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Biomedical subjects

H Inomata

Publications and source records attributed to H Inomata.

258 records · Page 15Linked to original sources

Electron microscopic study on the development of precapsular layer in eyes with exfoliation syndrome.

PURPOSE: To search for a pathogenic mechanism for the formation of the precapsular layer on the anterior lens surface in pre-exfoliative eyes. METHODS: We examined anterior lens capsules obtained during surgery from 38 patients (control, 16; exfoliation suspect, 10; exfoliation, 12) by transmission electron microscopy. RESULTS: A precapsular layer was found in 5 of 16 controls and 7 of 10 exfoliation suspects. It was composed mainly of microfibrils 5-8 nm in diameter. Degenerated zonular fragments were occasionally found interspersed in, and sometimes merged with microfibrils of the precapsular layer. CONCLUSION: Zonular fibers might contribute to the formation of the precapsular layer in pre-exfoliation stages.

Adult↗

Vogt-Koyanagi-Harada syndrome.

The Vogt-Koyanagi-Harada syndrome (VKH) is a bilateral, diffuse granulomatous uveitis associated with poliosis, vitiligo, alopecia, and central nervous system and auditory signs. These manifestations are variable and race dependent. This inflammatory syndrome is probably the result of an autoimmune mechanism, influenced by genetic factors, and appears to be directed against melanocytes. On histopathologic examination typical cases show nonnecrotizing diffuse granulomatous panuveitis with initial sparing and late involvement of the choriocapillaris and formation of Dalen-Fuchs' nodules. Fluorescein angiography, lumbar puncture, and echography are useful adjuncts in the diagnosis and management of VKH syndrome. Patients with this syndrome are treated generally with high dose systemic corticosteroids or, when necessary, with cyclosporine or cytotoxic agents. The prognosis of patients with VKH syndrome is fair, with nearly 60% of patients retaining vision of 20/30 or better. The complications of VKH syndrome that lead to visual loss include cataracts in about 25% of patients, glaucoma in 33%, and subretinal neovascular membranes (SRNVMs) in about 10%; the latter, however, are an important cause of late visual loss. These complications usually require medical and/or surgical intervention, including photocoagulation. The major risk factor for the development of cataracts, SRNVMs, and, to some extent, glaucoma, is chronic recurrent intraocular inflammation that may be resistant to corticosteroid therapy. It appears that initial treatment with high dose corticosteroids, combined with prolonged corticosteroid therapy at appropriate dosage, may minimize these complications and may improve visual prognosis.

Fluorescein Angiography↗

Interferon beta affects retinal pigment epithelial cell proliferation via protein kinase C pathways.

BACKGROUND: The aim of this study is to see the effect of interferon beta (IFN-beta) on cell proliferation and the protein kinase C (PKC) signaling pathway. METHODS: Proliferation of cultured human retinal pigment epithelium (RPE) cells, with various concentrations of IFN-beta, and with or without 3% fetal calf serum (FCS), was assessed by cell counting. Effects of short (3 h) or prolonged (48 h) exposure of RPE cells to natural human IFN-beta were assessed by (3)H-thymidine uptake. Cytosolic and membranous PKC activity over time in cells treated with IFN-beta and calphostin C was also measured. RESULTS: IFN-beta inhibited the increased proliferation by FCS in the prolonged-exposure assay. The PKC inhibitor calphostin C also showed an inhibitory effect on RPE cell growth and (3)H-thymidine uptake in the chronic exposure with FCS. Short treatment with IFN-beta had no inhibitory or stimulatory effect on (3)H-thymidine uptake. Cytosolic and membranous PKC activity was strongly upregulated after short IFN-beta exposure but returned to original levels after 1 h. PKC activity was downregulated both in the cytosol and membrane after 24 or 48 h. CONCLUSION: IFN-beta inhibited RPE proliferation in vitro and the effect is mediated by upregulation of the PKC pathway.

Cell Division↗

The suppressive effect of tecogalan sodium on in vitro angiogenesis via the periendothelial proteolytic activities.

The exact mechanisms of the angiostatic effect by tecogalan sodium (TS) remain unclear. We examined the effects of TS on in vitro angiogenic activity, proteolytic activity and proliferation of retinal vascular endothelial cells (RECs). TS markedly inhibited the in vitro angiogenic activity of RECs although the growth inhibition of RECs was small. TS apparently decreased the cell-associated urokinase-type plasminogen activator (uPA) activity and matrix metalloprotease 1 (MMP-1) activity even in the presence of anti-bFGF IgG. Thus, the suppression of the periendothelial matrix-degrading activities related to uPA and MMP-1 is suggested to be another possible mechanism of the antiangiogenic effect of TS, besides its prevention of bFGF REC binding which has previously been reported.

Animals↗

Endothelial and glial cell interaction in diabetic retinopathy via the function of vascular endothelial growth factor (VEGF).

VEGF, which is also known as vascular permeability factor (VPF), is a recently identified specific mitogen for endothelial cells, and has been paid much attention for the critical participation in the physiological and pathological angiogenesis/vasculogenesis in retinas. To investigate whether retinal glial cells (RGCs) synthesize VEGF under hypoxic state (2%) in vitro and in retinas in vivo of streptozotocin-induced diabetic rats, VEGF mRNA and activity expressed by cultured RGCs were assessed with Northern blot analysis and in vitro angiogenesis assay, and the in vivo expression of VEGF mRNA and protein was examined in diabetic retinas by in situ hybridization and immunohistochemistry using rabbit anti-IgG against human VEGF. Cultured RGCs synthesized and released VEGF and this VEGF production was markedly enhanced by hypoxia through the activation of AP-1 promotor gene. However, the expression of bFGF mRNA by RGCs was not enhanced under the hypoxic condition. Retinal capillary endothelial cells (RECs) expressed flt-1 mRNA. Therefore, conditioned media harvested from RGCs under hypoxic condition significantly accelerated not only thymidine incorporation by RECs but also in vitro angiogenesis, namely, the formation of capillary-like tubes by RECs in type I collagen gels. In normal rat retinas astrocytes located just beneath the inner limiting membrane revealed immunohistochemically the weak expression of VEGF, while in diabetic retinas six months after the streptozotocin treatment, the enhanced expression of VEGF mRNA and protein mainly by glial cells such as Muller cells and astrocytes, was confirmed by immunohistochemistry and in situ hybridization. These diabetic retinas were associated with the hyperpermeability of albumin, but not angiogenic retinopathy. These findings indicate that VEGF expressed by RGCs under hypoxia or diabetic condition plays an integral role in the maintenance of retinal circulation via the VEGF-VEGF receptor (flt-1) interaction.

Animals↗