Comparative morphology of epicorneal conjunctival membranes in rabbits and human pterygium.

A rarely described ocular lesion in the rabbit is presented following the observation of four cases. It is a membrane of conjunctival origin that advances progressively, without adhering, towards the center of the cornea. Clinically the lesion in rabbits looks like pterygium in man, but with several differences: in rabbits, the conjunctival fold is absolutely free and does not penetrate into the superficial corneal layers. It originates from all the limbal circumference in a symetric growth. The cornea itself remains unaltered. The fold consists of fibroblasts and collagen. The microscopic findings suggest the lesion is possibly of a collagenous dysplasia.

Somatically acquired genetic alterations in flat colorectal neoplasias.

Somatically acquired mutations in several genes have been reported as playing an important role during colorectal tumorigenesis. Two alternative groups of carcinomas, termed LOH+ and RER+, have been defined on the basis of their genetic anomalies, a biallelic inactivation of the APC or the TGF-betaRII genes, occurring as an alternative, in LOH+ or RER+ tumors. It is a generally accepted hypothesis that most of colorectal cancers (CRC) develop from a pre-existing adenomatous polyp. Such benign lesions are usually exophytic polyps, a small proportion of adenomas having been described as flat lesions. The latter histological category has thus been proposed to bear specific genetic alterations. In order to examine this hypothesis, we have characterized a series of 44 flat colorectal neoplasias for their RER status and for somatic APC, KRAS and TGF-betaRII genes mutations. Flat colorectal neoplasias were found to be of the RER+ subtype in 22% of cases, all of them exhibiting a TGF-betaRII mutation. A mutation of the APC and KRAS genes has been found in 42% and 4% of tumors, respectively, none of these tumors being of the RER+ subtype. With the exception of a low KRAS mutation rate, flat adenomas appear to follow tumorigenesis pathways very similar to those identified in exophytic adenomas and carcinomas.

Tolfenamic acid in the control of ocular inflammation in the dog: pharmacokinetics and clinical results obtained in an experimental model.

Tolfenamic acid (TA) was tested in two studies to investigate its value in controlling ocular inflammation in the dog. First, TA was assayed within primary and secondary aqueous humour (AH) and in plasma 0, 4 and 24 hours after a 4 mg/kg subcutaneous injection. Secondly, an experimental ocular surgery model was set up in 10 dogs-five receiving TA two hours before surgery and five left untreated. TA was shown to diffuse into AH, reaching lower levels than in plasma: 1:126 ratio in primary AH and 1:43 in secondary AH. In the model, TA-treated dogs versus untreated dogs showed a significant reduction of miosis (P < 0.05) and a clear trend to a reduced ocular discharge and corneal oedema (P = 0.06). Prostaglandin E2 (PGE2) levels increased significantly less in AH after TA treatment (P < 0.05). These results show that TA, even if the whole concentration measured in AH is lower than in plasma, is able to limit the synthesis of the inflammatory mediator PGE2 in AH and to control ocular inflammatory symptoms induced by corneal surgery.