class as a reference and included explanatory variables such as age, sex, city, dose and various cataract-related risk factors. When the grades in an individual differed, the worst grade was used.

RESULTS

Results indicate that odds ratios (ORs) at 1 Sv were 1.07 (95% confidence intervals [CI] 0.90, 1.27) in nuclear colour, 1.12 (95% CI 0.94, 1.30) in nuclear cataract, 1.29 (95% CI 1.12, 1.49) in cortical cataract and 1.41 (95% CI 1.21, 1.64) in posterior subcapsular cataract. The same was true after excluding 13 people whose posterior subcapsular cataracts had been previously detected.

CONCLUSION

Significant radiation effects were observed in two types of cataracts in A-bomb survivors.

Clinical significance of topical instillation technique in Japanese glaucoma patients

The clinical significance of a proper eye drop application technique was evaluated in Japanese glaucoma patients. Patients diagnosed with primary open-angle glaucoma having intraocular pressure (IOP) greater than 21 mmHg were treated with eye drops at home. In some patients, however, the topical treatment was ineffective. They returned to the hospital to receive surgical treatment. On admission, 56% of these patients had IOP greater than 21 mmHg. Patient instillation technique was evaluated based on the proximity of the eyedropper tip to the eyes, application position, eyelid closure, treatment (removal) of excess fluid, and nasolacrimal occlusion. In addition, pharmacists interviewed patients to determine the level of understanding of glaucoma, knowledge of prescribed drugs, home application technique, and sensation after application. Multivariate analysis revealed that the key factors influencing the control of IOP to less than 21 mmHg with topical medication were: application of drops in the center of the eye and removal of excessive fluid, in addition to gender and age. Proper topical application at home was dependent on the patient's understanding of the disease, knowledge of prescribed drugs, patient education on the use of drugs, the competence of the instructor, and knowledge of correct application technique. This study indicates that easily comprehensible patient education on the use of eye drops, the nature of glaucoma and the proper use of prescribed drugs is vital to improving the clinical efficacy of topical ophthalmic medication of glaucoma in adult patients.

Aqueous humour levels of cytokines are correlated to vitreous levels and severity of macular oedema in branch retinal vein occlusion

AIM

To investigate whether the aqueous levels of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) are correlated to the vitreous levels of these substances and to the severity of macular oedema in branch retinal vein occlusion (BRVO).

METHODS

Aqueous and vitreous samples were obtained during cataract and vitreous surgery from 24 patients (24 eyes) with macular oedema in BRVO. The VEGF and IL-6 levels in aqueous humour, vitreous fluid, and plasma were determined by enzyme-linked immunosorbent assay. The degree of retinal ischaemia was evaluated in terms of the area of capillary nonperfusion using the Scion Image. The severity of macular oedema was evaluated using the OCT.

RESULTS

The aqueous level of VEGF was significantly correlated with the vitreous level of VEGF (P<0.0001). Vitreous levels of VEGF and IL-6 were significantly correlated with the nonperfusion area of BRVO (P<0.0001, P=0.0061, respectively), as were the aqueous levels of VEGF and IL-6 (P<0.0001, P=0.0267, respectively). Furthermore, the vitreous levels of VEGF and IL-6 and the aqueous level of VEGF were significantly correlated with the severity of macular oedema of BRVO (P=0.0001, P=0.0331, P=0.0272, respectively).

CONCLUSION

Our results suggest that the aqueous level of VEGF may reflect its vitreous level. Measurement of the aqueous level of VEGF may be clinically useful to indicate the severity of macular oedema with BRVO.

Subretinal neovascularization associated with retinochoroidal coloboma

PURPOSE

To report a case of subretinal neovascularization associated with retinochoroidal coloboma.

METHODS AND RESULTS

A 44-year-old female presented with metamorphopsia in her right eye for 4 weeks. Funduscopic examination revealed bilateral inferior retinochoroidal coloboma. Fluorescein angiography disclosed foci of subretinal neovascularization at the margin between the colobomatous defect and the normal-appearing retina. Five month later, multiple small areas of subretinal hemorrhages were noted. The hemorrhage was gradually absorbed. Six years after initial presentation, subretinal hemorrhage did not recur and her right VA was 0.2.

CONCLUSIONS

Ophthalmologists should be aware of this rare but important complication of retinochoroidal coloboma.

Characteristics and surgical outcomes of paediatric retinal detachment

PURPOSE

To report the clinical features and surgical and visual outcomes of rhegmatogenous retinal detachment (RRD) in the paediatric population.

METHODS

A retrospective review of children (aged 0-15 years) who underwent primary surgical repair for RRD at the Hiroshima University Hospital between 1988 and 2001.

RESULTS

In all 53 eyes of 49 patients were identified; paediatric RRD accounted for 3.1% of 1779 eyes with RRD operated on during this period. The causes of RRD included blunt trauma (27%), myopia (25%), idiopathic (20%), familial exudative vitreoretinopathy (13%), and others. Among 55 eyes, 12 (22%) already had proliferative vitreoretinopathy (PVR) of grade C or D preoperatively. The median initial visual acuity (VA) was 0.3. Retinal reattachment was achieved with a single operation in 78%. Final retinal reattachment was achieved in 87%. Retinal reattachment rates with and without PVR were 42% and 100%, respectively (P<0.01). Median final VA was 0.7. Final VA was > or =0.1 in 73% and > or =0.5 in 53%; four eyes had a final VA of no light perception. The presence of preoperative PVR (P=0.03) and the initial VA (P<0.0001) significantly affected final VA.

CONCLUSIONS

Paediatric RRD is characterised by a delay in diagnosis, as evidenced by the high rate of PVR at presentation. Retinal reattachment was adversely affected by the presence of PVR. Final VA correlated with the initial VA and was significantly affected by preoperative PVR. Early diagnosis may improve the visual prognosis of paediatric retinal detachment.

Role of TGF-beta in the retinoic acid-induced inhibition of proliferation and melanin synthesis in chick retinal pigment epithelial cells in vitro

The purpose of this study was to investigate the effects of all-trans retinoic acid (RA) on the induction of transforming growth factor-beta (TGF-beta) that is concerned with the proliferation and melanin synthesis of chick retinal pigment epithelial (RPE) cells in vitro. Chick RPE cells were cultured in the presence or absence of RA and anti-TGF-beta antibody for 7 days. The effects of RA and pan-specific TGF-beta antibody on RPE cell proliferation were assessed by counting the number of cells, and their effects on melanin synthesis were evaluated by measuring the melanin content of the cells. TGF-beta activity in the culture supernatant of RPE cells was measured using CCL-64 cells. RA significantly inhibited RPE cell proliferation and increased melanin synthesis. The addition of pan-specific TGF-beta antibody to the culture blocked the inhibition of RPE cell proliferation and the increased melanin synthesis. RA induced TGF-beta production in the culture supernatant of RPE cells. These findings indicate that RA regulates the proliferation and melanin synthesis of RPE cells via induction of TGF-beta.

Alpha-helix 2 in the amino-terminal mad homology 1 domain is responsible for specific DNA binding of Smad3

Smads, signal transducers of the transforming growth factor-beta (TGF-beta) superfamily proteins, directly bind to DNA and regulate transcription of target genes. Smad3 binds to CAGA box, whereas Smad1 and Smad5 preferentially bind to GC-rich sequences. The beta-hairpin loop in the amino-terminal Mad homology 1 (MH1) domain is the direct DNA-binding site of Smad3; however, the amino acid sequences of the beta-hairpin loop of Smad3 and Smad1/5 are identical, suggesting that other regions may be responsible for the differential DNA binding of Smad3 and Smad1/5. To identify regions other than the beta-hairpin loop responsible for specific DNA binding of Smad3, we generated chimeras containing various regions of Smad3 and Smad1. Luciferase assays using a TGF-beta-responsive reporter (CAGA)9-MLP-Luc and gel-mobility shift assays using 3xCAGA as a probe revealed that alpha-helix 2 (H2) in the amino-terminal part of the MH1 domain plays an important role in specific DNA binding and transcriptional activation of Smad3. Luciferase assays using natural TGF-beta-responsive reporters also revealed the functional importance of H2 in the Smad3 MH1 domain in direct DNA binding. Smad3 thus binds to DNA directly through the beta-hairpin loop, and H2 supports specific DNA binding of Smad3.

Autologous blood injection for marked overfiltration early after trabeculectomy with mitomycin C

PURPOSE

After trabeculectomy with mitomycin C, extremely low intraocular pressure (IOP) with excess filtration may cause hypotonous maculopathy in the early postoperative period. We evaluated the effect of injecting autologous blood on reversing early postoperative marked hypotony after trabeculectomy with mitomycin C.

METHODS

Trabeculectomy with mitomycin C was performed in 258 eyes between 1994 and 1998. Peribleb autologous blood injection was performed in five eyes in which pressure patches were ineffective in reversing excess filtration. Approximately 0.1 to 0.3 ml of whole unclotted blood was slowly injected at least 3 mm from the edge of the flap using a sterile 27-gauge needle.

RESULTS

None of these eyes developed hypotonous maculopathy after injection. After a mean 31-month follow-up, all eyes had well-controlled IOP and visual acuity in three eyes was much improved. Postoperative complications included mild IOP elevation in one eye treated with laser suturelysis, and fibrinous pupillary membrane in one eye.

CONCLUSION

In the early postoperative period, autologous blood injection is effective in reversing excess filtration.

Mathematical and optimal clustering of test points of the central 30-degree visual field of glaucoma

PURPOSE

To determine a mathematically optimal sector pattern of the central 30 degree visual field for the follow-up of glaucomatous visual field change based on a large number of actual visual field test data of patients with glaucoma.

METHODS

Visual field test data obtained from 1,039 eyes of 1,039 patients with open-angle glaucoma (OAG) using the 30-2 program of the Humphrey Field Analyzer were used for sectorization of the central 30 degree visual field. Of the 1,039 visual field data, 698 (modeling data) were used for determining the sector pattern and 341 (testing data) for checking the sector pattern. The modeling data were further divided into three groups according to the mean deviation (MD) (MD > or = -10 dB, -20 < or = MD < -10 dB, and MD < -20 dB), and the sector pattern was constructed from visual field data of each group using a clustering procedure called VARCLUS. The testing data were used for determining the optimal sector pattern. In a separate set of repeated visual field data of 303 patients with OAG, the fluctuation of MD, sector values of each sector determined, and total deviation of each test point were calculated and compared.

RESULTS

The sector pattern constructed from visual field data of MD > or = -10 dB summarized the visual field performance most effectively. The fluctuation of the sector value of each sector was roughly 1.5 times smaller than the total deviation of each test point.

CONCLUSION

The sector pattern determined may be useful in analyses of the visual field data of patients with glaucoma.

Results of filtering surgery in young patients with aniridia

To evaluate whether filtering surgery is effective in controlling the intraocular pressure of young aniridic patients with glaucoma, we retrospectively reviewed the charts of aniridic patients with glaucoma under the age of 40 years. We defined a good intraocular pressure control period as the time from surgery until IOP exceeded 20 mm Hg, with or without glaucoma medication. Twenty filtering surgeries (17 trabeculectomies and 3 trabeculectomies with mitomycin C) were performed on 10 eyes in 6 patients for more than 20 years. The mean good intraocular pressure control period after the filtering surgery was 14.6 months (range, 2 to 54 months). Aside from mild choroidal detachment, no other serious complications were encountered. We believe that filtering surgery is efficacious for control of intraocular pressure of young aniridic patients with glaucoma.

Involvement of the protein kinase pathway in melanin synthesis by chick retinal pigment epithelial cells

Protein kinases are involved in a variety of cellular functions and cell proliferation in eyes. We have explored the involvement of protein kinase C (PKC) in cell proliferation and melanin synthesis by chick retinal pigment epithelial (RPE) cells in vitro. This was achieved by incubation of confluent RPE cells with known inhibitors of protein kinase, H-7, W-7, H-8, and staurosporine. Chick RPE cells were cultured in the presence or absence of the protein kinase inhibitors for a 10-day period. Effects of the inhibitors on cell proliferation and melanin synthesis, as an indication of cell differentiation, were assessed by counting the number of surviving cells and by measuring the melanin content in the cells, respectively. H-7, W-7, and staurosporine inhibited cell proliferation and increased melanin synthesis in a concentration-dependent manner during culture; however, H-8 did not produce these cellular effects. These findings indicate that PKC and calcium/calmodulin-dependent kinase pathways are involved in the proliferation and differentiation of chick RPE cells.

Localization of prostaglandin E receptor subtypes in the ciliary body of mouse eye

Prostaglandin E2 (PGE2) markedly reduces intraocular pressure (IOP) when applied topically and induces strong relaxation of pre-contracted isolated ciliary muscle through PGE2 receptor. Because the ciliary muscle relaxation reduces IOP by enhancing uveoscleral aqueous outflow, the ciliary muscle where the existence of PGE2 receptors has been demonstrated is thought to be one of the target tissues for PGE2-induced IOP reduction. To investigate the subtypes of PGE2 receptors in the ciliary muscle, the regional distribution of four PGE2 receptor subtypes (EP1, EP2, EP3 and EP4) in the mouse ciliary body was investigated by in situ hybridization using specific probes. Consistent messenger RNA signals for EP1 and EP4 receptors were expressed in the ciliary muscle, although signal levels for these subtypes were less potent as compared with the kidney, which was used as a reference organ. EP2 and EP3 signals were not detected. Stimulation of the EP4 receptor activates adenylate cyclase, which should induce ciliary muscle relaxation. Therefore, the IOP reduction induced by PGE2 analogs may be mediated by the EP4 receptor. In contrast, stimulation of the EP1 receptor is believed to promote intracellular Ca2+ mobilization, and hence should cause ciliary muscle contraction. Thus, the coexistence of EP1 and EP4 receptors in the ciliary muscle suggests that the regulation of ciliary muscle tone by PGE2 is based on a complex mechanism involving multiple receptor subtypes.

Growth regulation of bovine retinal pericytes by transforming growth factor-beta2 and plasmin

PURPOSE

Transforming growth factor -beta2 (TGF-beta2) is a predominant isoform of TGF-betas in the eye and plasmin is a peptidase with many functions. To better understand the pathogenesis of retinal microcirculation disorders, the effects of TGF-beta2 and plasmin on cultured bovine retinal pericytes were investigated.

METHODS

Exogenous TGF-beta2 or plasmin was added to some cultures, DNA synthesis during cell cycle progression was investigated using [(3)H]thymidine incorporation. Anti-TGF-beta2 antibody was added to neutralize the effects of TGF-beta2. TGF-beta2 in the culture medium was measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Exogenous TGF-beta2 (10 pg to 100 ng/mL) suppressed DNA synthesis. Pericytes produced TGF-beta2. Anti-TGF-beta2 antibody neutralized TGF-beta2 and accelerated DNA synthesis, which shows that pericytes regulate their own cell cycle by action of the autocrine and/or paracrine system of TGF-beta2. Plasmin (0.2 to 0.5 U/mL) accelerated DNA synthesis in a dose-dependent manner, while addition of aprotinin, a protease inhibitor, counteracted this effect of plasmin. The concentration of TGF-beta2 in the culture medium decreased with the addition of plasmin. Simultaneous addition of both plasmin and anti-TGF-beta2 antibody accelerated DNA synthesis. High and low glucose concentrations of the culture medium did not affect DNA synthesis.

CONCLUSIONS

Our results suggest that TGF-beta2 and plasmin respectively decrease and increase DNA synthesis. In a retinal microcirculation disorder, they may play competitive roles in the cell cycle of pericytes.

Characterization of a bone morphogenetic protein-responsive Smad-binding element

Bone morphogenetic proteins (BMPs) are pleiotropic growth and differentiation factors belonging to the transforming growth factor-beta (TGF-beta) superfamily. Signals of the TGF-beta-like ligands are propagated to the nucleus through specific interaction of transmembrane serine/threonine kinase receptors and Smad proteins. GCCGnCGC has been suggested as a consensus binding sequence for Drosophila Mad regulated by a BMP-like ligand, Decapentaplegic. Smad1 is one of the mammalian Smads activated by BMPs. Here we show that Smad1 binds to this motif upon BMP stimulation in the presence of the common Smad, Smad4. The binding affinity is likely to be relatively low, because Smad1 binds to three copies of the motif weakly, but more repeats of the motif significantly enhance the binding. Heterologous reporter genes (GCCG-Lux) with multiple repeats of the motif respond to BMP stimulation but not to TGF-beta or activin. Mutational analyses reveal several bases critical for the responsiveness. A natural BMP-responsive reporter, pTlx-Lux, is activated by BMP receptors in P19 cells but not in mink lung cells. In contrast, GCCG-Lux responds to BMP stimulation in both cells, suggesting that it is a universal reporter that directly detects Smad phosphorylation by BMP receptors.

Efficacy and safety of latanoprost eye drops for glaucoma treatment: a 1-year study in Japan

PURPOSE

To evaluate the intraocular pressure (IOP)-lowering effect and safety of latanoprost, a prostaglandin analogue, in patients with primary open-angle glaucoma or ocular hypertension.

METHOD

One hundred and twenty-four Japanese patients with primary open-angle glaucoma or ocular hypertension were enrolled in this open-labeled study and were treated with 0.005% latanoprost once daily for 1 year.

RESULTS

At all follow-up visits there was a significant (P < .001) reduction in IOP compared with the baseline value. After 1 year, the IOP was reduced by 5.4 +/- 2.9 (mean +/- SD) mm Hg from a baseline value of 23.5 +/- 2.2 mm Hg. No evidence of an upward drift in the IOP was observed during the treatment period. The most frequently reported adverse ocular events were mild conjunctival hyperemia and iris pigmentation. Very few adverse systemic events were observed.

CONCLUSIONS

Latanoprost eye drops showed a marked and stable IOP-lowering effect during the 1-year treatment period. Furthermore, latanoprost was well-tolerated and should be a valuable contribution to the management of glaucoma.

Attenuation by PACAP of glutamate-induced neurotoxicity in cultured retinal neurons

The effects of pituitary adenylate cyclase activating polypeptides (PACAPs: PACAP27, PACAP38) on glutamate-induced neurotoxicity were examined using cultured retinal neurons obtained from 3- to 5-day old Wistar rats. Cell viability was evaluated by double staining with fluorescein diacetate and propidium iodide. Effects of PACAPs on the increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) in retinal neurons was investigated using the Ca(2+) image analyzing system with fura-2. The cAMP contents and the mitogen-activated protein (MAP) kinase activity in retinal cultures were measured by radioimmunoassay. Concomitant application of PACAPs (10 nM-1 microM) with glutamate (1 mM) for 10 min inhibited the delayed death of retinal neurons, which was observed 24 h after glutamate (1 mM) treatment in a dose-dependent manner. Protection by PACAPs (100 nM) against glutamate-induced neurotoxicity was antagonized by PACAP6-38 (1 microM), a PACAP antagonist, and H-89 (1 microM), a protein kinase A (PKA) inhibitor. However, PACAPs did not affect the glutamate-induced increase in [Ca(2+)](i), but PACAPs (1-100 nM) increased the cAMP levels in a dose-dependent manner. In addition, activation of MAP kinase by PACAP38 (1 microM) was inhibited by simultaneous application with H-89 (1 microM). These findings suggest that PACAPs attenuate glutamate-induced delayed neurotoxicity in cultured retinal neurons by activating MAP kinase through the activation of cAMP-stimulated PKA.

Role of P-glycoprotein in distribution of rhodamine 123 into aqueous humor in rabbits

PURPOSE

Examination of the contribution of functional P-glycoprotein (P-gp), an ATP-dependent efflux pump, in blood-aqueous barrier in rabbits.

METHODS

Rhodamine-123 (Rho-123), a P-gp substrate, was administered intravenously via the marginal ear vein of rabbits. Rhodamine B (Rho-B), an analogue of Rho-123, was also injected with the same dose, as a reference compound. Quinidine at different concentrations was applied topically to the corneal surface by eye drops prior to the intravenous administration of a Rho compound. The aqueous distribution (a ratio of concentration in aqueous humor to that in plasma) of these Rho compounds was analyzed in relation to the aqueous concentration of quinidine. Transport study across Caco-2 cell monolayers was carried out to examine the involvement of P-gp in Rho-B transport.

RESULTS

It was proved that Rho-B is not a P-gp substrate by a transport study across Caco-2 cell monolayers, in contrast to Rho-123 (a P-gp substrate). The aqueous distribution of Rho-123 given intravenously was significantly lower than that of Rho-B. Topical quinidine (a P-gp inhibitor) markedly increased the aqueous distribution of Rho-123, depending on the aqueous concentrations of quinidine, though it did not affect the aqueous distribution of Rho-B.

CONCLUSIONS

The contribution of functional P-gp in blood-aqueous barrier was clearly demonstrated by analyzing the aqueous distribution of Rho-123 in the presence or absence of quinidine. These experiments only allow us to address one part of the blood-aqueous barrier, the capillary endothelium, and, to do so by using different substrates for P-gp, a sort of chemical analogy with the presumed blood-aqueous barrier across capillary endothelia. The alteration of P-gp function by pharmacotherapy or in pathological state should be considered in the ophthalmic medical treatment.

Rat retinal ganglion cells culture enriched with the magnetic cell sorter

The magnetic cell sorter (MACS) technique was applied to isolate retinal ganglion cells (RGCs) for culture. RGCs were labeled retrogradely with 1.1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (Dil). Subsequently retinal cell suspensions were incubated with biotinylated anti-rat Thy-1 antibody and MACS Streptavidin MicroBeads, and then applied onto the column in the magnetic fields. Cells attached on the column were flashed out without magnetism and plated on glass cover slips. RGCs were enriched to 31.0% of all cells with MACS from 0.55% before applying onto the magnetic column. Mean diameters of Dil-labeled cells were significantly larger than those of unlabeled cells. All cells with soma diameter over 11 microm were labeled. The number of viable RGCs were counted in the 10 fields of six cultures at a magnification of x200; the mean numbers on the 2nd, 7th and 14th culture-day were 53+/-3, 24+/-2 and 21+/-3, respectively (mean +/- SEM, n = 6). Thus, the MACS technique was confirmed to be useful for enrichment of RGCs and long-term study of cultured RGCs.

Evaluation of 9-cis retinoic acid for a new remedy of human retinoblastoma

We investigated the effect of two isomers of retinoic acid (RA), all-trans RA and 9-cis RA, on the proliferation of Y79 human retinoblastoma cells. The two isomers inhibited the cell proliferation in a concentration-dependent manner. The IC50 for this inhibition by all-trans RA and 9-cis RA was 1.50 and 0.15 microM, respectively. The inhibitory effect of 9-cis RA on Y79 cell growth was observed within 24 hr, thereafter the cell number was gradually decreased. In contrast, no inhibition by all-trans RA of Y79 cell growth was observed within 24 hr, thereafter the cell number was slightly increased. In these cases, the cell viability at 4 days after the addition of 9-cis RA and all-trans RA was more than 90% and 95%, respectively. These results indicate that the two RA inhibit the proliferation of Y79 human retinoblastoma cells without inducing the cell death and that the effect of 9-cis RA on the inhibition of Y79 cell growth is much greater than that of all-trans RA.

Protective effects of vasoactive intestinal peptide against delayed glutamate neurotoxicity in cultured retina

The effects of vasoactive intestinal peptide (VIP) on glutamate-induced delayed death were examined using the primary cultures of rat retinal neurons. Effects of VIP on glutamate-induced neurotoxicity were evaluated by double staining with fluorescein diacetate and propidium iodide. Glutamate (1 mM) was applied to the culture for 10 min in the presence and absence of VIP, and visible cells enumerated 24 h after culture in normal medium. Effects of VIP on increase in the intracellular Ca2+ concentration and currents induced by glutamate in retinal neurons were investigated using the Ca2+ image analyzing system with fura-2 and whole-cell patch-clamp recording, respectively. The cAMP contents in retinal cultures were measured by radioimmunoassay. VIP (10 nM-1 microM) dose-dependently protected against glutamate-induced neurotoxicity in cultured retinal neurons. Protection by VIP (100 nM) against glutamate (1 mM)-induced neurotoxicity was antagonized by VIP6-28 (1 microM), a VIP antagonist, and H-89 (100 nM and 1 microM), a protein kinase A inhibitor. However, VIP had no effect on glutamate-induced inward currents nor glutamate-induced increase in the intracellular Ca2+ concentration. A 10-min exposure of VIP (100 nM) with glutamate (1 mM) resulted in an increase in the cAMP level to 446+/-58 from 22+/-1 pmol/mg protein. These findings suggest that VIP protects against the glutamate-induced neurotoxicity in retinal cultures by elevating the cAMP level via VIP receptors and thereby activating protein kinase A.

Effects of retinoic acid and TGF-beta 1 on the proliferation and melanin synthesis in chick retinal pigment epithelial cells in vitro

PURPOSE

The purpose of this study was to investigate the effects of all-trans retinoic acid (RA) and transforming growth factor-beta 1 (TGF-beta 1) on proliferation and melanin synthesis of chick retinal pigment epithelial (RPE) cells in vitro.

METHODS

Chick RPE cells were cultured in the presence or absence of RA (10(-5) to 10(-7) M) or TGF-beta 1 (1 to 100 U/ml) for a 10-day period. The effects of RA and TGF-beta 1 on RPE cell proliferation were assessed by counting the number of cells, and their effects on melanin synthesis were evaluated by measuring the melanin content in the cells.

RESULTS

RA significantly inhibited RPE cell proliferation in a time-dependent manner. The most marked inhibition was observed on day 10 of culture, and the most effective concentration of RA was 10(-6) M. Melanin synthesis was increased on day 10, and the most effective concentration of RA was also 10(-6) M. TGF-beta 1 also inhibited RPE cell proliferation and increased melanin synthesis.

CONCLUSIONS

These findings indicate that RA and TGF-beta 1 have regulatory effects on the proliferation and differentiation of chick RPE cells in vitro.

Protection against glutamate neurotoxicity in retinal cultures by acidic conditions

We evaluated the effects of extracellular acidic conditions on glutamate-induced death in cultured retinal neurons. Primary retinal cultures, obtained from 3- to 5-day-old Wistar rats, were estimated to be consisted of mainly amacrine cells (90%) together with a small population of horizontal (8%) and ganglion cells (2%). We examined the effects of acidic pH (pH 6.0 to 7.0) on glutamate neurotoxicity by monitoring the delayed death of retinal neurons induced by brief (10 min) exposure to 1 mM glutamate followed by a 24-hr incubation. The glutamate-induced delayed death of cultured retinal neurons was attenuated with an acidic pH between 6.0 and 7.0. Furthermore, whole-cell patch-clamp recordings were taken from retinal neurons to examine the effects of acidic pH on N-methyl-D-aspartate (NMDA) or kainate receptor-mediated currents. NMDA- and kainate-induced currents were suppressed at pH 6.0 to 7.0 and pH 6.0 to 6.5, respectively. The acidity of the medium protected the retinal neurons from glutamate-induced delayed death, probably by inhibiting NMDA and/or kainate receptor activation.

Involvement of CD8+ RT1.B+ and CD4+ RT1.B+ cells of cervical lymph nodes in the immune response after corneal transplantation in the rat

Graft rejection reactions have been observed with concomitant lymphocyte infiltrations after allogenic corneal transplantation, although the cornea is considered to be relatively protected from the systemic immune response. In order to characterize the lymphocytes that accumulate in cervical lymph nodes following transplantation, we used a model of orthotopic penetrating keratoplasty in inbred rats. After grafting, the time course of the pathological scoring was monitored, and subpopulations of CD4+ RT1.5+ and CD8+ RT1.B+ cells were analyzed in the cells harvested from the cervical lymph nodes. The number of CD8+RT1.B+ cells increased 1 week after grafting, reaching the maximum at 3 weeks; whereas CD4+ RT1.B+ cells were induced 1 week after the grafting and remained constant during the next 3 weeks. There were four times as many CD4+ RT1.B+ cells as CD8+ RT1.B+ cells 1 week after grafting when there was no rejection. Therefore, it appears that CD8+RT1.B+ and CD4+RT1.B+ cells in the cervical lymph nodes do participate in ocular immunologic responses.

Cytokine- and neuropeptide-mediated differentiation in retinal pigment epithelial cells in vitro

To determine the mechanism of growth and differentiation of retinal pigment epithelial (RPE) cells it is important to understand the pathogenesis of several retinal diseases. Recently it has been reported that several cytokines and neuropeptides regulate the growth of RPE cells. In this study, the role of cytokines and neuropeptides in melanin synthesis, which is one indication of the RPE cell differentiation, was examined using chick RPE cells in vitro IL-1beta, TNF-alpha, substance P, beta-endorphin and methionine-enkephalin stimulated the melanin synthesis of RPE cells in a dose-dependent manner. The most effective concentrations of these agents on RPE cell melanin synthesis were not the same as that for RPE cell proliferation. These results indicate that cytokines and neuropeptides play an important role not only for the growth but also for the differentiation of RPE cells.

Purification and characterization of alpha,beta-ketoalkene double bond reductases from bovine eyes

PURPOSE

To explore the alpha,beta-ketoalkene double bond reductases responsible for xenobiotic metabolism in bovine ocular tissues using trans-phenyl-l-propenyl ketone as a model substrate.

METHODS

A mixture of trans-phenyl-l-propenyl ketone, NADPH or NADH, and an enzyme source in 0.1 M K,Na-phosphate buffer (pH 7.4) was incubated for 15 min at 37 degrees C. Phenyl propyl ketone formed was quantified by high performance liquid chromatography (HPLC).

RESULTS

The lens, ciliary body, iris, retinal pigment epithelium (RPE)-choroid, retina, and cornea exhibited alpha,beta-ketoalkene double bond reductase activities in the presence of NADPH or NADH. An alpha,beta-ketoalkene double bond reductase was purified to homogeneity from the iris-ciliary body cytosol. The molecular weight was estimated to be 58,000 by gel filtration, and 40,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme activity was inhibited by dicumarol, quercitrin, indomethacin, disulfiram, and p-chloromercuribenzoic acid. The enzyme exhibited double bond reductase activity toward 2-alkenals as well as alpha,beta-ketoalkenes. Another alpha,beta-ketoalkene double bond reductase was also purified to homogeneity from the lens cytosol. The molecular weight was estimated to be 105,000 by gel filtration and 40,000 by SDS-PAGE. The enzyme activity was inhibited by dicumarol and quercitrin. The enzyme exhibited double bond reductase activity toward some alpha,beta-ketoalkenes.

CONCLUSIONS

Two kinds of enzymes responsible for reduction of the carbon-carbon double bond of xenobiotics were purified for the first time from ocular tissues. The molecular weights, substrate specificities, and sensitivities to inhibitors of the enzymes were different from each other.

Circadian intraocular pressure management with latanoprost: diurnal and nocturnal intraocular pressure reduction and increased uveoscleral outflow

Based on their mechanism of action, the most frequently used ocular hypertensive agents, the beta-blockers, cannot be assumed to reduce IOP during sleep. The need for drugs that reduce IOP around-the-clock is underscored, however, by the fact that inadequate nocturnal ocular perfusion pressure is considered to be one of the likely causes of glaucomatous optic neuropathy especially in some cases of normal tension glaucoma. The studies reviewed here demonstrate that latanoprost, a new ocular hypotensive prostaglandin F2 alpha analogue, applied once a day at a concentration of 0.005%, maintains a statistically highly significant IOP reduction around-the-clock. The magnitude of this IOP reduction was found to be essentially identical during the day and at night, both in patients maintained on timolol and in those not receiving other glaucoma medication. Latanoprost-induced IOP reduction was also found to be associated with increased uveoscleral outflow in normotensive volunteers, both during the day and at night. These circadian studies suggest that this new ocular hypotensive agent can be expected to be particularly useful for the medical management of some forms of glaucoma, such as normal tension glaucoma, when the cause of the glaucomatous damage cannot be linked specifically to diurnal IOP abnormalities.

Incidence of retinal vein occlusion at the Glaucoma Clinic of Hiroshima University

We prospectively surveyed the incidence of retinal vein occlusion (RVO) at the glaucoma clinic of Hiroshima University between 1986 and 1991. Among 433 glaucoma patients, 18 (4.2%) subsequently presented with RVO, 9 had central retinal vein occlusion (CRVO) and 9 exhibited branch retinal vein occlusion (BRVO). Seven of 87 (8.1%) patients with primary angle closure glaucoma exhibited RVO, showing the highest incidence among glaucoma types. The incidence of RVO detected by the general outpatient clinic was 0.59% during the same period. The BRVO/CRVO ratio in the glaucoma clinic was 1.0, while it was 4.3 in the general outpatient clinic. Glaucoma is an important risk factor for the development of RVO, especially CRVO.

A comparison of latanoprost and timolol in primary open-angle glaucoma and ocular hypertension. A 12-week study

OBJECTIVE

To evaluate the intraocular pressure (IOP)-reducing effect and the side effects of latanoprost (PhXA41), a new phenyl-substituted prostaglandin F2 alpha-isopropyl ester analogue, in patients with elevated IOP, using timolol maleate as the reference drug.

METHODS

A total of 184 patients with primary open-angle glaucoma or ocular hypertension at 35 medical centers participated in this randomized double-masked study. The patients were randomized to receive either 0.005% latanoprost once daily or 0.5% timolol maleate twice daily, for a period of 12 weeks. Intraocular pressure was measured 24 hours after the administration of timolol, at 2, 4, 8, and 12 weeks of treatment.

RESULTS

Latanoprost reduced IOP at the end of 12 weeks by 6.2 +/- 2.7 mm Hg (mean +/- SD) (26.8%), while timolol reduced IOP by 4.4 +/- 2.3 mm Hg (19.9%). At all visits latanoprost reduced IOP significantly more than timolol did. The main ocular side effects observed in both groups were conjunctival hyperemia and smarting. The main systemic side effect was a reduced pulse rate, which occurred in patients treated with timolol.

CONCLUSIONS

The results of this study demonstrated that 0.005% latanoprost taken once daily is well tolerated and more effective in reducing IOP than 0.5% timolol taken twice daily. Thus, latanoprost may become an important choice for the medical treatment of glaucoma.

Stimulation of retinal pigment epithelial cell growth by neuropeptides in vitro

PURPOSE

The proliferation of many cell types are regulated by cytokines and neuropeptides by autocrine and paracrine mechanisms. Retinal pigment epithelial (RPE) cells are also regulated by cytokines. But RPE cells are very close to the neural retina which has some neuropeptides. The present study was to investigate the effects of neuropeptides on the growth of RPE cells.

METHODS

RPE cells were obtained from the eyes of 11 day old chick embryos and cultured in Dulbecco's modified Eagle's culture medium containing 10% fetal calf serum. The growth of RPE cells was evaluated by [3H]-thymidine uptake.

RESULTS

Substance P, beta-endorphin and calcitonin gene-related peptide markedly stimulated the growth of RPE cells. The effects of methionine-enkephalin, somatostatin and vasoactive intestinal peptide were intermediate. The strongest effects of substance P, beta-endorphin and calcitonin gene-related peptide were observed at 10(-6) to 10(-7) M. The stimulation of RPE cells with beta-endorphin was inhibited by naloxone, suggesting that the stimulation with beta-endorphin is mediated by an opioid receptor. beta-endorphin and substance P induced RPE cell growth stimulating activity. Leucine-enkephalin and neuropeptide Y did not affect the growth of RPE cells.

CONCLUSIONS

These results suggest that neuropeptides play an important role in the regulation of RPE cell growth.

Ultrasound biomicroscopic study of ciliary body thickness after topical application of pharmacologic agents

PURPOSE

To examine the changes in ciliary body thickness after topical application of pilocarpine, cyclopentolate hydrochloride, and PhXA41, a prostaglandin F2alpha analog.

METHOD

We used high-frequency Humphrey UBM840 ultrasound biomicroscope to examine 36 healthy young Japanese subjects.

RESULTS

The mean ciliary body thickness increased from 0.67 +/- 0.07 mm to 0.073 +/- 0.08 mm (P < .01) after application of 2% pilocarpine; 1% cyclopentolate hydrochloride and 0.005% PhXA41 decreased the mean ciliary body thickness from 0.75 +/- 0.07 mm to 0.69 +/- 0.05 mm (P < .05) and from 0.78 +/- 0.06 mm to 0.75 +/- 0.06 mm (P < .01), respectively.

CONCLUSIONS

Our ultrasound study clearly indicates that pilocarpine increased comparative thickness of the ciliary body by 8.3%, whereas PhXA41 decreased comparative thickness by 3.3% in a manner similar to cyclopentolate hydrochloride.

Characterization of ciliary muscle relaxation induced by various agents in cats

PURPOSE

To understand the cellular mechanism underlying the relaxation of ciliary muscle, relaxation induced by prostaglandins (PGs) and some other agents was characterized in the cat.

METHODS

Tone of isolated ciliary muscle was measured by means of a force-displacement transducer. Adenylate cyclase activity was determined with membrane fraction of ciliary muscle by measuring the formation of cyclic adenosine monophosphate (cAMP).

RESULTS

The addition of various PGs and isoproterenol relaxed the ciliary muscle that had been precontracted with 3 x 10(-6) M carbachol. The relaxation was dose dependent, with an EC50 of 2 x 10(-7) M for PGE2. The rank order of potency by which PGs induced relaxation (PGE2 = E1 > D2 > F2 alpha > I2) was identical with that reported for EP type prostaglandin receptor-mediated responses except for PGD2, which was more potent than expected. Agents that increased cellular cAMP, such as forskolin and IBMX, also relaxed the precontracted muscle. Nitric oxide donors, such as sodium nitroprusside and S-nitroso-N-acetyl-DL-penicillamine (SNAP), also caused dose-dependent relaxation. PGs and isoproterenol, but not nitroprusside, stimulated adenylate cyclase. The rank order of potency by which PGs stimulate adenylate cyclase was similar to that observed for muscle relaxation, suggesting that cAMP is the cellular second messenger for the PG-induced muscle relaxation and thus that PG receptors of EP2 and DP type are involved.

CONCLUSIONS

Relaxation of cat ciliary muscle is mediated by two independent mechanisms: a cAMP-dependent one, which includes beta-adrenergic, EP2, and DP receptor-mediated responses, and a cAMP-independent one, which includes the nitric oxide-induced mechanism.

Effect of cytokines and prostaglandins on the growth of chick retinal pigment epithelial cells

The effect of cytokines and prostaglandins on the growth of chick retinal pigment epithelial (RPE) cells was studied in vitro. The growth of RPE cells was evaluated by [3H]-thymidine uptake. Human recombinant interleukin-1 beta, interferon-beta and tumor necrosis factor-alpha stimulated the growth of RPE cells at 50-200 units/ml. Prostaglandins such as PGE1, PGE2 and PGF2 alpha suppressed RPE cell growth at 10(-5) approximately (-6)M. Indomethacin, an inhibitor of cyclooxygenase, did not affect the spontaneous RPE cell growth at 10(-7) approximately (-9) M. However, 10(-7) M indomethacin enhanced RPE cell growth stimulated by cytokines synergistically. The addition of 10(-6) M PGF2 alpha suppressed the enhanced growth of RPE cells which was induced with cytokines and indomethacin. Furthermore, RPE cells stimulated with cytokines produced PGE2. These results suggest that RPE cells produce prostaglandins which have a negative regulatory role in RPE cell growth.

Growth regulation of retinal pigment epithelial (RPE) cells in vitro

Studies of growth factor production by chick embryo retinal pigment epithelial (RPE) cells and the effects of cytokines on chick and human RPE cells were performed in vitro. RPE cell growth was evaluated by tritiated thymidine uptake. Chick RPE cells produced growth factors whose molecular weights were 15 and 108 kD. These fractions contained interleukin (IL)-1-like activity which stimulated murine thymocyte proliferation. 100-150 U/ml human IL-1 beta, interferon (IFN)-beta, IFN-gamma and tumor necrosis factor (TNF)-alpha stimulated the growth of both RPE cells. The activity of IFN-beta was the most potent of these cytokines, while IL-2 and IFN-alpha had no effect in chick RPE cells. 100-150 U/ml transforming growth factor (TGF)-beta 1 suppressed cytokine-induced growth of both RPE cells. RPE cells therefore produce growth factors, respond to several growth factors and are regulated by a network of cytokines.

15-Ketoprostaglandin delta 13-reductase activity in bovine ocular tissues

The present study provides the first evidence for delta 13-reduction of 15-ketoprostaglandins (15-keto-PGs) by bovine ocular tissues. The 9,000xg supernatants of cornea, iris, ciliary body, retina, and RPE-choroid except lens exhibited delta 13-reductase activity toward 15-keto-PG E2 and F2 alpha in the presence of NADPH or NADH as an electron donor. Among the tissues tested, the highest activity was observed in ciliary body and iris, followed by RPE-choroid, retina, and cornea. The NADPH- and NADH-linked double bond reductase activities were inhibited by dicumarol, quercitrin, indomethacin and disulfiram, but not by potassium cyanide. NADPH-linked 15-keto-PG F2 alpha delta 13-reductase was purified from bovine iris-ciliary body cytosol by fractionation with ammonium sulfate and high performance liquid chromatography (HPLC) with TSK gel DEAE-5PW, and TSK gel Blue-5PW. The purified enzyme was homogenous by the criterion of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its molecular weight was estimated to be about 57,000 by electrophoresis, and about 55,000 by gel filtration HPLC with Superose 12.

A cyclic AMP phosphodiesterase inhibitor, 8'-pivaloyloxymethyl ester (POM-ester) of griseolic acid, lowers rabbit intraocular pressure

The effects of griseolic acid (GA), a cyclic-AMP phosphodiesterase (PDE) inhibitor, and its 8'-pivaloyloxymethyl (POM) ester on intraocular pressure (IOP) in rabbits were investigated. When 50 microliters of 1 and 2% GA POM ester solutions were topically applied to one eye in normal rabbits, significant IOP decreases were detected at 2 hrs and at 1 to 5 hrs, respectively. Other than ocular hypotension, no other ocular effects were detected locally even after administration of 2% GA POM ester. A more marked reduction in IOP occurred after the intravitreal injection of the GA POM ester. IOP was also reduced when GA was used in an intravitreal injection but not when it was topically applied. The difference in permeability between GA and GA POM ester across the corneal epithelium may explain why GA failed to reduced IOP following topical administration. GA and the GA POM ester inhibited cAMP PDE in rabbit ciliary body at low concentrations, the I50 being 0.075 microM and 2.4 microM, respectively, with 0.25 microM cAMP as substrate. GA and the GA POM ester markedly increased cAMP levels in vitro in iris-ciliary body specimens. Possibly, GA POM ester or its analogues may represent a new mechanistic class of ocular hypotensive agents.

Primary orbital malignant lymphoma: a clinicopathology study of 17 cases

We investigated the clinicopathologic characteristics of 17 patients (13 men and 4 women) with primary orbital malignant lymphoma using the Working Formulation. Most of the cases belonged to the low-grade malignancy group, and more women than men were in the histologically high-grade malignancy group. The phenotype of the tumor cells was investigated immunohistochemically. All cases showed the monoclonal feature of a B-cell lineage. All patients received chemotherapy with or without radiotherapy. Of 16 subjects, 15 achieved a complete remission; none of these patients has had a recurrence since the completion of the initial therapy (range of follow-up from 16 months to 10 years). One patient died.

Metabolism of drugs in the eye. Menadione-dependent reduction of tertiary amine N-oxide by preparations from bovine ocular tissues

As described previously, the microsomes and cytosol from bovine ciliary body exhibited a significant reductase activity toward tertiary amine N-oxide such as imipramine N-oxide when supplemented with menadione. In the present study, the menadione-dependent N-oxide reduction was further examined with preparations of bovine ocular tissues. The reduction of imipramine N-oxide occurred much more significantly when the microsomes and cytosols from bovine ciliary body were supplemented with both menadione and NAD(P)H, compared with menadione alone. The cytosolic menadione-dependent reduction, but not the microsomal one, was markedly inhibited by dicumarol, suggesting the involvement of DT-diaphorase in the reaction. Localization of the menadione-dependent N-oxide reductase activity in bovine ocular tissues indicated that the highest activity resided in the ciliary body, followed by retinal pigment epithelium-choroid, iris, retina and cornea. When the cytosol from bovine ciliary body was fractionated with ammonium sulfate, the distribution of the menadione-dependent N-oxide reductase activity in the resultant fractions was parallel, but roughly, to that of DT-diaphorase activity, supporting the assumption that the flavoenzyme was involved in the cytosolic menadione-dependent N-oxide reduction. We proposed a new mechanism for the metabolic reduction of tertiary amine N-oxide in the eye: Menadione is reduced to the corresponding diol by quinone-reducing enzymes and then tertiary amine N-oxide is reduced by the diol to the corresponding amine nonenzymatically.

Purification of aldehyde oxidase from bovine ciliary body

Ocular aldehyde oxidase was purified for the first time from bovine ciliary body cytosol by ammonium sulfate fractionation and successive HPLC using DEAE anion-exchange and hydroxyapatite columns. The purified enzyme was homogeneous by the criterion of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weight of the enzyme was estimated to be about 150,000 by electrophoresis and to be about 300,000 by gel filtration HPLC on a TSK gel G3000SWXL column, indicating that the enzyme consists of two subunits with the same molecular weight. On the other hand, nicotinamide N-oxide reductase activity was associated with aldehyde oxidase activity throughout the purification steps of the latter enzyme. This fact indicated that nicotinamide N-oxide reductase activity of the ciliary body cytosol is due to aldehyde oxidase present in the tissue preparation.