Lyophilized allografts without pre-treatment with glutaraldehyde are more suitable than cryopreserved allografts for pulmonary artery reconstruction

Various methods are available for preservation of vascular grafts for pulmonary artery (PA) replacement. Lyophilization and cryopreservation reduce antigenicity and prevent thrombosis and calcification in vascular grafts, so both methods can be used to obtain vascular bioprostheses. We evaluated the hemodynamic, gasometric, imaging, and macroscopic and microscopic findings produced by PA reconstruction with lyophilized (LyoPA) grafts and cryopreserved (CryoPA) grafts in dogs. Eighteen healthy crossbred adult dogs of both sexes weighing between 18 and 20 kg were used and divided into three groups of six: group I, PA section and reanastomosis; group II, PA resection and reconstruction with LyoPA allograft; group III, PA resection and reconstruction with CryoPA allograft. Dogs were evaluated 4 weeks after surgery, and the status of the graft and vascular anastomosis were examined macroscopically and microscopically. No clinical, radiologic, or blood-gas abnormalities were observed during the study. The mean pulmonary artery pressure (MPAP) in group III increased significantly at the end of the study compared with baseline (P=0.02) and final [P=0.007, two-way repeat-measures analysis of variance (RM ANOVA)] values. Pulmonary vascular resistance of groups II and III increased immediately after reperfusion and also at the end of the study compared to baseline. The increase shown by group III vs group I was significant only if compared with after surgery and study end (P=0.016 and P=0.005, respectively, two-way RM ANOVA). Microscopically, permeability was reduced by ≤75% in group III. In conclusion, substitution of PAs with LyoPA grafts is technically feasible and clinically promising

Learned predictiveness influences automatic evaluations in human contingency learning

<p>Experiments used an affective priming procedure to investigate whether evaluative conditioning in humans is subject to bias as a consequence of differences in the learned predictiveness of the cues involved. Experiment 1, using brief prime presentation, demonstrated stronger affective priming for cues that had been predictive of a neutral attribute prior to evaluative conditioning than for those that had been nonpredictive. Experiment 2, using longer prime presentation, found a reversed priming effect for previously predictive cues but not for previously nonpredictive cues. The implication is that the effect observed with brief prime presentation reflects the operation of fast-acting, automatic evaluation mechanisms and hence that evaluative conditioning can be biased by our previous learning about the predictiveness of cues.</p>