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Biomedical subjects

S Okisaka

Publications and source records attributed to S Okisaka.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Mitotic activity of rabbit corneal epithelium in vitro].

It is difficult to maintain corneal epithelial cells for several passages in culture. At a first step to establish a culture system for corneal epithelium, the authors evaluated factors which seemed to be involved in the growth kinetics and mitotic activity of rabbit corneal epithelium in vitro. First of all, to compare the growth kinetics of peripheral and central epithelium, we measured the areas and distances of the epithelium that outgrew from peripheral and central explants in culture. The peripheral corneal epithelium grew 1.2-to 1.6-fold better than the central corneal epithelium. However, there was no significant difference between them. Secondly, we evaluated the effects of epidermal growth factor (EGF), cholera toxin (CTX) and insulin, which were contained in supplemented hormonal epithelial medium (SHEM) developed by Jumblatt et al, on the mitotic activity of rabbit corneal epithelium. Among these drugs, only EGF had the ability to increase the epithelial cell number after 10 days of incubation. By contrast, CTX which elevated the level of cyclic AMP inhibited the proliferation of the epithelium.

Animals↗
PubMed1991

[Histopathological study on the monkey retina and choroid by diode laser endophotocoagulation].

The fundi of three cynomolgus monkeys were coagulated using a diode laser endophotocoagulator. The histopathological changes of the retina and the choroid were investigated periodically up to 3 months. The damage of the retina extended into the outer plexiform layer following mild burn, into the inner nuclear layer with moderate burn and into the nerve fiber layer on severe burn. The pigment epithelium proliferated with multiple layer cells 1-3 months after the irradiation. The choriocapillaries were obstructed, regardless of the degree of burns, immediately after the irradiation, but recanaliculation was observed at the mild and moderate burns 1-3 months after the irradiation. The effects on the choroid were localized to the inner layer following mild burn, but the damage extended into the outer layer with moderate burns. Following severe burns obstruction of the medium size vessels was observed. The fibrous changes of the choroid increased in accordance with the degree of the burn. The damaged melanophore in the choroid recovered considerably 1 month after the mild burn. On the other hand, many macrophages still remained in moderate and severe burn lesions. These results suggested that diode laser photocoagulation might be effective for the treatment of the choroidal diseases rather than retinal diseases, because diode laser photocoagulation produced the considerable change in the choroid as well as in the retina.

Animals↗
PubMed1990

[Quantitative analysis of collagen fiber in keratoconus].

In order to identify the direct pathogenic factors involved in the stromal thinning of keratoconus, quantitative analysis of keratocytes, collagen fibers and collagen lamellae in keratoconus cornea was performed histologically by light and electron microscopy. Both normal and keratoconus corneas showed a similar cell density of keratocytes in the central stroma, therefore the total number of keratocytes in keratoconus cornea might be smaller than that of controls, because of the thinning of stroma in the keratoconus. The collagen lamellae in keratoconus corneas showed a significant decrease in number compared with controls. There was a direct relationship between the stromal thickness and number of collagen lamellae. On the other hand, there was no statistical significance between normal and keratoconus corneas in terms of the thickness of collagen lamellae. These results suggest that the thinning of the cornea in keratoconus might occur as the result of a defect of some collagen lamellae due to a disorganization during the process of collagen lamellae formation.

Adolescent↗
PubMed1990

[Photocoagulation with free-running mode Nd: YAG laser on neovascular maculopathy].

Seventeen eyes in 14 cases of early neovascular maculopathy were treated with free-running mode Nd: YAG laser and followed up for 7 to 56 months by examination of visual acuity, fluorescein angiography and static perimetry. Obliteration of subretinal neovascularization could be achieved with both mild and moderate photocoagulation. Retinal sensitivity after moderate photocoagulation decreased moderately. Damaged retinal sensitivity after mild photocoagulation recovered one month later. Two out of 11 eyes in which only the neovascular membrane was treated showed recurrent neovascularization adjacent to the treated lesion 6 months and 9 months after photocoagulation. One out of 6 eyes received mild photocoagulation on the neovascular membrane and the surrounding area showed recurrent neovascularization adjacent to the treated lesion 6 months after photocoagulation. Retinal hemorrhage occurred in one out of 14 eyes that received mild photocoagulation and in one out of three moderately photocoagulated eyes. The recurrent neovascularization occurred in two eyes with retinal hemorrhage and in one mild burned eye without retinal hemorrhage. Recurrent neovascularization may correlate with retinal hemorrhage.

Adult↗
PubMed1990

Retinal pigment epithelial cells in culture secrete angiogenic inhibitors: in vitro study.

Conditioned medium wherein bovine retinal pigment epithelial cells have been cultured (RPE-CM) inhibited proliferation of the capillary endothelial cells (CEC) of the bovine adrenal gland. The RPE-CM was fractionated into three fractions; molecular weight of more than 30 kilo Daltons (kDa) (30 kDa fraction), between 10 and 30 kDa (10 kDa-30 kDa fraction), and less than 10 kDa (10 kDa fraction). Each fraction was tested for its effect on the proliferation, morphology and movement of the CEC. The proliferation of CEC was inhibited in the more than 30 kDa fraction and less than 10 kDa fraction, but not in the 10 kDa-30 kDa fraction. The RPE-CM changed morphology of the CEC into slender shape. This morphological change was observed only in the more than 30 kDa fraction, and the CEC in the other fractions maintained normal morphology. When the CEC proliferation was arrested by hydroxyurea, RPE-CM and the more than 30 kDa fraction did not change morphology. Unfractionated RPE-CM and the more than 30 kDa fraction which changed the morphology of the CEC also inhibited movement of the CEC, such as the migration of cells from a confluent cell layer and single cell movement. These findings suggested that the RPE in culture secrete soluble anti-angiogenic factors into the medium.

Adrenal Glands↗
PubMed1990

[A case of necrotizing scleritis with angiitis of papilla].

A case of a 66-year-old woman suffering from polymyalgia rheumatica with necrotizing scleritis followed central retinal artery occlusion in the left eye was studied clinico-pathologically. The left eye was enucleated because of severe pain in spite of the steroid therapy, and was examined histopathologically. The necrotic granulomatous changes of the deep sclera in the ciliary body and peripheral fundus were observed. Lymphocytes, plasma cells and epitheloid cells infiltrated in the central retinal artery at the papilla. It seemed that subconjunctival injection of steroid had induced scleral necrosis. When scleritis is very severe, it might be suggested that systemic steroid should be given in large suppressive doses.

Female↗
PubMed1989

[The role of the cytoskeletal components in cell culture in collagen gel as a model system of vitreous contraction].

We previously reported a cell culture system in artificial collagen gel as a model system of vitreous contraction. In this report, the epithelium cultured in the collagen gel elongated and induced gel contraction. The motile cytoskeletal components were thought to be important for morphological changes of the cells and the gel contraction. In order to examine the relationship between the cytoskeletal components and morphological changes of the cells and gel contraction, colchicine and cytochalasin B, known to be inhibitors for microtubules and microfilaments respectively, were added to the gels and the culture media. Bovine lens epithelia were cultured in the gels and the media containing 0-1000 nM colchicine or 0-10 microM cytochalasin B. Both inhibitors arrested the elongation of the cells and the contraction of the gels. These results suggested that the cell movement caused by the functions of microtubules and microfilaments were related to the vitreous contraction.

Animals↗
PubMed1989

[Pattern reversal electroretinogram--effect of check size, luminance, field size and defocusing].

Using a high water-content soft-contact-lens electrode we recorded pattern electroretinograms (P-ERGs) of subjects responding to reversal checkerboard stimuli and the stimulus parameters were varied in order to investigate normal P-ERG properties. The P-ERG varied with changing luminance, field size and defocusing parameters in the same way as P-VECP, but differed from P-VECP with changes in the check size parameter. These results suggest that the spatial tuning observed in P-VECP could not be discerned in this P-ERG study. It cannot be denied that P-ERG is distorted by P-VECP, which has a larger amplitude at about 100 ms after stimulation. In the future it will be necessary to investigate the origin of P-ERG under experimental conditions separating contrast-related response from luminance-related response.

Adult↗
PubMed1986

The relation between the after-negative potential of the pattern electroretinogram and the visually evoked cortical potential.

The relationship between the after-negative potential of the pattern electroretinogram (PERG) and the visually evoked cortical potential (VECP) was studied. The PERG was recorded through the use of Toray's high water content, soft contact lens electrode. The PERG consisted of an initial positive potential, a subsequent negative potential and then a slow positive potential. To reduce or avoid contamination of the VECP on the PERG, the most important factor was found to be the reference electrode position; special attention was paid in cases where the amplitude of the VECP was large. In the steady-state condition, the PERG was thought to be modulated by the VECP when the ear lobe was used as the reference electrode position; when the temple was used as the reference electrode position, the amplitude of the PERG was thought to represent that of the after-negative potential.

Contact Lenses↗