Autologous and allogenic human pericardia used as biomaterials for cardiovascular surgery are traditionally crosslinked with glutaraldehyde. In this work, we have evaluated the resistivity to collagenase digestion and the cytotoxicity of human pericardium crosslinked with various concentrations of glutaraldehyde in comparison with pericardium crosslinked by genipin, nordihydroguaiaretic acid, tannic acid, and in comparison with unmodified pericardium. Crosslinking retained the wavy-like morphology of native pericardium visualized by second harmonic generation microscopy. The collagenase digestion products were analyzed using SDS-PAGE, capillary electrophoresis, and a hydroxyproline assay. Glutaraldehyde and genipin crosslinking protected the native pericardium efficiently against digestion with collagenase III. Only low protection was provided by the other crosslinking agents. The cytotoxicity of crosslinked pericardium was evaluated using xCELLigence by monitoring the viability of porcine valve interstitial cells cultured in eluates from crosslinked pericardium. The highest cell index, reflecting both the number and the shape of the monitored cells was observed in eluates from genipin. Crosslinking pericardium grafts with genipin therefore seems to be a promising alternative procedure to the traditional crosslinking with glutaraldehyde, because it provides similarly high protection against degradation with collagenase, without cytotoxic effects.
A New Discovered Franciscian Chronicle of Ablauff de Rheno De novella plantatione provincie Austrie Bohemie et Polonie quo ad fratres minores de observantia Cronica.
The alternative prey hypothesis suggests that generalist predators switch from their primary prey to secondary when the former is scarce. We tested this hypothesis during a two-year study combining data on predation of ground dummy nests and the numbers of small mammal populations in a highly fragmented landscape in the Krušné hory Mts, the Czech Republic. A significant decrease of small mammal numbers between 2002 and 2003 was followed by a considerable increase of predation on artificial nests from 34% to 76%. Most of the nests (64.7% of the documented cases in 2002) were predated by medium-sized mammals such as marten and fox, common in our study area. Only 8.8% were predated by avian predators (corvids) occurring infrequently in our study area. The results support the alternative prey hypothesis and suggest that in the Krušné hory Mts the nesting success of ground nesting birds may vary strongly from year to year depending on the cycle phase of small mammals, the main prey of dominant predators.