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See Inside June 2009

News Scan Briefs: Hand Transplant Recipients Switch Handedness

Also: ending nerve damage from needles, "caveman" connection to humans, electromagnetic chatter, and laser beams that curve

On the Other Hand
Double-hand transplantations could switch the handedness of patients. Two men who lost both hands in work injuries received transplants after three to four years of waiting. Despite such a long time—the brain typically reassigns areas linked with control of the amputated limb to other muscles—researchers at the French Center for Cognitive Neuroscience in Lyon found the patients’ brain could connect to the new hands, which subsequently could perform complex tasks (in a demonstration, one patient repaired electrical wires). Although both men were right-handed, their left hand connected with their brain at least a year sooner than their right hand did, and they stayed left-handed. The reason for this switch, reported online April 6 by the Proceedings of the National Academy of Sciences USA, is unclear—perhaps the prior dominance of the right hand made the corresponding brain regions less flexible to reconnections or the surgeries were done slightly differently.  —Charles Q. Choi

Point Taken
Every year hundreds of thousands of people develop medical complications such as nerve injury when hypodermic needles penetrate deeper than they should. A novel needle devised by researchers at Harvard Medical School and their colleagues automatically stops itself from going too far. The force from the first push of the device’s plunger goes only to a blunt, flexible wire inside the hollow needle. As long as this filament remains unbent, a special clutch keeps the rest of the needle from advancing. On encountering resistance from tissue, the wire buckles and the clutch permits the entire needle to move forward. On reaching a target cavity, such as a blood vessel, the filament no longer faces resistance and so straightens out, preventing the needle from proceeding but uncovering the tip to allow medicine out. Described in the April 7 Proceedings of the National Academy of Sciences USA, the needle might reach clinics in three to five years.  —Charles Q. Choi

Living Alike
The Geico “caveman” advertising campaign might be on to something. Evidence presented in April at the Paleoanthropology Society meeting in Chicago suggests that Neandertal behavior resembled that of early modern humans. Bruce Hardy of Kenyon College studied artifacts from Hohle Fels, a site in southwestern Germany. It contains tools made by Neandertals between 36,000 and 40,000 years ago as well as items manufactured by early modern humans between 33,000 and 36,000 years ago. Both groups lived under similar environmental conditions at this site, making their cultural remains ideal for comparison. Hardy examined the wear patterns and residue on the tools and found that although modern humans had a larger range of implements, both groups engaged in similar activities, such as using tree resin to bind stone points to wooden handles and crafting tools from bone and wood. He speculates that the Neandertals did not invent more tools because they could survive just fine with what they had.  —Kate Wong

Electromagnetic Chatter
Single-celled organisms may communicate via radiation. Daniel Fels of the Swiss Tropical Institute in Basel grew the microbe Paramecium caudatum in complete darkness in clear tubes, which prevented the cells from passing chemical messages to one another. Fels discovered the microorganisms could influence the feeding behavior and growth rates of neighbors in other tubes, suggesting that electromagnetic signals were involved. The microbes seemed to use at least two frequencies to communicate, one of which was in the ultraviolet (UV) range. For instance, small populations of paramecia grew significantly better when separated from larger ones by glass that blocks UV light than by quartz glass, which permits UV rays. The cellular structures behind these messages have not yet been identified, but in the April 1 PLoS ONE, Fels suggests that these signals could lead to novel noninvasive medical techniques.  —Charles Q. Choi

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