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Biomedical subjects

M Uyama

Publications and source records attributed to M Uyama.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Effects of local administration of interferon-beta on proliferation of the retinal pigment epithelium].

PURPOSE: We demonstrated effects of local administration of human interferon (IFN)-beta on the repair process of the rabbit retinal pigment epithelium (RPE). MATERIAL AND METHODS: We used adult pigmented rabbits in this experiment. We measured IFN-beta levels in the ocular tissues after sub-Tenon administration of human IFN-beta by means of enzyme-linked immunosorbent assay (ELISA) methods. Laser photocoagulation in moderate intensity was applied after IFN administration. The repair process of the RPE in laser lesion sites was examined histopathologically. RESULTS: Locally administrated IFN spread by diffusion into the intraocular tissues. The highest IFN level was detected in the choroid. In eyes treated with IFN, RPE cells proliferated vigorously to the center of the photocoagulated lesions on early stages after laser photocoagulation. Proliferation of RPE cells after laser photocoagulation was remarkable in eyes treated with large amounts of IFN. CONCLUSION: It was demonstrated histopathologically that sub-Tenon administration of IFN-beta promoted proliferation of RPE cells during the repair process after laser photocoagulation.

Administration, Topical↗
PubMed1999

[Vascular endothelial growth factor promotes experimental choroidal neovascularization in monkey eyes].

PURPOSE: To evaluate the effect of vascular endothelial growth factor (VEGF) on experimental choroidal neovascularization (CNV) in monkey eyes through clinical, morphometric, and histological observations. METHOD: CNV was induced in both eyes of 6 rhesus monkeys by intense photocoagulation by red krypton laser. Immediately after photocoagulation, 2.5 micrograms of exogenous human VEGF was injected into the vitreous of the left eye in each animal. The right eyes served as controls. The eyes were enucleated 3 days to 12 weeks after photocoagulation and were examined by light and electron microscopy. RESULTS: VEGF-treated eyes developed remarkable serous retinal detachment around the sites of photocoagulation with manifest CNV one week after photocoagulation. Although there was no difference in the incidence of CNV between the treated and control eyes, the treated eyes showed more intense leakage of fluorescein from the CNVs for up to 4 weeks after treatment. Morphometrically, the CNVs were significantly larger and continued to grow longer in the treated than in the control eyes after one week of photocoagulation. Histologically, newly formed vessels with a distinct lumen were present in the treated eyes after 3 days of photocoagulation. CONCLUSION: Intravitreal injection of human VEGF promotes experimental choroidal neovascularization in monkey eyes.

Animals↗
PubMed1999

[Effects of corticosteroid on porcine retinal pigment epithelial cells in culture--1. Inhibitory effect on cell proliferation].

PURPOSE: Proliferation is an important function of the retinal pigment epithelial (RPE) cells. The effect of a corticosteroid on the proliferation of cultured porcine RPE cells was investigated. METHODS: After administration of various concentrations (10-1,000 nM) of betamethasone sodium phosphate (betamethasone), we counted RPE cell numbers at 1, 3, 6, 9, and 14 days. RESULTS: Betamethasone administration resulted in a dose-dependent decrease in RPE cell proliferation. The proliferation of the cultured RPE cells was significantly inhibited by betamethasone, at a dose of 300 nM in 9 days. Ten-nM betamethasone neither inhibited nor promoted the RPE cell proliferation in culture. CONCLUSIONS: These results suggest that corticosteroids inhibit proliferation of cultured porcine RPE cells.

Animals↗
PubMed1999

[Angiographic findings and histological localization of indocyanine green in N-methyl-N-nitrosourea induced retinal degeneration in rats].

PURPOSE: We used N-methyl-N-nitrosourea (MNU) to induce chorioretinopathy as a model of retinitis pigmentosa, and compared the histological localization of indocyanine green (ICG) with ICG angiographic features. METHODS: Brown-Norway pigmented rats received a single intraperitoneal injection of MNU (75 mg/kg body weight). At 3 and 21 days after treatment, we compared ICG angiographic findings with histological localization of ICG in the retina and choroid. Histological localization of ICG was observed with an infrared light microscope. RESULTS: 3 days after treatment, destruction of the photoreceptor cells and photoreceptor segments had developed, and the retinal pigment epithelial cells (RPEs) were also damaged. In ICG angiography, diffuse hyperfluorescence was evident. In histological localization of ICG, RPEs were stained by ICG, and ICG was seen in the sensory retina through the damaged RPEs. At 21 days after treatment, the inner nuclear layer directly contact with the choroid. The photoreceptor cells, RPEs and choriocapillaris had disappeared. In ICG angiography, hypofluorescence was seen in the chorioretinal atrophic area. In histological localization of ICG, there was no ICG in the atrophic area, but ICG leaked from the remaining choriocapillaris into the neighboring sensory retina. CONCLUSION: These results support the precise interpretation of ICG angiographic findings in clinical use.

Animals↗
PubMed1999

[Histological proof of indocyanine green angiography--healthy eyes].

PURPOSE: To determine the histological localization of indocyanine green (ICG) in the healthy rat eye and to correlate this with ICG angiographic findings. METHODS: After intravenous ICG dye injection, the rat eyes were enucleated and processed by freeze-substitution fixation with acetone. The tissue sections were stimulated with an 805-nm diode laser and observed with an infrared microscope with an intensified charge coupled device camera. The histological examinations of ICG localization were correlated with the ICG angiographic images. RESULTS: ICG dye did not leak from the retinal and iris vessels. However, in the choroid, extravasation of ICG from the choriocapillaris was observed. The extravascular ICG from the choriocapillaris slowly diffused to the choroidal stroma but did not diffuse to the neurosensory retina through the retinal pigment epithelium. CONCLUSIONS: Change in the localization of ICG in ocular tissue was demonstrated in the ICG angiographic findings. These results help to interpret clinical ICG angiographic findings.

Animals↗
PubMed1998

Time-course expression of vascular endothelial growth factor as related to the development of the retinochoroidal vasculature in rats.

Growth factors involved in angiogenesis are critical to both the normal and pathological vascular development in the retina and choroid. In the present experiment, the relationship between the vascular endothelial growth factor (VEGF) expression and the retinochoroidal vasculogenesis in Sprague-Dawley rats was investigated using in situ hybridization and immunohistochemistry. It was found that VEGF was produced mainly by astrocytes and Muller cells in the neural retina, and this was correlated temporally and spatially with the retinal vasculogenesis. In addition, it was observed that, although the VEGF expression in the retinal pigment epithelium (RPE) decreased with increasing age, it persisted from the embryonic stage to adulthood. These findings indicate that the VEGF expression in RPE may play a role in the development of the choroidal vessels as well as in the maintenance of the normal structure and permeability of the choriocapillaris in adults.

Animals↗
PubMed1998

Immunolocalization of transforming growth factor beta during wound repair in rat retina after laser photocoagulation.

BACKGROUND: Scatter photocoagulation induces regression of retinal neovascularization, but the mechanism of its therapeutic effect is incompletely understood. To elucidate the mechanism of therapeutic effect of photocoagulation is the main focus of our research. We have already demonstrated basic fibroblast growth factor (bFGF) immunolocalization during retinal wound repair following laser photocoagulation. Transforming growth factor beta (TGF beta) reportedly inhibits endothelial cell growth and bFGF-induced cell proliferation in vitro. In the present study, we evaluated the immunohistochemical localization of TGF-beta 1 and -beta 2 during wound repair in the rat retina following laser photocoagulation. METHODS: Krypton laser photocoagulation was performed on the eyes of pigmented rats. The eyes were then enucleated on day 1, 3, 7, 14, 28 or 56 following the photocoagulation and enrolled into the analysis of immunohistochemical localization of TGF-beta 1 and -beta 2. RESULTS: Immunoreactivity for TGF-beta 1 and -beta 2 was present in the ganglion cell layer and photoreceptor outer segments of the normal adult rat retina. The cytoplasm of RPE cells at the photocoagulated lesion showed intense TGF-beta 1 and -beta 2 immunoreactivity on day 3 after laser photocoagulation. Macrophages that migrated into the lesion lacked positive staining for TGF-beta 1 and -beta 2. TGF-beta immunoreactivity in RPE cells continued to be upregulated for more than 1 month compared with that in normal RPE cells. Controls did not exhibit any positive staining. CONCLUSION: An elevated expression of TGF-beta immunoreactivity for a longer period of time than bFGF was observed in RPE cells at the photocoagulated lesion in vivo. In the late phase of retinal wound repair, TGF-beta may inhibit cell proliferation induced by mitogens, introduce an end stage of cellular events, and induce extracellular matrix induction.

Animals↗
PubMed1998

Apoptosis of photoreceptor cells in ornithine-induced retinopathy.

BACKGROUND: The intravitreal injection of ornithine produces selective damage to the retinal pigment epithelium (RPE) and results in a loss of RPE, choriocapillaris and photoreceptor cells. To elucidate the mechanism of secondary retinal atrophy, we investigated the presence of apoptotic cells in a rat model of ornithine-induced retinopathy. METHODS: At 6 and 12 h and 1, 2, 4, 7, 14 and 28 days after an intravitreal injection of L-ornithine hydrochloride in rat eyes, we removed the eyes and subjected them to histopathological examination. We detected apoptotic cells by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate digoxigenin nick end labeling (TUNEL) assay, which stains the 3'-OH ends of fragmented DNA. We used electron microscopy to detect the apoptotic cells morphologically. RESULTS: RPE cells were selectively damaged immediately after ornithine administration. TUNEL-positive photoreceptor cells appeared exclusively in the photoreceptor cell layer 12 h after ornithine administration. The number of TUNEL-positive cells increased throughout the 2 days following the injection, then decreased markedly. TUNEL-positive cells remained until 28 days, when the photoreceptor cells had disappeared. The ganglion cell layer, inner nuclear layer and damaged RPE cells were negative for TUNEL staining during all stages. The electron microscopic study also revealed the pyknotic nuclei of apoptotic photoreceptor cells. CONCLUSION: An intravitreal injection of ornithine caused primary damage to the RPE, and subsequently some of the photoreceptor cells revealed apoptosis by TUNEL assay. These findings suggest the dysfunction of the RPE causes photoreceptor cell death according to the intrinsic program of an apoptotic mechanism.

Animals↗
PubMed1998

Expression of basic fibroblast growth factor and its receptor mRNA in retinal tissue following ischemic injury in the rat.

BACKGROUND: Our purpose was to determine the time-dependent changes of expression of basic fibroblast growth factor (bFGF) and its receptor in pressure-induced retinal ischemia in rats. METHODS: Retinal ischemia was induced in Wistar rats by increasing the intraocular pressure to 110 mmHg for 45 min by cannulation into the eyes. At the end of the ischemic period, reperfusion of the retinal vasculature was confirmed. Localization of bFGF and FGF receptor-1 (FGF-R) mRNAs were evaluated by in situ hybridization at various times after reperfusion. The reverse-transcription polymerase chain reaction (RT-PCR) method was used to detect the expression of bFGF and FGF-R mRNA in the sensory retina. RESULTS: In normal sensory retina, bFGF and FGF-R mRNAs were observed in the ganglion cell layer and inner nuclear layer. bFGF gene expression in the sensory retina increased within 24 h, particularly at 6-12 h. FGF-R gene expression increased earlier than that of bFGF. By RT-PCR, expression of bFGF gene reached a peak at 6-24 h, and FGF-R reached a peak at 3-12 h. These RT-PCR results are comparable to those of in situ hybridization. CONCLUSIONS: These results demonstrate that transient retinal ischemia leads to the induction of bFGF mRNA synthesis, and suggest that bFGF has a protective role, e.g., a defense mechanism for the sensory retina.

Animals↗
PubMed1998

Retinal degeneration induced by N-methyl-N-nitrosourea in Syrian golden hamsters.

BACKGROUND: The sequential retinal changes in Syrian golden hamsters induced by N-methyl-N-nitrosourea (MNU) have not been studied. METHODS: Female hamsters received a single intraperitoneal injection of 90 mg/kg MNU at 50 days of age, and the retina was examined light and electron microscopically, immunohistochemically and by the TdT-mediated dUTP-digoxigenin nick end labeling (TUNEL) method until 20 weeks after the treatment. RESULTS: The retinal changes were as follows: (1) Photoreceptor apoptosis occurred 1 day after the treatment and resulted in photoreceptor loss at day 7. During the degeneration, Müller cell proliferation was conspicuous at day 5. (2) After the photoreceptor cell loss, migration of the pigment epithelial cells in all layers of the retina which were in contact with blood vessels occurred. Due to the Müller cell proliferation, gliosis was prominent at the later stage. CONCLUSIONS: The MNU injection caused photoreceptor apoptosis followed by pigment epithelial cell migration around the blood vessels, accompanied by gliosis. The primary event and the course of this disease closely resemble those of retinitis pigmentosa in humans.

Animals↗
PubMed1998

Midkine expression in transient retinal ischemia in the rat.

PURPOSE: Midkine (MK), a 13-kDa heparin-binding growth factor, is known to exert neurotrophic activities on various nerve cells including retinal cells. To initiate studies toward determining the physiological role of endogenous MK, we investigated the spatial and temporal expression profile of MK before and after intraocular pressure-induced retinal ischemia. METHODS: Retinal ischemia was induced in Wistar strain rats by increasing the intraocular pressure to 110 mm Hg for 45 min via cannulation into the anterior chamber. The localization and abundance of the MK protein and mRNA were determined by the use of immunohistochemistry and in situ hybridization in the normal retina, as well as the retina after reperfusion. The protein expression profile was confirmed by Western blot analysis. RESULTS: Immunohistochemical analysis showed that MK protein was expressed in the ganglion cell layer, the inner portion of the inner nuclear layer, and in the retinal pigment epithelium of the normal rat. MK expression transiently decreased 3 h to 2 days after reperfusion, and then dramatically increased to a level higher than normal after 7 to 28 days. The temporal expression profile of the MK protein was confirmed by Western blot analysis. In situ hybridization analysis gave results comparable to those obtained with immunohistochemistry. CONCLUSIONS: MK was expressed in the neural cells of the retina in the normal state, but became more abundant after pressure-induced retinal ischemia. Thus, endogenous MK responds to ischemic treatment by an initial decrease in expression and then a period of expression above basal levels.

Animals↗
PubMed1998

Expression of vascular endothelial growth factor and its receptor, KDR, following retinal ischemia-reperfusion injury in the rat.

PURPOSE: There is considerable evidence that vascular endothelial growth factor (VEGF) mediates ocular neovascularization in retinal vascular diseases. We investigated the time-dependent changes in the expression of VEGF and its receptor KDR/ Flk in a transient retinal ischemia-reperfusion injury model. METHODS: Transient retinal ischemia was induced by increasing the intraocular pressure in albino rats eyes for 45 min. In situ hybridization was used to identify the retinal cells synthesizing VEGF mRNA and KDR mRNA at various times following reperfusion. Immunohistochemical analysis was also carried out to detect VEGF immunoreactivity. RESULTS: In the control, non-ischemic retinas, signals for VEGF mRNA and KDR mRNA were observed in the cells of the ganglion cell layer. Immunoreactivity to VEGF was also found in the nerve fiber layer, the ganglion cell layer, and the retinal pigment epithelial (RPE) cell layer. Immediately and 6 h after reperfusion, VEGF and KDR mRNA expression was markedly decreased, but recovered by 24 h to the levels observed in normal retinas. Immunoreactivity for VEGF was also decreased immediately and 6 h after reperfusion, and was detected in the endothelial cells of the retinal vessels after 24 h. Immunoreactivity to VEGF recovered by 48 h after reperfusion. CONCLUSIONS: The hybridization pattern of VEGF and KDR mRNA in the ganglion cell layer strongly suggests that the ganglion cells are the major source of this growth factor. The decrease of VEGF mRNA, KDR/Flk mRNA and VEGF protein levels after ischemia and recovery after reperfusion suggest that transient hypoxia might mediate short-term down-regulation of VEGF and KDR mRNA.

Animals↗
PubMed1998

Granulocyte-macrophage colony-stimulating factor expressed in T cells mediates immunity against herpes simplex virus type 1 encephalitis.

A model of herpes simplex virus type 1 (HSV-1) infection was developed in rats to study systemic immune responses elicited by intravitreous inoculation of the virus. HSV-1 inoculation led to distinct granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing memory T cells, which did not develop in rats inoculated with either HSV-1 intraperitoneally or inactivated HSV-1 intravitreously. On subsequent intraperitoneal viral boosting, systemic GM-CSF production was elicited as a secondary immune response that caused neutroeosinophilia. To examine the role of GM-CSF in anti-herpetic immunity, cytokine-producing and -nonproducing rats were intravitreously challenged with HSV-1, which causes lethal encephalitis. Only intravitreously primed rats were protected upon production of GM-CSF. Furthermore, pretreatment with recombinant GM-CSF protected unimmunized rats against the encephalitis. It is thus strongly suggested that the production of GM-CSF leads to anti-HSV-1 immunity against the transneuronal spread of challenged HSV-1 within the visual system.

Adoptive Transfer↗
PubMed1998

Prevention of ornithine cytotoxicity by proline in human retinal pigment epithelial cells.

PURPOSE: To investigate the relationship between ornithine-delta-aminotransferase (OAT) deficiency and ornithine accumulation and the specific degeneration of retinal pigment epithelial (RPE) cells in gyrate atrophy. METHODS: Human RPE cells, human hepatoma cells, and human fibroblast cells were treated with 5-fluoromethylornithine (5-FMOrn), a specific irreversible inhibitor of OAT. Ornithine cytotoxicity was determined by using a [3H]thymidine incorporation assay and immunohistochemical staining for cytokeratin. The effects of various metabolites of ornithine and arginine, such as creatine, creatine phosphate, I-delta 1-pyrroline-5-carboxylic acid (L-P5C), and proline, which may be deficient in gyrate atrophy on RPE cell damage by ornithine, were determined by the same procedures. RESULTS: When the human RPE cells, HepG2 hepatoma cells, and WI-38 fibroblast cells were treated with 0.5 mM 5-FMOrn for 30 minutes, which inactivated OAT, ornithine exhibited severe time- and dose-dependent inhibition of DNA synthesis in the human RPE cells but not in the HepG2 hepatoma cells or WI-38 fibroblast cells. The inhibition of DNA synthesis was accompanied by drastic changes in morphologic appearance, disorganization of the cytoskeleton, and cell death. Ornithine or 5-FMOrn alone did not exhibit such cytotoxicity to the RPE cells. Proline prevented the cytotoxicity of ornithine. CONCLUSIONS: These findings suggest that an elevated level of ornithine combined with an increased sensitivity to ornithine as a result of OAT deficiency may be crucial to the specific RPE degeneration in gyrate atrophy. They suggest also that abnormalities of proline metabolism may be involved in the progress of gyrate atrophy.

Arginine↗
PubMed1998

Surgical outcome on combined procedures of lens extraction, intraocular lens implantation, and vitrectomy during removal of the epiretinal membrane.

BACKGROUND AND OBJECTIVE: The authors evaluated the outcome of combined procedures of lens extraction, intraocular lens implantation, and vitrectomy during procedures for the removal of the epiretinal membrane, and attempt to clarify which factors affected the outcome of surgery. PATIENTS AND METHODS: Surgery for the removal of the epiretinal membrane was performed and a 2-year follow-up program was maintained for 32 eyes at the authors' clinic during the past 5 years. The combined procedure was undertaken in 15 eyes, whereas a simple vitrectomy was performed in 17 eyes. Results were analyzed by postoperative ophthalmoscopic and slit-lamp examinations for visual acuity and complications. RESULTS: Six months after surgery, visual acuity improved similarly in both groups. But, 2 years after surgery, 11 eyes (65%) that underwent a simple vitrectomy showed decreased visual acuity due to the advancement of cataracts. The postoperative visual acuity at 6 months correlated to preoperative visual acuity, and the advancement of cataracts tended to correlate inversely to the age of the patients. Major complications did not occur in any of the cases. CONCLUSION: Earlier surgical management is better for treatment of the epiretinal membrane, and a combined procedure has advantages in cost reduction and is less troublesome, especially for elderly patients.

Adult↗
PubMed1997

Vascular endothelial growth factor expression in choroidal neovascularization in rats.

BACKGROUND: The pathogenesis of choroidal neovascularization is largely unknown. We investigated vascular endothelial growth factor (VEGF) expression in laser-induced choroidal neovascularization (CNV) in rats. METHODS: Intense krypton laser photocoagulation was applied to the posterior poles of the eyes of pigmented rats to induce CNV, which was confirmed by fluorescein angiography and histopathology. The eyeballs were enucleated 1, 3, 7, 14 and 28 days after laser photocoagulation. Cryostat sections were prepared for immunofluorescence staining using anti-VEGF and macrophage marker (ED1) antibodies. The posterior segments of eyeballs pooled from photocoagulated and control rats were submitted for immunoprecipitation and immunoblotting by the anti-VEGF antibody, and reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of VEGF mRNA. RESULTS: Very weak immunoreactivity for anti-VEGF antibody was found in the ganglion cell layer, inner nuclear layer, and retinal pigment epithelium (RPE) in the normal retina. In the development of CNV, strong positive staining for anti-VEGF antibody was found in photocoagulated areas in the subretinal space and choroid. Double immunofluorescence staining showed that many cells in lasered lesions were positive both for anti-VEGF and macrophage marker ED1 antibody staining in the early stage of this model. Immunoblots showed a positive band for the VEGF molecule in treated but not control animals. RT-PCR results demonstrated upregulation of VEGF transcripts in the CNV model compared with normal animals. CONCLUSIONS: Our findings showed the upregulation of VEGF expression in experimentally induced CNV, where it may be involved in promoting choroidal angiogenesis. Macrophages may be one of the main sources of VEGF in the early stage of the disease.

Animals↗
PubMed1997

Involvement of prostaglandin E2 in rabbit corneal injury by anterior segment ischaemia.

The involvement of prostaglandins (PGs) in the development of anterior segment ischaemia after occlusion of the bilateral long posterior ciliary arteries was investigated in rabbit eyes. In this experimental ischaemia, the tissue weight and protein content in the peripheral cornea and the protein content in the aqueous humour increased on the first postoperative day. Topically applied cyclooxygenase inhibitor diclofenac (0.1%) reduced corneal inflammation and further suppressed the elevation in the tissue weight and protein content in the peripheral cornea on day 1 after ischaemia, but did not affect the changes in the aqueous humour. Subconjunctivally administered PGE1 and PGE2 induced corneal oedema and increased corneal protein content in diclofenac-treated and ischaemia-induced eyes, but PGD2, PGF2alpha, and the stable PGI2 analogue cicaprost did not evoke any change. In fact, PGE2 content was markedly increased in the aqueous humour on day 1 after ischaemia, and diclofenac suppressed the increase. In addition, CPT-cAMP increased the corneal tissue weight and protein content in organ culture. These observations suggest that PGE2 may play an important role in developing corneal oedema at the initial stage of ischaemic damage, possibly through the cAMP-mediated pathway.

Alprostadil↗