DNA has the potential to achieve a controllable macromolecular structure, such as hydrogels or droplets formed through liquid-liquid phase separation (LLPS), as the design of its base sequence can result in programmable interactions. Here, we constructed “DNA droplets” via LLPS of sequence-designed DNA nanostructures and controlled their dynamic functions by designing their sequences. Specifically, we were able to adjust the temperature required for the formation of DNA droplets by designing the sequences. In addition, the fusion, fission, and formation of Janus-shaped droplets were controlled by sequence design and enzymatic reactions. Furthermore, modifications of proteins with sequence-designed DNAs allowed for their capture into specific droplets. Overall, our results provide a platform for designing and controlling macromolecular droplets via the information encoded in component molecules and pave the way for various applications of sequence-designed DNA such as cell mimics, synthetic membraneless organelles, and artificial molecular systems.

This study suggests that short-term exposure to outdoor air pollution increases the risks of hemorrhagic stroke mortality as well as ischemic stroke mortality.

ObjectiveTo introduce and assess a new way of performing whole-body magnetic resonance imaging (MRI) using a non-integrated surface coil approach as available on most clinical MRI systems worldwide.MethodsTen consecutive asymptomatic subjects prospectively underwent whole-body MRI for health screening. Whole-body MRI included T1-, T2- and diffusion-weighted sequences, and was performed using a non-integrated surface coil to image four different stations without patient repositioning. The four separately acquired stations were merged, creating seamless coronal whole-body T1-, T2- and diffusion-weighted images. Anatomical alignment, image quality at the boundaries of adjacent stations, and overall image quality of all stations were qualitatively assessed.ResultsThe average time (±SD) taken to change the surface coil from one station to the next station was 53.8 (±7.1) s. The average total extra examination time ± SD was 2 min 41.4 s (±15.3 s). Anatomical alignment, image quality at the boundaries of adjacent stations, and overall image quality of all stations of T1-, T2- and diffusion-weighted whole-body MRI were overall graded as “good” to “excellent”.ConclusionThis study shows that a time-efficient and high-quality whole-body MRI examination can easily be performed by using a non-integrated sliding surface coil approach.Electronic supplementary materialThe online version of this article (doi:10.1007/s00330-009-1674-1) contains supplementary material, which is available to authorized users.

The neuroprotective effects of ethyl pyruvate (EP), a stable derivative of pyruvate, on energy metabolism of rat brain exposed to ischemia-reperfusion stress were investigated by (31)P-nuclear magnetic resonance ((31)P-NMR) spectroscopy. Recovery level of phosphocreatine after ischemia was significantly greater when superfused with artificial cerebrospinal fluid (ACSF) with 2 mM EP than when superfused with ACSF without EP. EP was neuroprotective against ischemia only when administered before the ischemic exposure. Intracellular pH during ischemia was less acidic when superfused ahead of time with EP. EP did not show neuroprotective effects in neuron-rich slices pretreated with 100 microM fluorocitrate, a selective glial poison. It was suggested that both the administration of EP before ischemic exposure and the presence of astrocytes are required for EP to exert neuroprotective effects. We suggest the potential involvement of multiple mechanisms of action, such as less acidic intracellular pH, glial production of lactate, and radical scavenging ability.