Biomedical subjects

Yasuo Tano

Publications and source records attributed to Yasuo Tano.

At least 19 recordsLinked to original sources

PubMed2007

Residual indocyanine green fluorescence pattern after vitrectomy for idiopathic macular hole with internal limiting membrane peeling.

BACKGROUND: Internal limiting membrane (ILM) peeling with indocyanine green (ICG) staining is a commonly used procedure to treat idiopathic macular holes (MH). AIM: To report changes in the patterns of residual ICG fluorescence over time after vitrectomy using the Heidelberg Retina Angiograph 2 (HRA2, Heidelberg Engineering, Heidelberg, Germany). METHODS: 10 patients (10 eyes) who had undergone vitrectomy for MH with ILM peeling were included. 9 (90%) patients underwent ILM peeling with ICG, and 1 (10%) patient had it with triamcinolone acetonide (TA). We observed residual ICG using HRA2, postoperatively. Autofluorescence, optical coherence tomography images and best-corrected visual acuity (BCVA) measurements were also obtained. The minimal follow-up was 3 months. RESULTS: The MHs were closed postoperatively in all patients (100%). In eyes that underwent ILM peeling with ICG, the BCVA improved significantly (p<0.001) in 8 (89%) eyes and was unchanged in 1 (11%) eye. HRA2 showed the ICG fluorescence patterns but not TA postoperatively. The ICG hyperfluorescent signal was typically diffuse at the posterior retina and was hypofluorescent around the fovea. The hyperfluorescence then migrated towards the optic nerve disc presumably along the nerve fibre, and the area of ILM peeling was clearly identified. A large number of hyperfluorescent dots were observed instead of diffuse hyperfluorescence that was observed just after surgery. CONCLUSIONS: Patterns of residual ICG fluorescence were sequentially observed with HRA2 after vitrectomy for MH with ICG-assisted ILM peeling.

Aged↗

PubMed2007

Tautomerism of histidine 64 associated with proton transfer in catalysis of carbonic anhydrase.

The imidazole (15)N signals of histidine 64 (His(64)), involved in the catalytic function of human carbonic anhydrase II (hCAII), were assigned unambiguously. This was accomplished by incorporating the labeled histidine as probes for solution NMR analysis, with (15)N at ring-N(delta1) and N(epsilon2), (13)Cat ring-Cepsilon1, (13)C and (15)N at all carbon and nitrogen, or (15)N at the amide nitrogen and the labeled glycine with (13)C at the carbonyl carbon. Using the pH dependence of ring-(15)N signals and a comparison between experimental and simulated curves, we determined that the tautomeric equilibrium constant (K(T)) of His(64) is 1.0, which differs from that of other histidine residues. This unique value characterizes the imidazole nitrogen atoms of His(64) as both a general acid (a) and base (b): its epsilon2-nitrogen as (a) releases one proton into the bulk, whereas its delta1-nitrogen as (b) extracts another proton from a water molecule within the water bridge coupling to the zinc-bound water inside the cave. This accelerates the generation of zinc-bound hydroxide to react with the carbon dioxide. Releasing the productive bicarbonate ion from the inside separates the water bridge pathway, in which the next water molecules move into beside zinc ion. A new water molecule is supplied from the bulk to near the delta1-nitrogen of His(64). These reconstitute the water bridge. Based on these features, we suggest here a catalytic mechanism for hCAII: the tautomerization of His(64) can mediate the transfers of both protons and water molecules at a neutral pH with high efficiency, requiring no time- or energy-consuming processes.

Binding Sites↗

PubMed2006

Allelic homogeneity in Avellino corneal dystrophy due to a founder effect.

Avellino corneal dystrophy (ACD) is a common corneal dystrophy that shows allelic homogeneity, R124H mutation in the transforming growth factor beta-induced (TGFBI) gene. There are distinct phenotypes of homozygous Avellino corneal dystrophy, termed types I and II. To investigate if the difference is caused by a modifier mutation, we sequenced the entire coding region of TGFBI of two types of ACDs. The sequences obtained from each type were identical, and we could not find any nucleotide alternations. Instead, we found seven single nucleotide polymorphisms (SNPs) compared with the normal control. Primer extension analysis revealed that all 14 homozygous patients were homozygotes in each SNP, which meant that all the patients shared the same disease haplotype. Subsequent analysis of 45 heterozygous ACD patients showed strong linkage disequilibrium between disease alleles of each SNP and ACD. These results strongly suggest that the allelic homogeneity of TGFBI associated corneal dystrophies (ACD, lattice corneal dystrophy types I and III, granular corneal dystrophy and Reis-Bucklers dystrophy) might not be caused by mutation hot spots but by the founder effects.

Alleles↗

PubMed2006

Conversion of mammalian Müller glial cells into a neuronal lineage by in vitro aggregate-culture.

Mammalian Müller glial cells are major glial cells in the retina. Here we report that these glial cells can be redirected towards a neuronal lineage by an aggregate-culture in vitro. Rat and macaque Müller glial cells did not express neuronal markers except after transfer to adhesive conditions. Furthermore, this expression could only take place in the presence of platelet-derived growth factor and valproic acid. We compared a normal monolayer-culture and an aggregate-culture, and rat Müller glial cells could only differentiate into neurons under non-adhesive conditions. However, Müller glial cells did not express the photoreceptor markers in vitro. After transplantation into the subretinal space, a retina-specific niche, rat Müller glial cells expressed the photoreceptor-specific marker, opsin (RET-P1). We demonstrate the potential of mammalian Müller glial cells as a source of photoreceptors, which may possibly contribute to the treatment of degenerative retinal diseases such as retinitis pigmentosa.

Animals↗

PubMed2006

Development of transplantable genetically modified corneal epithelial cell sheets for gene therapy.

The purpose of this study was to establish a method for the fabrication of exogenous gene-transferred, transplantable corneal epithelial cell sheets. Corneo-limbal epithelial cells collected from USA eye bank eyes were transduced with an EGFP-expressing lentiviral vector at differential MOI. Multi-layered corneal epithelial cell sheets were fabricated by co-cultivation of transduced cells and mitomycin C-treated 3T3 feeder layers on temperature-responsive culture dishes. These cultured epithelial cells could be harvested as intact sheets by simply lowering the temperature. The number of EGFP-positive cells was increased as the MOI raised, and at an MOI of 100, nearly 100% of the superficial cells showed strong EGFP expression. Histological analysis revealed that EGFP was expressed in all layers of the cell sheet of which cell source was transduced with the lentiviral vector at an MOI of 100. Immunofluorescence data showed that p63 was also expressed in the basal layer of the same cell sheet. These results suggest that this technique will likely be applicable to ex vivo gene therapies for various corneal disorders.

Cells, Cultured↗

PubMed2006

N-Cadherin is expressed by putative stem/progenitor cells and melanocytes in the human limbal epithelial stem cell niche.

Corneal epithelial stem cells are known to be localized to the basal layer of the limbal epithelium, providing a model system for epithelial stem cell biology; however, the mechanisms regarding the maintenance of these stem cells in their specialized niche remain poorly understood. N-cadherin is a member of the classic cadherin family and has previously been demonstrated to be expressed by hematopoietic stem cells. In the present study, we demonstrate that N-cadherin is expressed by putative stem/progenitor cells, as well as melanocytes, in the human limbal epithelial stem cell niche. In addition, we demonstrate that upon in vitro culture using 3T3 feeder layers, loss of N-cadherin expression occurs with cell proliferation. These results indicate that N-cadherin may be a critical cell-to-cell adhesion molecule between corneal epithelial stem/progenitor cells and their corresponding niche cells in the limbal epithelium.

Adult↗

PubMed2006

Self-retaining 27-gauge transconjunctival chandelier endoillumination for panoramic viewing during vitreous surgery.

PURPOSE: To report the development of a 27-gauge self-retaining transconjunctival chandelier endoilluminator for panoramic viewing during vitrectomy. DESIGN: New surgical instrument. METHODS: The tip of the illuminating fiber is 27-gauge (0.35 mm) and shaped like a cone to provide wide-angle illumination. The tip, inserted approximately 3 mm into the vitreous cavity transconjunctivally, provides diffuse illumination. The optical fiber covered by a malleable sleeve can be retained in the eyeball without a suture. RESULTS: The slim light fiber design (0.35 mm) stabilizes the 27-gauge tip in the eye and provides up to 25 lumens of measured illumination. The adequate lighting potential and self-retaining design allow wide-angle visualization and bimanual manipulation in challenging cases. Easy insertion and removal without suture placement make it convenient to change the position of the device during surgery and efficiently shorten surgical time. CONCLUSIONS: This suture-free 27-gauge endoillumination chandelier improves the efficacy and efficiency of vitreous surgery.

Conjunctiva↗

PubMed2006

Matrix morphogenesis in cornea is mediated by the modification of keratan sulfate by GlcNAc 6-O-sulfotransferase.

Matrix assembly and homeostasis in collagen-rich tissues are mediated by interactions with proteoglycans (PGs) substituted with sulfated glycosaminoglycans (GAGs). The major GAG in cornea is keratan sulfate (KS), which is N-linked to one of three PG core proteins. To ascertain the importance of the carbohydrate chain sulfation step in KS functionality, we generated a strain of mice with a targeted gene deletion in Chst5, which encodes an N-acetylglucosamine-6-O-sulfotransferase that is integral to the sulfation of KS chains. Corneas of homozygous mutants were significantly thinner than those of WT or heterozygous mice. They lacked high-sulfated KS, but contained the core protein of the major corneal KSPG, lumican. Histochemically stained KSPGs coassociated with fibrillar collagen in WT corneas, but were not identified in the Chst5-null tissue. Conversely, abnormally large chondroitin sulfate/dermatan sulfate PG complexes were abundant throughout the Chst5-deficient cornea, indicating an alteration of controlled PG production in the mutant cornea. The corneal stroma of the Chst5-null mouse exhibited widespread structural alterations in collagen fibrillar architecture, including decreased interfibrillar spacing and a more spatially disorganized collagen array. The enzymatic sulfation of KS GAG chains is thus identified as a key requirement for PG biosynthesis and collagen matrix organization.

Animals↗

PubMed2006

Three-dimensional optical coherence tomographic findings in central serous chorioretinopathy.

PURPOSE: The purpose of this study was to evaluate three-dimensional optical coherence tomographic findings at the leakage point on fluorescein angiography in central serous chorioretinopathy (CSC) with OCT-ophthalmoscope. METHODS: Twenty-seven eyes of 26 patients (23 men, three women; mean age, 50 years; range, 30-72) diagnosed with CSC were examined with OCT-ophthalmoscope, and transverse and longitudinal images were compared with fundus and fluorescein angiography findings. RESULTS: Transverse images (C-scan) clearly showed serous retinal detachment in all eyes and irregular lesions in retinal pigment epithelium (RPE) in 26 of 27 eyes (96%). These results agreed with the location of lesions in areas of fluorescein dye leakage on fluorescein angiography. Longitudinal images (B-scan) of irregular RPE lesions in transverse images showed RPE detachment (PED) in 17 eyes (63%), small protrusion of the RPE layer in five eyes (19%), and rough RPE layer in four eyes (15%). CONCLUSIONS: OCT-ophthalmoscope detects morphologic changes easily and noninvasively at the point of dye leakage in eyes with CSC.

Adult↗

PubMed2006

Evaluation of residual retinal function by pupillary constrictions and phosphenes using transcorneal electrical stimulation in patients with retinal degeneration.

BACKGROUND: To evaluate inner-retinal function by pupillary constrictions and phosphenes evoked by transcorneal electrical stimulation (TES) in patients with hereditary retinal degeneration. METHODS: Consecutive 20 eyes of 20 patients (16 with retinitis pigmentosa (RP); and four with cone-rod dystrophy (CRD)) whose visual acuity was equal to or worse than 20/2000 at Osaka University Hospital and eight eyes of eight healthy subjects were enrolled. TES was performed on with a contact lens stimulating electrode. The electrically evoked pupillary response (EEPR) was recorded by a pupillometer, and the phosphenes by the subjective responses. Three electrical current thresholds were determined: T1, threshold current for initial phosphene; T2, threshold for eliciting a phosphene extending into the central field; and P, threshold for a relative pupillary constriction > or = 3%. The EEPR and phosphene thresholds were compared with the visual acuity or the visual field. RESULTS: All T1, T2 and P were significantly higher in patients than in normals (Mann-Whitney, P<0.001). Both T1 and T2 were not correlated with visual acuity but depended on the area and location of the residual visual field. T1 and T2 in RP eyes with a EEPR was significantly lower than that in RP eyes without an EEPR. During TES, all subjects and patients had no pain, and no complications except for a slight corneal superficial punctuate keratopathy. CONCLUSIONS: The safety and the efficacy of TES to estimate the residual inner-retinal function in patients with retinal degeneration indicate that TES can be used as one of the most important test to select candidates for retinal prostheses.

Adult↗

PubMed2006

Transplantable retinal pigment epithelial cell sheets for tissue engineering.

The native retinal pigment epithelium (RPE) exists as a monolayer structure and is critically involved in the maintenance of photoreceptors. Damage or destruction of the RPE due to a variety of diseases therefore often results in loss of vision. With regenerative purposes in mind, we have examined various culture conditions such as the initial cell density and the addition of various supplements in an effort to produce transplantable RPE cell sheets that can be harvested without defects. We demonstrate that the cell density in cultured RPE sheets increased linearly with the number of seeded cells and that RPE sheets were harvested without defects and limited contraction due to cytoskeletal reorganization, when TGF-beta2 was added to the growth medium. Results from histological analysis and the measurement of trans-epithelial resistance also demonstrates that these RPE cell sheets exist as monolayer structure, similar to the native RPE, with intact cell-to-cell junctions. Therefore, these methods provide significant insight into the fabrication of transplantable RPE cell sheets that can be applied to RPE regenerative therapies to restore lost vision.

Cell Count↗

PubMed2006

Repeated intravitreal triamcinolone injections in Behçet disease that is resistant to conventional therapy: one-year results.

PURPOSE: To determine whether repeated intravitreal triamcinolone (IVTA) injections in patients with Behçet disease that is resistant to conventional therapy will prevent recurrences of uveitis. DESIGN: Prospective preliminary clinical trial. METHODS: Nine eyes of five patients with Behçet disease with sight-threatening uveitis that was resistant to conventional therapy received repeated IVTA injections. Each patient was examined monthly, and IVTA was given when the TA particles that remained in the vitreous were judged to be gone before the next visit. RESULTS: Repeated IVTA completely prevented the recurrence of uveitis in eight eyes, and the one eye that had an attack experienced the uveitis when the TA particles disappeared quicker than expected. It was possible to stop systemic corticosteroid and/or immunosuppressive agents within 1 year after IVTA in three patients. CONCLUSION: These results indicate that repeated IVTA will prevent the recurrence of uveitis in patients with Behçet disease with frequent ocular attacks that is resistant to conventional therapy.

Adult↗

PubMed2006

Reoperation for persistent myopic foveoschisis after primary vitrectomy.

PURPOSE: We performed vitrectomy on two eyes for persistent myopic foveoschisis (MF) after primary surgery that did not include internal limiting membrane (ILM) peeling. DESIGN: Interventional case reports. METHODS: Two highly myopic eyes of two patients with persistent MF after primary vitrectomy and gas tamponade but without ILM peeling were treated with pars plana vitrectomy, residual vitreous cortex removal, ILM peeling, and long-term gas tamponade. RESULTS: Total foveal reattachment was achieved and best-corrected visual acuity (BCVA) improved in both eyes. CONCLUSIONS: Reoperation including complete vitreous cortex removal and ILM peeling could be beneficial for patients with persistent MF after primary surgery, indicating that vitreous cortex removal and ILM peeling are critical in treating MF.

Aged↗

PubMed2006

Vitrectomy for macular holes associated with myopic foveoschisis.

PURPOSE: We reviewed the surgical results of vitrectomy for macular holes (MHs) associated with myopic foveoschisis (MF). DESIGN: Noncomparative, interventional case series. METHODS: setting: Institutional. participants: Eight eyes of eight patients with MHs associated with MF. intervention procedure: All patients underwent vitrectomy, internal limiting membrane peeling, and gas tamponade. main outcome measures: Slit-lamp-based biomicroscopy, optical coherence tomography examinations, and best-corrected visual acuity (BCVA) measurement. RESULTS: The MHs closed in two eyes (25%), and the BCVA improved more than 2 lines in three (37.5%) eyes, remained unchanged in three (37.5%), and worsened in two (25%). The MH size increased significantly in a case with an unresolved MH (P < .05). The postoperative BCVA was significantly correlated with the preoperative BCVA (P < .05). CONCLUSIONS: Although significant visual improvement occurs in less than 50% of cases, vitrectomy can be beneficial for some cases.

Aged↗

PubMed2006

Wavefront analysis of eye with monocular diplopia and cortical cataract.

PURPOSE: To determine whether higher-order aberrations can explain the monocular diplopia reported by a patient. DESIGN: Observational case report. METHODS: A patient complaining of monocular diplopia was examined with the Hartmann-Shack aberrometer to determine if the higher-order wavefront aberrations could account for the diplopia. The patient had a mild cortical cataract, and measurements were made before and after lensectomy. In addition, the retinal image was simulated using Zernike polynomials. RESULTS: Spherical aberration (0.20 microm for 4-mm pupil) and secondary astigmatism (-0.12 microm) were increased in the eye. The simulated retinal image had a double configuration that was approximately the same as the subjective image reported by the patient. After cataract surgery, the diplopia disappeared, and the spherical aberrations and secondary astigmatism were considerably decreased. CONCLUSIONS: The monocular diplopia probably stemmed from the combined effects of spherical aberration and secondary astigmatism caused by the cortical cataract.

Adult↗

PubMed2006

Ultrasound biomicroscopic examination of acute hydrops in patients with keratoconus.

PURPOSE: To investigate the possible factors involved in the development of acute hydrops in patients with keratoconus. DESIGN: Prospective interventional case series. METHODS: Thirteen consecutive keratoconic eyes of 13 patients with acute hydrops were examined by ultrasound biomicroscopy (UBM). RESULTS: Ultrasound biomicroscopy (UBM) examinations revealed a rupture of Descemet membrane and intrastromal clefts in all eyes. In 11 of 13 eyes, the intrastromal clefts were connected to the anterior chamber. CONCLUSIONS: Formation of intrastromal clefts may be an important factor in the development of acute hydrops in keratoconic eyes. The clefts may cause severe corneal edema and delay the closure of Descemet membrane during the resolution of corneal edema.

Acute Disease↗

PubMed2006

Regression of iris neovascularization after intravitreal injection of bevacizumab in patients with proliferative diabetic retinopathy.

PURPOSE: To assess the short-term safety and efficacy of intravitreal injection of bevacizumab for iris neovascularization (INV). DESIGN: Noncomparative, interventional case series. METHODS: Intravitreal bevacizumab was injected in seven eyes of five patients with INV that was associated with proliferative diabetic retinopathy (PDR). The main outcome measurements were visual acuity, intraocular pressure (IOP), and regression of INV by fluorescein angiography before and one week, one month, and two months after injection. RESULTS: Regression of INV was confirmed in all eyes (100%) from one week after injection. Repeated injections stabilized the recurrence (two eyes; 29%) that was observed two months after the initial injection. The visual acuity remained stable or improved, and the intraocular pressure was controlled in six eyes (86%) throughout the follow-up period. No inflammation or complications were observed. CONCLUSIONS: Intravitreal injection of bevacizumab may be an effective and safe alternative for patients with INV that is refractory to conventional treatments.

Adult↗

PubMed2006

Tractional internal limiting membrane detachment in highly myopic eyes.

PURPOSE: To report the clinical features of tractional internal limiting membrane (ILM) detachment in highly myopic eyes with posterior staphyloma. DESIGN: Observational case report. METHODS: We reviewed the optical coherence tomography images of 249 eyes in the high myopia clinic. ILM detachment was observed in six eyes (2.4%). We investigated the clinical feature of this finding. RESULTS: Myopic foveoschisis (MF) was present in four of the six eyes (67%) (six patients, two men and four women; mean age, 57.3 years). The mean axial length was 29.3 mm and the mean refractive error was -15.0 diopters. The best-corrected visual acuity levels ranged from 20/400 to 20/13. CONCLUSIONS: Rigidity of the ILM seems to cause tangential traction and results in a major cause of a disease specific to high myopia; that is, MF.

Aged↗