Search PubMed⌕ Search

Biomedical subjects

Yasuo Tano

Publications and source records attributed to Yasuo Tano.

At least 109 records · Page 6Linked to original sources
PubMed2003

Fourier analysis of corneal astigmatic changes following photorefractive keratectomy.

The purpose of this study was to evaluate the corneal irregular astigmatism following photorefractive keratectomy (PRK) for myopia. The corneal topography of 30 eyes of 26 patients was measured with the TMS-1 videokeratoscope before and 1 month after PRK. Axial dioptric data were decomposed into four components; A0 (Sphericity), C1 x 2 (Asymmetry), C2 x 2 (Regular astigmatism), and C3 (higher-order irregularity) for the central 3 and 6 mm zone by Fourier series harmonic analysis. Post-operative topographies were divided into those with an irregular and those with a homogeneous pattern, and the Fourier components were compared. In the 6 mm zone, A0 was significantly decreased (P < 0.001), and C1 x 2, C2 x 2, and C3 were significantly increased (P = 0.001, 0.005, 0.002, respectively). In the 3 mm zone, A0 decreased (P < 0.001) and C1 x 2 increased (P < 0.001) significantly. C1 x 2 was correlated with the post-operative corrected visual acuity (P < 0.001, r = 0.647). The irregular pattern group had a larger C1 x 2 component (P < 0.001). The treatment displacement was not correlated with any component. In conclusion, irregular topography due to intraoperative drift or asymmetrical wound healing may play a more important role in the post-operative corneal optical property than mild treatment displacement.

Adult↗
PubMed2003

Comparison of ocular higher-order aberrations and visual performance between photorefractive keratectomy and laser in situ keratomileusis for myopia.

The purpose was to compare the ocular higher-order aberrations and the visual performance between photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Ocular aberrations and visual performance were measured after PRK in 26 eyes, after LASIK in 39 eyes, and in 29 normal myopic control eyes. Ocular aberrations were measured with a Hartmann-Shack aberrometer. Visual performance was evaluated with grating contrast sensitivity, high and low contrast visual acuity, and letter contrast sensitivity under full correction with spectacles. The results were that the root mean square (RMS) values of ocular higher-order aberrations after PRK or LASIK were significantly greater than that of normal controls for both 4-mm and 6-mm zones (PRK; 0.22 +/- 0.09 and 0.85 +/- 0.24 microm, LASIK; 0.20 +/- 0.06 and 0.82 +/- 0.24 microm, normal; 0.10 +/- 0.03 and 0.33 +/- 0.11 microm. P < 0.05 between PRK and normal, LASIK and normal, One Way ANOVA on Ranks). There were no significant differences between PRK and LASIK. The ocular higher-order aberrations increased in proportion with the attempted refractive correction by PRK and LASIK. The ocular higher-order aberrations correlated better with grating contrast sensitivity, low contrast visual acuity, and letter contrast sensitivity than with high contrast visual acuity. There was no difference among normal, PRK and LASIK in all the visual function tests, except between normal and PRK, or between normal and LASIK with letter contrast sensitivity. In conclusion, there was no difference in both ocular higher-order aberrations and visual performance between PRK and LASIK. The result suggests that surgeons can choose refractive procedures according to the corneal conditions or daily activities of patients.

Adult↗
PubMed2003

Expression and localization of tenomodulin, a transmembrane type chondromodulin-I-related angiogenesis inhibitor, in mouse eyes.

PURPOSE: To explore the role in the eye of tenomodulin (TeM), a chondromodulin (ChM)-I-related glycoprotein, the expression, localization, and antiangiogenic potential of TeM were investigated. METHODS: Gene expression and protein localization of TeM in mouse eyes were examined by Northern blot analysis, in situ hybridization, and immunohistochemical analysis. Antiangiogenic function included in the C terminus of TeM and ChM-I was examined in vascular endothelial cells through adenoviral gene transduction. RESULTS: TeM expression was detectable from day 15 of the embryonic stage and was clearly present in the eye and skin. In situ hybridization of the eye tissues revealed TeM mRNA in the tendon of the extraocular muscle, the sclerocornea, the lens fiber cells, and the ganglion cell layer, inner nuclear layer cells, and pigment epithelium of the retina. Corresponding immunoreactivity of TeM was present in most of these cells. Western blot detected 40- and 45-kDa immunoreactive bands of TeM in the eye as differently glycosylated forms of the transmembrane protein. Production of a secreted form of TeM and ChM-I through adenoviral gene transfer caused effective autocrine suppression of cell proliferation and capillary-like morphogenesis of retina vascular endothelial cells. The condition media from soluble TeM- and ChM-I-overexpressing cells also showed a marked inhibitory effect on in vitro angiogenesis. CONCLUSIONS: These results indicate a potential role for TeM in prevention of vascular invasion in the mouse eye and the possibility of both TeM and ChM-I as candidates for use in gene therapy approaches to treatment of ocular angiogenesis.

Adenoviridae↗
PubMed2002

Protective effects of timolol against the neuronal damage induced by glutamate and ischemia in the rat retina.

The purpose of this study was to determine whether timolol, an ocular hypotensive drug, has retinal neuroprotective effects in experimental in vitro and in vivo models. For in vitro studies, we used retinal neuron cultures from rat embryos and purified retinal ganglion cells (RGCs) from newborn rats. In the former, neurotoxicity was induced using 1 mM glutamate and cell viability was assessed. In RGCs, neurotoxicity was induced using 25 microM glutamate for 3 days and cell viability was assessed. For the in vivo study, we used a rat model of retinal ischemic injury induced by elevating intraocular pressure (IOP) by raising the hydrostatic pressure. The retinal damage was evaluated by counting the number of cells in the ganglion cell layer (GCL) and by examining the a- and b-waves in the electroretinogram (ERG). For the intraocular distribution study, 0.5% [3H]timolol was topically applied to rat eyes, and these were enucleated after various intervals and divided into parts. Each part was combusted and the radioactivity measured. Timolol (0.1 and 1 microM) markedly reduced the glutamate-induced neuronal cells in retinal neuron cultures and in RGCs. After ischemic-reperfusion, both the number of cells in the GCL and a- and b-waves in the ERG decreased; however, topically applied 0.5% timolol reduced these effects. Topically applied 0.5% timolol was detected at a concentration of approximately 1 microg/g wet tissue in retina-choroid at 30 min after its application. In conclusion, timolol was effective against retinal neuron damage both in vitro and in vivo. Furthermore, topically applied timolol reached the retina-choroid. These findings suggest that timolol has a direct neuroprotective effect against retinal damage.

Action Potentials↗
PubMed2002

The postsynaptic density and dendritic raft localization of PSD-Zip70, which contains an N-myristoylation sequence and leucine-zipper motifs.

The postsynaptic site of the excitatory synapse, which is composed of the postsynaptic density (PSD) attached to the postsynaptic membrane, is a center for synaptic plasticity. To reveal the molecular organization and functional regulation of the postsynaptic site, we cloned a 70 kDa protein that is concentrated in PSDs using a monoclonal antibody against the PSD. This protein, named PSD-Zip70, is highly homologous to the human FEZ1/LZTS1 gene product. PSD-Zip70 contains an N-myristoylation consensus sequence, a polybasic cluster in the N-terminal region and four leucine-zipper motifs in the C-terminal region. Light and electron microscopy showed that this protein was localized to the dendritic spines, especially in the PSD and the postsynaptic membrane. Fractionation of the synaptic plasma membrane demonstrated that PSD-Zip70 was localized to the PSD and the dendritic raft. In Madin-Darby canine kidney (MDCK) cells, exogenous PSD-Zip70 was targeted to the apical plasma membrane of microvilli, and its N-myristoylation was necessary for this targeting. In hippocampal neurons, N-myristoylation was also required for the membrane localization and the C-terminal region was critically involved in the synaptic targeting. These results suggest that PSD-Zip70 may be involved in the dynamic properties of the structure and function of the postsynaptic site.

Amino Acid Sequence↗
PubMed2002

Allelic homogeneity due to a founder mutation in Japanese patients with lattice corneal dystrophy type IIIA.

Lattice corneal dystrophies (LCDs) are caused by mutations of the transforming growth factor beta-induced gene (TGFBI, formerly betaig-h3). LCD type IIIA (LCDIIIA) has been reported mostly from Japan. In this study, we demonstrate allelic homogeneity for Japanese patients with LCDIIIA, using intragenic polymorphic markers. When exon 11 of TGFBI was analyzed, all 18 patients examined were found to be heterozygous for both a P501T mutation and an IVS10-3C --> T variation. On the other hand, none of 54 normal Japanese control subjects had the P501T, and 5 of the controls were heterozygous for IVS10-3C --> T. Haplotype analysis of the patients revealed that both P501T and IVS10-3C --> T were located on the same chromosome, and a significant linkage disequilibrium (P < 0.001, Fisher's exact probability test) was observed between LCDIIIA (P501T) and IVS10-3C --> T. When exon 8 of the gene was analyzed, all these patients possessed the "G allele" of a 1028G/A polymorphism. A significant linkage disequilibrium (P < 0.003; chi-square test) was also observed between P501T and the G allele in the patients. These results suggest that allelic homogeneity seen in Japanese patients with LCDIIIA may result from a single founder mutation.

Alleles↗
PubMed2002

Intramolecular interaction of SUR2 subtypes for intracellular ADP-Induced differential control of K(ATP) channels.

ATP-sensitive K+ (K(ATP)) channels are composed of sulfonylurea receptors (SURs) and inwardly rectifying Kir6.2-channels. The C-terminal 42 amino acid residues (C42) of SURs are responsible for ADP-induced differential activation of K(ATP) channels in SUR-subtypes. By examining ADP-effect on K(ATP) channels containing various chimeras of SUR2A and SUR2B, we identified a segment of 7 residues at central portion of C42 critical for this phenomenon. A 3-D structure model of the region containing the second nucleotide-binding domain (NBD2) of SUR and C42 was developed based on the structure of HisP, a nucleotide-binding protein forming the bacterial Histidine transporter complex. In the model, the polar and charged residues in the critical segment located within a distance that allows their electrostatic interaction with Arg1344 at the Walker-A loop of NBD2. Therefore, the interaction might be involved in the control of ADP-induced differential activation of SUR2-subtype K(ATP) channels.

ATP-Binding Cassette Transporters↗
PubMed2002

Electrical stimulation enhances the survival of axotomized retinal ganglion cells in vivo.

In view of recent reports on the survival promotion of damaged spiral ganglion cells and motoneurons by electrical stimulation, we hypothesized that an electrical stimulation of the cut optic nerve (ON) may promote the survival of axotomized retinal ganglion cells (RGCs) in vivo. To test this hypothesis, we examined 1 week after ON transection the RGC densities in the retinas with or without electrical stimulation. The densities of surviving RGCs in the retinas with the electrical stimulation increased as compared with those without the electrical stimulation. We concluded that electrical stimulation of the ON enhances the survival of axotomized RGCs in vivo, probably due to electrical activation of their soma.

Animals↗
PubMed2002

Effect of simultaneous oblique muscle surgery in foveal translocation by 360 degrees retinotomy.

PURPOSE: To assess the effect of simultaneous oblique muscle surgery during foveal translocation surgery with 360 degrees retinotomy in patients with neovascular maculopathy. METHODS: Foveal translocation with 360 degrees retinotomy was performed on 31 eyes of 31 patients with neovascular maculopathy (21 with age-related macular degeneration 9 with myopic neovascular maculopathy, and 1 with idiopathic neovascular maculopathy). All eyes had simultaneous torsional muscle surgery with recession of the superior oblique muscle and tucking of the inferior oblique muscle. Visual acuity, binocular vision, and degree of cyclotorsion were assessed pre- and postoperatively. The angles of retinal and global rotation, distance of foveal shift, and surgical complications were also investigated. RESULTS: With a mean postoperative follow-up of 10.0 months, vision improved (>0.2 log MAR units) in 13 eyes, was unchanged in 9 eyes, and worsened (>0.2 log MAR units) in 9 eyes. Ten of 31 eyes (32%) had a final visual acuity of 20/50 or better. Eleven patients had binocular fusion, 13 patients showed suppression, and 7 patients developed diplopia that was managed by spectacles with prisms or by secondary muscle surgery. The mean retinal and global rotations were 30.3 degrees and 23.7 degrees, respectively. The average size of the choroidal neovascular membrane was 1.3 disc diameters (DD), while the average shift of the fovea was 1.5 DD. After the primary surgery, six eyes developed retinal detachment, two eyes macular hole, and three eyes proliferative vitreoretinopathy. These complications were successfully managed by additional surgery. CONCLUSION: Foveal translocation with 360 degrees retinotomy is effective in restoring vision in 40% of patients with neovascular maculopathy. Simultaneous oblique muscle surgery was effective in rotating the globe by about 20 degrees, corresponding to to a foveal shift of 1.5 DD. While the development of torsional diplopia is generally prevented by simultaneous oblique muscle surgery, the relatively high incidence of surgical complications with this procedure should be taken into account.

Aged↗
PubMed2002

Changes in fluorescein angiogram early after surgical removal of choroidal neovascularization in age-related macular degeneration.

BACKGROUND: Retinal pigment epithelial (RPE) defects inevitably occur in surgical removal of choroidal neovascularization (CNV) in age-related macular degeneration (AMD). RPE can proliferate and cover the denuded area, but the healing process has not been investigated in humans. To understand the RPE wound-healing process, we estimated the changes in fluorescein angiograms early after CNV removal. METHODS: Ten consecutive patients with exudative AMD underwent CNV removal without gas tamponade. Fluorescein angiography was performed within 4 days of surgery and again 1 or 2 weeks postoperatively. Areas of leakage were measured using a computer-assisted image analyser. The decreasing rate of leakage was calculated as the change in disc areas of leakage per day (DA/day). RESULTS: The rates of decreasing leakage ranged from 0 to 0.42 DA/day (mean, 0.24 +/- 0.15 DA/day; median, 0.26 DA/day). The rate of decreasing leakage correlated with changes in visual acuity (r = 0.642, P = 0.0456). CONCLUSION: The retinal pigment epithelial wound after surgical removal of choroidal neovascularization may heal at the rate of 0.24 disc areas/day based on the blood retinal barrier function in patients with age-related macular degeneration. A faster rate of decreasing leakage may be associated with better visual prognosis.

Aged↗
PubMed2002

Sutureless contact lens ring system during vitrectomy.

PURPOSE: To report a new sutureless ring system to fix corneal contact lens in place during vitrectomy. DESIGN: New surgical instrument. METHODS: The sutureless ring system consists of a stainless steel ring that has two upright tabs 180 degrees apart with a hook on the top and two elastic silicone bands 8 mm in diameter to fix the ring to the eyelid speculum. RESULTS: The contact lens fixed in place with the sutureless ring was stable and allowed intraoperative visualization of the fundus. CONCLUSION: This suture-free contact lens system facilitates visualization of the fundus during vitrectomy allowing shorter surgical time. It also enables us to avoid additional trauma associated with the lens ring fixation procedure.

Contact Lenses↗
PubMed2002

Effect of tear film break-up on higher-order aberrations measured with wavefront sensor.

PURPOSE: To investigate whether optical wavefront aberrations vary with tear film break-up. DESIGN: Observational case series. METHODS: Higher-order aberrations were examined for 20 eyes of 20 normal subjects with a Hartmann-Shack wavefront sensor before and after tear film break-up. RESULTS: Higher-order aberrations for photopic vision (central 4 mm diameter) after tear film break-up increased 1.44 fold compared to higher-order aberrations before tear film break-up (P =.001, paired t-test). Higher-order aberrations after tear film break-up for scotopic vision (central 6 mm diameter) were also 1.23 times higher than those before break-up (P =.005, paired t-test). CONCLUSION: Wavefront sensing enabled us to evaluate the induced irregular astigmatism caused by tear film break-up quantitatively. Wavefront aberrations should be measured carefully to avoid the effects of tear film break-up, especially in wavefront-guided refractive surgery.

Adult↗
PubMed2002

Effects of humidified and dry air on corneal endothelial cells during vitreal fluid-air exchange.

PURPOSE: To report the immediate anatomic and functional alterations in corneal endothelial cells following use of humidified air and dry air during vitreal fluid-air exchange in rabbits. DESIGN: Experimental study. METHODS: Rabbits undergoing pars plana vitrectomy and lensectomy were perfused with either dry or humidified air during fluid-air exchange for designated durations. Three different experiments were performed. First, control and experimental corneas were examined by scanning electron microscopy (SEM). Second, corneas were stained with Phalloidin-FITC and examined by fluorescein microscopy. Finally, third, transendothelial permeability for carboxyfluorescein was determined using a diffusion chamber. RESULTS: While different from the corneal endothelial cells, those cells exposed to humidified air were less stressed than cells exposed to dry air by SEM. Actin cytoskeleton was found highly disorganized with dry air exposure. Humidified air maintained the normal actin cytoskeleton throughout the 20 minutes of fluid-air exchange. Paracellular carboxyfluorescein leakage was significantly higher in dry air insufflated eyes compared with that of the humidified air after 5, 10, and 20 minutes of fluid-air exchange (P =.002, P =.004, and P =.002, respectively). CONCLUSIONS: Dry air stress during fluid-air exchange causes significant immediate alterations in monolayer appearance, actin cytoskeleton, and barrier function of corneal endothelium in aphakic rabbit eyes. Use of humidified air largely prevents the alterations in monolayer appearance, actin cytoskeleton, and barrier function of corneal endothelial cells.

Actins↗
PubMed2002

Evaluation of pulse corticosteroid therapy for vogt-koyanagi-harada disease assessed by optical coherence tomography.

PURPOSE: To evaluate the rapid effects of pulse corticosteroid therapy on the serous retinal detachment found at the acute phase of Vogt-Koyanagi-Harada disease. DESIGN: Interventional case series. METHODS: Nine Japanese patients determined to be at the acute phase of Vogt-Koyanagi-Harada disease with serous retinal detachment were treated with pulse corticosteroid therapy. Optical coherence tomography was used to follow the resolution of the retinal detachment. RESULTS: Optical coherence tomography images showed a marked decrease in the retinal detachment immediately after the first intravenous injection of corticosteroid and subsequent resolution. CONCLUSION: The rapid improvement of serous retinal detachment associated with Vogt-Koyanagi-Harada disease following pulse corticosteroid therapy supports an early therapeutic mechanism related to improved permeability of capillaries and permeability of the blood-retinal barrier rather than an anti-inflammatory or immunosuppressive action.

Acute Disease↗
PubMed2002

Two novel point mutations of the XLRS1 gene in patients with X-linked juvenile retinoschisis.

PURPOSE: To report two novel point mutations of the XLRS1 gene in two Japanese patients with X-linked juvenile retinoschisis. DESIGN: Observational case reports. METHODS: The exons, including the flanking introns of XLRS1, were amplified by polymerase chain reaction and analyzed by direct sequencing. RESULTS: One novel splice donor site mutation (IVS2 + 1g to a) and one missense mutation of exon 6 (Ala211Thr) were found. CONCLUSIONS: Genetic findings identifying mutations in the XLRS1 gene will lead to earlier and more accurate diagnosis of X-linked juvenile retinoschisis.

Base Sequence↗
PubMed2002

Reading ability after macular translocation surgery with 360-degree retinotomy.

PURPOSE: To report reading ability using a standardized reading chart after macular translocation with 360-degree retinotomy in eyes with age-related macular degeneration (AMD) or with myopic choroidal neovascularization (mCNV). DESIGN: Interventional case series. METHODS: In 34 eyes of 34 patients with subfoveal choroidal neovascular membrane (AMD, 23; mCNV, 11), macular translocation surgery with 360-degree retinotomy and simultaneous extraocular muscle surgery were performed. The average age was 67.4 +/- 7.9 years, and the average follow-up period was 7.6 +/- 3.3 months. The best-corrected far visual acuity (FVA) was measured with a standardized visual acuity chart using Landolt Cs, and the critical print size (CPS) was determined with the Japanese version of the Minnesota reading chart (MNREAD-J Chart) preoperatively and postoperatively. Preoperative and postoperative change in the CPS was compared with the subjective visual improvement as assessed by a questionnaire. RESULTS: The postoperative improvement of FVA was statistically significant in eyes with mCNV (P =.010) but not significant in eyes with AMD (P =.495). The postoperative improvement of CPS was statistically significant both in eyes with AMD (P =.027) and in eyes with mCNV (P =.004). The subjective visual improvement was significantly correlated with the change of CPS in patients after a second better eye surgery. CONCLUSIONS: After macular translocation with 360-degree retinotomy, the improvement of reading ability was significant in eyes with both AMD and mCNV. We conclude that this surgical method is well suited to improve reading ability of patients with AMD or mCNV.

Aged↗