Background-Current heart valve prostheses are constructed mimicking the native aortic valve. Special hemodynamic characteristics of the mitral valve such as a nonaxial central inflow with creation of a left ventricular vortex have so far not been taken into account. A new polycarbonaturethane (PCU) bileaflet heart valve prosthesis with special design for the mitral position is introduced, and results of animal testing are presented. Methods and Results-After in vitro testing, 7 PCU-prostheses and 7 commercial bioprostheses (Perimount, nϭ4; Mosaic, nϭ3) were implanted in mitral position into growing Jersey calves (age 3-5 months, weight 60 -97 kg) for 20 weeks. 2-Dimensional echocardiography was performed after implantation and before sacrification. Autopsy included histologic, radiographic, and electron microscopic examination of the valves. In vitro durability was proven for Ͼ15 years. After implantation 2-dimensional-echocardiography showed no relevant gradient or regurgitation of any prosthesis. Clinical course of the animals with PCU valves was excellent. In contrast, 5 of 7 calves with bioprostheses were sacrificed after 1-9 weeks because of congestive heart failure. 2-Dimensional echocardiography of the PCU valves after 20 weeks showed mild leaflet thickening with trivial regurgitation; mean gradient was 8.1Ϯ5.0 mm Hg (weight: 160 -170 kg). The explanted PCU prostheses revealed mild calcification and no structural degeneration. All of the Perimount bioprostheses were severely calcified and degenerated after 11Ϯ7 weeks. One Mosaic bioprosthesis was thrombosed after 1 week, and 2 showed severe and mild-to-moderate degeneration after 4 and 22 weeks, respectively. Conclusions-Polycarbonaturethane

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The widespread use of alloplastic materials as the standard procedure for hernia repair makes an evaluation of the long-term integration of these implants imperative. A total of 121 explanted meshes (mean implantation time 23.2 & 19.7 months) of polypropylene (Atrium((R)), n = 20; Marlex((R)), n = 50; Prolene((R)), n = 21), Polyester (Mersilene((R)), n = 19) and PTFE (Gore-Tex((R)), n = 11) were analyzed in regard to the tissue and cell response within the interface mesh-fiber/tissue. The mesh samples were investigated by light and electronmicroscopy, as well as immunohistochemistry. The morphometric results confirmed a persisting inflammatory proliferative foreign-body reaction with increased cell turnover in the recipient tissues. This reaction is mainly influenced by the selected mesh modification. The consequences of the arising "chronic wound" are discussed in detail, in particular with regard to possible malignant transformation.

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Our results indicate that patients with colonic neoplastic lesions or diverticular disease probably form heterogeneous groups. Because current results from molecular biology emphasize the impact of the extracellular matrix on the genesis of diverticulosis and colonic cancer, the observed heterogeneity could be an expression of a distinct composition of the local milieu.