September 27, 2012
For most of us, an ideal electronic device is durable and long-lasting. An interdisciplinary team of researchers, though, has developed a new class of circuits that forces us to rethink our concept of what electronics can do in the world.
Their invention—an ultrathin, clear, silicon-based circuit that functions for a precise period of time, ranging from minutes to years, then dissolves completely in water—could lead to routine implantation of tiny electronics inside the body or in the environment without any need to extract them after use. The research team, from Tufts University, Northwestern University and the University of Illinois, reveals their advance in a paper published today in Science. They refer to it as an initial entry into a new field called “transient electronics.”
“These electronics are there when you need them, and after they’ve served their purpose they disappear,” said Yonggang Huang, who led the Northwestern portion of the team, which focused on theory, design and modeling. “This is a completely new concept.”
The circuits inside conventional electronics are made of silicon, a material that naturally dissolves in water over time but at rates that mean a typical circuit would take hundreds of years to disappear. The sheets of silicon that make up these new transient electronics, however, are just a few nanometers thick, so they can dissolve over the course of minutes when they come in contact with even a tiny volume of water or a body fluid. Watch how the circuit dissolves (almost like a breath-freshening strip) when it gets sprinkled with water, 15 seconds into this video:
So far, by printing circuits using soluble conductors (like magnesium or magnesium oxide) on the ultrathin silicon sheets, the researchers have created functional transistors, diodes, wireless power coils, temperature and strain sensors, photodetectors, solar cells, radio oscillators, antennas and even simple 64 pixel digital cameras that dissolve completely.
The research team imagines a range of different applications for their invention. Currently, surgeons are reluctant to implant medical monitoring devices (say, to check for an infection post-surgery) because of the difficulty of extracting them. But an implant made out of transient electronics that performed a diagnostic or monitoring function for a set period of time, then dissolved safely in the body, could become a routine way for a doctor to follow up on a patient’s progress after surgery. Other transient devices could monitor temperature or muscle activity, or deliver medicine internally.
In rats, the team successfully demonstrated an implant that monitored for a bacterial infection at a surgical incision site and could eradicate it via heating if necessary. Three weeks after being implanted, only traces of the circuit remained in the rat’s skin.
Additionally, transient circuits could be used in environmental monitoring situations, such as using wireless sensors that are applied after an oil spill to track ground conditions before dissolving after a set period of time. Monitors could also be placed on buildings or roadways to detect gradual structural deformation over time. Transient circuits could even make their way into consumer electronics—a phone’s inner circuitry could perhaps be designed to dissolve in the presence of a particular liquid—to combat the increasing amount of electronic waste that’s produced as we frequently upgrade phones or other devices.
Because silicon is naturally abundant in the environment and the conducting material, magnesium, is biocompatible—and naturally occurs in the body—the researchers believe that the circuits will not harm our health or the environment when they dissolve. Of course, it remains to be seen whether this is the case, and further testing is necessary before the invention is implemented.
Each of these various applications would require different rates of decay. “A medical implant that is designed to deal with potential infections from surgical site incisions is only needed for a couple of weeks. But for a consumer electronic device, you’d want it to stick around at least for a year or two,” said John Rogers, who led the University of Illinois group that worked on experimentation and fabrication.
To control just how long a circuit sticks around, the researchers cover it with protective silk coats of different thicknesses. The thicker the silk, the longer it takes to dissolve, and only then does the silicon start to disintegrate. Until the silk is gone, the circuits can function while completely submerged in water or a phosphate buffered saline liquid, chemically similar to fluids in the human body.
The research group is currently refining their designs and conducting more animal tests, as well as working with a semiconductor manufacturer to test the potential for industrial-scale manufacturing. The fact that the technology relies upon printing circuits on a silicon surface—like the vast majority of electronics in existence—means that minor alterations to the manufacturing process could yield functional transient circuits.
“It’s a new concept, so there are lots of opportunities, many of which we probably have not even identified yet,” Rogers said. “We’re very excited. These findings open up entirely new areas of application.”
September 25, 2012
Acne afflicts nearly 90 percent of Americans at some point in their lives, but scientists have made surprisingly little headway in understanding and combating the skin condition. For sufferers of severe acne, the treatments available— benzoyl peroxide, antibiotics and Accutane—are limited in effectiveness and can cause a range of undesirable side effects.
New research, though, is pointing towards a novel approach that could someday serve as a solution: the use of viruses to attack the bacteria on the skin that cause acne breakouts. After studying the Propionibacterium acnes phages virus and sequencing its DNA, a team of researchers from the University of California, Los Angeles and the University of Pittsburgh believes that it could be an ideal candidate for the development of a new sort of anti-acne therapy. Their findings were published today in the journal MBio.
“Acne affects millions of people, yet we have few treatments that are both safe and effective,” said Robert Modlin of UCLA, a co-author of the paper. “Harnessing a virus that naturally preys on the bacteria that cause pimples could offer a promising new tool.”
Acne is caused by blockages in the skin’s follicles formed by an oil called sebum, which is produced by the body to prevent hair follicles from drying out. When sebum forms a plug in the follicle, it allows the naturally occuring bacteria P. acnes to trigger an inflammatory response in the skin, leading to swollen red bumps and other symptoms. Antibiotics and other prescription acne treatments work by killing these bacteria, but over time, antibiotic-resistant strains of the bacteria have emerged, rendering these products less effective.
The research team decided to explore the potential of an entirely different method—killing the bacteria by using a type of virus that also lives naturally on the human skin and has specifically evolved to infect P. acnes bacteria. To do so, they gathered both the bacteria and 11 different versions of the virus (P. acnes phages—named for the host bacteria it preys upon) from the faces of volunteers using over-the-counter pore-cleaning strips.
An analysis of the different viruses’ DNA, as collected from the volunteers, revealed surprisingly little genomic diversity (all samples were identical for at least 85 percent of their DNA)—a trait that would make developing an acne treatment simpler because it indicates that any formulation of the virus would be effective in killing the P. acnes bacteria for many different people. This conclusion was bolstered by the fact that, when the researchers cultured bacterial samples from different volunteers and added the varieties of virus, the viruses were effective in killing a broad range of different sub-varieties of bacteria.
Additionally, the specificity of the virus’ killing mechanism makes it an appealing candidate for an anti-acne treatment, in contrast to antibiotic treatments that can also harm populations of beneficial varieties of bacteria that live on our bodies. “Phages are programmed to target and kill specific bacteria, so P. acnes phages will attack only P. acnes bacteria, but not others like E. coli,” said lead author Laura Marinelli of UCLA. “This trait suggests that they offer strong potential for targeted therapeutic use.”
The researchers believe that the key to the virus’ killing ability is an enzyme it produces called endolysin, which may act by breaking down bacterial cell walls. A better understanding of how this enzyme works is a next step towards eventually developing a treatment, either based on endolysin isolated from the virus, or using the virus itself.
The team plans to test endolysin on its own to determine if can kill P. acnes bacteria on its own, without the virus. If the enzyme is successful in petri dishes, they may proceed by testing an extract made from the virus on participants to see whether it is a safe and effective way to prevent acne in human skin.
September 3, 2012
Some soldiers who serve in Afghanistan or other war-torn countries return home with visible injuries: concussions, broken bones or amputated limbs. Many others, though, suffer from injuries we can’t visibly see. The daily strain of being exposed to armed combat, enemy fire and unpredictable explosions can lead to a range of behavioral symptoms, including fatigue, slower reaction times and a difficulty in connecting to one’s immediate surroundings.
A new study of soldiers returning home from Afghanistan, published today online in the Proceedings of the National Academy of Sciences, hints at the underlying cause for these behavioral changes. Researchers from the Netherlands and elsewhere used neurological exams and MRI scanning techniques to examine 33 soldiers before and after a four-month deployment in NATO’s International Security Assistance Force, and compared them to a control group of 26 soldiers who were never deployed.
The results were sobering—and indicate that a relatively short period of combat stress can alter an individual’s neurological circuitry for a long time.
As compared to the pre-deployment baseline tests and the control group, the returning soldiers’ brains showed distinct differences, despite the fact than none had suffered physical injuries and only one had exhibited enough symptoms to be clinically diagnosed with post-traumatic stress disorder. A pair of different techniques using MRI—diffusion tensor imaging, which measures the diffusion of water in the brain, indicating tissue density, and fMRI, which measures blood flow in various parts of the brain—revealed that the soldiers’ midbrains had reduced tissue integrity and showed less neuron activity during a working memory task.
Working memory is related to sustained attention, the researchers note, which could explain the results of the study’s neurological performance tests. As part of the tests, the soldiers were asked to complete a complex, mentally draining task known as a dot cancellation test. When compared to the other groups, those returning from combat committed more errors in the task over time, indicating a reduced ability to pay sustained attention. On an individual basis, participants with a greater reduction in midbrain activity were more likely to be error-prone in completing the dot cancellation test.
Both of these changes appeared when the soldiers were tested six weeks after combat, but mostly disappeared when they returned for a follow-up another 18 months later. However, a related change in the soldiers’ neurological makeup—a reduction in connections between their midbrain and prefrontal cortex—persisted in the follow-up, nearly two full years after exposure to combat was over. This is good reason, the researchers feel, to suggest that combat stress can alter the brain over the long term, and perhaps alter other areas of the brain as well.
“These results suggest that the human brain can largely recover from the adverse effects of stress,” they write in the study. “However, the results also reveal long-term changes that may increase vulnerability to subsequent stressors and lead to long-lasting cognitive deficits.”
Other researchers have examined how acute periods of stress can alter brain chemistry. Many believe that sudden bursts of hormones associated with stress, such as cortisol and norepinephrine, can permanently impair brain tissue.
Of course, lab studies can test returning soldiers’ ability to pay sustained attention to a task for several minutes, but whether combat has affected their ability to navigate social situations or make long-term decisions is another question entirely. The researchers involved, though, note that we should consider the possibility.
“The persistent changes in mesofrontal connectivity may increase the vulnerability to subsequent stressors and promote later development of difficulties with cognitive, social and occupational functioning,” they write. What soldiers see in combat, it seems, can stay with them when they come back home.
August 16, 2012
The 1960 approval of the first oral contraceptive pill by the FDA for U.S. markets had a wide range of impacts on the nation. The availability of a reversible and reliable contraceptive method was unprecedented in human history; its rapid spread played a crucial role in the sexual revolution, made the cover of TIME Magazine and may have led to more women attending college and graduate school.
Ever since, scientists have been attempting to figure out a way to develop a contraceptive pill for men. Today, researchers from the Dana-Farber Cancer Institute and the Baylor College of Medicine announced that they have identified a chemical compound that could lay the groundwork for a future oral drug that reversibly inhibits male fertility.
“Our findings demonstrate that, when given to rodents, this compound produces a rapid and reversible decrease in sperm count and mobility with profound effects on fertility,” says James Bradner, the senior author of the study documenting the advance, to be published tomorrow in the journal Cell. ”These findings suggest that a reversible, oral male contraceptive may be possible.”
The researchers actually stumbled upon the compound, called JQ1, while on an entirely different mission: trying to find a cure for cancer. The chemical (named after lead chemist Jun Qi) was originally synthesized at Dana-Farber to block the activity of a cancer-causing protein known as BRD4—and in fact, tests in several laboratories have shown it to be a promising treatment for several forms of cancer, including leukemia, multiple myeloma and lung cancer.
“We previously had demonstrated it could inhibit a specific protein called BRD4, but we learned that the molecule also inhibits a related molecule called BRDT,” Bradner says. “BRDT has no role specifically in cancer but is very important for the development of mature sperm, and so we wondered: Could the JQ1 molecule, intended originally for cancer, have activity as a male contraceptive agent?” Computer modeling suggested that the molecule could be effective in this role, but the only way to know for sure would be to test it on live animals.
So Bradner and his colleagues sent samples of JQ1 off to Martin Matzuk‘s lab at Baylor, where his team injected the isolated compound into male mice daily for several weeks and allowed them to mate with females. Some mice required 50 mg per day, some 75 and some 100, but ultimately, the results were all the same: Despite their avid attempts at breeding, JQ1 prevented the mice from producing offspring. Examination showed that the mice had significantly lower sperm counts and sperm with reduced mobility, as compared with a control group of mice that received injections of an inactive fluid.
The molecule works by entering the testes and disrupting spermatogenesis, the process by which sperm mature into functional male gametes. Specifically, JQ1 interferes by binding to a pocket of BRDT, which facilitates the expression of genes important for sperm maturation.
Crucially, the mouse experiments showed that JQ1′s effects were rapid and reversible: In all mice, sometime between a month or two after JQ1 injections were discontinued, normal sperm production and fertility resumed. Additionally, the drug did not affect mating behaviors, alter levels of testosterone or other hormones or produce negative health effects in offspring that were conceived after JQ1 injections were stopped.
All of this does not mean that doctors will start prescribing a male contraceptive pill anytime soon. “At the time we made JQ1, we had not optimized it for its drug-like properties,” Bradner says. “So no, JQ1 is not intended for human use as a male contraceptive agent.” In addition to conducting further experiments to establish the safety and efficacy of JQ1 in humans, researchers would need to produce a form of it that could be delivered orally and enter the bloodstream in order to make a male contraceptive pill.
Still, because the structure of BRDT in mice and humans is similar, the new development is likely to get fans of a potential male contraceptive excited. “The structural and biochemical data provided by this paper are effectively a blueprint for developing a drug-like derivative of JQ1 that could be very potent,” Bradner says. ”JQ1 shows initial promise as a lead compound for male contraception.”
August 3, 2012
Octopoteuthis deletron, a species of squid found deep in the cold waters of the Pacific Ocean, has many natural predators: elephant seals, giant grenadier fish and the mysterious Perrin’s beaked whale.
To protect itself, the squid has developed a a rather unusual defensive mechanism, recently discovered by cephalopod researcher Stephanie Bush of the University of Rhode Island: When attacked, the squid plants its arms in its predator and then breaks them off. While seemingly counterproductive, there’s a reason for this tactic.
“If a predator is trying to attack them, they may dig the hooks on their arms into the predator’s skin. Then the squid jets away and leaves its arm tips stuck to the predator,” Bush explains. “The wriggling, bioluminescing arms might give the predator pause enough to allow the squid to get away.” In the squid’s extremely dark habitat—anywhere from 1,300 to 2,600 feet below the surface—this distracting, flashing “disarmament” could be the difference between staying alive and getting eaten.
Scientists have known for some time that lizards and other land-based species can voluntarily detach their appendages to elude predators, a tactic they call “arm autonomy.” But Bush’s discovery, revealed in a paper published this month in the journal Marine Ecology Progress Series, is the first ever documented case of a squid engaging in the practice.
Bush says she first became interested in looking into the phenomenon when she was working as a researcher at the Monterey Bay Aquarium Research Institute and noticed that many wild squid had extremely blunt arms that seemed to be in the process of regenerating. Scientists had speculated that damage caused by researchers’ nets was the underlying reason, but Bush wasn’t so sure. So she and her colleagues sent a remotely-controlled submersible equipped with a video camera deep into the waters of the Monterey Bay Submarine Canyon, found a squid and poked it with the control arm of the vehicle.
“The very first time we tried it, the squid spread its arms wide and it was lighting up like fireworks,” she says. Because the metal control arm was smooth, though, the squid’s arms slid off of it without detaching.
The team then came up with a makeshift solution: They attached a brush used to clean their laboratory glassware to the control arm of the vehicle and then used that to poke the squid. “It then came forward and grabbed the bottlebrush and jetted backwards, leaving two arms on the bottlebrush,” recounts Bush. “We think the hooks on its arms latched onto the bristles of the brush, and that was enough for the arms to just pop off.” Luckily, the team caught the fascinating encounter on camera for us to enjoy.
Bush later found other squid of the same species and repeated the test. Although some were more hesitant to discharge their arms than others, fighting back against the fearsome bottlebrush at first, all engaged in the unusual tactic after sufficient provocation. None of the other squid species she tested did the same. The species appeared to discharge their arms efficiently: Looking under a microscope afterward, Bush saw that most arms were torn as close as possible to the stress point, minimizing the amount of tissue lost.
The squid can regrow their arms, but that takes energy, and swimming around without an arm or two could make capturing food and mating more difficult (the bioluminescent organ on the arms’ tips are used to attract mates). Still, the strategy is a smart one under sufficiently dire circumstances. “There is definitely an energy cost associated with this behavior,” Bush says, “but the cost is less than being dead.”