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1 October 2011 | NewScientist | 19 Wake up after surgery with Ritalin ANAESTHETICS leave people groggy, but a dose of Ritalin could wake them up. Anaesthetised rats injected with the drug, which is used to treat attention-deficit hyperactivity disorder in children, awoke almost immediately, suggesting that the drug could be used to reverse the effects of general anaesthesia. Currently, there is no way to reverse anaesthesia. “We just sit and let the drugs wear off,” says Emery Brown of Massachusetts General Hospital in Boston. Since general anaesthetics seem to suppress the firing of neurons in the brain’s cortex, Brown’s team reasoned that boosting their activity might have the opposite effect. Ritalin increases levels of dopamine in the brain’s arousal pathways. The anaesthetised rats given the drug came to in an average of 90 seconds, compared with 280 seconds when left to wake up naturally (Anesthesiology, DOI: 10.1097/ALN.0b013e31822e92e5). If replicated in humans, Ritalin could enable patients to feel wide awake in minutes, rather than hours. Similar drugs are being investigated to help rouse people from coma. Non-toxic nanorockets could deliver drugs inside the body NANOROCKETS powered by a benign rocket fuel could one day carry drugs around the body. Nanotubes filled with rocket fuel act like missiles, propelling themselves through liquids at eye-watering speeds. But fuels such as hydrazine are toxic so can’t be used inside the body. Now the tiny rockets have been made to work with a less toxic fuel. Samuel Sanchez and colleagues at the Leibniz Institute for Solid State and Materials Research in Dresden, Germany, made nanotubes by rolling platinum- coated sheets of metal into tubes with the platinum on the inside. When the team placed the tubes in a warm, weak solution of hydrogen peroxide, the platinum catalysed the decomposition of peroxide into water and oxygen. This forced bubbles of gas out of one end of the tube, generating thrust in the opposite direction (Journal of the American Chemical Society, DOI: 10.1021/ja205012j). The result is a nanorocket that travels up to 200 times its own length per second, faster than the quickest bacteria. HABITS may be difficult to change, but now at least we have an insight into how they form. When neurons in a group fire simultaneously, the activity appears as a brainwave. Different brainwave frequencies are linked to different tasks in the brain. To track how brainwaves change during learning, Ann Graybiel and Mark Howe at the Massachusetts Institute of Technology used electrodes to analyse brainwaves in the ventromedial striatum of rats while they were taught to navigate a maze. As rats were learning the task their brain activity showed bursts of fast gamma waves. Once the rats mastered the task, their brainwaves slowed to almost a quarter of their initial frequency, becoming beta waves. Graybiel’s team suspects this transition reflects when learning becomes habit (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1113158108). Graybiel says the slower brainwaves may be the brain weeding out excess activity to refine behaviour. She suggests it might be possible to boost the rate at which you learn a skill by enhancing such beta-wave activity. Habits form when the brain slows ADRIANNA WILLIAMS/CORBIS The team can steer the tubes using a magnetic field and control the speed by varying the temperature of the fluid. The fuel is only 0.25 per cent peroxide but even this isn’t entirely safe. So the next step is to develop rockets that work with even less peroxide or a substance that is already present in the body, such as glucose. This is one of the few engines that can operate in blood, urine or saliva, says Joseph Wang, a nano-engineer at the University of California, San Diego. A nose for the time of death TINY finger-like projections lining the nose continue to beat after death. Since the beating of these cilia slows at a predictable rate, forensic teams should be able to estimate time of death more accurately. Pinpointing precisely when someone died can be a challenge for investigators. They can look at body temperature or decomposition rate, but these indicators can be confounded by temperature, or whether the person was involved in a struggle, say, shortly before death. The beating rate of cilia could provide an additional tool to help decide time of death, especially if it was within the previous 24 hours. Nasal cilia are tiny projections that waft mucous, dust and bacteria out of the nose and into the throat. Biagio Solarino of the University of Bari in Italy and his colleagues suspected that cilia continue to beat after death. So they took a scraping of the inside of the nose from 100 cadavers to examine the cilia. “Motility was observed as long as 20 hours after death,” says Solarino, who will present his results at the International Symposium on Advances in Legal Medicine in Frankfurt, Germany, this week. They hope to use the cilia to judge time of death since not only does the beating slow gradually but it also seems relatively immune to environmental factors. JOTI/SPL For new stories every day, visit newscientist.com/news
