Biomedical subjects

S Hayasaka

Publications and source records attributed to S Hayasaka.

At least 73 records · Page 4Linked to original sources

PubMed1997

Immunocytochemical detection and spatial distribution of myosin light-chain kinase in preimplantation mouse embryos.

As a follow-up to our previous study on the role of myosin light-chain kinase (MLCK), a Ca2+/calmodulin-dependent enzyme, in the development of preimplantation mouse embryos, we examined the presence and pattern of distribution of MLCK during preimplantation development of the mouse by whole-mount, indirect immunocytochemistry and by Western blotting, using a monoclonal antibody against MLCK. At all stages of preimplantation development, the nucleus was brightly stained with an unstained region around the nucleus, and regions near the cell membrane were also brightly stained. Using the optical sectioning capability of the confocal laser scanning microscope, we found that, up to the eight-cell stage, the regions of cell contact were mostly unstained, but along with the process of compaction, cell contact regions showed a clear staining pattern along with clearing of the cytoplasm. During formation of the blastocyst, a ring of immunofluorescence was found at the margin of the blastocoel. In the blastocyst, cells of the inner cell mass were less immunofluorescent than trophectoderm cells. These staining results appear to be due to specific immunoreaction between MLCK and the antibody, because the staining patterns were abolished when the antibody was preabsorbed by MLCK purified from chicken gizzard smooth muscle. In Western blotting of blastocysts, we found a band at 130 kD. We also show by immunoblotting and immunohistochemistry of various mouse tissues that the antibody used in this study has cross-reactivity to MLCK of various muscle and non-muscle tissues of the mouse. The presence and spatial distribution of MLCK at various stages of preimplantation development of the mouse suggest that it could play a crucial role in the regulation of the contractile events involved in the initial differentiation that occurs during formation of the mouse blastocyst.

Animals↗

PubMed1997

Ascorbic acid and amino acid values in the aqueous humor of a patient with Lowe's syndrome.

BACKGROUND: Aminoaciduria is found in Lowe's syndrome. No studies of concentrations of ascorbic acid and amino acids in the aqueous humor of the syndrome have been performed. We examined these concentrations in a patient with Lowe's syndrome. METHODS: Ascorbic acid and amino acid levels in the aqueous humor and plasma of a male infant were measured by means of high-performance liquid chromatography. The patient, who had congenital cataract, miotic pupils, opaque corneas, glaucoma, aminoaciduria, normal levels of ascorbic acid and amino acid in the plasma, and renal tubular acidosis, underwent trabeculotomy, lensectomy, and anterior vitrectomy in both eyes. RESULTS: Intraocular pressure in both eyes decreased to within the normal range, but both corneas remained opaque. The amino acid levels in the aqueous humor were similar to those in the plasma, but intracameral ascorbic acid levels were decreased. After topical instillation of ascorbic acid, the corneas became transparent. The proband's mother had good visual acuity but paracentral lens opacities in both eyes. His maternal grandmother had scattered cortical opacities in both lenses. CONCLUSION: In this infant with Lowe's syndrome, we found intracameral levels of amino acids similar to those in the plasma. Levels of ascorbic acid in the aqueous humor were decreased.

Adolescent↗

PubMed1997

Sites of disruption of the blood-aqueous barrier after application of prostaglandin E2 in pigmented rabbits.

We examined the disruption of the blood-aqueous barrier following prostaglandin (PG)-E2 application in rabbits. Vehicle or PGE2 in 10, 50 or 250 microg/ml concentration was applied to the cornea of pigmented rabbit with the use of a glass cylinder. After PGE2 administration, horseradish peroxidase (HRP) was injected intravenously. Then the eyes were enucleated, and distribution of HRP in the anterior segments was examined by electron microscopy. In control eyes, diffusion of HRP was blocked by vascular endothelial cells in the iris and by nonpigmented epithelial cells in the iridial and ciliary processes. In the iridial and ciliary processes of the eyes treated with 10 microg/ml PGE2, no HRP reaction product was seen in intercellular spaces of the nonpigmented epithelial cells, but it was found in pinocytotic vesicles. In the eyes treated with 50 microg/ml PGE2 HRP reaction product was found in intercellular spaces of the nonpigmented cells in the iridial processes. In the eyes treated with 250 microg/ml PGE2 HRP reaction product was further distributed in the iris stroma. The present study demonstrated that the sites of breakdown of the blood-aqueous barrier depended upon the doses of exogenous PGE2.

Administration, Topical↗

PubMed1997

Cycloplegic refractions in Japanese children: a comparison of atropine and cyclopentolate.

We examined refractions of 102 eyes in 51 Japanese children after the topical instillation of cycloplegics. Cyclopentolate 1% was instilled 3 times after 5-min intervals, and refractions were evaluated 45 min after the last instillation. Atropine, 0.5% or 1%, was instilled twice daily for 7 days. Refractions were measured by an autorefractometer. The mean refraction in 102 eyes measured after atropine instillation was +3.07 dpt, and the mean after cyclopentolate instillation was +2.35 dpt. The mean difference in the direction of meridians of maximal refractions measured after atropine and cyclopentolate was 22 degrees. Our finding showed that atropine instillation may be adequate to determine exact refractions in Japanese children.

Administration, Topical↗

PubMed1997

Right active retinitis and left focal retinochoroidal scar in a girl with congenital toxoplasmosis.

In congenital cases, ocular toxoplasmosis often presents as a focal whitish fluffy lesion in the retina adjacent to an inactive chorioretinal scar. We examined a girl who has visible floaters in the right eye. The patient had focal active retinitis in the right fundus, a focal chorioretinal scar in the left fundus, a positive enzyme-linked immunosorbent assay (ELISA) for IgG anti-Toxoplasma antibodies and a negative ELISA for IgM antibodies. We believe that active focal retinitis in one eye and a focal chorioretinal scar in the fellow eye in congenital toxoplasmosis, as demonstrated in our patient, may be rare.

Adolescent↗

PubMed1997

Concurrent bilateral posterior scleritis and Vogt-Koyanagi-Harada disease in a patient with positive rheumatoid factor.

We examined a 67-year-old man who complained of headache and pain and decreased visual acuity in both eyes. The patient had dilated conjunctival and episcleral vessels, intracameral cells, shallow anterior chambers, hyperemic swollen optic disks, exudative retinal detachment and choroidal detachment. Fluorescein angiography showed leakage of dye from the optic disks and choroid into the subretinal space. Scleral thickening was found by computed tomography. These abnormal findings disappeared within 1 week after treatment with a systemic corticosteroid. Laboratory test results showed positive rheumatoid factor. Sunset glow fundi and vitiligo developed a few months after the treatment. We believe that concurrent bilateral posterior scleritis, Vogt-Koyanagi-Harada disease and positive rheumatoid factor, as demonstrated in our patient, may be rare.

Aged↗

PubMed1997

Central retinal vein occlusion in a woman receiving bromocriptine.

We evaluated a unilateral retinal vascular abnormality in a 34-year-old woman receiving bromocriptine mesylate for the suppression of postpartum lactation. After using bromocriptine, 2.5 mg twice daily for 1 week, the patient complained of metamorphopsia in the left eye. A central retinal vein occlusion was found. We believe that central retinal vein occlusion in patients receiving bromocriptine, as demonstrated in our patient, is rare.

Adult↗

PubMed1996

The dilute-lethal (dl) gene attacks a Ca2+ store in the dendritic spine of Purkinje cells in mice.

The absence of smooth endoplasmic reticulum (SER) in the dendritic spine of Purkinje cells was found in dilute-lethal (dl) mouse cerebella as detected by immunohistochemistry using anti-inositol 1,4,5-triphosphate receptor antibody and electron microscopy. Since SER in the spine has been suggested to play a crucial role for synaptic regulation as an intracellular Ca2+ store (for reviews, see [Miller, R.J., Prog. Neurobiol., 37 (1991) 255-285: Simpson, P.B., Challiss, R.A.J. and Nahorski, S.R., Trends Neurosci., 18 (1995) 299-306]), a neurological defect, characterized by clonic convulsions with opisthotonus and ataxia, in the dilute-lethal mouse with homozygous trait may be attributable to the absence of SER in the dendritic spine of Purkinje cells.

Animals↗

PubMed1996

Endoplasmic reticulum is missing in dendritic spines of Purkinje cells of the ataxic mutant rat.

Dilute-opisthotonus (dop) is a spontaneous ataxic mutation in the rat, regulated by an autosomal recessive gene. Immunohistochemical staining with anti-inositol 1,4,5-trisphosphate receptor antibody and electron microscopic examinations revealed that the endoplasmic reticulum in dendritic spines of Purkinje cell was missing in the ataxic rat. This could impair the intracellular signal transduction in the parallel fiber-Purkinje cell synapse, and be a cause of the severe ataxic movement.

Animals↗

PubMed1996

Follow-up study on histogenesis of microcephaly associated with ectopic gray matter induced by prenatal gamma-irradiation in the mouse.

Brain malformation with ectopic gray matter was visualized with magnetic resonance imaging in small-sized heads of prenatally exposed atomic bomb survivors. The identical brain malformation was reproduced in mice and its histogenesis was studied in the present experiment. Pregnant mice were exposed to 60Co gamma-irradiation at a single dose of 1.5 Gy on embryonic day 13 (E13), and then injected intraperitoneally with 30 mg/kg BrdU on E15. The extensive dead cells appeared throughout the brain mantle at 6 hours (h) after exposure. On E16 cell aggregations formed rosettes. On E18 a high proportion of BrdU-labeled cells reached the superficial layers of the cortical plate with the remaining cells located in the ectopic neuronal masses. The quantitative study showed that labeled cells in layers II to III were fewer and those in layers IV to VI more numerous in the prenatally irradiated adult mice than in controls. The anti-GFAP immunostaining revealed that the glial fibers in the irradiated mice were preserved, but disorganized. These findings suggested that the majority of migrating neurons were able to arrive at their normal layers, but some neurons remained due to the interrupted migratory pathway and eventually formed ectopic neuronal masses beneath the subcortical white matter.

Age Factors↗

PubMed1996

Selective reduction of the S cone electroretinogram in diabetes.

AIMS: To determine whether the short wavelength sensitive (S) cone electroretinogram (ERG) is selectively altered in diabetic patients with and without retinopathy. METHODS: Ganzfeld spectral flashes in the presence of bright white background illumination were used to elicit S cone ERGs is 15 non-retinopathic diabetics, 16 background retinopathic diabetics, and 16 age matched normal controls. RESULTS: The amplitude of the S cone ERG b-wave was significantly reduced in both non-retinopathic and retinopathic diabetics. An action spectrum based on equal response criteria revealed a selective loss of S cone sensitivity in diabetics. However, no significant difference was observed in the long and middle wavelength sensitive cone ERG. CONCLUSIONS: Diabetic patients showed selective reduction of the S cone ERG, which is thought to reflect changes in the outer retina.

Adult↗

PubMed1996

Undetectable S cone electroretinogram b-wave in complete congenital stationary night blindness.

AIMS: The short wavelength sensitive (S) cone electroretinograms (ERGs) were examined in two patients with the complete type of congenital stationary night blindness (CSNB). METHODS: Ganzfeld spectral flashes in the presence of strong white adapting fields were used to elicit the S cone ERGs. RESULTS: The S cone ERG b-wave was not detectable to short wavelength stimuli, while the mixed long (L) and middle (M) wavelength sensitive cone responses appeared normal in waveforms with normal amplitude in both patients. Both patients had normal colour vision on the Farnsworth Panel D-15. CONCLUSIONS: These ERG results indicated that the S cone system as well as rod system is more impaired in complete CSNB than the L and M cone system and that normal colour vision may not depend on a normal S cone ERG to full field stimuli.

Child↗

PubMed1996

Decreased aqueous-flare reaction to repeated applications of prostaglandin E2 to the cornea in pigmented rabbits.

To evaluate the effect of single or repeated topical applications of prostaglandin E2 (PGE2) to the cornea on the blood-aqueous barrier, we have measured the extent of flare in the anterior chamber of rabbit eyes at various time intervals. PGE2 was applied to the cornea for 4 min with the use of a glass cylinder in pigmented rabbits. Aqueous flare was measured by a laser flare cell meter. The flare intensity following the second application of 25 or 50 micrograms/ml of PGE2 was smaller than that following the first application. When 50 micrograms/ml of PGE2 was applied every day for 6 days, the flare intensity decreased significantly day by day. After consecutive applications of 10 micrograms/ml of PGE2 at hourly intervals, flare intensity increased up to 3 h, remained elevated from 3 to 5 h, and decreased thereafter. Repeated applications of 10 micrograms/ml of PGE2, every hour for 14 h every Monday, significantly decreased flare intensity week by week. Weekly applications of 50 micrograms/ml of PGE2 did not change flare intensity. This study indicates that the extent of the breakdown of the blood-aqueous barrier in the rabbit eye, as measured by the development of flare in the anterior chamber, is reduced with repeated PGE2 application.

Administration, Topical↗

PubMed1996

Effects of a nitric oxide synthase inhibitor on prostaglandin-induced aqueous flare elevation in pigmented rabbits.

To evaluate the possible role of nitric oxide in the pathogenesis of exogenous prostaglandin (PG) induced aqueous flare elevation, we examined the effect of NG-nitro-L-arginine methyl ester (L-NAME), an L-arginine analogue acting as a specific inhibitor of nitric oxide synthase, on the elevation of aqueous flare in pigmented rabbits. L-NAME was injected into the ear vein of the animals. PGE1, PGE2, and PGF2 alpha were administered topically to the cornea using a glass cylinder. Aqueous flare was measured using a laser flare cell meter. PGE1, PGE2, and PGF2 alpha increased the aqueous flare dose dependently (5-100 micrograms/ml). L-NAME inhibited PGE1-, PGE2-, or PGF2 alpha-induced aqueous flare elevation. L-NAME, injected 30-90 min before PG application, inhibited the aqueous flare elevation maximally. We believe that nitric oxide may be involved in the pathogenesis of PG-induced aqueous flare elevation in rabbits.

Animals↗

PubMed1996

Unilateral acute posterior multifocal placoid pigment epitheliopathy.

A 24-year-old woman complained of paracentral scotomas in her left eye. Her visual acuity was good bilaterally. Multifocal, creamy, yellow-white lesions were seen at the level of the pigment epithelium and choroid in the left fundus. Fluorescein angiography showed blockage at the early phase and hyperfluorescence at the late phase in the left eye. The right fundus remained normal during the follow-up period of 1 year. We believe that unilateral acute posterior multifocal placoid pigment epitheliopathy, as found in our patient, may be uncommon.

Acute Disease↗

PubMed1996

Anterior ischemic optic neuropathy in a patient with positive antinuclear antibody and lupus anticoagulant findings.

A 64-year-old woman complained of blurred vision in her right eye. A pale optic disc with a blurred nasal margin was found in the right fundus. An inferior altitudinal defect in the right eye was observed on Goldmann perimetry. Her right visual acuity deteriorated to 0.1. Her antinuclear antibody and lupus anticoagulant test results were positive. Intravenous methylprednisolone (1,000 mg/day) improved her right visual acuity to 1.0. We believe that the anterior ischemic optic neuropathy in our patient may be associated with the presence of positive antinuclear antibody and lupus anticoagulant findings.

Antibodies, Antinuclear↗

PubMed1996

Branch retinal vein occlusion in a patient with Waardenburg syndrome.

A 43-year-old woman (case II-2) with dystopia canthorum, white forelock, blue iris in the left eye, hypopigmented fundi, and systemic hypertension complained of visible floaters in the left eye. Whitish branch retinal vein, preretinal hemorrhages and neovascularization were found in the left fundus. Her intraocular pressure in the left eye was sometimes elevated to 22 mm Hg. The patient's brother (case II-3) was reported to have blue irises in both eyes. We believe that these patients have Waardenburg syndrome, that branch retinal vein occlusion in case II-2 may be caused chiefly by systemic hypertension, and that elevated intraocular pressure associated with the blue iris may be partly involved in the pathogenesis of vein occlusion in the left eye.

Adult↗

PubMed1996

Incomplete occlusion of central retinal artery in a girl with iron deficiency anemia.

We examined a 13-year-old girl who complained of sudden loss of vision in her left eye. Ophthalmoscopic and fluorescein angiographic examinations revealed a clinical picture of incomplete occlusion of the central retinal artery. Laboratory test results showed iron deficiency anemia. The patient was treated with urokinase and ferrous sulfate. The patient's left visual acuity recovered from hand motion to 0.8.

Administration, Oral↗