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Biomedical subjects

Kei Shinoda

Publications and source records attributed to Kei Shinoda.

At least 37 records · Page 2Linked to original sources
PubMed2005

Massive bilateral vitreoretinal hemorrhage in patient with chronic refractory idiopathic thrombocytopenic purpura.

BACKGROUND: We describe a patient with chronic, refractory idiopathic thrombocytopenic purpura (ITP) who developed massive vitreoretinal hemorrhages in both eyes. METHODS: A 49-year-old woman complained of an acute decrease of vision, and ophthalmoscopy revealed bilateral preretinal and subretinal hemorrhages around the optic disc. Her platelet counts were less than 5000/mul in spite of repetitive administration of corticosteroids and immunoglobulins with splenectomy for the chronic refractory ITP. One month later, she developed massive vitreoretinal hemorrhages bilaterally, and vision decreased to hand-motion. RESULTS: Vitrectomy was performed on both eyes after medical treatment to increase platelet counts. The intraretinal hemorrhages were absorbed from the area around the disc and vision recovered to 20/100 in the right eye and 20/2000 in the left after one month. CONCLUSION: Massive vitreoretinal hemorrhages can develop in patients with chronic refractory ITP, and vitrectomy can be beneficial for this condition.

Chronic Disease↗
PubMed2005

Intraocular lens implantation after atopic cataract surgery decreases incidence of postoperative retinal detachment.

PURPOSE: To investigate the efficacy of intraocular lens (IOL) implantation in reducing the incidence of postoperative retinal detachment after cataract surgery in patients with atopic dermatitis. DESIGN: Retrospective review. PARTICIPANTS: One hundred sixty-nine eyes of 126 patients who underwent cataract surgery for atopic cataract were followed for more than 1 year. None of the eyes previously had a retinal detachment or retinal detachment surgery. METHODS: The eyes were divided into 132 eyes of 95 patients with an IOL implantation (IOL group) and 37 eyes of 31 patients without an IOL implantation (aphakia group). The postoperative visual acuity and incidence of postoperative retinal detachment were compared between the 2 groups. The effects of the location of the causative retinal breaks, intraoperative posterior capsule rupture, and postoperative posterior capsulotomy on the incidence of retinal detachments were evaluated. MAIN OUTCOME MEASURES: The postoperative corrected visual acuity, incidence of postoperative retinal detachment, and influence of intraoperative posterior capsule rupture on the retinal detachment. RESULTS: The final visual acuity was better than or equal to 20/20 in 128 eyes (97.0%) of the IOL group and in 29 eyes (78.4%) of the aphakia group (P = 0.0007). Retinal detachment after an uncomplicated cataract surgery occurred in 3 eyes (2.3%) of the IOL group and in 8 eyes (25.8%) of the aphakia group (P<0.0001, Mantel-Cox). Two of 3 eyes (66.7%) in the IOL group and 1 of 8 eyes (16.7%) in the aphakia group that later developed a retinal detachment had an intraoperative posterior capsule rupture. Posterior capsulotomy by yttrium-aluminum-garnet laser did not seem to alter the incidence of postoperative retinal detachment in either the IOL (2.0%) or the aphakia group (25.0%). CONCLUSIONS: The rate of postoperative retinal detachment in eyes with IOL and no intraoperative posterior capsule rupture seems to be low. Intraocular lens implantation with capsular bag fixation may reduce the incidence of postoperative retinal detachment triggered by lens surgery for atopic cataract.

Adolescent↗
PubMed2005

Toxicity study of erucylphosphocholine in a rat model.

PURPOSE: To investigate the effect of intraocular erucylphosphocholine (ErPC) on the retina, the retinal pigment epithelium (RPE), and the choroid in an in vivo rat model. METHODS: Adult male Brown Norway rats were injected intravitreally with ErPC dissolved in balanced salt solution (BSS) at a final concentration of 10 or 100 microM with BSS serving as control. Adverse effects on the anterior and posterior segment were assessed by slit-lamp biomicroscopy and ophthalmoscopy. Retinal toxicity was assessed by electroretinography (ERG), retinal ganglion cell (RGC) quantification, and histology 7 days after intravitreal administration of ErPC. RESULTS: There was neither a statistically significant difference in the clinical examination nor in the ERG waves of treated versus control rats 7 days after intravitreal administration of ErPC. Correspondingly, the number of RGC after BSS injection did not differ significantly from ErPC-injected animals. Histologic sections of the posterior segment of 10 and 100 microM ErPC-injected rats did not show any signs of retinal toxicity. Electron microscopy did not display a difference between the 10 microM and the control group. Only the 100 microM-injected animals showed a discrete irregularity of the Müller cell and the retinal ganglion cell cytoplasm at the ultrastructural level. CONCLUSIONS: ErPC can safely be injected into the vitreous of adult rats at a concentration of 10 microM without any retinal toxicity. Even a 10-fold increase in ErPC concentration leads only to a discrete cytoplasmic irregularity of the innermost retinal layers.

Animals↗
PubMed2005

Selective suppression of pathologic, but not physiologic, retinal neovascularization by blocking the angiotensin II type 1 receptor.

PURPOSE: To investigate the anti-inflammatory and anti-angiogenic effects of telmisartan, an angiotensin II type 1 receptor (AT1-R) antagonist, on ischemia-induced retinal neovascularization. METHODS: C57BL/6 neonatal mice were reared in an 80% concentration of oxygen from postnatal day (P)7 to P12, followed by room-air breathing until P17, to induce ischemia-initiated retinal neovascularization (i.e., a murine model of ischemic retinopathy). Tissue localization of AT1-R was examined by immunohistochemistry for murine retinal wholemounts and human fibrovascular tissues excised at vitrectomy for proliferative diabetic retinopathy. Animals received intraperitoneal injection of telmisartan or vehicle. A concanavalin A lectin perfusion-labeling technique was used to evaluate the areas of physiological and pathologic retinal new vessels and the number of leukocytes adhering to the vasculature. Retinal mRNA and protein levels of intercellular adhesion molecule (ICAM)-1, vascular endothelial growth factor receptor (VEGFR)-1, and VEGFR-2 were examined by RT-PCR and ELISA. RESULTS: Vessels in human fibrovascular tissues and the murine retinas were positive for AT1-R. Pathologic (P < 0.01), but not physiologic (P > 0.05), retinal neovascularization was significantly suppressed in telmisartan-treated mice compared with vehicle-treated animals. The number of adherent leukocytes (P < 0.01) was also significantly reduced, together with retinal ICAM-1 levels (P < 0.01) in the telmisartan-treated group compared with the control group. No significant difference was detected in retinal VEGFR-2 levels between the two groups, whereas retinal VEGFR-1 levels in the telmisartan-treated group were significantly (P < 0.05) lower than in the vehicle-treated group. CONCLUSIONS: The present findings suggest that the AT1-R signaling blockade leads to the selective suppression of pathologic, but not physiological, retinal neovascularization through the inhibition of the inflammatory processes related to pathologic neovascularization.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2005

Suppression of ocular inflammation in endotoxin-induced uveitis by blocking the angiotensin II type 1 receptor.

PURPOSE: To examine whether the angiotensin II type 1 receptor (AT1-R) signaling plays a role in ocular inflammation in endotoxin-induced uveitis (EIU). METHODS: EIU was induced in C57BL/6 mice by a single intraperitoneal injection of 150 mug lipopolysaccharide (LPS). Tissue localization, mRNA expression, and protein levels of AT1-R in murine retinas were examined by immunohistochemistry, RT-PCR, and Western blot analyses, respectively. Telmisartan, an AT1-R antagonist widely used as an antihypertensive agent, was administered intraperitoneally at a dose of 10 mg/kg daily for 5 days until the injection of LPS. Twenty-four hours after administration, leukocyte adhesion to the retinal vasculature was evaluated with a concanavalin A lectin perfusion-labeling technique. Retinal mRNA and protein levels of intercellular adhesion molecule (ICAM)-1 were examined by RT-PCR and ELISA, respectively. Protein concentration and inflammatory cells in the aqueous humor were also measured. RESULTS: Retinal vessels were positive for AT1-R. In mice with EIU, retinal AT1-R mRNA and protein levels were significantly increased when compared to the normal control. EIU animals also showed significant increases in the number of inflammatory cells infiltrating the anterior chamber and adhering to the retinal vessels and in retinal ICAM-1 levels. Administration of telmisartan to EIU mice resulted in significant suppression of retinal ICAM-1 expression and leukocyte adhesion and infiltration compared with vehicle treatment. Protein concentration in the aqueous humor of telmisartan-treated EIU mice tended to be lower than that of vehicle-treated EIU mice, but the difference was not statistically significant. CONCLUSIONS: AT1-R signaling blockade inhibited retinal ICAM-1 upregulation and leukocyte adhesion and infiltration in the EIU model. These results suggest the potential use of an AT1-R antagonist as a therapeutic agent to reduce ocular inflammation.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2004

Subretinal electrical stimulation of the rabbit retina with acutely implanted electrode arrays.

BACKGROUND: Subretinal implants intend to replace photoreceptor function in patients suffering from degenerative retinal disease by topically applying electrical stimuli from the subretinal space. This study intended to prove the feasibility of a newly developed transchoroidal surgery and, furthermore, of a subretinal electrode array, which closely resembles envisioned human implants to electrically stimulate the visual system in rabbits. METHODS: Five rabbits (ten eyes) were implanted with a 4x2-electrode array via a transchoroidal access to the subretinal space. The electrodes were connected to an arbitrary stimulus generator to apply voltage pulses. Retinae were accessed by light microscopy after stimulation with various intensities. RESULTS: The stimulating foil could be introduced into the subretinal space in all eyes. In seven of ten eyes electrically evoked cortical potentials following subretinal electrical stimulation could be elicited. Threshold voltages ranged from less than 0.1 to 2.38 V with a corresponding threshold charge of approximately 1.0 nC per electrode or 10 micro C/cm(2). Histology revealed localized retinal damage over some of the electrodes succeeding stimulation strengths of 2 V and consistent damage over all electrodes succeeding voltages of 3 V. CONCLUSIONS: The study demonstrates the feasibility of the transchoroidal surgical access to place subretinal implants in rabbit eyes and provides proof of successful cortical activation following subretinal electrical stimulation by an electrode array envisioned for human implantations.

Animals↗
PubMed2004

A clinicopathologic case report on macular hole associated with von Hippel-Lindau disease: a novel ultrastructural finding of wormlike, wavy tangles of filaments.

BACKGROUND: We describe a novel ultrastructural finding observed in an epiretinal membrane excised from a patient with von Hippel-Lindau disease. METHODS: This interventional case report presents a 45-year-old woman who noted decreased vision in her right eye and was referred for treatment of a macular hole secondary to von Hippel-Lindau disease. Blindness had occurred previously in the left eye because of exudative retinal detachment. Funduscopic examination revealed a macular hole associated with a delicate epiretinal membrane, multiple retinal angiomas, and multiple old laser scars. Vitrectomy was performed in her right eye. The epiretinal membrane was peeled off and processed for light and electron microscopy. RESULTS: Postoperatively the macular hole was successfully closed, and vision recovered to 20/20 from 20/40. In the excised epiretinal membrane, flattened glial cells and extracellular matrix containing fibrous elements formed a multilayered pattern. Ultrastructurally, the fibrous elements appeared as wormlike, wavy tangles of filaments (WWTF) with an orientation parallel to the surface of the epiretinal membrane. Just above the WWTF, flattened glial cells frequently extended thin cytoplasmic processes with pinocytotic vesicles. CONCLUSION: The ultrastructure suggested that retinal glial cells had induced a remodeling of the collagenous stroma in the posterior vitreous cortex, resulting in tangential macular traction.

Basement Membrane↗
PubMed2004

Novel 473-bp deletion in XLRS1 gene in a Japanese family with X-linked juvenile retinoschisis.

PURPOSE: To present the clinical features of two brothers with molecularly confirmed X-linked juvenile retinoschisis (xlRS) but with non-characteristic electrophysiological findings. METHODS: Comprehensive ophthalmological examinations were performed. The electroretinograms (ERGs) were recorded under ISCEV standards, and ERGs elicited by long-duration stimuli were also evaluated. Standard genetic analysis of peripheral blood leukocytes was performed. RESULTS: Molecular testing revealed a novel 473-bp deletion including exon 4 in the XLRS1 gene in both siblings. This resulted in a frameshift mutation and a premature termination at codon 78. The scotopic and photopic ERGs were reduced, but the "negative-type" ERG, characteristic of xlRS, was not observed. Flicker ERGs were also highly reduced. Long-duration stimuli elicited ERGs with a complete loss of the b-wave and a preservation of the off-response, i.e., negative-type ERG. The phenotype/genotype relationship was not determined. CONCLUSION: The consistency of the ERGs elicited by long-duration stimuli in xlRS patients suggests that this type of stimuli provides responses that are a better indicator for the progression or stage of the disease.

Adult↗
PubMed2004

Retinal neurodegeneration in the DBA/2J mouse-a model for ocular hypertension.

Mice of the DBA/2J strain spontaneously develop complex ocular abnormalities, including glaucomatous loss of retinal ganglion cells (RGC). In the present study ultrastructural features of retinal neurodegeneration in DBA/2J mice of different age (3, 6, 8 and 11 months) are described. By 3 months, RGC apoptosis characterized by electron-dense karioplasm and cytoplasm of ganglion cells was observed. The occurrence of apoptotic ganglion cells peaked at the age of 6 months. Past this age, necrosis characterized by swelling and electron-rare cytoplasm appeared to be the prevailing form of cell death. Müller glia activation increased with age, but there were no signs of leukocyte infiltration. At 8 and 11 months, signs of neoangiogenesis were found both at the ultrastructural level and in clinical examinations. In these older animals myelin-like bodies, most probably representing the intracellular aggregates of phospholipids in irreversibly injured cells, were also seen. Photoreceptor cells were not affected at any age. Our observations suggest that retinal degeneration in the DBA/2J mice does not involve recruitment of blood-borne inflammatory/phagocytosing cells, and that apoptosis is gradually replaced by necrosis as the predominant pathway of RGC death. Retinal degeneration in 3- to 11-month-old DBA/2J mice partially resembles human pigment dispersion syndrome and pigmentary glaucoma with characteristic anterior segment changes and elevation of intraocular pressure. However, neovasculogenesis and myelin-like bodies are observed during aging. Therefore, the DBA/2J model requires judicious interpretation as a glaucoma model.

Age Factors↗
PubMed2004

In vivo assessment of subretinally implanted microphotodiode arrays in cats by optical coherence tomography and fluorescein angiography.

BACKGROUND: Following multiple promising investigations into restoration of vision in degenerative retinal disease by implantation of a sub- or epiretinal prosthesis, the step to clinical use in humans is impending. In this study we intended to establish optical coherence tomography (OCT) and fluorescein angiography (FA) first in research animals for noninvasive assessment of the condition of the posterior pole of eyes after intraocular implant surgery. METHODS: Three adult cats that had undergone subretinal implant surgery were evaluated by OCT and FA between 1 and 470 days postoperatively. Eight adult cats served as control. In addition histology was performed. RESULTS: In all three cats OCT demonstrated stable positioning of the implants in the subretinal space during the complete examination period. Transient retinal edema was found in the early postoperative period but decreased during follow-up. The retina over the implants was well attached at all times in cats 1 and 2; however, in cat 3 localized retinal detachment was demonstrated. FA showed intact retinal vasculature over the subretinal implant in high detail without interference from choroidal background fluorescence. CONCLUSIONS: OCT and FA have been fruitfully applied to cats to assess the morphological and circulatory conditions of the neuroretina and of its interface with the subretinal implant. The techniques may therefore provide a tool for objective, noninvasive in vivo evaluation of eyes that have undergone subretinal implant surgery, both in research animals and in humans.

Animals↗
PubMed2004

Successful treatment of subfoveal choroidal neovascularization associated with combined hamartoma of the retina and retinal pigment epithelium.

PURPOSE: To describe a patient with subfoveal choroidal neovascularization (CNV) associated with combined hamartoma of the retina and retinal pigment epithelium (CHRRPE), treated successfully by submacular surgery. DESIGN: Interventional case report. METHODS: A 12-year-old girl was referred to our clinic for evaluation. Visual acuity was 20/30 in the affected left eye. Ophthalmoscopy disclosed juxtapapillary CHRRPE and subfoveal pigmented CNV. Vitreous surgery was carried out because of visual deterioration to 20/60. RESULTS: The posterior vitreous was strongly attached to glial tissue at the superior margin of the optic disk in the CHRRPE region. The CNV, which was not connected with the CHRRPE, was carefully removed, resulting in visual improvement to 20/20 5 months after surgery. Histologically, the excised membrane showed fibroblast-rich cellular component and a type 2 configuration. CONCLUSION: Submacular surgery can be effective for the treatment of secondary CNV associated with CHRRPE.

Child↗
PubMed2004

Evaluation of calcification of a hydrogel intraocular lens by optical coherence tomography.

We describe 2 cases of calcification of hydrogel intraocular lenses (IOLs) evaluated by optical coherence tomography. Dense or slight surface opacities of hydrogel IOLs were detected initially by slitlamp biomicroscopy in a 55-year-old woman and a 77-year-old woman. The opacities resulted in complaints of hazy vision after uneventful phacoemulsification and IOL implantation. Optical coherence tomography was used to further assess the opacities and showed calcification by high reflectivity on the anterior and posterior IOL surfaces in the first patient and on the anterior surface in the second patient. No abnormal reflectivity was seen on the surface of a hydrophobic acrylic IOL in the second patient's fellow eye. Optical coherence tomography may be useful to detect calcification of a hydrogel IOL.

Aged↗
PubMed2004

New method for detecting misrouted retinofugal fibers in humans with albinism by magnetoencephalography.

In humans with albinism, a large percentage of the ganglion cell axons from the temporal retina decussate abnormally in the chiasm and synapse in the contralateral LGN. The aim of this study was to determine whether the misrouting of the optic fibers can be detected by magnetoencephalography (MEG). Visually evoked magnetic fields (VEFs) were recorded from three patients with albinism. After monocular stimulation, the isofield contour maps of the VEFs showed a single current dipole pattern over the contralateral hemisphere in patients with albinism. These results clearly illustrated the reduced uncrossed retinofugal pathway of patients with albinism.

Adolescent↗
PubMed2004

Electroretinography as a screening method for mutations causing retinal dysfunction in mice.

PURPOSE: To detect mice with hereditary retinal impairment, a high-throughput electroretinography (ERG) screening system was established. METHOD: Mice from eight different strains without known retinal disorders (102, 129/SvJ, AKR, C57BL/6J, C57BL/6JIco, CBA/CaJ, and DBA/2NCrlBR) and one control strain with retinal degeneration (C3HeB/FeJ) were fixed on a specially constructed sled, ERG electrodes were placed on the cornea, and mice were moved into a Ganzfeld stimulator. From a luminance range of 0.0125 to 500 cd-s/m(2) in a pretest series two levels (5 and 125 cd-s/m(2)) were chosen to shorten examination times. The root mean square (RMS) of the ERG-recording was analyzed to detect animals with abnormal retinal function. ERG responses of the left and right eyes were compared in amplitudes and implicit times of the a- and b-waves. Statistical analysis of the latter parameters was performed in all wild-type animals. Histology was performed on selected mice. RESULTS: ERG recordings of individual animals for the left and right eye revealed good agreement in amplitudes and implicit times of the a- and b-waves (P < 0.05). Comparison of these parameters among the wild-type strains showed several differences. Evaluation of the RMS revealed, in addition to the C3HeB/FeJ mice, a subgroup of mice within the 129/SvJ strain with abnormal retinal function. Molecular analysis of these mice demonstrated the presence of the same retroviral insertion in the Pde6b gene, which is causative of the Pde6b(rd1) allele carried in C3HeB/FeJ mice. Histologic analysis demonstrated good correlation between retinal electrophysiology and morphology. CONCLUSIONS: The present results demonstrate the feasibility of ERG for screening a large number of mice to detect animals with functional retinal impairment.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2004

[Intravitreal injection of triamcinolone acetonide for cystoid macular edema resistant to vitreous surgery].

PURPOSE: To report the efficacy of intravitreal injection of triamcinolone acetonide(TA) for cystoid macular edema remaining after vitreous surgery. METHODS: Eight eyes of 7 patients aged from 32 to 84 years old were studied. The original diseases that caused macular edema were central retinal vein occlusion in 2 eyes, branch retinal vein occlusion in one eye, Irvine-Gass syndrome in 2 eyes, and diabetic retinopathy in 3 eyes. 4 mg of TA was injected intravitreally and visual acuity and foveal thickness measured by optical coherence tomography(OCT) were evaluated in before and after the surgery. RESULTS: Macular edema resolved rapidly after injection of TA in all cases and cysts were extinguished or diminished. The foveal thickness in OCT was reduced significantly from preoperative 495 +/- 116 (mean +/- standard deviation) microns to 267 +/- 117 microns after one week, and 246 +/- 81 microns after one month. The effect persisted for three months. Visual improvement of more than two Snellen lines was seen in 4 eyes. No side effects were observed except a temporary increase of intraocular pressure in one eye. CONCLUSION: Intravitreal injection of TA is effective in a short-term for cystoid macular edema remaining after vitrectomy.

Adult↗