Necrosis, unregulated cell death, is characterized by plasma membrane rupture as well as nuclear and cellular swelling. However, it has recently been reported that necrosis is a regulated form of cell death mediated by poly-(ADP-ribose) polymerase 1 (PARP1). PARP1 is thought to mediate necrosis by inducing DNA damage, although this remains unconfirmed. In this study, we examined the mechanisms of PARP1-mediated necrosis following doxorubicin (DOX)-induced DNA damage in human kidney proximal tubular (HK-2) cells. DOX initiated DNA damage response (DDR) and upregulated PARP1 and p53 expression, resulting in morphological changes similar to those observed during necrosis. Additionally, DOX induced mitochondrial hyper-activation, as evidenced by increased mitochondrial respiration and cytosolic ATP (cATP) production. However, DOX affected mitochondrial mass. DOX-induced DNA damage, cytosolic reactive oxygen species (cROS) generation, and mitochondrial hyper-activation decreased in cells with inhibited PARP1 expression, while generation of nitric oxide (NO) and mitochondrial ROS (mROS) remained unaffected. Moreover, DOX-induced DNA damage, cell cycle changes, and oxidative stress were not affected by p53 inhibition. These findings suggest that DNA damage induced necrosis through a PARP1-dependent and p53-independent pathway.

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Gadd45β is transcriptionally induced by p53 via direct binding under ischemia/anoxia. The induction of Gadd45β expression requires the p53 phosphorylation at Ser15/Ser20. p38α mediates the p53 phosphorylation at Ser15/Ser20 and the Gadd45β expression. Ischemia/anoxia-p38α-p53-Gadd45β axis serves as a novel apoptotic signaling module.

We report on the direct and facile method for noble metal/graphene nano-composites from graphite without reducing agents. In this system, the irradiant white-light instead of the chemical reducing agent exerts the influence on the synthesis of noble metal nanoparticles on graphene. Noble metal salts adsorbed on graphene flakes which were functionalized with ionic surfactants were reduced by irradiation with white light. In particular, noble metal nanoparticles were more evenly distributed on the surface of graphene which was functionalized with SDS than with CTAB.

Torsional behaviors of polymer-infiltrated carbon nanotube (CNT) yarn muscles have been investigated in relation to molecular architecture by using atomic force microscopy (AFM). Two polymers with different stiffnesses, polystyrene (PS) and poly(styrene-b-isoprene-b-styrene) (SIS), were uniformly infiltrated into CNT yarns for electrothermal torsional actuation. The torsional behaviors of hybrid yarn muscles are completely explained by the volume change of each polymer, based on the height and full width at half maximum profiles from the AFM morphological images. The volume expansion of the PS yarn muscle (1.7 nm of vertical change and 22 nm of horizontal change) is much larger than that of the SIS yarn muscle (0.3 nm and 11 nm change in vertical and horizontal directions) at 80 °C, normalized by their values at 25 °C. We demonstrate that their maximum rotations are consequently 29.7 deg mm(-1) for the PS-infiltrated CNT yarn muscle (relatively larger rotation) and 14.4 deg mm(-1) for the SIS-infiltrated CNT yarn muscle (smaller rotation) at 0.75 V m(-1). These hybrid yarn muscles could be applied in resonant controllers or damping magnetoelectric sensors.

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we describe the synthesis and solution properties of PCL-b-PPG-b-PCL triblock copolymers via ring-opening polymerization (ROP) of -caprolactone (CL) monomer initiated at the hydroxyl end group of poly(propylene glycol) (PPG) using HCl Et 2 O as a monomer activator.