Akira Takamiya

Constitutive nitric oxide synthase is associated with retinal vascular permeability in early diabetic rats

Abstract.Aims/hypothesis: We investigated the association between vascular permeability and constitutive nitric oxide synthase in rats with diabetes for a short duration (2 weeks). Methods: Retinal vascular permeability was evaluated in rats with diabetes induced by streptozotocin using vitreous fluorophotometry and a small animal adapter. We carried out in situ hybridization and semi-quantitative reverse transcription–polymerase chain reaction to study the expression of endogenous constitutive nitric oxide synthase mRNA in diabetic retinas. We also examined changes in the protein expression of constitutive nitric oxide synthase in diabetic retinas using immunohistochemistry and Western blotting. Results: Retinal vascular permeability was significantly higher in diabetic rats (median, 1.09 arbitrary unit) compared with control rats (median, 0.69 arbitrary unit) (p < 0.05). The expression of both neuronal nitric oxide synthase (NOS) and endothelial nitric oxide synthase mRNA was higher in diabetic retinas than in the retinas of control rats as determined by in situ hybridization and reverse transcription-polymerase chain reaction. Immunohistochemistry and Western blotting also showed that neuronal nitric oxide synthase increased in diabetic retinas. The immunohistochemistry of endothelial nitric oxide synthase indicated that non-vessel tissues increased in diabetic retinas while retinal vessels weakened. Western blotting showed that the amount of endothelial nitric oxide synthase increased. Conclusion/interpretation: These results suggest that increases in both constitutive NOSs (nNOS and eNOS) could be associated with retinal vascular permeability and that NOS is associated with clinical vascular dysfunction in the early stages of diabetes. [Diabetologia (2001) 44: 1043–1050]

Scotoma and Fixation Patterns Using Scanning Laser Ophthalmoscope Microperimetry in Patients With Macular Dystrophy

PURPOSE We used scanning laser ophthalmoscope microperimetry to evaluate the retinal scotoma and the fixation points in the patients with macular dystrophy. METHODS We studied 10 eyes of five patients with macular dystrophy (three patients with cone dystrophy and two patients with Stargardt disease). The mean patient age was 37 years (range, 13 to 64 years). An estimation of scotoma and fixation points on the retina was performed using scanning laser ophthalmoscope microperimetry. RESULTS All 10 eyes (100%) had one of two types of dense scotoma: type one was a dense ring scotoma (five eyes, 50%), and type two was a dense central scotoma (five eyes, 50%) that included the center of the fovea. In all eyes with a dense ring scotoma, the fixation points were stable and did not shift. In all eyes with a dense central scotoma, the fixation shifted. The logarithm of minimal angle of resolution of the visual acuity in the eyes with the dense central scotoma was significantly worse than that of eyes with the dense ring scotoma type (P =.005). CONCLUSIONS Scanning laser ophthalmoscope microperimetry findings demonstrate two types of dense scotoma (dense ring scotoma and dense central scotoma) in the patients with macular dystrophy. The two types of dense scotoma affect the shifting of the fixation points and the stability of fixation and may result in the difference in visual acuity in the patients with macular dystrophy.

Use of scanning laser ophthalmoscope microperimetry in clinically significant Macular edema in type 2 diabetes mellitus

PURPOSE We used scanning laser ophthalmoscope (SLO) microperimetry to evaluate scotomas in patients with clinically significant diabetic macular edema (CSME) in type 2 diabetes mellitus. METHODS We studied 19 patients (mean age = 63 years; range, 45-78 years) (19 eyes). SLO microperimetry was performed in all eyes. We divided patients into three groups as follows: dense scotoma, relative scotoma, and no scotoma. The following variables were documented: age; duration of diabetes, hemoglobin A(1c) levels; logarithm of the minimum angle of resolution (Log(MAR)) visual acuity; refractive power; a history of panretinal photocoagulation; presence or absence of proliferative diabetic retinopathy, vitreomacular separation, and cystoid changes; the type of macular edema; and stability of fixation. All variables were compared in the three groups. RESULTS We identified 4 eyes (21.1%) with dense scotoma, 10 (52.6%) with relative scotoma, and 5 (26.3%) with no scotoma. There were significant differences in log(MAR) visual acuity among those with dense scotoma (1.4 +/- 0.5), relative scotoma (0.6 +/- 0.2), and no scotoma (0.2 +/- 0.3) (P <.05), and in the prevalence of cystoid changes, diffuse edema, and unstable fixation among those with dense scotoma (75%, 75%, and 100%, respectively), relative scotoma (20%, 30% and 50%, respectively) and no scotoma (0%, 0% and 0%, respectively) (P <.05). CONCLUSIONS Macular scotoma was observed by SLO microperimetry in 74% of the patients in this study. A scotoma in CSME is related to the formation of cystoid changes and the type of macular edema. In eyes with CSME in type 2 diabetes mellitus, a scotoma in the macula causes visual acuity impairment and unstable fixation.

Oral fluorescein angiography with the confocal scanning laser ophthalmoscope

OBJECTIVE To evaluate the efficacy of oral fluorescein angiography with a confocal scanning laser ophthalmoscope (SLO) system. DESIGN Comparative case series. PARTICIPANTS The authors used a confocal SLO (Heidelberg Retina Angiograph [HRA]) to perform oral fluorescein angiography in 47 patients, 13 of whom were without any retinal disease and 34 with a variety of retinal diseases including macular holes and pucker, inflammatory diseases, retinal vascular diseases, and age-related macular degeneration. The images were also compared to images taken with a fundus camera after intravenous fluorescein injections in patients on whom both studies were done. INTERVENTION Color fundus photographs were taken of each eye (30 degrees fundus camera) before drinking 4 ml of 25% sodium fluorescein mixed with 60 ml of orange juice. After oral fluorescein ingestion, images of each eye were taken with a fundus camera (TriX film) and the HRA (using 512- x 512-pixel resolution). The images were repeated at 0-, 2.5-, 5-, 7.5-, 10-, 12.5-, 15-, 20-, 25-, and 30-minute intervals. Twenty of the 47 patients underwent intravenous fluorescein angiography performed with the fundus camera. MAIN OUTCOME MEASURE Images were analyzed by a masked reader, and foveal avascular zone visualization, branch retinal vessel identification, and image quality were scored. Statistical analysis was performed with a t test for paired data with a two-tailed test of significance (alpha = 0.05). RESULTS Foveal avascular zone was 100% as seen in 16 eyes (47%) in the HRA machine versus 1 eye (2%) in the conventional fundus camera (P < 0.0001). The third-order branch retinal vessels were identified in 59% of eyes in the HRA versus 26% in the fundus camera group (P < 0.0001), and the image quality was considered comparable to an intravenous angiogram in 47% with the HRA versus 9% with the conventional fundus camera (P < 0.0001). CONCLUSIONS Oral fluorescein angiography using the HRA produces sufficiently detailed images to diagnose, treat, and follow many types of retinal pathology.

Macular hole formation in fellow eyes with a perifoveal posterior vitreous detachment of patients with a unilateral macular hole.

PURPOSE To estimate the rate of macular hole formation in fellow eyes with a perifoveal posterior vitreous detachment (PVD) and early stage 1 intrafoveal lesions in patients with a unilateral idiopathic full-thickness macular hole (MH) using optical coherence tomography (OCT). DESIGN Retrospective observational case series. METHODS Fellow eyes of consecutive patients with a unilateral full-thickness MH were examined on OCT. A subset of fellow eyes with a perifoveal PVD had been followed to investigate the rates of macular hole formation in fellow eyes with early stage 1 intrafoveal lesions. RESULTS Of 176 patients with a unilateral full-thickness MH, 42 fellow eyes (42 patients) with a perifoveal PVD were identified. During follow-up, a foveolar detachment was seen in 16 eyes, and 4 eyes had a foveal pseudocyst alone. In the 16 eyes with a foveolar detachment, 9 eyes had concurrent inner foveal splits. Within another 2 years of follow-up, OCT showed that 5 of 16 fellow eyes (31%) with a foveolar detachment developed a second full-thickness MH and 5 of 9 fellow eyes with a foveolar detachment and inner foveal splits developed a second full-thickness MH. Two of 4 eyes with a foveal pseudocyst alone developed vitreofoveal separation without hole formation. The remaining 2 eyes with a foveal pseudocyst alone remained stable at the last follow-up visit. CONCLUSIONS Fellow eyes with a foveolar detachment and a perifoveal PVD may be at high risk, and fellow eyes with a foveolar detachment and inner foveal splits might be at higher risk for progression to macular hole formation.

Inhibitory effect of losartan on laser-induced choroidal neovascularization in rats

PURPOSE To investigate the inhibitory effects of losartan, an angiotensin receptor antagonist, on angiogenesis in a rat model of laser-induced choroidal neovascularization. METHODS Experimental study. Fifteen Brown-Norway male rats received losartan (approximately 5 mg/kg/d) in drinking water, and 15 Brown-Norway male rats received unsupplemented drinking water 1 week before photocoagulation, and it was continued to the end of the study. Two weeks after intense laser photocoagulation, choroidal neovascularization was evaluated by fluorescein angiography and histopathologic evaluation. RESULTS The incidence of choroidal neovascularization formation was 99.5 +/-.2% (mean +/- standard deviation) in controls and 72.5 +/- 8.8% in losartan-treated rats (P <.01). Quantitative morphometric assessment revealed mean choroidal neovascularization lesion thickness of 54 and 44.8 microm, respectively, in controls and losartan-treated rats (P <.01). CONCLUSION Losartan seems to inhibit development of laser-induced choroidal neovascularization. Angiotensin receptor antagonists may be useful as prophylaxis against choroidal neovascularization associated with age-related macular degeneration.

Idiopathic Full-Thickness Macular Holes and the Vitreomacular Interface: A High-Resolution Spectral-Domain Optical Coherence Tomography Study

PURPOSE To analyze the vitreomacular interface in idiopathic full-thickness macular holes (MHs) using spectral-domain optical coherence tomography. DESIGN Prospective cross-sectional case series. METHODS Ninety-one eyes of 86 consecutive patients with a MH were examined by spectral-domain optical coherence tomography. The vitreomacular interface was assessed and the presence or absence of an operculum was analyzed. RESULTS Fifty-two eyes had a stage 2 MH, 12 eyes a stage 3 MH, and 27 eyes a stage 4 MH. No posterior hyaloid membrane was detected in any eyes with a stage 4 MH. In 35 (54.7%) of the 64 eyes with an MH without a complete posterior vitreous detachment (PVD), we saw a perifoveal PVD with vitreofoveal adhesion and partial dehiscence of the raised inner retina with an outer retinal separation in the MHs. In 24 (37.5%) of the 64 eyes without a complete PVD, an operculum, which is a hyperreflective structure of the foveal retina, was in front of the MH. The posterior hyaloid membrane was separated completely but adhered to the optic disc. In 2 (3.1%) of the 64 eyes without a complete PVD, the posterior hyaloid membrane was separated from the macula without an operculum. In 3 (4.7%) of the 64 eyes without a complete PVD, vitreofoveal adhesion on both edges of the hole was connected to the taut posterior hyaloid membrane without an operculum. CONCLUSIONS The vitreomacular interface had 4 configurations in MHs without a complete PVD. Approximately 55% of cases with an open roof in the eyes without a complete PVD may be at risk for progression to operculum formation (loss of retinal tissue).

Inhibitory effect of bucillamine on laser-induced choroidal neovascularization in rats.

Purpose. We investigated the inhibitory effects of bucillamine on formation of laser-induced choroidal neovascularization (CNV) in a rat model. Methods. Bucillamine administration (approximately 150?mg/kg/day) was started 1 week before photocoagulation and continued to the end of the study. Control groups received drinking water. Two weeks after photocoagulation, choroidal neovascularization development was evaluated using simultaneous fluorescein and indocyanine green angiography, and the maximal thickness of the lesions was measured histologically. Results. The incidence of CNV formation was 99.5 ± 0.2% [mean ± standard deviation (SD)] in control rats and 64.3 ± 15.1% with bucillamine (P < 0.01). Histological study showed that the thickness of the CNV lesions was 23.4 ± 6.5 µm (mean ± SD) in the bucillamine-treated rats, which was significantly decreased compared to that in controls (60.8 ± 9.2 µm) (P < 0.01). Conclusions. Our results suggest that bucillamine may inhibit the development of laser-induced CNV in rats.

Retinal changes in juvenile X linked retinoschisis using three dimensional optical coherence tomography.

Juvenile X linked retinoschisis is a congenital X linked recessive retinal disorder, the characteristic funduscopic findings of which are a silver-grey retinal reflex, foveal retinoschisis, and peripheral retinoschisis. Electroretinograms (ERGs) typically record a reduced b-wave amplitude with relative preservation of the a-wave amplitude. Visual acuity (VA) usually deteriorates slowly until the patient is about 20 years of age, stabilises around 0.2∼0.5, and sometimes deteriorates further because of macular degeneration.1–4 Podoleanu and associates developed a novel integration of scanning laser ophthalmoscopy (SLO) and optic coherence tomography (OCT)—three dimensional optical coherence tomography (3-D OCT).5 Using transverse scanning, typical for SLO, the instrument simultaneously produces SLO and interferometric OCT images.6 We can obtain both cross sectional scans (B-scans) as with conventional OCT and transverse scans (C-scans) using 3-D OCT. This is the first report of 3-D OCT findings in juvenile X linked retinoschisis. A 7 year old boy presented with VA of 0.5 …

Inflammation induces serine protease inhibitor 3 expression in the rat pineal gland

In the rat pineal gland, prominent expression of serine protease inhibitor 3 (SPI-3) mRNA is seen after systemic injection of lipopolysaccharide. The up-regulation of SPI-3 mRNA expression is also confirmed by northern blotting. Most SPI-3 mRNA-positive cells simultaneously express synaptophysin, a marker for pinealocytes, but not glial fibrillary acidic protein, a marker for astrocytes. This indicates that SPI-3 mRNA-positive cells are pinealocytes. Almost all SPI-3 mRNA-positive cells also showed translocation of the signal transducers and activators of transcription 3 (STAT3) into nuclei after lipopolysaccharide injection. These data support previous in vitro results that SPI-3 expression is induced in a STAT3-mediated manner. In addition, the expression of ciliary neurotrophic factor receptor (CNTFR) and leukemia inhibitory factor receptor (LIFR) mRNAs, but not of interleukin 6 receptor mRNA, was up-regulated after systemic lipopolysaccharide treatment. Because these receptors are upstream of STAT3, the present results suggest that cytokines such as LIF and/or CNTF induce SPI-3 expression via STAT3 in the pineal gland in response to inflammatory stimulus. We conclude that although the functional consequences of SPI-3 in the pineal gland during systemic inflammation are unknown, SPI-3 may have a crucial role in preventing some degenerative proteolysis induced by inflammatory stimuli.