The mechanical behavior of calf pericardium, a biomaterial utilized in the manufacture of cardiac bioprostheses, in response to a short tensile cyclic test has been evaluated. The trial involved 120 samples cut longitudinally or transversely, subjected to 10 cycles until a stress of between 1 and 3 MPa was reached. Tests of hardness and tear propagation were performed, and the results were compared with a control series. The energy loss was also computed, and it was approximately 10-fold greater in the first cycle than the loss in the subsequent nine cycles. Despite this singularity, they correlated very precisely. The effect of the direction in which the tissue is cut on energy loss was not significant nor the difference between hardness prior to and after testing. The results of the tear propagation tests gave no statistical differences prior to and after testing. From the obtained results, it seems that the test carried out does not affect significantly the mechanical properties of calf pericardium.
Free radicals are involved in ischemia-reperfusion injury and inflammatory processes. The commercial formulation of the anesthetic propofol contains gamma-tocopherol and delta-tocopherol, which may exert antioxidant effects during transplantation. Animals were randomly assigned to a control group or experimental groups for lung transplantation after 3 and 24 h of ischemia. Individual tocopherols, malondialdehyde, biochemical indices, and hemodynamic, blood gas, and ventilatory parameters were determined during reperfusion. Results showed that administration of commercially available propofol provoked a time- and dose-dependent increment in serum gamma-tocopherol and delta-tocopherol in control animals and in the group receiving lungs subjected to 3 h of ischemia, but not in the group with 24 h of ischemia. Malondialdehyde levels increased during reperfusion and did not differ significantly between the two experimental groups, which did not differ with respect to lung function either. gamma-Tocopherol, supplied by the anesthetic, may act as an antioxidant that is consumed during reperfusion. This potential effect could be relevant to the choice of anesthetic agents in situations where free radical damage to tissues is expected.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.