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Part I: Speed
Could Discovery Lead to End of Sunburn Pain?
Aug. 5, 2013 — The painful, red skin that comes from too much time in the sun is caused by a molecule abundant in the skin's epidermis, a new study shows.
【Time1】
Blocking this molecule, called TRPV4, greatly protects against the painful effects of sunburn. The results were published the week of Aug. 5 in the Proceedings of the National Academy of Sciences (PNAS) Early Edition online. The research, which was conducted in mouse models and human skin samples, could yield a way to combat sunburn and possibly several other causes of pain.
"We have uncovered a novel explanation for why sunburn hurts," said Wolfgang Liedtke, M.D., Ph.D., one of the senior authors of the study and associate professor of neurology and neurobiology at Duke University School of Medicine. "If we understand sunburn better, we can understand pain better because what plagues my patients day in and day out is what temporarily affects otherwise healthy people who suffer from sunburn."
The vast majority of sunburns are caused by ultraviolet B or UVB radiation. In moderation, this component of sunlight does the body good, giving a daily dose of vitamin D and perhaps improving mood. But if people get too much, it can damage the DNA in their skin cells and increase their susceptibility to cancer. Sunburns are nature's way of telling people to go inside and avoid further damage.
Liedtke worked together with a multi-institutional team of researchers: Elaine Fuchs, Ph.D., a professor at Rockefeller University and an investigator with the Howard Hughes Medical Institute and skin biologist; and Martin Steinhoff, M.D., Ph.D., professor of dermatology and surgery at the University of California in San Francisco who is known for his studies on sensory function of skin in health and disease. Together, they investigated whether the TRPV4 molecule, which is abundant in skin cells and has been shown to be involved in other pain processes, might play a role in the pain and tissue damage caused by UVB over-exposure. TRPV4 is an ion channel, a gateway in the cell membrane that rapidly lets in positively charged ions such as calcium and sodium.
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【Time2】
First, the researchers built a mouse model that was missing TRPV4 only in the cells of the epidermis, the outermost layer of the skin. They took these genetically engineered mice and their normal counterparts and exposed their hind paws -- which most resemble human skin -- to UVB rays. The hind paws of the normal mice became hypersensitive and blistered in response to the UVB exposure, while those of the mutant mice showed little sensitization and tissue injury.
Next, they used cultured mouse skin cells to dissect the activities of TRPV4. Using a device engineered by Nan Marie Jokerst, Ph.D., a professor of electrical and computer engineering at Duke's Pratt School of Engineering, the researchers showed that UVB caused calcium to flow into the skin cells, but only when the TRPV4 ion channel was present.
Further molecular analysis uncovered the entire sequence of events in this pathway, with each event affecting the next: UVB exposure activates TRPV4, which causes the influx of calcium ions, which brings in another molecule called endothelin, which triggers TRPV4 to send more calcium into the cells. Endothelin is known to cause pain in humans and also evokes itching, which could explain the urge sunburned patients feel to scratch their skin.
To test whether these findings in mice and mouse cells have human relevance, the researchers used human skin samples to successfully demonstrate increased activation of TRPV4 and endothelin in human epidermis after UVB exposure.
To see if they could block this novel pain pathway, the researchers used a pharmaceutical compound called GSK205 that selectively inhibits TRPV4. They dissolved this compound into a solution of alcohol and glycerol -- basically, skin disinfectant -- and then applied it to the hind paws of normal mice. The researchers found that the mice treated with the compound were again largely resistant to the pain-inducing and skin-disrupting effects of sunburn. Similarly, when they administered the compound to mouse skin cells in culture, they found that it stopped the UV-triggered influx of calcium ions into the cells.
"The results position TRPV4 as a new target for preventing and treating sunburn, and probably chronic sun damage including skin cancer or skin photo-aging, though more work must be done before TRPV4 inhibitors can become part of the sun defense arsenal, perhaps in new kinds of skin cream, or to treat chronic sun damage," said Steinhoff, co-senior author of the study.
"I think we should be cautious because we want to see what inhibition of TRPV4 will do to other processes going on in the skin," Liedtke added. "Once these concerns will be addressed, we will need to adapt TRPV4 blockers to make them more suitable for topical application. I could imagine it being mixed with traditional sunblock to provide stronger protections against UVB exposure."
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http://www.sciencedaily.com/releases/2013/08/130805152420.htm
Sunshine Could Benefit Health and Prolong Life, Study Suggests May 7, 2013 — Exposing skin to sunlight may help to reduce blood pressure, cut the risk of heart attack and stroke - and even prolong life, a study suggests
【Time3】
Researchers have shown that when our skin is exposed to the sun's rays, a compound is released in our blood vessels that helps lower blood pressure.
The findings suggest that exposure to sunlight improves health overall, because the benefits of reducing blood pressure far outweigh the risk of developing skin cancer.
Heart disease and stroke linked to high blood pressure are estimated to lead to around 80 times more deaths than those from skin cancer, in the UK.
Production of this pressure-reducing compound - called nitric oxide - is separate from the body's manufacture of vitamin D, which rises after exposure to sunshine. Until now it had been thought to solely explain the sun's benefit to human health, the scientists add.
The landmark proof-of-principle study will be presented on Friday in Edinburgh at the world's largest gathering of skin experts.
Researchers studied the blood pressure of 24 volunteers who sat beneath tanning lamps for two sessions of 20 minutes each. In one session, the volunteers were exposed to both the UV rays and the heat of the lamps. In the other, the UV rays were blocked so that only the heat of the lamps affected the skin.
The results showed that blood pressure dropped significantly for one hour following exposure to UV rays, but not after the heat-only sessions. Scientists say that this shows that it is the sun's UV rays that lead to health benefits. The volunteers' vitamin D levels remained unaffected in both sessions.
Dr Richard Weller, Senior Lecturer in Dermatology at the University of Edinburgh, said: "We suspect that the benefits to heart health of sunlight will outweigh the risk of skin cancer. The work we have done provides a mechanism that might account for this, and also explains why dietary vitamin D supplements alone will not be able to compensate for lack of sunlight.
"We now plan to look at the relative risks of heart disease and skin cancer in people who have received different amounts of sun exposure. If this confirms that sunlight reduces the death rate from all causes, we will need to reconsider our advice on sun exposure."
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http://www.sciencedaily.com/releases/2013/05/130507195807.htm
Brain Games Versus Nature Documentaries
Brain games may not be as effective at boosting mental capacity as people hope. Rachel Kaufman
for National Geographic News
Published April 15, 2013
【Time4】
It seems brain-training games—online tests, quizzes, games, or flash cards designed to improve attention, memory, creativity, and concentration—are everywhere. But do they work? A recent study published in the journal PLoS ONE says … maybe not.
When researchers tested employees of the Australian Taxation Office to see if brain games boosted their mental capabilities, it turned out that workers who watched nature documentaries instead fared better on tests measuring language skills (as well as quality of life and self-esteem).
Cate Borness, a graduate researcher at the University of New South Wales in Sydney,Australia, tested 135 Australian public-sector employees on their productivity, stress, cognitive functions, and overall quality of life to get baseline performance levels.
Then she and her colleagues randomly assigned them to either a test group that underwent 16 weeks of short brain-training sessions using Happy Neuron software, or a control group that spent 16 weeks watching short nature documentaries and answering brief questions about them (to prove they'd watched the videos). The short clips were taken from National Geographic’s video website.
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【Time5】
Nature and Language
"We didn't find a huge impact in terms of the cognitive training program," Borness said. But, oddly enough, the group that watched the documentaries left the study with statistically significant benefits.
The nature video group said that their stress had gone down, their quality of life had increased, and—according to tests that Borness and her colleagues gave both groups—their language skills had improved.
That could be because the videos and short questionnaires were language-based, Borness said. "You're listening to a video and then answering questions about it."
The brain-training games, on the other hand, were designed to improve multiple measures of intelligence and cognitive function; only about 20 percent of the games emphasized language skills.
One such game involved users having to fit words into boxes such that the last letter of a word was also the first letter of another word. The language-game players did see a slight increase in their language skills, but not nearly as much of an increase as the video watchers.
In the paper, Borness speculates that this could be because the games focused on language only a fifth of the time, with other games dedicated to memory, attention, reasoning, and more. Yet those games didn't produce any measurable effects in the test population.
Brain games like these could still be useful for some people, Borness said. "The product may be questionable in its efficacy, [but] I think part of the problem is not doing enough of it to have an effect." However, she added, "we haven't figured out what is 'enough.'"
Despite the results of the study, Borness says she herself is still a user of brain-training games. "I think they're fun. I'm one of those people who can't do nothing, so I get on my phone and play games."
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http://news.nationalgeographic.com/news/2013/03/130410-brain-games-neuroscience-culture-science/
Part II: Obstacle
Small but deadly
The biggest extinction in history was probably caused by a space rock that changed the climate Jul 27th 2013 |From the print edition
【Time6】
AS EVERY schoolchild knows, the dinosaurs were wiped out in an instant, when a rock from outer space hit what is now southern Mexico. That happened 66m years ago, at the end of the Cretaceous period. Well-informed schoolchildren also know that this mass extinction was neither unique nor the biggest. The geological record speaks of four others since animal life became complex at the beginning of the Cambrian period 541m years ago.
What neither these clever schoolchildren nor anyone else knows, however, is whether these extinctions had similar causes. But evidence is accumulating that the biggest extinction of all, 252.3m years back, at the end of the Permian period, was indeed also triggered by an impact. Nevertheless, though the trigger was the same, the details are significantly different, according to Eric Tohver of the University of Western Australia.
When the dinosaurs vanished they were accompanied by more than 70% of the other animal species on Earth. At the end of the Permian, the extinction figure was more than 80%. And just as the Cretaceous slate-clearing permitted the rise of a hitherto obscure group called the mammals (including, eventually, one now referred to by biologists as Homo sapiens), so the Permian clearance permitted the rise of the reptiles, one branch of which turned into Tyrannosaurus, Diplodocus and all the other names familiar from childhood.
The idea that an impact caused the Permian extinction has been around for a while. As at the end of the Permian, as at the end of the Cretaceous, huge volcanic eruptions had been going on for hundreds of thousands of years. These may have weakened the world’s ecosystems, making them vulnerable to an external shock. But the abruptness of both extinctions indicates that the coup de grâce was administered by something else, and in the case of the Permian some fragments of meteorite of the correct age, found in rock in Antarctica, suggest that, as with the Cretaceous, that something was an asteroid or a comet. What was missing from the story, though, was a suitable crater.
Fracking hell!
Last year Dr Tohver and his colleagues thought they might have found it. They redated a hole that straddles the border of the states of Mato Grosso and Goiás in Brazil, called the Araguainha crater, to 254.7m years, with a margin of error of plus or minus 2.5m years. Previous estimates had suggested Araguainha was 10m years younger, but Dr Tohver has put it within geological spitting distance of the extinction date, which itself has a margin of error of plus or minus 200,000 years.
Which would all be fine and dandy, except most people think Araguainha is too small to be the culprit. It is a mere 40km (25 miles) across. The Chicxulub crater in Mexico, which did for the dinosaurs, is 180km in diameter, and it may have been paired with an even bigger impact in the Indian Ocean. (This could have happened if the incoming object was a comet that broke up in a close encounter with the sun.)
Dr Tohver, however, has an answer to this criticism. His latest paper, just published in Palaeogeography, Palaeoclimatology, Palaeoecology, describes the rock in the area in which Araguainha resides.
After an extensive geological survey, he and his team discovered that a sizeable amount of this rock is oil shale. Any hydrocarbons in the crater would certainly have been vaporised. More intriguingly, the researchers calculate that the impact would have generated thousands of earthquakes of up to magnitude 9.9 (significantly more powerful than the largest recorded by modern seismologists) for hundreds of kilometres around. In effect, it would have been the biggest fracking operation in history, releasing oil and gas from the shattered rock in prodigious quantities.
The upshot, Dr Tohver believes, would have been a huge burp of methane into the atmosphere. Since methane is a powerful greenhouse gas, that burp would have resulted in instant global warming, making things too hot for much of the planet’s animal life. Presto! The Permian mass extinction is explained.
Determining whether this was really what happened will take a lot more digging, of course. Even now, there are those who think the formation of the Chicxulub crater was a coincidence, and that what did for the dinosaurs was actually the volcanoes, so Dr Tohver will have to work hard to convince the sceptics. If he does, though, he will have proved himself a great geological detective, for he will have been responsible for solving one of the biggest puzzles in palaeontology.
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http://www.economist.com/news/science-and-technology/21582243-biggest-extinction-history-was-probably-caused-space-rock-changed