Bovine corneas

Dexamethasone (M S) l Adenylate cyclase activity Bovine cornea [20]... 

TABLE 17.5. Comparison between In Vivo Ocular Irritancy and Opacity Induced in Bovine Cornea... 

Muir, C.K. (1985). Opacity of bovine cornea in vitro induced by surfactants and industrial chemicals compared with ocular irritancy in vivo. Toxicol. Lett. 24 157-162. 

Several in vitro methods, including the hen s egg chorioallantoic membrane test (HET-CAM) the bovine cornea opacity and permeability assay (BCOP) and the isolated rabbit eye (IRE) test, have gained regulatory acceptance in Europe for the classification of severe eye irritants. Many companies are using such techniques successfully to reduce in vivo testing during development. ... 

CRITICAL ASSESSMENT OF THE METHOD Porcine cornea are similar to human cornea in that both have 5-7 layers of epithelial cells and a Bowman s membrane. Bovine cornea differs in that it has 10 layers of epithelial cells and no Bowman s membrane. Porcine and Bovine comeal cultures both differ in certain aspects from in vivo animal cornea. The latter has the presence of an overlying mucin layer... 

Ziegler C, Mersmann G. Influence of effectors of the complex-type-oligosaccharide biosynthesis on the formation of proteok-eratan sulfate in bovine cornea. Biochim. Biophys. Acta 1984 799(3) 203-208. 

Christner JE, Distler JJ, Jourdian GW. Biosynthesis of keratan sulfate - purification and properties of a galactosyltransferase from bovine cornea. Arch. Biochem. Biophys. 1979 192(2) 548-558. 

This mucopolysaccharide, possessing a strueture similar to those of chondroitin 4- and 6-sulfates but with a small content of sulfate, was isolated from bovine cornea (M16). Chondroitin resembles hyaluronic acid in its rate of hydrolysis by testicular and bacterial hyaluronidases, but was differentiated from hyaluronic acid ([a]n —65° to — 78°) by its optical rotation ( [o]d — 21°). Its structural similarity to chondroitin 4- and 6-sulfates was indicated by the fact that chondrosine was released in high yield on controlled, acidic hydrolysis (D3). The isolation of this mucopolysaccharide is of particular interest since it may be a precursor in the biosynthesis of chondroitin 4- and 6-sulfates. 

Keratan sulfate constitutes approximately half the total mucopolysaccharide fraction of bovine cornea, where it was isolated originally by Meyer et al. (M16). It occurs fairly widely in animal connective tissues, and its presence has been reported in nucleus pulposus (G2), aorta (B17), and costal cartilage (M20). Unlike the acid mucopolysaccharides described previously, keratan sulfate contains no uronic acid residue but is comprised of V-acetyl-n-glucosamine, D-galactose, and sulfate, in equimolar ratio. The small amount of L-fucose detected in acidic... 

MDCK cells/dye diffusion Cell and tissue physiology Epidermal slice/electrical conductivity Rabbit ileum/contraction inhibition Bovine cornea/corneal opacity Proptoses mouse eye/permeability test Inflammation/immunity Chorioallantoic membrane (CAM)... 

None of the in vitro alternative eye tests has proven applicable as a valid replacement for the Draize eye irritation test or has been acceptable for regulatory purposes (Table 5), though some are considered either reliable or reproducible. The most frequently used test has been the ex vivo bovine cornea opacity and permeability assay. The newer human corneal equivalents system, an in vitro culture of immortalized human corneal cells that develops into... 

The Bovine Corneal Opacity and Permeability test method (BCOP) is based on normal physiological and biochemical function of the bovine cornea in vitro. For the BCOP, the eyes are taken from animals slaughtered for human consumption. In this test method (OECD Test Guideline, TG 437), the damage caused by the test substance is assessed by quantitative measurements of changes in corneal opacity and permeability with an opacitometer or a visible... 

Additional in vitro models and assays for eye irritation testing have been proposed in the past. An example is the porcine-based corneal opacity and permeability (PCOP) assay to predict eye irritation of water-soluble cosmetic ingredients [99]. Porcine corneas were chosen due to their advantages in comparison to the bovine corneas such as no concerns about encephalopathy diseases, regular supply of eyes with an acceptable level of quality from a slaughterhouse, more closely related to the human cornea, and their use in ophthalmic research. Using a modified holder and adapted experimental procedures 50 cosmetic ingredients were tested and compared to the in vivo Draize MAS scores. Based on their results, the study concluded that the PCOP could better predict the irritation classes than the BCOP assay. 

White J, Werkmeister JA, Ramshaw JA, Birk DE. Organization of fibrillar collagen in the human and bovine cornea collagen types V and III. Connect Tissue Res 1997 36 165-174. 

Keratan sulphates I and II have been isolated and purified from bovine cornea and nasal cartilage, respectively. Desulphation of keratan sulphate I yielded both water-soluble and water-insoluble products, but keratan sulphate II yielded only water-soluble products. The water-soluble form contains glycopeptides from the protein-polysaccharide linkage region, and oligosaccharides derived from the main chain of the glycosaminoglycan associate forming water-insoluble species. 

Bakerman and Mitchell (1960) have examined bovine corneas in the near-infrared region shortly after excision, after drying for 5 hr and for 2 days, and after attempted regeneration of the tissue by soaking in water for 30 min and for 2 days. These workers concluded that the withdrawal of water led to structural changes in the cornea, but... 

Some sulfate ester groups are present. Found in amniotic fluid, aorta, leucocytes, cornea, placenta (but decreasing with term) and urine. A good source is bovine cornea. 

Msy or emphasis continues to be laid on the special relationship between structure and function in the structural proteins. The sequences of substantial portions of enzymically or chemically produced peptides from collagen from various sources (human liver type III, cartilage, chick skin, calf skin, and bovine cornea ) have been reported. The determination of the sequences in two helical segments (Types I and II) of 5-carboxymethylkerateine A from wool has allowed analysis for and detection of periodicity and large sequence repeats. ... 

A polysaccharide composed of glucosamine, a hexuronic acid, acetic and sulfuric acid units in equimolar ratio was isolated from bovine cornea by Meyer and Chaffee (266). By rotation and by enzymatic analysis with hyaluronidase obtained from pneumococcus and from testis, they characterized the compound s a sulfuric acid ester of hyaluronic acid. 

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