[Intermittent opening of a mechanical mitral valve prosthesis due to pannus formation; report of a case]

A 76-year-old woman with a history of severe mitral valve stenosis had undergone mitral valve replacement with a 27 mm St. Jude Medical (SJM) valve in 1991. Follow-up transthoracic echocardiography revealed an increase in the pressure gradient across the mitral prosthesis 16 years after the surgery. Prosthetic valve dysfunction was suspected, but transesophageal echocardiography and cineradiography failed to show mechanical valve dysfunction. Two years later, she presented with dyspnea on exertion and leg edema. Cineradiography revealed intermittent restriction of the opening of the mechanical valve leaflet approximately every 10 beats. Thus, we diagnosed intermittent prosthetic valve dysfunction and performed a reoperation. On inspection of the prosthesis, we observed semicircular pannus formation around the posterior leaflet in the ventricular side. It was considered that the pannus tissue had interfered with 1 leaflet opening of the mitral valve prosthesis, resulting in intermittent valve dysfunction. We replaced the prosthesis with a new 25 mm SJM valve. The patient was discharged after confirmation of normal prosthetic function.

Suppressive effects of a selective cyclooxygenase-2 inhibitor, etodolac, on 4-nitroquinoline 1-oxide-induced rat tongue carcinogenesis

The present study was conducted to examine effects of a clinically available selective cyclooxygenase (COX)-2 inhibitor, etodolac, on the development of rat tongue squamous cell carcinomas (SCCs) induced by 4-nitroquinoline 1-oxide (4-NQO), and on the immunohistochemically demonstrable expression of COX-2. Fischer 344 rats, 6 weeks old at the commencement, were administered 4-NQO at the doses of 20-30 ppm in their drinking water for 12 weeks. Then, etodolac was supplemented into the diet at doses of 150 and 300ppm for 16 weeks. Rats were sacrificed at 28 weeks and tongue lesions were histologically examined. The incidence and the multiplicity of SCCs induced by 4-NQO were dose-dependently reduced by etodolac, with significance at the highest dose of 300 ppm. Etodolac did not significantly affect the immunohistochemical expression of COX-2 in the lesions which did develop. These results indicate that etodolac can inhibit the development of rat tongue SCCs, probably by inhibiting COX-2 activity rather than its expression. Thus, etodolac may be a promising candidate chemopreventive agent for individuals at high risk of oral cancer.