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Biomedical subjects

S Hayasaka

Publications and source records attributed to S Hayasaka.

At least 253 records · Page 14Linked to original sources
PubMed1985

Enzymes in ornithine-proline metabolic pathway in bovine lens.

Various enzyme activities related to ornithine metabolism were studied using bovine lenses, ie, ornithine ketoacid transaminase, delta-1-pyrroline-5-carboxylate reductase, and delta-1-pyrroline-5-carboxylate dehydrogenase. Ornithine ketoacid transaminase activity was found in the lens epithelium; delta-1-pyrroline-5-carboxylate reductase activity was high in both lens epithelium and cortex plus nucleus; delta-1-pyrroline-5-carboxylate dehydrogenase activity was negligible in either lens epithelium or cortex plus nucleus. These results suggest that in the bovine lens ornithine is converted to proline by the cooperative action of ornithine ketoacid transaminase and delta-1-pyrroline-5-carboxylate reductase.

1-Pyrroline-5-Carboxylate Dehydrogenase↗
PubMed1985

Effects of melanin on lysosomal enzymes in bovine ciliary body and iris in vitro.

We studied biochemically the effects of melanin on activities of lysosomal enzymes prepared from the bovine ciliary body and iris in vitro. Melanin was prepared from the bovine ciliary body and iris by acid treatment. Acid phosphatase, N-acetyl-beta-D-glucosaminidase, alpha-D-mannosidase, alpha-L-fucosidase, and beta-D-glucuronidase in the ammonium sulfate fraction were used as lysosomal marker enzymes. After the enzyme solution was incubated with melanin, enzyme activity was reduced and protein content in the supernatant was decreased. Each enzyme showed a different activity. The data suggested that 1) the decreased activity may depend on the affinity of lysosomal enzyme protein for melanin and 2) each enzyme may have a different affinity for melanin. These findings were discussed with respect to biochemical interaction between melanin and lysosomal enzymes in the ocular tissue in vivo.

Acid Phosphatase↗
PubMed1985

Pericentral pigmentary retinal degeneration.

We studied five patients with pericentral pigmentary retinal degeneration, whose fundus lesions were bilateral, symmetrical grayish zones with pigments surrounding the macular region. All showed good visual acuity, normal color vision, mild deterioration of scotopic electroretinographic response, normal photopic electroretinographic response, subnormal electrooculogram and paracentral ring scotoma. The fluorescein angiography demonstrated hyperfluorescent dots around the macula. Their family history was noncontributory. The retinal lesions showed only very slow progression.

Adult↗
PubMed1985

Gyrate atrophy of choroid and retina complicated by vitreous hemorrhage.

We describe two patients with gyrate atrophy of the choroid and retina who suffered from vitreous hemorrhages in adolescence. The diagnosis of gyrate atrophy was confirmed biochemically and clinically; hyperornithinemia and a deficiency of ornithine ketoacid transaminase were confirmed biochemically. Typical fundus changes of scalloped chorioretinal atrophies with sharp margins, deteriorated dark adaptation, non-recordable electroretinogram, flat electrooculogram, and constricted visual fields were noted. We believe that the vitreous hemorrhage is an ocular complication in this disorder.

Adult↗
PubMed1985

Circinate choroidal degeneration.

We present a patient whose fundus lesions were bilateral, symmetrical grayish zones with pigments surrounding the macular region. She showed good visual acuity, normal color vision, mild deterioration of scotopic electroretinographic response, normal photopic electroretinographic response, subnormal electrooculogram and paracentral ring scotoma. Fluorescein angiography revealed regional atrophy of the choriocapillaris. The diagnosis of circinate choroidal degeneration was made. We believe that pericentral pigmentary retinal degeneration and circinate choroidal degeneration are distinct entities.

Choroid↗
PubMed1984

Ciliary and retinal changes in myotonic dystrophy.

We examined 15 patients with myotonic dystrophy by cycloscopy, ophthalmoscopy, and fluorescein angiography. In six cases, we found depigmentation in the relatively short ciliary processes, which may account for ocular hypotony in this disorder. Eight of the patients had retinal lesions, three with butterfly-shaped dystrophy, two with reticular dystrophy, and three with peripheral yellow flecks. These lesions were biomicroscopically at the level of the retinal pigment epithelium or in the deep retinal layer and did not substantially alter visual functions. Psychophysical and electrophysiologic test results were normal or only slightly affected. The butterfly-shaped and reticular dystrophies in myotonic dystrophy may be variant forms of patterned dystrophy of the retinal pigment epithelium. The peripheral yellow flecks in a stone-wall configuration noted in this disorder are particularly unique and, to our knowledge, have not been documented previously.

Adolescent↗
PubMed1984

Papilloedema in late-onset citrullinaemia: report of second case.

A young adult patient suddenly began to have episodes of unconsciousness that each lasted for several hours. Brief episodes of lethargy occurred monthly. Biochemical tests disclosed high levels of ammonia and citrulline in the serum. Brain oedema was suggested by CT scan, and optic disc swelling was observed ophthalmoscopically, indicating papilloedema. He died in coma. Deficient activity of argininosuccinate synthetase in the liver was demonstrated. Papilloedema was confirmed histologically. We believe that papilloedema is a serious sign indicating poor prognosis in late-onset citrullinaemia.

Adult↗
PubMed1984

In vitro effect of hyaluronate on lysosomal enzyme activities in the bovine ciliary body and iris.

The effect of hyaluronate on lysosomal enzyme activities in bovine ciliary body and iris was studied in vitro. Hyaluronates from both the human umbilical cord and bovine vitreous inhibited the activities of cathepsin B and acid phosphatase. Cathepsin D, beta-N-acetyl-glucosaminidase, beta-D-glucuronidase and alpha-L-fucosidase activities were not affected by the hyaluronate.

Acid Phosphatase↗
PubMed1984

Lens subluxation in homocystinuria. A case report.

A 6-year-old girl had bilaterally subluxated lenses and liver and platelet dysfunctions. A cyanide-nitroprusside test of the urine was positive. Serum and urinary levels of methionine and homocystine were high. Cystathionine synthetase activity in the cultured skin fibroblasts was negligible. Pyridoxine, 1000 mg/day orally, normalized the serum and urinary methionine and homocystine levels and the liver and platelet functions. Episodes of pupillary block glaucoma prompted lens extraction. The subluxated lenses were extracted under general anaesthesia after administration of pyridoxine and dextran to avoid thrombosis. A good result without serious complications was obtained. We believe that homocystinuria should not be considered a contra-indication to general anaesthesia. In the pyridoxine-responsive patient general anaesthesia is not hazardous if platelet function can be controlled by the vitamin.

Anesthesia, General↗
PubMed1984

Scanning electron microscopic study of polyvinyliden fluoride degradation by ocular tissue extracts.

A scanning electron microscopic study showed that the surface of the polyvinyliden fluoride thread, used to make loops for intraocular lenses in Japan, became significantly rough after treatment with bovine iris-ciliary body extracts. The polyvinyliden fluoride degrading factor in the extract was nondialyzable, heat-labile and active at an acidic pH, suggesting that a lysosomal system might be involved in this phenomenon. Bovine extracts from the retinal pigment epithelium and choroid degraded the surface of the polyvinyliden fluoride substantially, while extracts from the cornea, iris, ciliary body and neuroretina only moderately digested it. Lenticular extract did not affect the polyvinyliden fluoride surface. It is possible that the polyvinyliden fluoride loop undergoes degradation in the eye after a long time.

Animals↗
PubMed1984

Acidic lens-protein degrading activity: I. Distribution in bovine ocular tissues.

Bovine lens-protein degradation by ocular tissue homogenates was studied biochemically. Acidic lens-protein degrading activity was widespread in ocular tissues. The ciliary body enzyme, which showed the highest activity at pH 3.8, was inhibited by pepstatin and leupeptin. Lens-protein degrading activity may result from a combination of cathepsins B, D, H and L.

Animals↗
PubMed1984

Corneal arcus in Japanese family with type IIa hyperlipoproteinemia.

We examined ophthalmologically five affected members of a family with type IIa hyperlipoproteinemia. All of them had increased levels of cholesterol and low-density lipoprotein. Corneal arcus was found in three of the five members; a 50-year-old man, a 43-year-old woman and a 13-year-old boy. We believe that the corneal arcus begins at around 10 years of age in untreated type IIa hyperlipoproteinemia. Detection of corneal arcus at an early age is important to reduce cardiovascular complication in this disorder.

Adolescent↗
PubMed1984

Effect of chlorpromazine in vitro on release of enzymes from lysosomes of the bovine retinal pigment epithelium.

The effects of chlorpromazine on lysosomal enzymes and the release of enzymes from lysosomes of bovine retinal pigment epithelial cells were studied in vitro, using cathepsin D, arylsulfatase, and acid phosphatase as lysosomal marker enzymes. Chlorpromazine had little effect on the enzyme activity of cathepsin D and arylsulfatase and slightly decreased that of acid phosphatase. Chlorpromazine accelerated considerably the release of cathepsin D and arylsulfatase, but only minimally affected the release of acid phosphatase. The release of these enzymes from lysosomes depended on the dose of chlorpromazine.

Acid Phosphatase↗
PubMed1983

Effect of temperature and pH on release of enzymes from lysosomes of the bovine retinal pigment epithelium in vitro.

The effects of buffer concentrations, pH, and temperatures on the release of enzymes from lysosomes of the bovine retinal pigment epithelium were studied in vitro. Cathepsin D, arylsulfatase, and acid phosphatase were used as lysosomal marker enzymes. Elevation of temperature caused a marked increase in the release of cathepsin D and arylsulfatase from lysosomes, but little changes in the release of acid phosphatase. Acidic conditions accelerated the release of arylsulfatase and acid phosphatase. Different buffer concentrations had little effect on the release of these enzymes from lysosomes.

Acid Phosphatase↗
PubMed1983

Acute retinal necrosis.

We treated 2 patients with unilateral acute retinal necrosis in association with uveitis. The disorder began as anterior uveitis, secondary glaucoma, and retinal vasculitis, and then developed into retinal necrosis within a few months. The aetiology was obscure and the appropriate treatment debatable. We also review reports of patients showing the same clinical characteristics, termed Kirisawa-type uveitis and bilateral acute retinal necrosis, and believe the disorders to be identical.

Acute Disease↗
PubMed1983

Scanning electron microscopic study of Dacron degradation by ocular tissue extracts.

A scanning electron microscopic study showed that the surface of Dacron thread became significantly roughened after treatment with bovine iris-ciliary body extracts. The Dacron-degrading factor in the extract was nondialysable, heat-labile, and active at an acidic pH, suggesting that lysosomal enzymes may be a factor in this phenomenon. Bovine extracts from the iris, ciliary body, and sensory retina degraded the surface of Dacron most substantially, while the Dacron surface was moderately digested by extracts from the cornea and retinal pigment epithelium. Lenticular and choroidal extracts did not affect the Dacron surface. Possibly the factor that degrades Dacron may be different from that which affects nylon, and the Dacron suture may not be preferable for corneal surgery.

Animals↗