The corneal limbus harbors corneal epithelial stem cells and contributes to the unique microenvironment of the stem cell niche. Corneal conditions, such as infections, tumors, immunological disorders, trauma, and chemical burns, often lead to the deficiency of the corneal stem cells, and subsequent vision loss. One key feature of limbal stem cell deficiency is corneal neovascularization. There is a delicate balance between pro-angiogenic and anti-angiogenic factors that, in a normal cornea, maintain an avascular state. A pro-angiogenic shift in this balance can occur due to various mechanisms, such as inflammation, gene mutations, physical breach in the limbal barrier, and decreased production of anti-angiogenic molecules. Currently available treatment options for limbal stem cell deficiency include allogeneic and autologous limbal transplants, and more recently, transplantation of alternative sources of epithelium, such as cultivated corneal and oral mucosal stem cells. Further studies are needed to investigate the combination of limbal and stem cell transplantation and concurrent anti-angiogenic therapy.

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Nile tilapia Oreochromis niloticus were medicated with florfenicol (AQUAFLOR type A medicated article; Schering-Plough Animal Health, Summit, New Jersey) via a medicated ration at 15 mg florfenicol x kg fish body weight(-1) d(-1) for 10 d to compare the elimination kinetics of the test article in different size fish held at 25 degrees C. The groups of fish used in the study had mean weights of approximately 100, 250, and 500 g. In each trial, the fish were provided the medicated ration and 15 fish were processed at each of seven time points postfeeding for determination of the florfenicol concentration in serum and the florfenicol residue in the edible portion (composite muscle and skin). There was a trend toward shorter half-lives of elimination in the smaller fish. The elimination times in muscle-skin (times to reach the established tolerance concentration for channel catfish Ictalurus punctatus and salmonids of 1.0 microg florfenicol residue/g) and half-lives were 9.2 and 1.2 d (100 g), 8.6 and 1.7 d (250 g), and 12.7 and 2.2 d (500 g), respectively.