Photodynamic therapy (PDT) has been developed as an anticancer treatment, which is based on the tumor-specific accumulation of a photosensitizer that induces cell death after irradiation of light with a specific wavelength. Depending on the subcellular localization of the photosensitizer, PDT could trigger various signal transduction cascades and induce cell death such as apoptosis, autophagy, and necrosis. In this study, we report that both AMP-activated protein kinase (AMPK) and mitogen-activated protein kinase (MAPK) signaling cascades are activated following 5-aminolevulinic acid (ALA)-mediated PDT in both PC12 and CL1-0 cells. Although the activities of caspase-9 and -3 are elevated, the caspase inhibitor zVAD-fmk did not protect cells against ALA-PDT-induced cell death. Instead, autophagic cell death was found in PC12 and CL1-0 cells treated with ALA-PDT. Most importantly, we report here for the first time that it is the activation of AMPK, but not MAPKs that plays a crucial role in mediating autophagic cell death induced by ALA-PDT. This novel observation indicates that the AMPK pathway play an important role in ALA-PDT-induced autophagy.

No abstract

We present HeadBlaster, a novel wearable technology that creates motion perception by applying ungrounded force to the head to stimulate the vestibular and proprioception sensory systems. Compared to motion platforms that tilt the body, HeadBlaster more closely approximates how lateral inertial and centrifugal forces are felt during real motion to provide more persistent motion perception. In addition, because HeadBlaster only actuates the head rather than the entire body, it eliminates the mechanical motion platforms that users must be constrained to, which improves user mobility and enables room-scale VR experiences. We designed a wearable HeadBlaster system with 6 air nozzles integrated into a VR headset, using compressed air jets to provide persistent, lateral propulsion forces. By controlling multiple air jets, it is able to create the perception of lateral acceleration in 360 degrees. We conducted a series of perception and human-factor studies to quantify the head movement, the persistence of perceived acceleration, and the minimal level of detectable forces. We then explored the user experience of HeadBlaster through two VR applications: a custom surfing game, and a commercial driving simulator together with a commercial motion platform. Study results showed that HeadBlaster provided significantly longer perceived duration of acceleration than motion platforms. It also significantly improved realism and immersion, and was preferred by users compared to using VR alone. In addition, it can be used in conjunction with motion platforms to further augment the user experience.