Heart power

A tiny nanowire inserted inside a rat's body can turn energy from the rat's heartbeats or breathing into electric current, according to a recently published study from researchers at the Georgia Institute of Technology in Atlanta. These 'nanogenerators' could eventually be used for detecting medical conditions, such as low blood sugar.

Zinc oxide nanowires are piezoelectric, meaning that they generate electric fields in response to mechanical strain. In this study, Zhong Lin Wang and his team attached a zinc oxide nanowire to a flexible polymer substrate (Adv. Mater. 22, 1–4; 2010). To protect the device from bodily fluids, they encapsulated it in a polymer casing and then attached the nanodevice to the diaphragm of a rat. When the rat breathed, the nanowire stretched, causing the device to generate an average of two millivolts of voltage and four picoamperes of current per breath. When the device was attached to the heart of a rat, the device gave an output of 2 millivolts and 30 picoamperes per heartbeat.

Though this device generated only small amounts of energy, the authors note that their study provides “a feasible approach to scavenge the biomechanical energy inside the body.” According to Technology Review, the authors are planning to connect a nanosensor inside an animal to a higher-output nanogenerator.

Understanding acupuncture

Though acupuncture has been used for more than 4,000 years, researchers have had difficulty understanding how it works. Now, a recent study in mice helps to explain one way in which acupuncture might reduce pain (Nat. Neurosci. published online 30 May 2010; doi:10.1038/nn.2562).

Maiken Nedergaard of the University of Rochester (NY) and colleagues induced pain in the right hind paws of mice. To mimic a typical acupuncture treatment, they then gently inserted a needle just below the right knee of each mouse and rotated the needle once every 5 minutes for 30 minutes. For about an hour after the procedure, the injured paws of these mice were much less sensitive to touch or heat than before the treatment. Other analysis showed that acupuncture led to the release of adenosine, a natural painkiller, in nearby tissues. Mice lacking a key cell receptor for adenosine did not respond in the same way to acupuncture treatment as did the wild-type mice.

The team pretreated some mice with deoxycoformycin, a drug that inhibits the elimination of adenosine. After acupuncture, these mice had suppressed responses to pain for more than an hour than did mice that had been pretreated with control solution. The authors think that medications that interfere with adenosine receptors or with adenosine metabolism might help to improve the clinical benefits of acupuncture in humans.

New protection against Ebola virus

Outbreaks of Ebola virus infection are associated with hemorrhagic fever and high mortality rates. There are currently no preventive or protective treatments for Ebola infections, although some progress has been made in vaccine development. Development of strategies for managing infection once a person has been exposed to the virus has been much slower.

One research group previously reported that small interfering RNAs (siRNAs) targeting the Ebola virus could protect guinea pigs from infection. Although rodent studies are useful in identifying prospective treatments for Ebola, efficacy in guinea pigs may not accurately predict efficacy in primates because guinea pigs have relatively low susceptibility to Ebola infection. Therefore, the group, led by Thomas W. Geisbert (Boston University School of Medicine, MA), assessed the efficacy of siRNA treatment against Ebola infection in rhesus macaques.

First, macaques were exposed to Ebola virus. Two of three macaques given four siRNA treatments, and all of four macaques given seven treatments, survived the viral challenge (Lancet 275, 1896–1905; 2010). More work is needed to determine the optimal dosage and timing of the treatments, but the study proves that siRNA-based strategies can be effective in postexposure treatment of Ebola infection in primates.