The feasibility of using Gd dendrimer-based macromolecules (Gd-G8 dendrimer) as a dual CT and MR contrast agent for monitoring convection-enhanced delivery of therapy in the brain is evaluated both in vitro and in vivo with optimal dosing established. In vitro CT attenuation values of the Gd-based agents ( approximately 6.0 HU mM(-1)) were approximately 1.6 times greater than iodine-based agents and the attenuation of the Gd-DTPA was comparable to Gd-G8 dendrimer. Visible enhancement was observed on both CT and MR using Gd-G8 dendrimer over a range of 23-78 mM; however, a concentration of at least 47 mM in Gd was required for adequate delineation of the injection site on both CT and MR. MR offers greater sensitivity than CT in estimating the volume of distribution (V(d)) and effectively quantified the agent's concentration and diffusion using T(1) mapping at much lower concentrations of Gd (<10 mM in [Gd]).

Real-time in vivo CT scanning of CED of iopamidol appears to be safe, feasible, and suitable for monitoring convective delivery of drugs with certain features and low infusion volumes.

Hollander's model of idiosyncrasy credits and Moscovici's model of behavioral style propose different strategies by which group members holding a minority opinion may influence members holding the majority position. Two experiments compared the two models «nd the impact of member competence on the influence process. In Experiment 1 four-person male groups discussed three opinion issues that were selected to permit a confederate to argue for the minority position. In the Hollander strategy, the confederate argued the minority position only on the last issue, whereas in the Moscovici strategy he argued it on every issue. Groups also worked a difficult math puzzle, by which the confederate snowed (did not show) competence by solving (not solving) the problem. Experiment 2 followed the same procedure except that both male and female subjects were tested, groups contained six members with two confederates, and confederates worked two word problems to show competence. For males, results across both experiments showed that Hollander's model produced significantly greater influence than Moscovici's model and showed a pattern of greatest influence under conditions of high competence. In contrast, results for females (Experiment 2) showed the Moscovici and Hollander strategies to be equally effective, regardless of competence. Overall, female groups were influenced less than male groups, and both models showed significant influence relative to baseline control subjects.

Periphyton communities are an ecologically important source of information when conducting experimental stream ecotoxicological studies . Experimental stream studies often utilize unreplicated systems in order to understand dose-response phenomena . The objective of this study was to examine the robustness of such a dose-response investigation . Autotrophic and heterotrophic periphyton were evaluated in replicated control experimental streams with open recruitment (once-through flow design) . Measurements of population and community structure and community function over an eleven week colonization period were made on unglazed clay tile and cobble substrata . Several measures were significantly different during the study ; however, most of these were a result of initial stochastic colonization events or associated with relatively rare algal populations . During the latter half of the study autotrophic and heterotrophic community measurements on tile and cobble substrata displayed similar trends in both control streams . Population and community metrics were significantly different for approximately 5% of the 400 measurements made after the initial sampling . These results strongly suggest that the driving forces behind structuring aquatic population and community responses will be test chemical exposure and not spuriously developed stream ecosystems with individual trajectories . Recruitment in these open systems is evenly distributed across the replicated experimental stream ecosystems .

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