Seiji Hayasaka

Lysosomal enzymes in ocular tissues and diseases

Lysosomal enzymes are distributed widely in various ocular tissues. Among these tissues, the uvea and retina show the higher enzyme activities of acid phosphates, beta-blucuronidase, alpha-fucosidase, alpha-mannosidase, arylsulfatase, cathepsin D, cathepsin B and others. The particular role of lysosomal enzymes in the pathogenic processes of ocular diseases such as storage disease, uveitis, retinal degeneration, retinal detachment, corneal dystrophy and glaucoma is strongly suggested. The enzymes also have additional importance in ocular physiopathology.

Distribution and some properties of cathepsin D in the retinal pigment epithelium

Abstract Cathepsin D in the retinal pigment epithelium of the bovine eye was studied using standard enzymological techniques. In the bovine eye the retinal pigment epithelium revealed the highest specific activity, the activity being highest in the lysosomal fraction. The enzyme activity in the lysosomal extract of the retinal pigment epithelium was proportional to both the enzyme concentration and incubation time. When the enzyme was heated, the enzyme activity was lost completely. The initial rate of the tyrosine release was dependent on the concentration of the bovine serum albumin, exhibiting a hyperbolic saturation curve. The optimal pH of the enzyme was about 4·0. The enzyme activity was not affected by thiol agents.

A Scanning Electron Microscopic Study of Nylon Degradation by Ocular Tissue Extracts

A scanning electron microscopic study showed that the surface of the nylon used for corneoscleral wound closure was smooth, while the nylon suture thread used to fix the intraocular lens against the iris showed cracks and roughness on its surface. The surface of the nylon thread was also roughened after treatment with bovine iris-ciliary body extracts. The nylon-degrading factor in the extract was nondialyzable, heat-labile, active at acidic pH, and inhibited in part by leupeptin, suggesting that lysosomal enzymes may be a factor in this phenomenon. Of the bovine ocular tissues, ciliary body extract degraded the surface of the nylon thread most significantly. The nylon surface was moderately digested by the retinal pigment epithelial extract, and slightly eroded by the extracts from the iris, sensory retina, and choroid. Corneal and lenticular extracts did not affect the nylon surface. Nylon suture thread may be hydrolyzed by lysosomal enzymes and should be considered a late-degrading suture.

Systemic corticosteroid treatment in Vogt-Koyanagi-Harada disease

Twenty patients with Vogt-Koyanagi-Harada disease who had been given systemic corticosteroids were retrospectively analyzed. Sixteen patients were successfully treated with systemic corticosteroids without recurrence of uveitis. Since the advent of corticosteroid treatment, there have been fewer ocular complications as well as extraocular signs and symptoms in most cases. Recurrence of the inflammation, however, occurred in four cases. Drip infusion of 200 mg prednisolone daily, widely employed for the treatment, did not always have good results. It is suggested that the dosage of corticosteroid should be adjusted according to the severity of uveomeningitis. Oral administration of corticosteroid (less than 100 mg prednisolone daily) may be enough for suppression of the inflammation in the Harada type, while a drip infusion of the massive dosage (more than 200 mg prednisolone daily) with gradual tapering off is possibly requisite in the Vogt-Koyanagi type.

Lysosomal Enzymes in Subretinal Fluid

Samples of subretinal fluid (SRF) from patients with primary rhegmatogeneous retinal detachment of various duration were studied using standard enzymologic techniques. The protein content in SRF increased with the duration of detachment. The activities of lysosomal enzymes in SRF, which were acid phosphatase, β-glucuronidase, and cathepsin D, also increased with the duration of detachment. Especially cathepsin D, which was not detected in serum, was present in SRF. The activity of a nonlysosomal enzyme, i. e., lactic dehydrogenase, which was used as a marker of cell disruption and of serum transudation was the same as that of serum. Because lysosomal enzymes are known to be able to degrade cells and tissues, the enzymologic analysis of SRF contributes to our understanding of the pathology of primary rhegmatogeneous retinal detachment. Bericht über enzymatische Untersuchungen von subretinaler Flüssikeit (SRF) bei Patienten mit primär rhegmatogener Netzhautablösung unterschiedlicher Dauer. Der Proteingehalt in der SRF nahm mit der Dauer der Abhebung zu, ebenso die Aktivitäten der lysosomalen Enzyme (saure Phosphatase, β-Glucuronidase und Kathepsin D). Insbesondere fand sich in der SRF Kathepsin D, das im Serum nicht enthalten war. Die Aktivität eines nicht-lysosomalen Enzyms (Laktat-Dehydrogenase) war die gleiche wie im Serum. Da die lysosomalen Enzyme dafür bekannt sind, daß sie Zellen und Gewebe verändern, trägt die Analyse der Enzyme der SRF zum Verständnis der Pathologie der primär rhegmatogenen Netzhautablösung bei.

Distribution of acid lipase in the bovine retinal pigment epithelium.

Abstract Acid lipase in the retinal pigment epithelium of the bovine eye was studied biochemically using triglyceride as substrate. The retinal pigment epithelium revealed the highest specific activity, the activity being highest in the lysosomal fraction. The lysosomal distribution of acid lipase was supported by the evidence that other hydrolytic enzymes were also localized with highest specific activity in the lysosomal fraction prepared by differential pelleting. The optimal pH of the enzyme was 4–5. Acid lipase in the retinal pigment epithelium had maximum activity with glycerol tridecanoate as substrate. Specific activity of retinal pigment epithelium was about 10-fold higher than that of liver. The possible role of acid lipase in the retinal pigment epithelium was discussed.

Distribution and some properties of cathepsin B in the bovine eyes.

Abstract Cathepsin B in the bovine eye was studied biochemically using α- N -benzoyl- l -arginine amide as substrate. The highest specific activity of cathepsin B was observed in the ciliary body among bovine eye tissues, the activity being highest in the lysosomal fraction. The optimal pH of the enzyme in the ciliary body was about 5·1. The enzyme activity in the ciliary body was activated by thiol agents, and inhibited by p -chloromercuribenzoate, leupeptin and heavy metal ions.

Control of δ-aminolevulinate synthetase activity in Rhodopseudomonas spheroides: II. Requirement of a disulfide compound for the conversion of the inactive form of fraction I to the active form

Abstract The inactive form of Fraction I of δ-aminolevulinate synthetase of R. spheroides was converted to the active form by incubation with low molecular weight substance(s) and a protein fraction which were contained in cell extracts of R. spheroides. The low molecular weight substances could be prepared from cell extracts by treatment with trichloroacetic acid (TCA) or Sephadex G-25 column. By fractionation of the TCA soluble fraction by paper chromatography, three active fractions were obtained. All three fractions were shown to have a disulfide bond. Moreover, the TCA-soluble fraction could be replaced by some disulfide compounds such as l -cystine, d, l -homocystine, d -pantethine, oxidized glutathione and lipoic acid. The optimal pH for the activation reaction was about 6.7. The protein fraction required for the activation, though not well identified yet, appeared to function as a modifying enzyme in the conversion of the inactive form of Fraction I to the active form in the presence of disulfide compounds. 14C-Cysteine moiety was not incorporated into the activated Fraction I when the inactive form was incubated with 14C-cystine in the presence of the activating protein fraction, suggesting that the activation of the inactive form is not associated with the incorporation of cysteine into the enzyme protein.

Regional distribution of lysosomal enzymes in the retina and choroid of human eyes

Regional distribution of lysosomal enzymes in the retina and choroid of human eyes was studied biochemically. Specific activities of acid phosphatase, cathepsin D, and arylsulfatase in the retina and choroid varied by area were also studied. The macular area showed the highest activities in comparison to other areas.

Distribution and some properties of lysosomal arylsulfatases in the bovine eye

Abstract Lysosomal arylsulfatases (arylsulfatases A and B) in the bovine eyes were studied biochemically using p -nitrocatechol sulfate as substrate. In bovine ocular tissues arylsulfatases were widely distributed. Among them the neurosensory retina revealed the highest specific enzyme activity, and the activity was found to be highest in the lysosomal fraction. The optimal pH of the enzymes in the homogenate and the lysosomal fraction of the neurosensory retina was 5 to 6. The homogenate of the neurosensory retina showed an anomalous time-activity curve, and the activity was inhibited by SO 4 2− , SO 3 2− and Ag + . These data suggest that arylsulfatase A is the main p -nitrocatechol sulfate hydrolyzing enzyme in the homogenate of the neurosensory retina.