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Regional and zonal variations in the sulfation patterns of chondroitin sulfate in normal equine corneal stroma

Daniel J. BirosDepartment of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610.
Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, 20 Staniford St, Boston MA 02114.

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Dennis E. BrooksDepartment of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610.

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Murray P. BrownDepartment of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610.

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Kelly A. MerrittDepartment of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610.

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Paul S. KubilisDepartment of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610.

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Abstract

Objective—To determine regional and zonal variation in sulfation patterns of chondroitin sulfate in normal equine corneal stroma.

Sample Population—22 normal eyes from 11 horses.

Procedure—Corneas were collected within 24 hours of death from equine necropsy specimens. After papain-chondroitinase digestion of corneal tissue, disaccharides ΔDi4S and ΔDi6S were quantified by use of capillary zone electrophoresis in the superficial, middle, and deep zones of central and peripheral regions of the cornea.

Results—For the 2 regions combined,ΔDi6S/ΔDi4S values were significantly lower in the deep and middle zones, compared with that of the superficial zone. In the central region, deep and middle zones had significantly lower ΔDi6S/ΔDi4S values than the superficial zone did. In the peripheral region, the deep zone had significantly lower ΔDi6S/ΔDi4S values, compared with superficial and middle zones. In the deep zone, the peripheral region had significantly lower ΔDi6S/ΔDi4S values than the central region did.

Conclusion and Clinical Relevance—Distribution of ΔDi6S/ΔDi4S values follows a gradient across the healthy equine cornea, being smallest in the deep and middle zones of the central region and the deep zone of the peripheral region. Regional and zonal differences in the distribution of stromal ΔDi6S and ΔDi4S may influence the role of glycosaminoglycans in health, disease, and wound repair of the equine cornea. (Am J Vet Res 2002;63:143–147)

Abstract

Objective—To determine regional and zonal variation in sulfation patterns of chondroitin sulfate in normal equine corneal stroma.

Sample Population—22 normal eyes from 11 horses.

Procedure—Corneas were collected within 24 hours of death from equine necropsy specimens. After papain-chondroitinase digestion of corneal tissue, disaccharides ΔDi4S and ΔDi6S were quantified by use of capillary zone electrophoresis in the superficial, middle, and deep zones of central and peripheral regions of the cornea.

Results—For the 2 regions combined,ΔDi6S/ΔDi4S values were significantly lower in the deep and middle zones, compared with that of the superficial zone. In the central region, deep and middle zones had significantly lower ΔDi6S/ΔDi4S values than the superficial zone did. In the peripheral region, the deep zone had significantly lower ΔDi6S/ΔDi4S values, compared with superficial and middle zones. In the deep zone, the peripheral region had significantly lower ΔDi6S/ΔDi4S values than the central region did.

Conclusion and Clinical Relevance—Distribution of ΔDi6S/ΔDi4S values follows a gradient across the healthy equine cornea, being smallest in the deep and middle zones of the central region and the deep zone of the peripheral region. Regional and zonal differences in the distribution of stromal ΔDi6S and ΔDi4S may influence the role of glycosaminoglycans in health, disease, and wound repair of the equine cornea. (Am J Vet Res 2002;63:143–147)