Biomedical subjects

M Uyama

Publications and source records attributed to M Uyama.

At least 91 records · Page 5Linked to original sources

PubMed1994

Immunocytochemical analyses of distributions of Na, K-ATPase and GLUT1, insulin and transferrin receptors in the developing retinal pigment epithelial cells.

The retinal pigment epithelium (RPE) is unique in that Na,K-ATPase is predominantly localized on its apical surface. We studied the distributions of Na,K-ATPase and glucose transporter GLUT1, insulin and transferrin receptors in developing rat RPE cells immunocytochemically. Na,K-ATPase, first detected in 17-day-old embryonic eyes, was already distributed predominantly on the apical surface. This reversed distribution of Na,K-ATPase was maintained throughout their life. Insulin receptor and transferrin receptor were distributed exclusively on the basolateral surface. By quantitative immunogold electron microscopic technique we found that glucose transporter GLUT1 is distributed almost equal in amount on both the apical and basolateral surfaces of RPE cells, thus presumably constructing an efficient pathway for glucose transport from the choriocapillaries to the neural retina through the blood-retinal barrier. These results suggest that in the RPE cells the intrinsic basolateral plasma membrane proteins are sorted out at least in three different ways.

Animals↗

PubMed1994

Purification and characterization of neurotrophic factor for retinal cholinergic neurons derived from cultured hippocampal neurons.

A neurotrophic factor that supports the development of cholinergic retinal neurons was purified from media conditioned by a primary culture of embryonic hippocampal neurons. Retinal choline acetyltransferase (ChAT), which is located exclusively in amacrine cells, served as a marker for the development of retinal cholinergic neurons. In a serum-free control culture, retinal neurons from 17-day-old rat fetus displayed little increase in the enzyme activity and a low proportion of neurite-bearing cells (15-20%) within 7 days. The conditioned media, when added to the retinal neuron culture, dose-dependently increased ChAT activity and the number of neurite-bearing cells (40-60%), the maximum ChAT activity being approximately sixfold higher than that in the control. The fraction with these stimulatory activities was purified by Sephadex G-15 column chromatography and two times reverse-phase HPLC. The final fraction showed approximately 3,000-fold higher purification as compared with that in the Sephadex G-15 fraction. Gas-phase protein sequencing analysis of the final fraction yielded a peptide sequence: Tyr-Leu-Leu-Pro-Ala-Gln-Val-Asn-Ile-Asp. A synthetic peptide with this sequence dose-dependently stimulated ChAT activity in the retinal cell culture and dissociated cell culture of the septal nucleus. These findings suggest that the developing hippocampal neurons produce a neurotrophic peptide that stimulates the development of cholinergic neurons.

Amino Acid Sequence↗

PubMed1994

[Experimental choroidal neovascularization in the rat].

We successfully produced, highly (78%) reproducible experimental choroidal neovascularization (ChNV) in the subretinal space of pigmented rats with intense diode laser photocoagulation. ChNV in the pigmented rat was characterized by rapid development of neovascular membrane and proliferation of retinal pigment epithelium in the subretinal space. This procedure may be useful as an experimental model for ChNV.

Animals↗

PubMed1994

[Light-induced retinal damage in pigmented rabbits--1. Histopathological observations of the natural course of healing].

Pigmented rabbits were exposed for 2 hours to xenon light to evaluate the light induced retinal damage clinicopathologically. The xenon light was passed through a heat filter to avoid the influence of long waves, and through the fundus contact lens on the cornea to avoid focusing the light on the retina. No abnormal findings were detected in the retina in fluorescein angiography immediately after the light exposure. Three hours later, hyperfluorescence was found in the center of the exposed area and gradually grew worse. This was most marked twelve hours later. After 6 days, granular hyperfluorescence appeared at the edge of the damaged area and in 2 weeks the whole damaged area showed granular hyperfluorescence. Histopathologically, immediately after the light exposure, slight changes appeared in the retinal pigment epithelium (RPE). Twelve hours later, the cytoplasm of the RPE was edematous, and in 24 hours the RPE became necrotic, but the outer segments of the photoreceptor cells appeared intact. After 6 days, the RPE showed double layering, many macrophages were found in the subretinal space, and the outer segments of the photoreceptor cells were severely damaged. The RPE was primarily damaged and photoreceptor cells were damaged subsequently by xenon light without long waves.

Animals↗

PubMed1994

[Light-induced retinal damage in pigmented rabbit--2. Effect of alpha-tocopherol].

We have reported previously that xenon light exposure without long waves primarily damages the retinal pigment epithelium (RPE) of pigmented rabbits. Alpha-tocopherol, which is a free radical scavenger, was administered systemically to pigmented rabbits before light exposure in order to evaluate the protective effect against retinal light damage. In fluoresceine angiography, at 12 hours after the light exposure, diffuse and marked hyperfluorescence was seen in the lower portion of the retina adjacent to the optic disc in the untreated group, and slight hyperfluorescence in a small area was seen in the treated group. Histopathologically, the RPE became necrotic 12 hours after the light exposure in the untreated group. In the treated group, only slight damage appeared in the RPE 12 hours after the light exposure. The light-induced retinal damage, particularly in the RPE, was remarkably reduced by administration of alpha-tocopherol before the light exposure.

Animals↗

PubMed1994

[Immunohistological study in Bruch's membrane of senescence accelerated mouse].

Age-related macular degeneration is one of the major causes of severe visual loss is elderly individuals. However, relatively little is known about its etiology. The disease may be associated with senescence. Ultrastructural and immunohistochemical studies on SAM (senescence accelerated mouse) eyes were carried out to learn details of aging changes in the retinal pigment epithelium (RPE) and Bruch's membrane. SAM P 1 mice aged 2, 10, 14 months were examined in this study. The eyes were analysed for type IV collagen and heparan sulfate proteoglycan (HSPG) by the avidin-biotin-peroxidase complexes (ABC) method and post-embeddig immunolocalization with colloidal gold. With the ABC method, the basement membranes of both the RPE and the choriocapillaris showed markedly positive staining when treated with anti-type IV collagen antibody and moderately positive staining when treated with anti-HSPG antibody. In ultrastructural immunolocalization, both basement membranes showed fairly heavy labeling in response to the antibodies to type IV collagen, and moderate labeling in response to the antibodies to HSPG. With aging, the thickness of the basement membrane of the choriocapillaris and gold particle labeling by the antibodies to type IV collagen increased. The gold particle labeling by the antibodies to HSPG increased slightly, but was distributed sparsely. These results showed the advancing process of senescence changes in Bruch's membrane.

Aging↗

PubMed1994

[Indocyanine green fluorescence angiography in Harada disease].

Indocyanine green fluorescence angiography (ICG angiography) can reveal choroidal circulation, and so it is used to observe uveitis. We examined 29 eyes of 15 patients with Harada disease using ICG angiography. In the early phase, filling delay of choroidal circulation was the most remarkable finding in cases with flat retinal detachment in the posterior pole. In the early to late phase choroidal vessels were indistinct, and speckled hypofluorescence on the diffuse background fluorescence was seen. Leakage from the choroid into the subretinal space was seen in ICG angiography at the same leak points seen in fluorescein angiography. In 3 patients, the area of retinal detachment showed hypofluoresence in the late phase. Areas of Dalen-Fuchs spots showed hypofluorescence. ICG angiography clearly revealed severe disturbance of choroidal circulation in Harada disease, and filling delay of the choroidal circulation and indistinct choroidal vessels correlated with the severity of this disease. ICG angiography helps to evaluate the pathology of Harada disease clinically.

Adolescent↗

PubMed1994

[Morphological change in the retina after injection of calcium and netilmicin sulfate in the rabbit vitreous body].

We reported previously selective damage of the outer segment of the photoreceptors and retinal pigment epithelium after intravitreal injection of netilmicin sulfate in the rabbit. The cellular damage was thought due to active damage of phospholipase C enzyme, preventing it from performing phospholipid inositol metabolism, and to the presence of calcium. Therefore we investigated the retinal damage following after intravitreal injection of calcium and netilmicin sulfate in the rabbit. Morphologically, the retina did not show any structural change after intravitreal injection of CaCl2 at any concentration. After an intravitreal injection of netilmicin sulfate mixed with CaCl2, the damage in the photoreceptor outer segment was reduced at a concentration of 200 micrograms/0.1 ml and in the retinal pigment epithelium at a concentration of 1,000 micrograms/0.1 ml. This showed that retinal damage due to netilmicin sulfate can be reduced by the addition of calcium.

Animals↗

PubMed1994

Acidification of phagosomes and degradation of rod outer segments in rat retinal pigment epithelium.

PURPOSE: The authors investigated the phagocytic processes of the rod outer segments (ROS) in rat retinal pigment epithelium (RPE) cells, and the appearance of lysosomal enzymes, acidification, and degradation of the contents in the phagolysosomes. In particular, they examined the effect of bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPase, on the degradation of ROS in the RPE cells in vivo. METHODS: A lysosomal enzyme (cathepsin D), a lysosomal membrane protein (LGP107), and opsin were localized in the RPE cells by the immunogold electron microscopic technique. Bafilomycin A1 was injected into the vitreous, and acidification of the phagosomes was measured in vivo by injecting 3-[2,4-dinitroanilino]3'amino-N-methyldipropylamine (DAMP) in the vitreous and detecting the accumulation of DAMP in the phagolysosomes using anti-dinitrophenol antibody. RESULTS: Opsin was abundantly detected in phagosomes that did not contain cathepsin D, but the immunolabeling of opsin rapidly disappeared soon after the appearance of cathepsin D. By double staining with cathepsin D and DAMP, it was shown that the pH of the phagosomes dramatically decreased after fusion with lysosomes. When bafilomycin A1 was injected into the vitreous, many large phagolysosomes containing cathepsin D appeared in the RPE cells, in which the immunoreactivity of opsin was well preserved. CONCLUSIONS: Degradation of opsin and acidification proceeded almost parallel with the appearance of cathepsin D in the phagolysosomes. Bafilomycin A1 did not inhibit the fusion of phagosomes with lysosomes, but it increased intraphagosomal pH and markedly inhibited the degradation of ROS in the phagolysosomes. This result indicates that vacuolar-type H(+)-ATPase is essential for acidifying the lumen of phagolysosomes and subsequent protein degradation of ROS in the RPE cells.

Animals↗

PubMed1994

[An experimental study of diode laser photocoagulation and indocyanine green dye-enhanced diode laser photocoagulation in the primate retina].

A diode laser, emitting light in the near-infrared range (803 nm), was used for photocoagulation at mild, moderate, and strong intensities with or without intravenous administration of indocyanine green (ICG) in 7 eyes of 4 rhesus monkeys. The retinochoroidal lesions were studied histopathologically from 24 hours to 3 months after treatment, and choroidal vascular casts were studied by electron microscopy. Mild diode laser burns caused occlusion of the choriocapillaris and slight outer retinal damage. Moderate and severe burns caused more marked occlusion of the choriocapillaris, deep choroidal vessels, and choroidal nerves. There was little difference between ICG-enhanced and non-enhanced mild burns, but ICG-enhanced moderate and severe burns showed larger retinochoroidal lesions and more complete obstruction of the choriocapillaris than did burns without ICG enhancement. It seems that at moderate and strong levels, ICG-enhanced diode laser burns have more apparent effect on the retina and choroid, particularly on the choroidal vessels.

Animals↗

PubMed1994

[Sympathetic ophthalmia in an elderly man].

A 78-years-old man suffered from sympathetic ophthalmia. He had been treated with 5-fluorouracil (5-FU) for metastasis of colon cancer in the liver. He received a perforating eye injury in the left eye thereafter the eye became phthisic. Two months after the injury, he noticed visual disturbance in the right eye. He was treated with large doses of systemic corticosteroid after a diagnosis of uveitis of the right eye, but the visual acuity of the right eye became worse. The eye showed non-specific diffuse uveitis. A diagnosis of sympathetic ophthalmia was made from previous history and ocular findings. We enucleated the injured eye and continued the systemic corticosteroid. Then the right eye improved. Histopathological examination of the enucleated eye revealed the choroid was infiltrated with a granulomatous lesion of lymphocytes and epithelioid cells. HLA typing showed DR4, DR8, DR52, DR53, and DQ1, and we made a final diagnosis of sympathetic ophthalmia. It is probable that the clinical findings were modified by the 5-FU treatment and the patient's advanced age.

Aged↗

PubMed1994

[Immunohistochemical localization of herpes simplex virus type 1 in experimental retinitis--2. The brain, contralateral optic nerve and retina].

Unilateral intravitreal inoculation of herpes simplex virus type 1 (HSV) induced bilateral retinitis and encephalitis in rats. In a previous paper, we demonstrated immunohistochemical localization of HSV in the ipsilateral retina. In this paper, we report immunohistochemical localization of antigen to HSV in the brain and opposite eye. HSV was found in the optic chiasm, and bilaterally in the suprachiasmatic nuclei, lateral geniculate nuclei, superior colliculus, pretectum, and visual cortex. HSV was also found in the retinal ganglion cells, neural cells in the inner nuclear layer, and Müller cells in the opposite eye. We demonstrated HSV infection in the retina of the opposite eye via the optic nerve, visual pathway, and nuclei, but not through the blood stream.

Animals↗

PubMed1994

[Proteoglycan in Bruch's membrane of senescence accelerated mouse: localization and age-related changes].

We demonstrated the distribution of sulfated proteoglycans in Bruch's membrane of Senescence Accelerated Mouse histochemically and ultrastructurally using cuprolinic blue in conjunction with specific enzyme treatments and nitrous acid digestion. Two kinds of proteoglycan filaments were observed in the inner and outer collagenous layers, i.e., small collagen fibril-associated filaments (11 nm in average length), and large filaments (32 nm in average length). Intermediate size filaments (25 nm in average length) were seen in the basement membranes of the retinal pigment epithelium and choriocapillaris. Chondroitinase AC treatment eliminated the staining of filaments in the collagenous layers (chondroitin sulfate). Chondroitinase ABC treatment also eliminated the staining of filaments in the collagenous layers (chondroitin sulfate and dermatan sulfate). Nitrous acid eliminated the staining of filaments in both basement membranes (heparan sulfate). Proteoglycans containing chondroitin sulfate and dermatan sulfate were associated uniquely with collagen fibrils. Heparan sulfate proteoglycans were associated with the basement membranes of the pigment epithelium and choriocapillaris. With aging, the thickness of the basement membrane of the choriocapillaris and the staining of the filaments in the basement membranes of the pigment epithelium and choriocapillaris (heparan sulfate proteoglycans) increased. Collagen fibers became disarranged and the staining of both filaments in the collagenous layers decreased. The results of the staining characteristics probably reflect the aging of Bruch's membrane.

Aging↗

PubMed1993

Corneal PAF acetylhydrolase increases in anterior segment ischemia in rabbits.

The involvement of platelet-activating factor (PAF) in the development of anterior segment necrosis after occlusion of the bilateral long posterior ciliary arteries was investigated in rabbits. With the progression of anterior segment necrosis, which was characterized by corneal edema and neovascularization, the contents of protein and total phospholipids increased in the cornea and aqueous humor, but not in the iris. PAF acetylhydrolase activity was significantly increased on the first postoperative day in the peripheral cornea and on the second day in the central cornea prior to the development of marked corneal edema and neovascularization, but it did not increase in the iris. The accumulation of newly synthesized PAF in the cornea reached a plateau level on the third postoperative day, which coincided with the progression of the corneal lesion. In the aqueous humor, PAF acetylhydrolase activity was increased by the induced ischemia, but no PAF was detected. The increased PAF acetylhydrolase activity may reflect adaptation to the participation of PAF in the progression of anterior segment necrosis.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed1993

[Age-related changes in Bruch's membrane of the senescence accelerated mouse].

We studied pathological changes in Bruch's membrane of Senescence Accelerated Mouse (SAM) P/1. Tannic acid was used to demonstrate collagen fibers and microfibrils in Bruch's membrane. With aging, thickening of Bruch's membrane, especially thickening of the basement membrane of the choriocapillaris, was remarkable. The distance between collagen fibers also became wider, and many more fine fibrils appeared around each collagen fibril with aging. These changes were observed mor in the posterior area than in the periphery.

Aging↗

PubMed1993

[Fibronectin in the chorioretinal wound after laser photocoagulation].

Fibronectin (Fn) is a glycoprotein which mediates adhesion, extension, migration, and chemotaxis of the cells. We did a histochemical study of the time course of appearance and distribution of Fn in the chorioretinal wound after laser photocoagulation. In the normal chorioretinal tissue, Fn was detected in the internal limiting membrane, Bruch's membrane, and the endothelium of chorioretinal vessels. Shortly after laser photocoagulation, Fn appeared on Bruch's membrane and in the endothelium of choroidal vessels and choroidal stroma, and was prominent by one week after laser photocoagulation. Although Fn disappeared when wound healing was accomplished, it was still detected on Bruch's membrane one month after laser photocoagulation. These findings suggest that Fn is related to chorioretinal wound healing after laser photocoagulation.

Animals↗

PubMed1993

[Diagnostic vitrectomy for chronic uveitis].

Uveitis is diagnosed by ophthalmologic and systemic examination, but it may be difficult to diagnose accurately in some chronic cases. We performed diagnostic and therapeutic vitrectomy for chronic uveitis in 6 eyes of 4 patients, and examined vitreous specimens with immunohistochemical staining. Visual acuity improved in all cases due to clearing up of the vitreous cells. One patient had sarcoidosis, one had B cell malignant lymphoma (ocular reticulum cell sarcoma), and two had reactive lymphoid hyperplasia. Vitrectomy for chronic uveitis is useful for diagnosis and improvement of vision, and we recommend immunohistological staining of vitreous specimens. Particularly, when intraocular lymphoma is suspected, vitrectomy must be performed early.

Aged↗

PubMed1993

[Recanalization of venule following experimental retinal branch vein occlusion].

Retinal branch vein occlusion was experimentally produced in monkey (macaca irus) by dye laser photocoagulation. Venous dilatation, retinal edema and punctate hemorrhages were the ophthalmoscopic changes immediately after the occurrence of venous occlusion by photocoagulation. Fluorescein angiography revealed delay of retinal circulation and dye leakage from these venules. Fluorescein angiography on the 2nd day revealed caliber irregularities in the venules distal to the photocoagulated points. Histopathologically, thrombus formation and partial defect of the endothelial cells were observed in the venules in the areas which showed recovery with immature endothelial cells on the 4th day. Young endothelial cells proliferating along the endothelial basement membrane, which remained around the thrombi, and recanalization were observed on the 7th day. These results reveals a process of recanalization in the thrombogenous retinal venous occlusion.

Animals↗