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Biomedical subjects

Shiro Amano

Publications and source records attributed to Shiro Amano.

At least 55 records · Page 3Linked to original sources
PubMed2004

Damaged DNA-binding protein 2 accelerates UV-damaged DNA repair in human corneal endothelium.

PURPOSE: To determine damaged DNA-binding protein 2-gene expression levels in vitro and ex vivo, and the degree of DNA repair in damaged DNA-binding protein 2-overexpressing cultured human corneal endothelium after ultraviolet irradiation. METHODS: Constitutive damaged DNA-binding protein 2-gene expression levels in various human tissues were determined by semi-quantitative reverse transcription-polymerase chain reactions. The dynamics of nucleotide excision repair-related gene expression in cultured human corneal endothelium were investigated in a ribonuclease protection assay after ultraviolet-irradiation. The effect of damaged DNA-binding protein 2 on DNA repair was studied after ultraviolet-irradiation in cultured human corneal endothelium infected with adenovirus carrying damaged DNA-binding protein 2. RESULTS: Human corneal endothelium and epithelium in the donor cornea had the highest constitutive damaged DNA-binding protein 2-gene expression of the various human tissues studied. Gene expression level dynamics associated with nucleotide excision repair factors after ultraviolet-irradiation showed that the increase in the rate of damaged DNA-binding protein 2-gene expression in cultured human corneal endothelium was highest of the nucleotide excision repair-related genes studied. An in vivo DNA repair assay showed that DNA repair efficiency in damaged DNA-binding protein 2-overexpressing cultured human corneal endothelium after ultraviolet-irradiation was significantly improved as compared with that in the control human corneal endothelium. CONCLUSION: The human corneal endothelium abundantly expresses the damaged DNA-binding protein 2-gene that is produced efficiently on ultraviolet exposure. This overexpressed damaged DNA-binding protein 2 in the human corneal endothelium contributes to the protection system against DNA damage after ultraviolet-irradiation. Our findings show a critical role for damaged DNA-binding protein 2 in DNA repair to maintain the human corneal endothelium function.

Adult↗
PubMed2004

Correlations between allergen-specific IgE serum levels in patients with allergic conjunctivitis in spring.

PURPOSE: The purpose of this study was to evaluate the relation between various specific class E immunoglobulins (IgE) in serum and allergic conjunctivitis in spring. METHODS: Forty patients with allergic conjunctivitis and fifty healthy volunteers were selected for this trial. Total IgE and specific IgE to twelve inhalant allergens were measured using the CAP system. RESULTS: Specific IgE levels caused by cedar and cypress pollen, house dust, Dermatophagoides pteronyssinus, acarus, and moth allergens were higher in the allergy group than in the control group. No correlation was proven between the specific IgE levels and the total IgE level. The highest positivity rate for a specific allergen in patients with allergic conjunctivitis was 52.5% for cedar pollen, followed by cypress pollen at 37.5%. CONCLUSIONS: These results suggest that cypress pollen was the largest cause of allergic conjunctivitis and that the total IgE level had no correlation with each specific IgE.

Adult↗
PubMed2004

Corneal epithelial barrier function in diabetic patients.

PURPOSE: To evaluate the corneal epithelial barrier function in diabetic patients. METHODS: In 29 eyes of 29 diabetic patients and 55 eyes of 55 nondiabetic controls, corneal epithelial permeability to fluorescein was measured using an anterior fluorophotometer. The average fluorescein concentration in the central cornea was compared between diabetic patients and controls. Multiple regression analysis was used to assess the factors that affect corneal epithelial barrier function in diabetic patients. RESULTS: The average fluorescein concentrations in diabetic patients and nondiabetic controls were 44.1 +/- 25.3 ng/mL and 29.9 +/- 19.8 ng/mL (mean +/- SD), respectively (P = 0.0057, unpaired t test). An explanatory variable relevant to the impaired corneal epithelial barrier function was the serum hemoglobin A1c (HbA1c) concentration (standardized partial regression coefficient = 0.466, P = 0.0163). CONCLUSIONS: The corneal epithelial barrier function is impaired in diabetic patients. Diabetic patients with higher serum HbA1c levels are more predisposed to impaired barrier function in the corneal epithelium.

Aged↗
PubMed2004

Refractive change after transscleral fixation of posterior chamber intraocular lenses in the absence of capsular support.

PURPOSE: To report the refractive change that occurred over 12 years after secondary transscleral fixation of posterior chamber intraocular lenses (PC IOLs). METHODS: A total of 21 patients who underwent transscleral fixation of PC IOLs were studied. We were able to follow 15 eyes of 15 patients for more than 12 years. We evaluated refractive change in each patient for 12 years after the operation. RESULTS: The spherical refractive equivalent was -0.95 +/- 2.21 D immediately after the operation, -1.16 +/- 2.28 D after 2 years and -1.37 +/- 1.94 D after 12 years. CONCLUSION: There were few changes in the spherical refractive equivalent up to 12 years after the operation.

Humans↗
PubMed2004

VEGF164(165) as the pathological isoform: differential leukocyte and endothelial responses through VEGFR1 and VEGFR2.

PURPOSE: Vascular endothelial growth factor (VEGF) induces angiogenesis and vascular permeability and is thought to be operative in several ocular vascular diseases. The VEGF isoforms are highly conserved among species; however, little is known about their differential biological functions in adult tissue. In the current study, the inflammatory potential of two prevalent VEGF isoform splice variants, VEGF(120(121)) and VEGF(164(165)), was studied in the transparent and avascular adult mouse cornea. METHODS: Controlled-release pellets containing equimolar amounts of VEGF(120) and VEGF(164) were implanted in corneas. The mechanisms underlying this differential response of VEGF isoforms were explored. The response of VEGF in cultured endothelial cells was determined by Western blot analysis. The response of VEGF isoforms in leukocytes was also investigated. RESULTS: VEGF(164) was found to be significantly more potent at inducing inflammation. In vivo blockade of VEGF receptor (VEGFR)-1 significantly suppressed VEGF(164)-induced corneal inflammation. In vitro, VEGF(165) more potently stimulated intracellular adhesion molecule (ICAM)-1 expression on endothelial cells, an effect that was mediated by VEGFR2. VEGF(164) was also more potent at inducing the chemotaxis of monocytes, an effect that was mediated by VEGFR1. In an immortalized human leukocyte cell line, VEGF(165) was found to induce tyrosine phosphorylation of VEGFR1 more efficiently. CONCLUSIONS: Taken together, these data identify VEGF(164(165)) as a proinflammatory isoform and identify multiple mechanisms underlying its proinflammatory biology.

Animals↗
PubMed2004

Effects of TGF-beta2 on immune response-related gene expression profiles in the human corneal endothelium.

PURPOSE: To determine the effects of transforming growth factor (TGF)-beta2 on immune-response-related gene expression profiles in the stimulated human corneal endothelium (HCE). METHODS: A human complementary DNA (cDNA) expression array analysis was used to investigate the effects of TGF-beta2 on cultured HCE incubated with interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha. Gene-specific semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were performed to examine the gene expression patterns revealed by the cDNA expression array analysis. Moreover, the expression of newly identified genes in HCE was confirmed by RT-PCR in human donor corneas. RESULTS: cDNA expression array analysis and semiquantitative RT-PCR revealed that TGF-beta2 downregulated the expression of IL-6, growth-related (Gro)-alpha (CXCL1), monocyte chemotactic protein (MCP)-1 (CCL2), granulocyte-colony stimulating factor (G-CSF), and insulin-like growth factor binding protein (IGFBP)-5 and upregulated the expression of tissue inhibitor of metalloproteinase (TIMP)-1. ELISA confirmed TGF-beta2-mediated changes in the expression of IL-6, CXCL1, CCL2, G-CSF, IGFBP-5, and TIMP-1 at the protein level. CXCL1, G-CSF, and IGFBP-5 mRNAs were detected for the first time in the HCE of donor corneas. CONCLUSIONS: TGF-beta2 downregulates IL-6, CXCL1, CCL2, G-CSF, and IGFBP-5, and upregulates TIMP-1 in cultured HCE stimulated with proinflammatory cytokines, suggesting the immunomodulatory role of TGF-beta2 in the aqueous humor and the pathophysiological significance of TGF-beta2 in the anterior chamber of the eye.

Cell Culture Techniques↗
PubMed2004

Cultured human corneal endothelial cell transplantation with a collagen sheet in a rabbit model.

PURPOSE: To evaluate the function of cultured human corneal endothelial cells (HCECs) in vivo and the feasibility of HCEC transplantation with a collagen sheet as the substitute carrier of HCECs. METHODS: Adult human donor cornea derived from cultured HCECs was labeled with the fluorescent tracker DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate) and seeded on a collagen sheet. The pump function of the HCEC sheet was evaluated by measurement of the potential difference and short-circuit current. A 6-mm sclerocorneal incision and Descemetorhexis were performed on rabbit eyes. The HCECs on a collagen sheet was brought into the anterior chamber and fixed to the posterior stroma (HCEC group). Rabbit corneas with collagen sheet transplantation after Descemetorhexis (collagen group) and with only Descemetorhexis (no-transplantation group) were the control. Each group, observed for 28 days after surgery, underwent histologic and fluorescence microscopic examinations. RESULTS: Pump function parameters of the HCEC sheets were 76% to 95% of those of human donor corneas. Mean corneal thickness in the HCEC group was significantly less than in the collagen and no-transplantation groups 1, 3, 7, 14, 21, and 28 days (P < 0.05) after surgery. DiI-labeled cells were spread over the rear corneal surface in the HCEC group. Marked stromal edema was present in the collagen and no-transplantation groups with hematoxylin-eosin staining, but none in the HCEC group with collagen sheets bearing monolayer cells. CONCLUSIONS: The findings indicate that cultured HCECs transplanted from adult human donor cornea by means of a collagen sheet can retain their function of corneal dehydration in a rabbit model and suggest the feasibility of transplantation for CEC dysfunction using cultured HCECs with a collagen sheet.

Animals↗
PubMed2004

[Significance of leukocytes in the regulation of retinal edema, ischemia, and angiogenesis].

BACKGROUND: Involvement of leukocytes in three major pathologic conditions in the retina, i.e., edema, ischemia, and angiogenesis, has recently been thoroughly investigated. The accumulated evidence will lead to an integrated understanding of the relationship between leukocytes and retinal disorders, which is required for clinical applications of new medical treatment. METHOD: Leukocyte roles in the retinal vascular pathology were assessed by reviewing the related literature. RESULTS: Vascular endothelial growth factor(VEGF)-induced leukocyte adhesion to the retinal vessels was shown to result in blood-retinal barrier breakdown, and the leukocyte-mediated pathogenesis was also seen in a model of diabetic retinopathy. A possible mechanism by which retinal angiogenesis develops intraviteral proliferation instead of compensating the avascular retina is that VEGF-producing monocytes/macrophages infiltrate the vitreous with subsequent migration of retinal vascular endothelial cells. On the other hand, cytotoxic T lymphocyte-mediated apoptosis of endothelial cells appears to cause the suppression of pathological retinal angiogenesis and the formation of ischemic retina secondary to vascular regression. CONCLUSION: Leukocytes are considered to regulate retinal edema, ischemia, and angiogenesis.

Animals↗
PubMed2003

VEGF164-mediated inflammation is required for pathological, but not physiological, ischemia-induced retinal neovascularization.

Hypoxia-induced VEGF governs both physiological retinal vascular development and pathological retinal neovascularization. In the current paper, the mechanisms of physiological and pathological neovascularization are compared and contrasted. During pathological neovascularization, both the absolute and relative expression levels for VEGF164 increased to a greater degree than during physiological neovascularization. Furthermore, extensive leukocyte adhesion was observed at the leading edge of pathological, but not physiological, neovascularization. When a VEGF164-specific neutralizing aptamer was administered, it potently suppressed the leukocyte adhesion and pathological neovascularization, whereas it had little or no effect on physiological neovascularization. In parallel experiments, genetically altered VEGF164-deficient (VEGF120/188) mice exhibited no difference in physiological neovascularization when compared with wild-type (VEGF+/+) controls. In contrast, administration of a VEGFR-1/Fc fusion protein, which blocks all VEGF isoforms, led to significant suppression of both pathological and physiological neovascularization. In addition, the targeted inactivation of monocyte lineage cells with clodronate-liposomes led to the suppression of pathological neovascularization. Conversely, the blockade of T lymphocyte-mediated immune responses with an anti-CD2 antibody exacerbated pathological neovascularization. These data highlight important molecular and cellular differences between physiological and pathological retinal neovascularization. During pathological neovascularization, VEGF164 selectively induces inflammation and cellular immunity. These processes provide positive and negative angiogenic regulation, respectively. Together, new therapeutic approaches for selectively targeting pathological, but not physiological, retinal neovascularization are outlined.

Animals↗
PubMed2003

A novel grading method for superficial punctate keratopathy magnitude and its correlation with corneal epithelial permeability.

OBJECTIVES: To propose a novel grading method for superficial punctate keratopathy (SPK) magnitude and to examine the quantitativeness of the method. METHODS: In 351 eyes diagnosed as having dry eye syndrome, SPK was graded as follows. After fluorescein staining, the total sum of the area of SPK was graded from A0 through A3, and the density was graded from D0 through D3. The grading was represented as the combination of the area and density grades. The correlation between the SPK grade and the corneal epithelial permeability to fluorescence, measured using an anterior fluorophotometer, was analyzed in the 351 eyes. MAIN OUTCOME MEASURES: The correlation between the fluorescein concentration in the cornea and the sum of the area and density grades. RESULTS: The higher the density and area grades, the higher the fluorescein concentration, except for A3D2. There was a clear exponential correlation between the sum of the area and density grades and the fluorescein concentration in the cornea, measured using an anterior fluorophotometer. The regression curve was y = 61.2e(0.59x), where y is the fluorescein concentration (nanograms per milliliter), and x is the sum of the area and density grades (P<.001). CONCLUSIONS: The SPK grade is positively correlated with the corneal epithelial permeability to fluorescence, measured using an anterior fluorophotometer. Our results indicate that this grading method can be clinically useful.

Corneal Diseases↗
PubMed2003

Relationship between human leukocyte antigen status and proliferative diabetic retinopathy in patients with younger-onset type 1 diabetes mellitus.

PURPOSE: To investigate the relationship between human leukocyte antigen (HLA) status and proliferative diabetic retinopathy (PDR) to assess the genetic basis of PDR in younger type 1 diabetic patients. DESIGN: Retrospective, nonrandomized, comparative trial. METHOD: Patients who were diagnosed with type 1 diabetes under 30 years of age (range, 13-28) and had a disease duration of more than 10 years were studied. The patients were divided into two groups: 30 patients who had undergone vitreous surgery younger than 40 years old (the PDR group) and 50 patients without retinopathy (the non-DR group). The duration of diabetes and the level of glycemic control were matched between the two groups. The control group consisted of 50 healthy patients. HLA-A, -B, -C, -DR, and -DQ typing of blood samples was done using the standard microcytotoxicity method. RESULTS: The frequency of HLA-B62, Cw4, and DQ4 was significantly higher in the PDR group than in the non-DR group (P =.0020, P =.048, and P =.0026, respectively). The Cw4-DR4-DQ4 haplotype frequency was significantly higher in the PDR group than in the control group and the non-DR group (P =.0059). CONCLUSIONS: Our results suggests that HLA-B62, Cw4, and DQ4 may be useful for predicting the prognosis of retinopathy in patients with younger-onset type 1 diabetes.

Adolescent↗
PubMed2003

10-year follow-up study of secondary transscleral ciliary sulcus fixated posterior chamber intraocular lenses.

PURPOSE: To study the outcome of transscleral ciliary sulcus fixated posterior chamber intraocular lenses (transscleral fixation of PC IOLs) at 10 years after surgery. DESIGN: Longitudinal observational study. METHODS: A total of 16 patients (16 eyes) who had undergone transscleral fixation of PC IOL were studied. We evaluate the clinical outcome in each patient at 10 years after the operation. SETTING: The Department of Ophthalmology, University of Tokyo Graduate School of Medicine, Tokyo, Japan. RESULTS: Visual loss and other complications occurred within 2 years of the operation but not later. Postoperative complications were cystoid macular edema in three eyes (18.8%) and age-related macular degeneration in one eye (6.3%). CONCLUSIONS: It is important to carefully observe and adequately treat patients for 2 years postoperatively.

Aged↗
PubMed2003

Diabetic retinopathy with repeated amaurosis fugax caused by orthostatic hypotension.

PURPOSE: To evaluate the blood flow velocity in the ophthalmic artery using color Doppler imaging in two patients who had diabetic retinopathy with amaurosis fugax caused by orthostatic hypotension. DESIGN: Interventional case reports. METHODS: A 40-year-old woman (Case 1) and a 65-year-old man (Case 2) had diabetic retinopathy and amaurosis fugax caused by orthostatic hypotension. We evaluated the blood flow velocity in the ophthalmic artery using color Doppler imaging in the two patients. SETTING: Department of Ophthalmology, Diabetes Center Tokyo Women's Medical University, Tokyo, Japan. RESULTS: For Case 1, the maximum systolic blood flow velocity in the ophthalmic artery (V max) was 10 cm/sec in the supine position. In a seated position, visual acuity was decreased from 20/20 to light perception as V max fell to 1 cm/sec. For Case 2, the V max was 14 cm/sec in the supine position, but it was too low to measure in a seated position. CONCLUSIONS: The decrease of V max by orthostatic hypotension may cause amaurosis fugax in patients with diabetic retinopathy.

Adult↗
PubMed2003

Magnetic attraction of iron-endocytosed corneal endothelial cells to Descemet's membrane.

PURPOSE: To evaluate the feasibility of a novel method of magnetic attraction of iron-endocytosed corneal endothelial cells to Descemet's membrane. METHODS: Cultured rabbit corneal endothelial cells (RCEC) were exposed to spherical iron powder at various concentration ranging 0-100 micro moll(-1). After 24hr, the cell density and morphology were evaluated. RCEC that had been exposed to spherical iron powder (RCEC-iron), were trypsinized and poured onto a culture dish where a neodium magnet was fixated paracentrally. After 24hr, the cell density was measured at the areas with and without a magnet. Rabbits' corneas were cryo-injuried to detach corneal endothelial cells and 1x10(5)/200 micro l RCEC-iron were injected into the anterior chamber. Neogium magnet was fixed on the lid for 24hr to attract RCEC to Descemet's membrane. Each operated eye was observed up to 2 months after the injury. RCEC group (rabbits with cryo-injury and injection of normal cultured RCEC) and cryo group (rabbits with cryo-injury but without injection of RCEC) served as controls. RESULTS: The RCEC-iron density on the dish decreased in the medium containing iron powder of 10 micro moll(-1) or more. When RCEC had been exposed to iron powder of between 5 and 10 micro moll(-1), the ratio of RCEC in the field with a magnet to RCEC in the field without a magnet increased. In the RCEC-iron group, the mean corneal thickness gradually decreased and was significantly less than in the other two groups at 2, 4, and 8 weeks after the cell injection. Fluorescein microscopic examination showed a monolayer of DiI-labelled cells on the Descemet's membrane. CONCLUSION: Magnetic attachment of iron-endocytosed corneal endothelial cells to Descemet's nembrane can be a method of choice for corneal endothelial decompensation.

Animals↗
PubMed2003

Corneal bed perforation by laser ablation during laser in situ keratomileusis.

A 34-year-old man was referred to our department with corneal perforation after multiple laser in situ keratomileusis procedures for myopia. Corneal perforation occurred at the time of laser application during the fourth surgery, and the anterior chamber became completely flat. The perforation was sealed shortly thereafter and the corneal edema disappeared in 3 weeks, but there was an 86 microm forward shift of the cornea associated with an 8.0 diopter myopic shift during the subsequent 6 months. No further forward bulging of the cornea was observed. The refraction had stabilized up to 2 years postoperatively, but corneal irregular astigmatism limited the patient's best spectacle-corrected visual acuity.

Adult↗
PubMed2003

Corneal thickness measurements: scanning-slit corneal topography and noncontact specular microscopy versus ultrasonic pachymetry.

PURPOSE: To compare central corneal thickness measurements taken with 3 pachymetry systems: Orbscan scanning-slit corneal topography/pachymetry, Topcon SP2000P noncontact specular microscopy, and Tomey ultrasonic pachymetry. SETTING: Multicenter study, Tokyo, Japan. METHODS: In 216 healthy eyes of 114 subjects, scanning-slit topography, noncontact specular microscopy, and ultrasonic pachymetry were used in that sequence to record central corneal thickness. In another 20 healthy eyes of 13 subjects, 2 sets of measurements were repeated for each pachymetry to assess repeatability. RESULTS: The mean central corneal thickness was compatible between scanning-slit topography (546.9 micrometers +/- 35.4 [SD] ) and ultrasonic pachymetry (548.1 +/- 33.0 micrometers); however, noncontact specular microscopy gave a significantly smaller mean (525.3 +/- 31.4 micrometers) than the other 2 tests (P<.001, Tukey multiple comparison). There were significant linear correlations between scanning-slit topography and noncontact specular microscopy (r = 0.846, P<.001), noncontact specular microscopy and ultrasonic pachymetry (r = 0.897, P<.001), and ultrasonic pachymetry and scanning-slit topography (r = 0.852, P<.001). Noncontact specular microscopy tended to show the best repeatability; however, the difference was not statistically significant (P =.663, repeated-measure analysis of variance). CONCLUSIONS: Corneal thickness readings were comparable between scanning-slit topography and pachymetry; noncontact specular microscopy gave significantly smaller values. The measurements of the 3 methods showed significant linear correlations with one another. All methods provided acceptable repeatability of measurements.

Adult↗
PubMed2003

Oculocardiac reflex caused by contact lenses.

PURPOSE: To report two cases of patients who fell unconscious because of the oculocardiac reflex when attempting to wear contact lenses. CASE REPORTS: Case 1: A 15-year-old healthy boy came to our clinic to be fitted with contact lenses. As soon as a hard contact lens was inserted forcibly, he became unconscious. Case 2: A 22-year-old man fell unconscious the instant that the eye was compressed with a hard contact lens. Neither patient had used glasses or contact lenses before. Their blood pressure was decreased while unconscious. They recovered consciousness after about 10 min, and nausea and vomiting settled subsequently. Contact lens insertion was tried again carefully after 1 week avoiding compression of the eyes and there were no problems. They are currently using contact lenses without any problems. CONCLUSION: Insertion of contact lenses may rarely provoke the oculocardiac reflex.

Adolescent↗