R. Praus

Glycosaminoglycans in Embryonic and Postnatal Human Cornea

Human corneas were analyzed for glycosaminoglycans during various stages of embryonic development and at different postnatal ages. The development and aging of the cornea was accompanied by a transient increase of glycosaminoglycan hexosamine up to 2 years of age and thereafter by a stepwise decrease to a value which seemed to be constant in all age groups. Keratan sulphate formed a minor part of glycosaminoglycans in fetal, premature and newborn corneas but it predominated in older corneas. The development of the cornea was characterized by a decrease in sulphation of chondroitin sulphate. No hyaluronate was found in the fetal corneas available for this study.

Glycosaminoglycans in the Developing Chicken Cornea

The development and aging of the chicken cornea is accompanied by the stepwise disappearance of the non-sulphated glucosaminoglycan and by the increase of keratan sulphate and chondroitin sulphate con

Penetration of Radioactive Sulphate and Glucose from Hydrophilic Gel Contact Lenses into the Eye of the Rabbit

Soft poly(hydroxyethylmethacrylate) gel contact lenses soaked with a solution containing either radioactive sulphate or D-glucose-14C were applied to the rabbit eyes for time intervals rang

Intraocular Penetration of Bacitracin and Polymixin B after Administration by Means of Hydrophilic gel Contact Lenses

Hydrophilic contact lenses made of poly(hydroxyethylmethacrylate) gel were saturated with 1-percent [14C]-glycyl-bacitracin or 0.1 -percent[14C]-glycyl-polymixinBand then applied

Glycosaminoglycans in Human Comeal Buttons Removed at Keratoplasty

Microfractionation and analysis of individual human corneal buttons were performed on both normal corneas and on corneas removed at keratoplasty from eyes with keratoconus or swollen, opaque corneas. Keratoconus buttons were found to have a relative increase in the glucosaminoglycan (keratan sulfate) fraction and a significant decrease in the galactosaminoglycan (chon-droitin sulfate) fraction. There was decreased sulfation of galactosaminoglycans in keratoconus buttons. Both the glucosamino glycans and the galactosaminoglycans were decreased in some swollen opaque corneas. In these corneas a highly sulfated glycosaminoglycan was recovered not present in normal corneas, which was comparable in many ways to dermatan sulfate.

Changes of Glycosaminoglycan Sulphation in the Cornea of Lathyric Chick Embryos

Lathyrogen β-aminopropionitrile and radioactive sulphate were administered to 15-day-old chick embryos by injection into allantoic cavity. On consecutive days, experimental lathyrism was evidenced by a decrease of the tensile strength of the neck of the chick embryos and by the inhibition of radioactive sulphate incorporation into corneal stroma and nasal cartilage. After the chromatographic separation of corneal glycosaminoglycans, it was found that β-aminopropionitrile specifically lowered the sulphation of galactosaminoglycan with radioactive sulphate by about 30% compared with the control, whereas the sulphation of glucosaminoglycan remained unchanged.

Tetracycline: Release from Hydrophilic Gel Contact Lens and Intraocular Penetration

Application of tritiated tetracycline by means of hydrophilic gel contact lenses in rabbits revealed that about 20% of the antibiotic was released from the gel during a contact time of 5 h. Abrasion of the epithelium increased the intraocular penetration considerably. No accumulation of tetracycline in the eye tissues was observed even after 72 h of continuous application of contact lenses presoaked in tetracycline. Compared with the instillation of tetracycline solution, the application of contact lenses presoaked in tetracycline is much more effective with respect to the achieved level of the antibiotic in the eye.

Ethylenediamine tetraacetate: Its Release from Hydrophilic Gel Contact Lenses, Intraocular Penetration and Effect on Calcium in the Cornea after Lime Burns

In spite of a standard lime burn technique, the injured rabbit eyes revealed a great variety of corneal damage with totally or partially denuded epithelium and stromal opacities of varying intensity. Irrigation of the eye with water removed more than half of the calcium from the cornea. A further significant decrease of the calcium level was achieved by the action of hydrophilic gel contact lens presoaked with a 1.85% ethylenediamine tetra acetate (EDTA) solution. The lime-burned cornea does not prevent intraocular penetration of EDTA from contact lens fitted on the injured eye. A delay of 1 or 2 h in application of EDTA contact lens after the lime burn and water irrigation of the eye seems to enhance permeation of the chelating agent into the cornea

Use of Hydrophilic Contact Lens for Application of IDU. Study on Rabbits with Artificial Cornea Lesions and Herpetic Keratitis

Poly-(hydroxyethylmethacrylate) gel contact lenses saturated with a 0.1% solution of IDU containing 5-iodo-2’-desoxyuridine-3H were applied onto normal rabbit eyes and after scarification of the epithelium, wounding of the stroma and experimental herpetic keratitis, IDU was easily released from the gel. The intraocular penetration was 2–3 times higher in the eyes with corneal defects as compared with intact eyes. The results indicate that hydrophilic contact lens can be used as a carrier of IDU in the treatment of herpetic keratitis and iritis.

Effect of Lathyrogens on Glycosaminoglycans of Bovine Cornea in vitro

Bovine corneas were incubated in vitro with various lathyrogens in a medium containing radioactive sulphate. The effect of lathyrogens resulted in the decrease of the content of ester sulphate radioactivity in the corneal matter proportional to the concentration of lathyrogens in the incubation medium. Isolated glycosaminoglycans showed lower specific radioactivity after the action of lathyrogens on the cornea. By means of cetylpyridinium chloride-cellulose fractionation technique, it was found that preferential sulphation of galactosaminoglycans was inhibited whereas sulphation of glucosaminoglycans did not reveal any change. Tensile strength of corneal strips incubated in vitro in the presence of lathyrogens as well as the total collagen content in the corneal dry weight were not influenced by the action of lathyrogens.