Resistance to rupture

Samples of calf pericardium, cut from the pericardial sac in two perpendicular directions, longitudinally, or from root to apex, or transversely, were subjected to tensile testing.

The pericardium had previously been treated for 24 h with 0.625% glu-taraldehyde (pH 7.4) prepared from a commercially available solution of 25% glutaraldehyde (Merck) at a ratio of 1/50 (w/v), in 0.1 M sodium phosphate buffer. Then 60 samples, 30 cut in longitudinal direction (series LP) and 30 cut transversely (series TP), were cut in half and glued with Glubran 2, with an overlap of 0.5 cm (for a total surface area of 1 cm2). Twelve additional samples, 6 longitudinal (series LC) and 6 transverse (series TC), were used as controls.

The samples were stored until the assay at 4 °C in saline (0.9% NaCl) plus two antibiotics: streptomycin at a concentration of 333 |xg/mL and penicillin at a concentration of 2000 U/mL. Six samples each from series LP and TP were subjected to uniaxial tensile testing, always in the direction of the principal axis of the sample, until rupture 7, 30, 60, 90, and 120 days after being glued. The controls were assayed on day 7. The trials were performed on an Instron TTG4 tensile tester (Instron Ltd., High Wycombe, Buck, U.K.), which determines tensile stress and the elongation, or strain, it produces.

The mean results at rupture in kilogram, according to the load being exerted by the machine at that moment, are shown in Tables 9.6 and 9.7. While Table 9.6 shows a statistically significant loss of resistance in the glued samples when compared with the controls on day 7, Table 9.7 demonstrates that the results in the glued samples assayed up to and on day 120 do not change significantly, indicating the stability of the bond.

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