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Objective Aortic homografts were compared with pulmonary homografts in the setting of right ventricular outflow tract reconstruction in adolescent sheep. Furthermore, clinically available stentless porcine and bovine xenografts were studied as an alternative to homografts. Methods In 51 adolescent sheep cryopreserved aortic and pulmonary (ovine) homografts, as well as 6 different types of clinically available stentless bioprostheses (Prima Plus, Toronto SPV, Toronto BiLinx, Freestyle, Pericarbon Stentless, and Contegra) were implanted in the pulmonary position. After 5 to 6 months, the valves were explanted and studied for structural valve degeneration by means of radiographic analysis, histology, and calcium content determination. Results Pulmonary homografts calcified significantly less than aortic homografts in the wall portion. Leaflet calcification was mild, hardly detectable on radiographic analysis, and comparable between aortic and pulmonary homografts. Stentless porcine xenografts showed severe calcification in the aortic wall portion, irrespective of the antimineralization treatment. Leaflet calcification was mild and in the range of that seen in homografts. Pannus formation was present but never induced leaflet retraction or cusp immobilization. Calcification was absent in the stentless Pericarbon valve implants, but all valves showed extensive pannus overgrowth, leaflet retraction, and cusp immobilization. The Contegra valves showed wall calcification, but the leaflets were completely free of calcification and pannus. Conclusions For right ventricular outflow tract reconstruction, the pulmonary homograft remains the first choice. All xenografts result in either calcific degeneration or cusp immobilization.

At present, resting state functional MRI (rsfMRI) is increasingly used in human neuropathological research. The present study aims at implementing rsfMRI in mice, a species that holds the widest variety of neurological disease models. Moreover, by acquiring rsfMRI data with a comparable protocol for anesthesia, scanning and analysis, in both rats and mice we were able to compare findings obtained in both species. The outcome of rsfMRI is different for rats and mice and depends strongly on the applied number of components in the Independent Component Analysis (ICA). The most important difference was the appearance of unilateral cortical components for the mouse resting state data compared to bilateral rat cortical networks. Furthermore, a higher number of components was needed for the ICA analysis to separate different cortical regions in mice as compared to rats.