Effect of the Thawing Process on Cryopreserved Arteries

This study was designed to explore the changes that occur in cryopreserved pig arteries following different thawing procedures, before and after being placed in an in vitro flow circuit. Segments of minipig iliac artery were cryopreserved in complete minimal essential medium plus 10% dimethylsulphoxide and stored in liquid nitrogen at -196 degrees C for 30 days. Three study groups were established according to whether the arterial specimens were fresh (control, n = 20), cryopreserved and rapidly thawed (RT) at 37 degrees C (n = 22) or cryopreserved and subjected to controlled, automated slow thawing (ST) (n = 22). Half of the specimens of each group were subsequently placed in the flow circuit for 72 hr. Evaluation was made of morphological and ultrastructural changes. Cell damage was established using the TUNEL method. All cryopreserved specimens showed endothelial denudation that was most extensive in those subjected to rapid thawing. Slowly thawed specimens showed improved cell viability and organization of the vessel wall, compared to those thawed rapidly. Under conditions of flow, the damage induced by the freezing/thawing process was enhanced. These findings suggest that (a) slow thawing of cryopreserved arteries results in improved preservation of the structure and viability of vessels, and (b) the damage induced by freezing/thawing is enhanced when vessels are subjected to flow in an in vitro circuit.     

Enacting regulation: tissue in practice

This paper steps to the side of the usual discussions of the status of tissue in ethics and law to consider instead the enactment of regulation in the daily practice of researchers. This is a separate and often overlooked area between regulation as drafted by legislators and policy makers, and as experienced by those who work within that regulatory frame. The paper considers the governance and procedures put in place and the expertise made available in one research centre.Focus on the bridging, facilitation activity of a particular research tissue bank affords an on-the-ground account of how ethical and legal requirements related to the use of human tissue in research in the United Kingdom work out in the everyday practice of collecting, storing and providing tissue for research.     

The neural fate of neutral information in emotion‐enhanced memory

In this study, we report evidence that neural activity reflecting the encoding of emotionally neutral information in memory is reduced when neutral and emotional stimuli are intermixed during encoding. Specifically, participants studied emotional and neutral pictures organized in mixed lists (in which emotional and neutral pictures were intermixed) or in pure lists (only‐neutral or only‐emotional pictures) and performed a recall test. To estimate encoding efficiency, we used the Dm effect, measured with event‐related potentials. Recall for neutral items was lower in mixed compared to pure lists and posterior Dm activity for neutral items was reduced in mixed lists, whereas it remained robust in pure lists. These findings might be caused by an asymmetrical competition for attentional and working memory resources between emotional and neutral information, which could be a major determinant of emotional memory effects.