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Objective: The aim of the current study is to determine the efficiency of an external prosthesis made of expanded polytetrafluoroethylene reinforced with a continuous silicone spiral to prevent postanastomotic stenosis after surgical correction of extensive tracheal defects in rabbits. Methods: Forty-five rabbits were used, divided into three groups of 15 animals each. Group A was the control group. Group B animals underwent resection of six-ring segments of the cervical trachea and primary anastomosis. The procedure used in group C was similar to that used in group B, but the tracheal anastomosis was supported by an external expanded polytetrafluoroethylene prosthesis. Results: Direct anastomosis after resection of six tracheal rings caused anastomotic stenosis in 100% of the animals. We did not observe tracheal stenosis in any rabbit when we applied an expanded polytetrafluoroethylene tube as an external stent for the tracheotracheal suture. Conclusion: We conclude that an external stent can be used to prevent tracheal stenosis resulting from the resection of six cervical tracheal rings in rabbits(J Thorac Cardiovasc Surg 1997;114:76-83)

To assess and characterize mutations in the vhl gene in tumor tissue samples from 30 patients undergoing surgery for renal cell carcinoma in our department.Descriptive, observational and analytical study of 30 patients undergoing surgery for RCC, analyzing the vhl gene sequence in tumor tissue, and using healthy renal tissue from the same patients as controls. Tissues were processed by DNA extraction, PCR amplification of the three exons that conform the gene, and ulterior automatic sequence analysis of the amplified exons between intronic primers previously designed. The sequence is compared with the corresponding exons included in the GeneBank. Alterations were checked by backwards sequence analysis.9 mutations (30%) were found in the tumoral samples analyzed. 7 of them were punctual (one of them intronic); the other two were deletions. Mutations were distributed among the three exons: 3 in exon 1, 4 in exon 2, 1 in exon 3 and 1 intronic. One of the samples showed 2 mutations. Control tissue was free of mutations.Sporadic RCC shows mutations in the vhl gene which mainly appear in the clear cell subtype. Such alterations result in severe disturbances in the protein, disturbing its tumor suppressing function.