Critical illness-induced bone loss is related to deficient autophagy and histone hypomethylation

BACKGROUND Survivors of critical illness are at increased risk of fractures. This may be due to increased osteoclast formation during critical illness, leading to trabecular bone loss. Such bone loss has also been observed in Paget's disease, and has been related to deficient autophagy. Deficient autophagy has also been documented in vital organs and skeletal muscle of critically ill patients. The objective of this study was to investigate whether deficient autophagy can be linked to critical illness-induced bone loss. METHODS Osteoclasts grown in vitro and their precursor cells isolated from peripheral blood of critically ill patients and from matched healthy volunteers were analysed for the expression of autophagy genes (SQSTM1, Atg3 and Atg7), and proteins (p62, Atg-5, and microtubule-associated protein light chain 3-II (LC3-II)) and for autophagy and epigenetic signalling factors via PCR arrays and were treated with the autophagy inducer rapamycin. The effect of rapamycin was also investigated at the tissue level in an in vivo rabbit model of critical illness. RESULTS Many more osteoclasts formed in vitro from the blood precursor cells isolated from critically ill patients, which accumulated p62, and displayed reduced expression of Atg5, Atg7, and LC3-II compared to healthy controls, suggesting deficient autophagy, whilst addition of rapamycin reduced osteoclast formation. PCR arrays revealed a down-regulation of histone methyltransferases coupled with an up-regulation of negative regulators of autophagy. Critically ill rabbits displayed a reduction in trabecular and cortical bone, which was rescued with rapamycin. CONCLUSIONS Deficient autophagy in osteoclasts and their blood precursor cells at least partially explained aberrant osteoclast formation during critical illness and was linked to global histone hypomethylation. Treatment with the autophagy activator Rapamycin reduced patient osteoclast formation in vitro and reduced the amount of bone loss in critically ill rabbits in vivo. These findings may help to develop novel therapeutic targets to prevent critical illness-induced bone loss

Why UX Research Matters for HRI: The Case of Tablets as Mediators

Many human-robot interaction systems involve a third component: a tablet, which can either be separate or integrated in the robot (as is the case in SoftBank Robotics' Pepper robot). Such a tablet can be used, for instance, to present information to the human user or to gain control over the robot's complex surroundings, by introducing a virtual environment as a substitute for interactions that would normally happen in the physical world. While such a tablet can potentially have a big impact on the usability of the entire system and affect the interaction between human and robot, it is often not explicitly included when evaluating the user experience of human-robot interaction. This paper describes a case study where three evaluation methods were combined in order to get a comprehensive overview of the user experience of an Intelligent Tutoring System (ITS), consisting of a robot and a tablet. The results show several major usability issues with the virtual environment, which could have affected the experience of interacting with the robot. This underlines the importance of including not only the robot itself, but also any other interaction mediators in an iterative design process