Alteration of vascular endothelium and endothelium smooth muscle interaction after carbogen gas perfusion of isolated rat and guinea pig heart.

The aim of the study was to alter the vascular endothelium of the mammalian myocardium with respect to coronary flow regulation and vascular permeability. For this purpose, carbogen gas perfusion (GP) of Langendorff-type isolated rat and guinea pig heart was chosen. Perfusion of the hearts with carbogen gas was possible, as well as replacement of the GP by fluid perfusion. The energetic and mechanical state, the creatine kinase release, and the electron microscopic examination of the rat heart indicated only a moderate to minimal alteration of the cardiomyocytes after GP. As a result of GP a massive alteration of the vascular endothelium could be demonstrated in the rat heart, based on the release of the cytosolic endothelial marker enzyme, purine nucleoside phosphorylase, the partly altered vascular permeability and the morphologically detected endothelial damage to arterioles, capillaries and venules. Moreover, the reduced coronary flow response to short periods of anoxia (rat, guinea pig) and the inverted flow response to serotonin administration with maintained response to sodium nitroprusside (rat) in the post-gas perfusion period reflected an alteration of endothelial smooth muscular interaction in the rat and guinea pig heart. Furthermore, the distensibility of the coronary vasculature was increased in the rat and guinea pig heart in the post-gas perfusion period, where a relative autoregulatory behavior was maintained (rat) or partly maintained (guinea pig) in passively predilated vessels. In conclusion, carbogen gas perfusion of isolated hearts allows to induce preferred alteration of endothelium and endothelium-smooth muscle interaction.

Signet ring cell carcinoma in adenomatous polyp at site of ureterosigmoidostomy 16 years after conversion to ileal conduit.

The case of a signet ring cell carcinoma of the colon arising in an adenoma at the site of ureterosigmoidostomy after conversion to an ileal conduit is reported. Urine exposure to the colonic mucosa was present only for a short period before development of an adenoma with subsequent signet ring cell carcinoma transformation more than 15 years later. In the face of recent reports on adenocarcinoma in cases of bladder substitution or augmentation without any possible promoting influence of the fecal stream, the well known risk of neoplasia after sigmoidostomy remains unclear in its etiology.