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Background: Calcium (Ca 2+ ) plays a pivotal role in regulating physiological processes in the heart including excitation-contraction coupling, Ca 2+ signaling, and mitochondrial function. It is well established that both Ca 2+ dysregulation and altered cardiac energy metabolism are universal features of heart failure (HF). Dwarf open reading frame (DWORF), a newly discovered microprotein, increases SERCA2a activity in part by relieving SERCA2a inhibition by phospholamban (PLN). DWORF overexpression via cardiac specific transgene or gene therapy is cardioprotective in genetic and experimental HF mouse models. In addition to activation of SERCA2a by PLN displacement, preliminary data indicates that enhanced mitochondrial function contributes to the cardioprotective effects of DWORF. Here we tested the effects of DWORF overexpression on cardiac mitochondrial function and Ca 2+ dynamics. Methods and Results: We isolated mitochondria from wildtype (WT) and DWORF transgenic (Tg) mouse hearts and measured O 2 consumption rates using a Seahorse mito stress test. We found that DWORF Tg mice have increased respiratory capacity compared to WT (DWORF Tg 1150.0 pmol/min, WT 799.4 pmol/min +/-146.2) and enhanced spare respiratory capacity (DWORF Tg 489.1 pmol/min, WT 229.4 pmol/min +/- 102.1). To measure mitochondrial Ca 2+ dynamics, we performed Ca 2+ retention capacity assays and found that DWORF Tg mice have increased Ca 2+ uptake rates compared to WT (DWORF Tg 32.32 s, WT 46.46 s +/- 4.39). Western blot analysis of the mitochondrial Ca 2+ uniporter (MCU) in mito extracts from WT and DWORF Tg hearts indicated elevated levels of MCU. However, electron transport chain (ETC) protein expression indicated no significant differences, indicating the enhanced mitochondrial activity observed in DWORF Tg mice was not due to increased ETC levels. Conclusions: DWORF Tg mouse heart mitochondria exhibit increased maximal respiration rates and enhanced spare respiratory capacity. However, ETC protein levels are unchanged, indicating altered enzyme activity rather than expression. Additionally, mitochondria from DWORF Tg hearts uptake Ca 2+ faster into the mitochondria through the increased levels of MCU, suggesting enhanced mitochondrial Ca 2+ dynamics.

The purpose of this study was to discover relationships between metrics and usability standards to assess the success of the University of North Carolina System Office website. Though no relationship was arguably found, the study results will be used to improve the UNC System Office website and other non-transactional websites that convey policy based information to the general public. Remote usability testing with nine users on desktop computers revealed that the site succeeds in terms of aesthetic design and top-level navigation but suffers from critical errors, poor organization, and an overuse of industry-specific terminology. The testing results demonstrate the importance of presenting the wide breadth of information to the general public in a way that is visually appealing and topical for some while direct and deeply specialized for others. Above all, the study provides a case study in conducting usability testing.

Novel technology can be a powerful tool for enhancing students' interest in many learning domains. However, the sustainability and overall impact of such interest is unclear. This study tests the longer-term effects of technology on students' task and course interest. The experimental study was conducted with students in foreign language classes (n = 122): a 12-week experimental trial that included pre- and post-course interest, and a sequence of task interest measures. Employing a counterbalanced design, at three week intervals students engaged in separate speaking tasks with each of a Human and “Chatbot” partner. Students' interest in successive tasks and in the course (pre-post), were used to assess differential partner effects and course interest development trajectories. Comparisons of task interest under different partner conditions over time indicated a significant drop in students' task interest with the Chatbot but not Human partner. After accounting for initial course interest, Structural Equation Modelling indicated that only task interest with the Human partner contributed to developing course interest. While Human partner task interest predicted future course interest, task interest under Chatbot partner conditions did not. Under Chatbot partner conditions there was a drop in task interest after the first task: a novelty effect. Implications for theory and practice are discussed.