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Biomedical subjects

M Uyama

Publications and source records attributed to M Uyama.

At least 109 records · Page 6Linked to original sources
PubMed1993

[The effect of corticosteroid on the repair of the retinal pigment epithelium].

The effect of corticosteroid on the repairing process of the retinal pigment epithelial cells (RPE) after laser photocoagulation was investigated. Mild-intensity krypton red laser photocoagulations were performed on the monkey retina. After laser photocoagulations, betamethasone (0.5 mg/kg) were administered intramuscularly every day for 1-14 days. Moreover, the same doses of betamethasone were also administered intramuscularly for one week from the 1st to 7th day after laser photocoagulation on other monkeys. The photocoagulated lesions were observed with light and transmission electron microscopy. In monkeys that received corticosteroids, the migration and the proliferation of RPE were markedly inhibited, and the metaplasia to fibroblast-like cells of RPE was not observed. These results showed that large doses of corticosteroid inhibited the repair process of the injured RPE.

Animals↗
PubMed1993

[Immunohistochemical investigation on intraneural localization of herpes simplex virus type 1 in experimental retinitis. 1. Observation of the retina and optic nerve on the injected side].

In order to examine transfer of herpes simplex virus type 1 (HSV-1) in the retina and optic nerve in rats with experimental retinitis, an HSV-1 suspension (Miyama strain, 1 x 10(7) plaque-forming units per ml, 10 microliters) was inoculated into the vitreous body. One to seven days after HSV-1 inoculation, the animals were perfused through the heart with Zamboni's fixative. Fifty-microns-thick cryostat-cut sections through the retina and optic nerve were immunostained for HSV-1 antigen with rabbit anti-HSV-1 antiserum and avidin-biotin-peroxidase complex. Some sections were counterstained with hematoxylin. At an early stage of the postinoculation period, HSV-1 immunoreactivity was first seen in the cytoplasm of Müller cells and then in various cells of the inner nuclear layer. HSV-1 immunoreactivity was extremely dense in the nuclei of these cells, suggesting that HSV-1 replicates in the nuclei and propagates through the cytoplasm to the membrane of cell processes. At a later stage of the postinoculation period, HSV-1 immunoreactivity was seen in some retinal ganglion cells and optic nerve fibers. The labeling of the optic nerve fibers was found even in the optic tract and often accompanied by labeled glial cells adjacent to the nerve fibers.

Animals↗
PubMed1993

[Changes in the intermediate stage of retinal degeneration after intravitreal injection of ornithine].

We reported previously that intravitreal injection of a small amount of 1-ornithine hydrochloride in monkey eyes damages the retinal pigment epithelium (RPE), selectively. At one year after administration, sharply demarcated chorioretinal atrophy was seen. This paper describes the intermediate stage of retinal degeneration caused by ornithine. Two weeks following intravitreal injection of ornithine, RPE cells at the equator became necrotic and disappeared. However RPE regenerated to cover Bruch's membrane at the border of RPE degenerated area. In 2 months at an area where RPE cells disappeared, the photoreceptors and choriocapillaris degenerated to disappear. However, in the area in where RPE regenerated, they maintained their structure. This report demonstrated that damage of RPE resulted in disappearance of the photoreceptor and choriocapillaris.

Animals↗
PubMed1993

[Histological observations on the sclera in uveal effusion].

The author performed sclerectomy in six cases of uveal effusion syndrome and examined the excised sclera histologically. From the findings of the sclera during the surgery and histological findings of the excised sclera, uveal effusion syndrome was divided into three groups: 1) nanophthalmos, 2) non-nanophthalmos with hypertrophic sclera, 3) non-nanophthalmos with normal thick sclera. In all cases, glycosaminoglycans were found to be deposited around the scleral collagen fibers. In the nanophthalmic eyes (group 1) and non-nanophthalmic eyes with the hypertrophic sclera (group 2), much glycosaminoglycans were demonstrated around the collagen bundles and enlarged the collagen bundle spaces. In these groups, sclerectomy procedures were successful and, based on the successful result of the operation, the cause of uveal effusion was considered to be disturbance of outflow of intraocular fluid through the hypertrophic sclera. In non-nanophthalmic eyes with normal thick sclera (group 3), few glycosaminoglycans was demonstrated around the collagen bundles with less abnormality, and sclerectomy procedure was not effective. In this group, the occurrence of uveal effusion was another cause but abnormal sclera.

Adult↗
PubMed1992

Localization of nonspecific lipid transfer protein (nsLTP = sterol carrier protein 2) and acyl-CoA oxidase in peroxisomes of pigment epithelial cells of rat retina.

We investigated the localization of nonspecific lipid transfer protein (nsLTP) in rat retina, especially in the pigment epithelial (RPE) cells, by the avidin-biotin-peroxidase complex method on cryosections for light microscopy and by the cryoimmunogold method for electron microscopy. Light microscopic observation revealed that the RPE, inner segment layer, nerve fiber layer, and Müller cells contain nsLTP. In the RPE cells gold particles were exclusively concentrated in the small peroxisomes (microperoxisomes; 0.1-0.3 micron in diameter), which were identified by double staining using anti-nsLTP and anti-catalase antibodies. In the peroxisomes gold particles were distributed homogeneously in the matrices and no preferential binding to the limiting membrane was observed. Acyl-CoA oxidase was also localized in the matrices of the peroxisomes. We suggest that the peroxisomes in RPE cells play important roles in the metabolism of lipids of the outer segment disk membranes, especially in the beta-oxidation of polyunsaturated long-chain and very long-chain fatty acids, such as docosahexaenoic acid which is composed of approximately one third of fatty acids in the disk membranes.

Acyl-CoA Oxidase↗
PubMed1992

[Laser photocoagulation of experimentally produced choroidal neovascularization. 2. Comparison of effects by dye and argon blue-green lasers].

Choroidal neovascularization was produced in 18 eyes of 12 rhesus monkeys by application of intense krypton laser photocoagulation. Eight weeks or later, a total of 34 choroidal neovascularizations were treated either by dye laser at wavelengths of 577 or 630 nm or by argon blue-green laser. The treated lesions were evaluated clinically and histopathologically from 24 hours to 3 months after treatment. All the treated lesions were apparently healed by each of the 3 laser modalities. Histopathologically, all the treated choroidal neovascularizations were occluded 24 hours after treatment. At 2 weeks to 3 months after treatment, newly-formed choroidal vessels were present in 3 of 9 lesions (33%) after 577 nm dye laser treatment, in 8 of 9 lesions (89%) after 630 nm dye laser treatment, and in 5 of 8 lesions (62%) after argon blue-green laser. These results seemed to show the clinical superiority of 577 nm dye laser in treating choroidal neovascularization.

Animals↗
PubMed1992

Ultrastructural localization of Na+, K(+)-ATPase in the exorbital lacrimal gland of rat.

Ultrastructural localization of Na+, K(+)-ATPase in the exorbital lacrimal gland of rat was investigated quantitatively by protein A-gold technique. Na+, K(+)-ATPase was purified from the rat kidney, and anti-holo Na+, K(+)-ATPase antibody was obtained from the rabbit by injecting the purified enzyme. A specific antibody against the alpha-subunit of Na+, K(+)-ATPase was affinity purified. Immunoblot analysis revealed that the antibody bound specifically to the alpha-subunit of Na+, K(+)-ATPase of the lacrimal gland. Rats were fixed by perfusion with 4% paraformaldehyde containing 1% glutaraldehyde, and the lacrimal glands were embedded in LR White resin. Ultrathin sections were incubated with affinity purified antibody against the alpha-subunit of Na+, K(+)-ATPase, and then with protein A-gold complex. The sections were observed under an electron microscope. Light microscopy with silver enhancement procedure revealed that Na+, K(+)-ATPase was located mainly on the basal region of the cells of intralobular and interlobular ducts. Quantitative immunoelectron microscopic analysis showed that gold particles were found on the basolateral surfaces of the interlobular and intralobular ducts cells and on the basolateral surface of the acinar cells, whereas no significant binding was observed on any part of the apical surfaces of these cells. Labeling density of gold particles was highest on the basolateral surface of the interlobular duct cells, secondarily highest on the basolateral surface of the intralobular duct cells, and lowest on the basolateral surface of the acinar cells. The distribution pattern of Na+, K(+)-ATPase in the acinar cells and the duct cells suggest that this enzyme may play an important role in primary secretion and in determining the composition of electrolytes in the final secretion, respectively.

Animals↗
PubMed1992

[Laser photocoagulation for experimental choroidal neovascularization. 1. Mild dye laser photocoagulation].

The author treated experimentally produced choroidal neovascularization (ChNV) with mild dye laser photocoagulation (PHC). We treated these ChNVs with 590 nm wavelength, 200 microns spot size, 0.2 second duration and 50 mW of power. Eleven eyes of nine rhesus monkeys were used. Then these ChNVs were examined clinically and histopathologically at 24 hours, 2 weeks and a month after therapeutic PHC. Small ChNVs, less than 1/3 disc diameter healed successfully and histopathologically most of them were coagulated and disappeared. A few poorly developed ChNVs remained, but were well enveloped by the proliferating retinal pigment epithelial (RPE) cells. On the other hand, ChNVs of more than 1/3 disc diameter did not respond to weak PHC, grew actively over a month, and were not completely surrounded by proliferating RPE cells. These results suggest that by mild PHC, small ChNVs may be treatable, however, in large ChNVs, mild PHC may rather accelerate their activity.

Animals↗
PubMed1992

[Retinal degeneration after intravitreal injection of ornithine. 2. Late change after administration].

The influence of intravitreal injection of a small amount of l-ornithine hydrochloride in monkey eyes has been investigated morphologically. In a previous paper, the author demonstrated that acute selective damage was caused in the retinal pigment epithelium (RPE) by ornithine. This paper will demonstrate retinal degeneration at the late stage by intravitreal injection of ornithine. At one year after administration, sharply demarcated chorioretinal atrophy was seen ophthalmoscopically from the equator to the peripheral retina. These areas corresponded to those where RPE became necrosis at early stage following administration of ornithine. Histopathologically, the photoreceptor cells, RPE, and choriocapillaris disappeared completely in these areas, and the inner retina was directly contact with the Bruch membrane with the proliferating Müller fibers. On the other hand at the posterior pole, the photoreceptor cells, RPE, and the choriocapillaris maintained intact. This study demonstrated that necrosis of RPE by intravitreal injection of ornithine leads to complete loss of the visual cells and choriocapillaris, at the late stage.

Animals↗
PubMed1992

[Histological changes in the retinal pigment epithelium and Bruch's membrane in senescence accelerated mouse].

Senescence associated changes of the retinal pigmented epithelium (RPE) and Bruch's membrane were investigated in senescence accelerated mouse (SAM), which is an aging model mouse, by light and electron microscopy. The most characteristic changes in RPE were swelling of basal infoldings, extension of intercellular space and accumulation of lipofuscin granules. In Bruch's membrane, discontinuation of elastic layer and abnormal increase of fine fibrils in the outer collagenous layer were observed. The aging changes in SAM were severer in the posterior retina than in the peripheral one. Moreover, these changes were seen younger age than in those of the normal BALB/c mouse.

Aging↗
PubMed1991

Ontogeny of thymic B cells in normal mice.

Ontogeny of thymic B cells and their surface characteristics were analyzed using monoclonal antibodies (mAbs) against B220 molecules (CD45, CD45R). A small number of B cells were detected in fetal thymus on Gestation Day 14 (approximately 3.5% of the low-density fraction). Similarly, the percentage of B cells in the low-density fraction was 3.2% on Gestation Day 18, and 3.5% on Day 1 after birth. These were the same level as that of adult mice. CD5+ B cells, which form the major population of thymic B cells, were also found in the fetal life (0.5% on Day 14 and 2.2% on Day 16 in the low-density cells). The percentage of CD5+ B cells in B cell-enriched fraction was about 65% on Day 1 after birth, which is the same level as that in adult mice. These results indicate that a small number of B cells or cells in the B-cell lineage are present in the fetal thymus and also suggest the importance of these thymic B cells in the negative selection of T cells during early developmental stages.

Animals↗
PubMed1991

[Detection of destruction of anionic sites in the outer blood-retinal barrier and damage caused by iron].

We studied the alteration of the anionic charge in the outer blood-retinal barrier in ocular siderosis by electron microscopy using the cationic probe, polyethyleneimine (PEI). The eyes of four days after injection of iron powder and control rabbit eyes demonstrated numerous PEI-positive sites at the basement membrane of the retinal pigment epithelium, collagen fiber of Bruch's membrane, and the basement membrane of the choriocapillaris. Seven days after injection of iron powder, no change was observed in the retina by light microscopy, but PEI positive sites at the basement membrane of the retinal pigment epithelium were decreased. At 14 days, it was seen that the outer layer of the retina disappeared and was replaced by pigment containing macrophages and Müller cells. Berlin blue reaction became positive in some of those macrophages and retinal pigment epithelia. PEI positive sites decreased. At 28 days, the retina was completely disorganized, and became thin, while the retinal pigment epithelium proliferated and became double layered. Berlin blue reaction was strongly positive in pigment-laden macrophages and retinal pigment epithelium. PEI-positive sites became scarce. As a result of these methods, anionic sites decreased, despite negative iron reaction of 7 days after injection of iron powder. It was shown that in ocular siderosis at an early stage, the barrier function of anionic sites between choroid and retina decreased before histological change.

Animals↗
PubMed1991

[Choroidal neovascularization, experimental and clinical study].

As a special lecture at the 95th annual Congress of the Japanese Ophthalmological Society in 1991, we presented experimental studies on choroidal neovascularization (ChNV), and clinical studies on senile disciform macular degeneration (exudative age-related macular degeneration). We produced experimentally ChNV on monkey eyes using intense photocoagulation with krypton laser. We showed the retinal pigment epithelium (RPE) played a heavy role as inducer or inhibitor for ChNV at different stages of development or involution of experimental ChNV. Senile disciform macular degeneration is becoming a leading cause of blindness in the elderly in Japan. We examined 473 eyes in 398 cases of this disease during the past 5 years. Nineteen percent were bilaterally affected, males were affected 3 times prevalent than in female, and average age was 67 in years. Predisposing signs were degeneration or atrophy of RPE, hard or soft drusen, and serous detachment of RPE in the macula. In early stage, serous retinal detachment stage appeared and showed good outcome by laser treatment. Subretinal hematoma form showed next better outcome in acute onset and acute course. Advanced form of disciform lesion showed worse outcome. A form (subretinal cystic form) associated with large serous RPE detachment showed the worst outcome and scarcely indicated for laser treatment. We describe clinical features of each form and stages of the disease and clinical course. Early detection, early correct diagnosis and early laser treatment must be essential for prevention of blindness due to this disease.

Adult↗
PubMed1991

[Morphological changes in the retina following one-shot injection of netilmicin sulfate into the vitreous].

Morphological changes of the retina following one-shot injections into the vitreous of netilmicin sulfate were investigated. The concentrations of netilmicin in the vitreous after intravitreal injection showed the curve of y = a/xb, where y is the concentrations in the vitreous body, x in the number of days since injection and a, b are constant. Concentration decreased rapidly after the injection, and almost totally disappeared after one week. Morphologically, the retina showed normal structure following injections of 100 micrograms/0.1ml and 200 micrograms/0.1ml. Following injections of over 500 micrograms/0.1ml, the outer segment of the photoreceptor disappeared and many phagosomes appeared in the retinal pigment epithelium cell. Following one shot injections of over 500 micrograms/0.1ml damage to the photoreceptor and retinal pigment epithelium was demonstrated. The above data suggested that one-shot injection of netilmicin in concentrations of up to 200 micrograms/0.1ml could be mode without retinal damage.

Animals↗
PubMed1991

[Experimental retinal branch vein occlusion].

Experimental retinal branch vein occlusion in monkeys (macaca irus) were produced by yellow wavelength (577nm) dye laser photocoagulation. The clinical sequence was observed in terms of the structural and ultrastructural findings occurring during the natural history of experimental branch vein occlusion, particularly in the early stage. Immediately after the occlusion, venous dilatation and retinal edema and hemorrhage appeared. Extravascular leakage of dye in fluorescein angiography and hemorrhage appeared from small venules at an early stage. Leakage from the larger vessels was observed later. Opening of the intercellular junctional complexes, which signifies breakdown of the blood-retinal barrier was detected by electron microscopy. Subsequently degenerative or necrotic changes in endothelial cells appeared with the formation of intravascular thrombi and extravascular leakage of blood components appeared from these vessels.

Animals↗
PubMed1990

Immunocytochemical localization of Na+,K(+)-ATPase in rat retinal pigment epithelial cells.

We investigated quantitatively the ultrastructural localization of the alpha-subunit of Na+,K(+)-ATPase in rat retinal pigment epithelial cells by the protein A-gold technique, using an affinity-purified antibody against the alpha-subunit of rat kidney Na+,K(+)-ATPase. Immunoblot analysis showed that the antibody bound specifically to the alpha- and alpha(+)-subunits of Na+,K(+)-ATPase in the whole retina [the sensory retina plus retinal pigment epithelium (RPE)]. Rat eyes were fixed by perfusion with 4% paraformaldehyde containing 1% glutaraldehyde and embedded in Lowicryl K4M. Ultra-thin sections were incubated with affinity-purified antibody against the alpha-subunit of rat kidney Na+,K(+)-ATPase and subsequently with protein A-gold complex. Light microscopy with a silver enhancement procedure revealed Na+,K(+)-ATPase localized to both the apical and the basal plasma membrane domains of the RPE. Quantitative immunocytochemical analysis by electron microscopy showed a higher density of gold particles on the apical surface than on the basolateral one. Microvilli are so well developed on the apical surface of the RPE that the apical surface profile is much longer than the basolateral one. This means that Na+,K(+)-ATPase is mainly located on the apical surface of the RPE cells.

Animals↗
PubMed1990

[A role of the retinal pigment epithelium in the involution of subretinal neovascularization].

We clarified a role of the retinal pigment epithelium (RPE) in the regression of experimentally induced subretinal neovascularization (SRN) in monkey. Eight eyes of 5 rhesus monkeys were used in this study. Two weeks after intense krypton laser photocoagulation to the posterior pole of the fundus, 0.5M l-ornithine hydrochloride solution 0.03 ml was injected intravitreously for the purpose of selective RPE damage. After ornithine injection, SRN continued without any evidence of spontaneous regression over 8 weeks following photocoagulation. Histopathologically, SRN developed with wide lumen in the subretinal space accompanied with serous detachment of the sensory retina, and new vessels were not enveloped completely by the proliferating RPE cells. We already showed that experimentally induced subretinal neovascularizations naturally regress spontaneously by envelopment of RPE cells 5 to 8 weeks after photocoagulation. Our results suggested that SRN persist actively without regression due to incomplete enclosure by RPE by selective damage of RPE at the active stage of SRN. We have confirmed that the RPE cells played an important role at the involution stage of SRN.

Animals↗