A hormone produced in the gut appears to limit bone formation, scientists report in Cell [subscription required]. The hormone, serotonin, is the same one produced by the brain to regulate mood, learning, and sleep, but the new study finds that serotonin produced by the gut has an entirely separate function. Mice engineered to produce extra serotonin formed weak bones, while mice engineered to produce less serotonin developed extra-strong bones. The research, though still basic, suggests new avenues of osteoporosis research in humans. “It’s what you’d call a landmark study,” Bjorn Olsen [a Harvard cell biologist who was not involved with the study] says. “It opens new doors” [Science News].
Although serotonin produced by the gut makes up 95 percent of the body’s serotonin, its function had not been well understood. The connection between serotonin and bone formation revealed itself through two types of rare human diseases, both involving the gene Lrp5. People with one mutation produced less Lrp5 protein, developing fragile bones and blindness, while people with another mutation produced extra Lrp5 protein, developing unusually dense bones and resistance to osteoporosis. However, when the authors of the new study looked into the gene further, they were surprised to find that it acted not in bone cells but in cells of the gut. “We, as bone [researchers], thought of the skeleton as functioning independent of everything else,” said [Cliff Rosen, a bone biologist]. This group “asked the question, ‘could there be other regulators outside the skeleton that are regulating bone?’ and found the answer to be ‘yes.’” [The Scientist].
One-third of China‘s Yellow River is no longer fit for any use, and only one-sixth is safe to drink, according to a bulletin released over the weekend by the Chinese government. It reported the results of a 2007 study that surveyed water quality along the 5,464-kilometer-long river, which has become increasingly polluted from booming riverside industries and raw human sewage. Li Xiaoqiang of the Yellow River Conservancy Committee, which ran the study, called for “urgent action” to save the river, and added forlornly: “I wish that a harmony could be achieved between development, utilisation and protection of the river someday” [Telegraph].
The 2007 study monitored the river’s mainstream and its 35 tributaries, with the combined length totaling 13,492.7 km, and found 4,557.6 km, or 33.8 percent of the waterways monitored, to have polluted water classified as type-five negative [XinHua]. The United Nations Environmental Program considers level five water to be unfit for drinking, aquaculture (such as fish farming and oyster farming), agriculture, and industrial use. Only 16.1 percent of the river water was rated level one or two, considered safe for drinking and household use. Of the 4.29 tons of pollution discharged into the river, industry and manufacturing contributed 70 percent and human sewage made up most of the rest, the bulletin reported. Specific pollutants were not reported. Wen Bo of the environmental group Pacific Environment said “It’s not surprising…They are just treating the river as a dumping site. It’s basically a sewage channel for the provinces that share the river” [AP].
A cooling climate, not human hunters, were at fault for the extinction of the prehistoric cave bear (Ursus spelaeus), according to a new study. Researchers examining cave bear remains now say the giant vegetarians died from starvation and much earlier than previously thought. “The disappearance of the cave bear around 27,500 years ago was probably due to the significant decline in quantity and quality of plant food, which in turn was the result of marked climatic cooling,” [Telegraph] said researcher Anthony J. Stuart.
Previous radiocarbon dating of cave bear remains incorrectly placed their apocalypse at 14,000 years ago because some of the remains were actually those of brown bears, still alive today, that were mistakenly identified. The new study excludes previous errors and includes new data taken from remains found in ancient hibernation sites in the Alps. The new extinction date, 27,800 years ago, coincides with a period of significant climate change, known as the Last Glacial Maximum [or Ice Age], when a marked cooling in temperature resulted in a reduction or total loss of the vegetation that the cave bears ate (today’s brown bears are omnivores) [LiveScience.com].
The secret to a dolphin’s speed is sheer strength, according to a new study that used high-tech measurements to finally put a 70-year-old conundrum to rest. In 1936, British zoologist James Gray incredulously observed dolphins swimming at speeds of over 20 mph. He estimated that the dolphins should only be able to produce a tenth of the necessary force and imagined that something about the dolphins’ skin allowed them to overcome the force of drag in the water and reach high speeds. “For the first time, I think we can safely say the puzzle is solved,” said [researcher] Tim Wei…”The short answer is that dolphins are simply much stronger than Gray or many other people ever imagined.” [BBC News].
Although most biologists had long rejected what became known as Gray’s Paradox, there has never been a study to determine the strength of a dolphin’s kick. To observe the powerful swimmers up close, researchers recruited two retired U.S. Navy dolphins, Primo and Puka, to swim in a specially designed tank filled with tiny bubbles that make the movement of water visible. The tank was too small to capture video of the dolphins at full speed, so they also videotaped them performing tail stands on the water (think Sea World). The thrust was calculated based on the dolphins’ weight and measurements of the wake created by their tails [AP].
One in five breast cancer tumors may regress without treatment, a new study suggests. Researchers screening women who had a history of regular mammograms and those who did not report that those in the first group were diagnosed with 22 percent more breast cancers, implying that such a percentage of cancers would have eventually gone away on their own. The study opens up a controversial debate on whether early and aggressive treatment of breast cancer is always the best procedure. But many experts are wary of the new findings, saying the conclusions were incorrectly drawn and fearing they will discourage women from getting mammograms. “The idea that somehow these cancers go away entirely is, I would say, an intriguing hypothesis, but one we don’t have a lot of evidence to support,” [Reuters] said Dr. Eric Winer.
Researchers in Norway followed two groups of women, each numbering more than 100,000, for six years. The first group, monitored from 1992 to 1997, did not receive mammograms until the end of the study. (Mammograms were not common in Norway until 1996.) The second group, monitored from 1996 to 2001, received mammograms every two years. For every 100,000 women who were screened regularly, 1,909 were diagnosed with invasive breast cancer over six years, compared with 1,564 women who did not have regular screening [New York Times]—a difference of 22 percent. The researchers attribute this difference to the number of undetected tumors in the first group that vanished on their own during those six years.
Unfavorable results of drug trials are often swept under the rug, according to a new review of FDA drug applications. Nearly a quarter of drug trial outcomes submitted to the FDA by pharmaceutical companies—most of them unfavorable—remained unpublished or only partially published after five years. Published results were often positively skewed from those originally reported to the FDA. “These new findings confirm our previous suspicions that this is happening on a much broader systemic level. It shows that information is unavailable to those who really need it the most — the clinicians and the researchers,” [Science News] says An-Wen Chan of the Mayo Clinic.
Drug companies are required to submit the results of all drug trials to the FDA as part of new drug applications. After approval, these results are supposed to be made public, usually in the form of scientific publications. However, the new review published in PLoS Medicine found disturbing omissions and bias on the road to publication. The new analysis examined 164 trials for 33 new drugs that were approved by the FDA from January of 2001 to December 2002. By June 2007, one quarter of the trials were either published only in a partial form — as an abstract, or part of a pooled publication — or were not published at all [Science News]. Of 43 negative outcomes reported to the FDA, only 20 were later published. Nine percent of all published outcomes were more positive than those originally reported to the FDA.
Ocean acidification is happening at 10 to 20 times the rate predicted by existing climate models, according to an eight-year study. The rapid acidification of the oceans is linked to global warming and may be a sign that the oceans, the largest absorber of atmospheric carbon dioxide, may not be as hardy as presumed. The changes threaten disaster for marine life with shells that are easily corroded by acid. Marine biologist Nancy Knowlton said, “This is typical of so many climate studies—almost without exception things are turning out to be worse than we originally thought.” [National Geographic News].
The study was done around Takoosh Island off the coast of Washington state and represents the first detailed dataset on variations of coastal pH at a temperate latitude, where the world’s most productive fisheries are found [Times of India]. The researchers took over 24,000 measurements of ocean pH over an 8-year period. During that time, the pH of the seawater was predicted to decrease by only 0.015 points. Instead, the data showed that seawater pH dropped by 0.36 to about 8.1. “The increase in acidity we saw during our study was about the same magnitude as we expect over the course of the next century,” said study co-author Timothy Wootton [National Geographic News].
Contrary to conventional wisdom, marijuana may actually fight memory loss, scientists report—but only if taken in small doses amounting to just one puff a day. Researchers tested a compound similar to THC, the main psychoactive substance in marijuana, on rats and found that the chemical reduces inflammation in the brain and promotes the growth of new brain cells. Elderly rats given the compound performed better on learning and memory tasks. “Could people smoke marijuana to prevent Alzheimer’s disease if the disease is in their family? said [researcher Gary Wenk]. “We’re not saying that, but it might actually work” [Telegraph].
In one part of the study, researchers injected the THC-mimicking drug, called WIN-55212-2, into young rats with inflammation in their brains. The drug reduced inflammation. In a second part, the researchers injected WIN into older rats that were then put into a swimming tank with hidden resting spots. The medicated rats were better able to find and remember the resting spots. Dissection of the rat brains revealed not only reduced inflammation but the growth of new neurons. The results were presented at last week’s Society of Neuroscience meeting.
For the first time, carbon dioxide has been detected in the atmosphere of an exoplanet, astronomers working with the Hubble Space Telescope report. Although the Jupiter-sized planet, which closely orbits the star HD 189733 about 63 light-years from Earth, is much too hot to support life, scientists are hailing the discovery as an exciting technical achievement. “In that context, the carbon dioxide measurement constitutes a dress rehearsal …for our long-term goal of trying to detect signs of life or signs of habitability on terrestrial-mass planets or super Earths in the habitable zone,” [Science News] says Mark Swain of NASA’s Jet Propulsion Laboratory.
Researchers deduced the presence of carbon dioxide by measuring the planet’s light spectrum with the Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS). To isolate the light spectrum coming from the planet, researchers used a method known as “secondary transit.” This involves recording the light spectrum of the planet and its star, and then measuring the spectrum of the star alone while the planet is hidden behind it. The difference of the two spectra is the spectrum of the light coming directly from the planet [Nature News]. Unlike previous measurements that focused on the mid-infrared range, NICMOS took measurements in the near-infrared range, enabling detection of the carbon dioxide signature.
Indonesia’s Papua province may be the first region in the world to force some HIV/AIDS patients to be implanted with microchip trackers. A controversial bill requiring the extreme measures already has full backing from the provincial parliament and will become law with a majority vote from the provincial legislative body. The microchips are meant to monitor “aggressive” sexual behavior in an effort to control the spread of the disease. Lawmaker John Manangsang said, “It’s a simple technology. A signal from the microchip will track their movements and this will be received by monitoring authorities” [Reuters].
The bill does not specify who would qualify as “sexually aggressive” patients, but if the bill is passed, a committee will be formed to decide who will be implanted; the executive director of the committee will be a physician with a knowledge of epidemiology. Supporters say authorities would be in a better position to identify, track and ultimately punish those who deliberately infect others with up to six months in jail or a $5,000 fine [AP]. Meanwhile, health care workers and AIDS activists called the proposal “abhorrent” and a clear violation of human rights. “No one should be subject to unlawful or unnecessary interference of privacy,” [said Nancy Fee, the UNAIDS country coordinator], adding that while other countries have been known to be oppressive in trying to tackle AIDS, such policies don’t work. They make people afraid and push the problem further underground, she said [AP].