Memory performance of 118 individuals who had been in close dating relationships for at least 3 months was studied. For a memory task ostensibly to be performed by pairs, some Ss were paired with their partners and some were paired with an opposite-sex partner from another couple. For some pairs a memory structure was assigned (e.g., 1 partner should remember food items, another should remember history items, etc.), whereas for others no structure was mentioned. Pairs studied together without communication, and recall was tested in individuals. Memory performance of the natural pairs was better than that of impromptu pairs without assigned structure, whereas the performance of natural pairs was inferior to that of impromptu pairs when structure was assigned. Knowledge is of two kinds: we know a subject ourselves, or we know where we can find information upon it.-Samuel Johnson People in close relationships know many things about each other's memories. One partner may not know where to find candles around the house, for instance, but may still be able to find them in a blackout by asking the other partner where the candles are. Each partner can enjoy the benefits of the pair's memory by assuming responsibility for remembering just those items that fall clearly to him or to her and then by attending to the categories of knowledge encoded by the partner so that items within those categories can be retrieved from the partner when they are needed. Such knowledge of one another's memory areas takes time and practice to develop, but the result is that close couples have an implicit structure for carrying out the pair's memory tasks. With this structure in place, couples in close relationships have a transactive memory that is greater than either of their individual memories. Transactive memory is a shared system for encoding, storing, and retrieving information (Wegner, 1986; Wegner, Giuliano, & Hertel, 1985). This research was designed to examine transactive memory by introducing new structures for memory organization in the couple. We expected that couples formed on an impromptu basis in the laboratory might gain in group memory performance as a result of an imposed organizational strategy, as such a plan would help them to focus their individual memory efforts to the pair's benefit. Because close couples already have an understood structure in place, however, we expected that an imposed organizational strategy might interfere with their implicit arrangement and thus undermine their memory performance. We thank Julie Aniol for assisting in the conduct of the research and Toni Wegner for helpful comments on an earlier draft.

The accessibility of suppressed thoughts was compared with the accessibility of thoughts on which Ss were consciously trying to concentrate. In Experiment 1, Ss made associations to word prompts as they tried to suppress thinking about a target word (e.g., house) or tried to concentrate on that word. Under the cognitive load imposed by time pressure, they gave the target word in response to target-related prompts (e.g., home) more often during suppression than during concentration. In Experiment 2, reaction times for naming colors of words were found to be greater under conditions of cognitive load when Ss were asked to suppress thinking of the word than under conditions of no cognitive load or when Ss were asked to concentrate on the word. The results support the idea that an automatic search for the suppression target increases the accessibility of the target during suppression.

Destruction of existing tumor blood vessels may be achieved by targeting vascular endothelial growth factor (VEGF) signaling, which mediates not only endothelial cell proliferation but also endothelial cell survival. In this study, however, intravital microscopy failed to demonstrate that targeting of VEGFR-2 (by the tyrosine kinase inhibitor SU5416) induces significant regression of experimental tumor blood vessels. Immunohistochemistry, electron microscopy, expression analyses, and in situ hybridization provide evidence that this resistance of tumor blood vessels to VEGFR-2 targeting is conferred by pericytes that stabilize blood vessels and provide endothelial cell survival signals via the Ang-1/Tie2 pathway. In contrast, targeting VEGFR-2 plus the platelet-derived growth factor receptor (PDGFR)-beta system (PDGFR-beta) signaling (by SU6668) rapidly forced 40% of tumor blood vessels into regression, rendering these tumors hypoxic as shown by phosphorescence quenching. TUNEL staining, electron microscopy, and apoptosis blocking experiments suggest that VEGFR-2 plus PDGFR-beta targeting enforced tumor blood vessel regression by inducing endothelial cell apoptosis. We further show that this is achieved by an interference with pericyte-endothelial cell interaction. This study provides novel insights into the mechanisms of how 1) pericytes may provide escape strategies to anti-angiogenic therapies and 2) novel concepts that target not only endothelial cells but also pericyte-associated pathways involved in vascular stabilization and maturation exert potent anti-vascular effects.

The mental control of mood and mood-related thought was investigated. In Experiment 1, Ss reminiscing about a happy or sad event were asked to make their mood positive, were given no instructions, or were asked to make their mood negative. Ss attempting mood control without an imposed cognitive load were successful, whereas those who attempted control while rehearsing a 9-digit number not only failed to control their moods but also showed self-reported mood change opposite the mood they intended to create. In Experiment 2, Ss attempting to control mood-related thoughts under cognitive load showed increased accessibility of those thoughts contrary to the direction of intended control in a Stroop-type color-naming task.