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Mummified Forest Reveals Clues About Climate Change
Environment
Mummified Forest Reveals Clues About Climate Change
Warming temperatures and retreating glacial ice sheets expose land where ancient forests once stood
Rosanne Skirble | Washington, D.C. 22 December 2010
Mummified tree remains, dating back between 2 and 10 million years, were discovered on Ellesmere Island in the Canadian High Arctic.
Photo: Joel Barker
Mummified tree remains, dating back between 2 and 10 million years, were discovered on Ellesmere Island in the Canadian High Arctic.
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A discovery of a mummified forest that's between two and 10 million years old is giving scientists a new window on climate change.
Joel Barker, a research scientist at the Byrd Polar Research Center at the Ohio State University, discovered the mummified forest in 2009. He says a forest ranger on a remote Island in the Canadian Arctic pointed out a stick in the mud in an otherwise barren landscape.
"And sure enough there was all this wood debris at the bottom of this valley," Barker says.
The Ellesmere Island site is one of about a dozen in the Canadian Arctic where warming temperatures and reduced snowfall have caused the glacial ice sheets to retreat and expose land where ancient forests once stood. Barker says what makes this particular forest site unique is that it was so far north.
"To find the source of where this stuff was coming from was pretty exciting. And then to sort of dig in the soil and find leaves, much like the leaves that you'd find in the Spring sort of emerging from a melting snow pack. They look sort of weathered, but you can pick them up and they are still leaves you are holding in your hands from a couple of million years ago."
Barker says these mummified trees - unlike petrified or fossilized wood - didn't decompose or turn to stone. He suspects they were buried suddenly by a massive landslide and entombed in the dry, airless soil. "So, you take away water. You take away oxygen. Things get preserved," he says.
The ancient forest debris looks much as nature left it. The birch, pine and spruce logs, branches and leaves from long ago are remarkably well-preserved, and it's easy to see that they don't match the hardy scrub growing in the Arctic today. The mummified woods more closely resemble the trees found in forests now hundreds of kilometers south.
Ocean sediment cores and the absence of the previously common Metasequoia redwood known to have lived in the region 10 million years ago date the newly-found arctic forest to between two and 10 million years. Barker says the low species diversity is a sign of an ecosystem on the edge of extinction.
The ancient forest was discovered in a valley that today is largely barren landscape.
Joel Barker
The ancient forest was discovered in a valley that today is largely barren landscape.
"This forest existed at a time when the Arctic was cooling and climate was deteriorating very quickly. And so I think this allows us, by looking at the mummified remains, to see how the ecosystem responded to the cooling, how rapidly the cooling occurred and to maybe identify any thresholds that were reached. And once we identify those thresholds, we can start making predictions about how quickly the ecosystem will respond to future warming."
The growth rings on some trees put their age at about 75 years old when they were suddenly buried. Barker notes that the branches appear spindly, with very narrow rings, suggesting the trees were suffering a great deal of stress when they were alive. The polar scientist plans to do further analysis with chemical and DNA testing. His preliminary findings were presented this week at the American Geophysical Union meeting in San Francisco.
Researchers Develop More Effective Prostate Cancer Screening
Health
Researchers Develop More Effective Prostate Cancer Screening
Genetic test could help better detect disease
Art Chimes | St. Louis, Missouri 17 December 2010
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Researchers in Iceland say they've developed a more effective test to screen for prostate cancer.
In many countries, prostate cancer is among the leading causes of cancer deaths in men. Doctors rely on a blood test called PSA (prostate-specific antigen) to screen for the disease. But there are big problems with the PSA test. Now, the researchers in Iceland report having a genetic tweak that will make PSA results a much better indicator of prostate cancer.
Prostate cancer can develop even when PSA scores are in the normal range. Likewise, men with high PSA levels can be completely free of disease. Genetics researcher Kári Stefánsson says the problem is that there's really no such thing as a "normal" PSA level that applies to all men.
"Among normal men - men without any disease in their prostate - there is considerable difference in how high their normal PSA level is. And we managed to find genetic markers that allow us to classify men into those who normally have high PSA, and those who have normally low PSA."
Stefánsson is the CEO of deCODE Genetics, in Iceland, and was earlier on the medical school faculties of the University of Chicago and Harvard. He says adding genetic information to the PSA score personalizes the prostate cancer test.
"So you may actually be a man who was born with naturally very low PSA, and you could actually double your PSA level because you have cancer, and it would still be read as normal. So what we have now is a test that allows us to control for all of this."
Stefánsson and his colleagues describe the new genetic supplement to the PSA test in the journal Science Translational Medicine.
For their study, they used genetic samples from about 2,500 men in Iceland and Britain. Iceland's population is famously homogeneous, and the British component was mostly men of European descent, which raises the question of how reliable the results would be for men of other ethnic groups. Stefánsson acknowledges the issue.
"Most of the drugs on the market today have been developed by doing clinical trials in people of European descent. So there is always a bit of a concern that some of them may work less well for people of other ethnic backgrounds, and the same thing applies to diagnostic instruments."
That may be especially true for Africans and men of African descent, he said, because they have higher rates of prostate cancer and die more often of the disease.
Kári Stefánsson of deCODE Genetics says the genetic supplement to the PSA test could be on the market as soon as next year.
Research Finds Possible New Way to Attack Sleeping Sickness
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Research Finds Possible New Way to Attack Sleeping Sickness
Scientists discover previously unknown part of parasite lifecycle
Art Chimes | St. Louis, Missouri 17 December 2010
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New research on the parasite that causes sleeping sickness suggests possible new ways to attack the disease.
African sleeping sickness affects mostly rural people in 36 sub-Saharan countries. The World Health Organization says there are currently an estimated 30,000 cases. Left untreated, it is fatal.
Sleeping sickness is caused by a parasite that is transmitted to humans by the tsetse fly. The parasite is a one-cell protozoa like ones you might have seen under a classroom microscope, floating around in fluid.
"But it turns out that, under the right conditions, they can actually transition to a multi-cellular form," says Kent Hill, a professor at the University of California, Los Angeles (UCLA) Department of Microbiology. "And in that form there's groups of cells that can sense their environment, that can communicate with one another, and that can engage in coordinate activities."
Hill and his colleagues used an artificial material in the lab to simulate a surface like the tissue inside an infected person. They found that the parasites gathered together in groups on these lab surfaces.
"And that is when we discovered that they change from acting as individual organisms, where they'd come together as these little groups, and then the little groups would actually send out parasites to look for more parasites and make the group bigger."
For years, microbiologists knew about this sort of grouping behavior in bacteria, but it had never been observed before in microbes like the sleeping sickness parasite.
"So we're really, really excited about it because it was kind of a really new observation," Hill says. "It was something we weren't expecting. And it turns out that once we discovered it, if we look at other microbes and bacteria, we kind of felt that we were a little surprised we didn't see it before."
According to Hill, the discovery of this previously-unknown aspect of the parasite's lifecycle opens up new possibilities for disrupting that lifecycle to stop the disease.
For example, when they are grouped together, the individual parasites communicate with each other by exchanging proteins, which bind to receptors on the surface of the cell.
"And so what we've got now are proteins on the parasite that are accessible on live cells to small molecules - meaning like drugs - that you could add to live cells, and they interfere with behavior of the parasite. And so we hope that this will lead to more ability to develop drugs for targets that are accessible on the parasites."
Although this work is still very much in the early research stage, Hill says it's possible that if drugs can be developed to target the sleeping sickness parasite, the same general principle might also be used against the parasites that carry some other tropical diseases including malaria and leishmaniasis.
Hill of the UCLA Department of Microbiology presented his research at the annual meeting of the American Society for Cell Biology in Philadelphia.
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New Technique Avoids Major Surgery If Aneurysm Caught in Time
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New Technique Avoids Major Surgery If Aneurysm Caught in Time
Carol Pearson 17 December 2010
Photo: VOA - C. Pearson
A man points at the Aorta, the largest artery in the body, while holding a model of the human heart
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The American Heart Association reports that the death rate from diseases affecting the heart and blood vessels has dropped by almost 30 percent since the 1990's. Still, heart disease remains a major killer in the United States. It is what claimed the life of US diplomat Richard Holbrooke, who died of a burst aorta December 13.
The aorta is the biggest artery in the body. It travels from the heart to the abdomen and carries blood to the other organs and other arteries. Healthy arteries are smooth and elastic, but in a weak one, blood flowing through can cause it to form a bulge. If that bulge tears open, chances of survival are slim.
There are few symptoms beforehand and even with immediate medical treatment, only a small percentage patients survive. Risk factors include age.
Dr. Richard Rubin, the chief cardiologist at Sibley Hospital in Washington, said, "As we get older, the aorta gets a little more brittle. Forces like high blood pressure and athrosclerotic plaque in the arteries can weaken the wall of the aorta and make it more brittle, and then at some point, if the pressure is excessive, it can rupture."
There are other factors, such as excessive weight or sudden bursts of energy.
"What is especially dangerous is a sudden surge in the pressure, for example, when you are shoveling snow or if somebody askes you to move a piece of furniture and you give a tremendous exertion, your blood pressure can skike up suddenly, and that can be especially tearing to the wall of the aorta," said Dr. Rubin.
Aneurysms can be detected by X-ray or by imaging techniques such as an echocardiogram, an MRI (magnetic resonance imaging) or a CT scan. That's how Kevin Healey's doctor detected his aneurysm two years ago.
"He did an echogram, and noticed an irregularity in the size of the heart. So he followed that up with a CT scan and found an aneurysm on the aorta," said Healey.
Doctors repaired Healey's aneurysm, but Dr. Rubin explains that when the aneurysm suddenly bursts, the situation becomes a life-or-death emergency. "When this happens, the volume of blood in your body gets dumped into the chest cavity or the abdominal cavity, and that is a medical emergency. Your blood will leak out, your blood pressure will drop, and then all of the vital organs of the body will not receive the proper amount of blood because it has leaked out through the tear," he said.
Doctors can cut out the aneurysm and replace it with a patch or artificial piece of blood vessel. Some Australian doctors have devised a way to repair an aneurysm without major surgery.
Dr. Tony Grabs performs this procedure at St. Vincent's Hospital in Sydney. "The significant improvement in the design, the technology, has enabled us to undertake this operation really from two small cuts in the groin and also a small cut in the arm to get access to the arteries. So it really is revolutionary and changes the whole way that certainly I think about the treatment of aneurysms," he said.
While age can be a factor, doctors say keeping your cholesterol, blood pressure and weight within normal limits can help keep your aorta healthy and reduce your chances of having an aneurysm.
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