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【速度】 【计时1】 Alzheimer's Research Strategy Announced [attachimg=200,209]100999[/attachimg]
An international panel of experts released recommendations today for future research on Alzheimer's disease. The recommendations will help guide the research component of the new national plan for Alzheimer's disease announced Tuesday by Health and Human Services Secretary Kathleen Sebelius. The plan sets the ambitious goal of developing effective prevention and treatment strategies for Alzheimer's by 2025. The new research strategy was developed by experts who met during a 2-day summit at the U.S. National Institutes of Health (NIH) in Bethesda, Maryland, earlier this week. The panel acknowledges a number of challenges facing the field, including the need to develop better experimental models and to initiate clinical trials at earlier stages of the disease. Their recommendations include conducting more interdisciplinary research on the biological mechanisms of Alzheimer's disease and therapeutic targets, enabling more rapid and extensive sharing of data and biological specimens, and fostering more public-private partnerships (along the lines of the Alzheimer's Disease Neuroimaging Initiative, a successful biomarker development effort jointly funded by NIH and the pharmaceutical industry). The panel also calls for more research on nondrug interventions, such as lifestyle changes, that might prevent or slow the disease. A financial stimulus for Alzheimer's research appears to be in the works: President Barack Obama's proposed 2013 budget includes $80 million in new funding. Congress has yet to weigh in on that plan. 【227】
【计时2】 Japanese Earthquake Yields Clues to Posttraumatic Stress Disorder [attachimg=200,150]101000[/attachimg]
Most traumatized people don’t develop the vivid flashbacks and relentless thoughts of the incident that are hallmarks of posttraumatic stress disorder (PTSD). But researchers know little about how trauma changes the brain—and whether some people's brains are more susceptible to PTSD to begin with. Now, neuroscientists in Japan who are working with survivors of the 2011 earthquake and tsunami have identified one brain region whose size seems to predict susceptibility to PTSD symptoms and another brain region that shrank slightly in people with the highest number of symptoms. Previous imaging studies have found that in PTSD sufferers, parts of the brain involved in memory, fear, and mood control are smaller compared with the brains of people who come through their trauma more-or-less unscathed. But it has been difficult to tell whether these differences were always there or appeared after the trauma. For cognitive neuroscientist Atsushi Sekiguchi, who was studying the neural underpinnings of stress at Tohoku University in Sendai, the earthquake was a rare opportunity to tease apart cause and effect. “We had a lot of brain imaging data for university students before the earthquake,” he says. The coastal region of Tohoku was one of the hardest hit, with tsunami waves as high as 40 meters sending floods up to 10 kilometers inland. In Sendai, the largest city, waves flooded the streets and the airport, sending cars and even planes swirling through the city while black smoke billowed from the burning Nippon Oil refinery. To investigate the effects of the disaster on residents, the researchers recruited 42 of their earlier subjects for magnetic resonance imaging scans 3 to 4 months after the quake. The subjects also rated the frequency and intensity of their PTSD symptoms, such as intrusive memories, avoiding people or places associated with the trauma, heightened startle response, and feelings of reexperiencing the event. 【315】
【计时3】 None of the subjects had full-blown PTSD at the time of the test; the highest score on the symptom scale, 39, was just below the cutoff for a PTSD diagnosis. But the MRI scans showed that even 3 months after the trauma, some of the students’ brains were already changing in a way that tallied with PTSD symptoms. Even before the earthquake, a brain region called the pregenual anterior cingulate cortex was smaller in subjects with higher scores than in subjects with few or no symptoms. Previous research has revealed that this region, which plays a key role in monitoring and controlling emotions, is smaller in PTSD sufferers. According to Sekiguchi, the new finding suggests that the reduced size is a “vulnerability factor” for the disorder. Another area, called the orbitofrontal cortex, seemed to be affected by the trauma itself. Students who showed a decrease in volume in this area, compared with their earlier scans, had higher PTSD scores, the team reports online today in Molecular Psychiatry. Because this region is involved in eliminating fear-related memories, the fact that it proved to be smaller in subjects with more intense symptoms makes sense, Sekiguchi explains. Psychiatrist Roger Pitman of Harvard Medical School in Boston calls the findings tantalizing. “The study shows how sensitive the brain is even at comparatively low levels of symptoms,” he says. The ability to identify the brain areas affected by the condition—as well as those that set the stage for it—adds to our knowledge but doesn’t have immediate implications for treatment, Pitman believes. He adds that future strategies might include scanning people in advance who are expected to be involved in trauma—soldiers, for instance—to spot those at risk for the disorder. Researchers might also develop neuroprotective drugs for specific brain areas. “But we aren’t there yet,” Pitman says. 【305】
【计时4】 U.S.-China Research Projects Draw Congressman's Ire
The United States government is "insane" to be funding collaborative research with China according to a senior Republican member of the U.S. House of Representatives Committee on Science, Space, and Technology. Representative Dana Rohrabacher (R-CA), a 12-term lawmaker and frequent critic of China's human rights record, last night took to the floor of the House for nearly 30 minutes to read a list of dozens of federally funded projects "that go directly to supporting development and the economy of China." Many involved grants for research involving physics, climate science, and environmental studies—but a few covered topics that included "judicial education" and green manufacturing. "Couldn't we have spent this money better in the United States?" Rohrabacher asked. Among his targets were a $63,000 National Science Foundation grant to Siena College in Loudonville, New York, for neutrino physics at China's Daya Bay nuclear facility, a $300,000 Department of Energy grant for modeling regional climate change in China, and a $100,000 U.S. Department of Agriculture grant for "climate change adaptation." "Now isn't that great?" Rohrabacher said in one of many ironic asides. "We're paying for them to adapt to climate change." Rohrabacher also alleged that "Chinese cyberspies have stolen all of our trade secrets. All of the money we put in to invest in research and development they steal and utilize." He ended his remarks by "suggesting that what we are doing is insane." U.S.-China relations are often a flashpoint for controversy. Two years ago, Congress banned the White House and NASA from spending any money on scientific collaborations with China. The Obama Administration resisted on the grounds that it infringed on the president's authority to conduct foreign policy. The issue was resolved after White House science officials agreed to give Congress 30 days' notice of any pending collaborations and to certify that none of the exchanges pose a threat to national security. The Administration has also defended such collaborations by highlighting their potential benefits for the United States, for example, in controlling the spread of avian flu or reducing global greenhouse gas emissions. 【348】
【计时5】 Your Inner Bugs Are What You Eat [attachimg=660,432]101001[/attachimg]
The United States may be the home of multiculturalism, but American guts sport much less diversity than those of rural residents of Malawi and Venezuela. That's the conclusion of a new study, which finds that the protein-rich diet consumed by people in western countries may have a profound effect on the microbes they harbor. American gut populations also seem more adapted to a meat-rich diet. In the body, microbes outnumber human cells by a factor of 10 to one. Research into these vast bacterial populations—together called microbiomes—is booming. Scientists have discovered that microbial boarders play a crucial role in breaking down certain nutrients in the diet and turning other molecules into a form that is useful to humans. The composition of the microbiome also impacts how susceptible a host is to certain diseases, they suspect. To test that hypothesis, however, scientists first need to get a handle on what the microbiome of healthy adults looks like. So gastroenterologist Jeffrey Gordon at Washington University in St. Louis and his colleagues collected fecal samples from 532 individuals of all ages, more than half of them living across the United States, the rest Amerindians living in two villages in Venezuela and members of rural communities in Malawi. The researchers froze the samples, pulverized them, and extracted DNA. By picking out and sequencing 16S rDNA, a piece of DNA common to all microbes and used to classify them, the scientists could identify the species present in the gut microbial community. They found that the microbiome in all three populations matured in a similar way: Infants started out with fewer microbe species, but at age three, the diversity of their microbiome had reached that of adults. "Like other organs, it takes the microbiome time to develop," says Dusko Ehrlich, a microbial geneticist at the National Institute for Agricultural Research in Paris who is coordinating a European project to establish associations between the genes of human intestinal microbes and disease. 【333】 【自由】 The adult microbiomes of Amerindians and Malawians were surprisingly similar, the team reports online today in Nature, but those in the United States differed significantly. For one thing, they were much less diverse, harboring roughly 25% fewer species than Venezuelan microbiomes. Ehrlich calls that "a very strong and unexpected finding. … There seems to be a loss in diversity in Western microbiomes," he says. By fully sequencing 110 of the samples, the researchers also found differences in which genes were represented in the microbiomes of adults in the three countries. Alpha-amylase, an enzyme involved in the breakdown of starch, was more common in the microbes found in samples from Malawi and Venezuela; U.S. microbiomes contained more genes involved in breaking down amino acids and simple sugars. The researchers speculate that the disparity reflects differences between the U.S. diet, rich in proteins and sugars, and those in Malawi and Venezuela, which are dominated by corn and cassava. An analysis of the gut microbiome of 33 mammals done by Gordon's group and published in Science in 2011 also showed that microbiomes correlate with diet. Overall, Amerindian microbiomes most closely resemble those of herbivorous mammals, he says, while U.S. microbiomes look more like those found in carnivores. "At least one facet of our genetic landscape is being impacted by our Western diet," Gordon concludes. "What that means for the risk of disease will have to be ascertained in future studies." Microbiologist Jonathan Eisen of the University of California, Davis, compares the work to the exploration of a new continent: "Everything is new, everything is discovery." But he thinks it's too early to single out diet as the causative factor behind the variation. "There are a million differences between these samples, now they have microbial differences to go with them, but we have no idea which change goes with which," he says. David Relman, microbiologist at Stanford University School of Medicine in Palo Alto, California, also cautions against drawing broad conclusions. "Although the current study represents a heroic effort," he says, "we still have a long way to go before we have a truly global picture of variation in the human microbiome." 【358】
【越障】 Life at the Top Can Be Good for Your Health [attachimg=588,516]101002[/attachimg]
Many studies in humans and animals suggest that chronic stress is bad for one’s health, in part because it suppresses the immune system. But nearly 30 years of data on wild baboons shows that top-ranking males, despite showing signs of increased stress, recover more quickly than low-ranking baboons from wounds and illness. The results may help explain why some people escape from the negative effects of stress while others do not. Most studies in humans have shown a clear correlation between higher socioeconomic status and lower risk of death or illness from stress-related diseases such as heart attacks and diabetes. Some of the most famous of these are the so-called Whitehall studies of the British Civil Service, which showed that death and illness rates decreased in a step-wise fashion the higher an employee was on the service’s 6-grade pay and responsibility scale. These and other studies also have found that being at the bottom of the totem pole leads to greater stress as a result of increased work loads and time pressures, as well as more job insecurity. But studies of animals, especially other primates, have shown that the relationship between stress and status largely depends on the social organization of the species in question. For example, in species such as baboons that have rigid social rankings and hierarchies, with so-called alpha males dominating other males and females over extended periods of time, it can apparently be more stressful at the top. In a study reported last year in Science, a team that included ecologist Jeanne Altmann of Princeton University revealed that baboon alpha males had the highest levels of glucocorticoid hormones, such as cortisol, as well as testosterone in their feces, indicators that they were under greater stress than lower-ranking individuals. To try to tease out the relationship between social rank, stress, and health, Altmann teamed up with Elizabeth Archie, a behavioral ecologist at the University of Notre Dame in South Bend, Indiana, and Susan Alberts, a behavioral ecologist at Duke University in Durham, North Carolina, to analyze data collected from 1982 through 2009 in the Amboseli region of Kenya, home to a large population of wild baboons. Working with three Kenyan field assistants who observed the baboons 6 days a week, 52 weeks each year, the team noted 633 cases of either illness or injury in 166 adult male baboons over the 27-year course of the study. Illnesses included digestive and respiratory problems, while injuries included cuts, slashes, and puncture wounds. The team found that the highest incidences of illness occurred in the oldest and lowest-ranking males, rather than the highest-ranking alpha males, as might be expected if the alpha males’ higher stress levels were suppressing their immune systems. And the highest rates of injury were found in middle-aged, mid-ranking males, the authors report online today in the Proceedings of the National Academy of Sciences. To further investigate the effect of stress levels on the baboons’ immune systems, the team analyzed healing rates in 144 of the baboons. The researchers found that low-ranking males typically required about 31 days to recover, whereas high-ranking males required about only 25 days. Since age and rank are correlated—older baboons are less likely to be high-ranking—the team corrected for the effect of age, but found that rank was still the most important factor in predicting wound-healing time. The researchers also identified a correlation between speed of wound-healing and the size of the social group the baboon belonged to: Males from larger groups recovered more quickly than those in smaller groups. These results are “somewhat surprising,” the team writes in its report, because a number of studies with laboratory animals and captive primates have shown a clear relationship between stress levels—as measured especially by fecal glucocorticoid concentrations—and immune suppression. The researchers suggest that primates such as baboons and humans have benefited from an “evolutionary flexibility” in how they respond to stress and that immune suppression is not always the result. Thus the higher levels of stress hormones in alpha males, the team contends, are probably due to the stress of expending the energy necessary to stay competitive and on top of the hierarchy, whereas low-ranking males are stressed out by social factors such as being the targets of aggression by alpha males. Nevertheless, the researchers argue, alpha males and lower-ranking males seem to benefit from the social support they receive by being in larger groups. “Our results suggest that even though alpha males experience high stress, they seem to escape from the negative consequences,” Archie says. “In humans, we probably see similar patterns. Although people of high socioeconomic status experience stressful events, they probably also have better access to resources and coping mechanisms.” In contrast, Archie says, “low-ranking baboons and people of low socioeconomic status experience long-term stressors with little chance to escape.” Nevertheless, Archie and her co-workers say, more research will be necessary to determine the precise relationship between health and rank—that is, whether healthy animals achieve higher ranks or higher-ranking animals achieve better health. Michaela Hau, an evolutionary physiologist at the Max Planck Institute for Ornithology in Germany, says that the new study is “immensely valuable” because it was carried out with a large number of baboons who lived in the wild rather than a captive population, which might be suffering from different kinds of stresses due to captivity, social isolation, or variable food quality. Hau adds that while the alpha males show higher levels of stress-related hormones in their feces, this might be due to numerous short spikes of acute stress episodes rather than one long, continuous state of chronic stress such as humans low on the totem pole might face. Such acute spikes in stress hormones, Hau says, have been associated in previous research with higher healing rates, especially in the skin. Bruce McEwen, a neuroendocrinologist at Rockefeller University in New York City, agrees. “An acute stress hormone response is likely to enhance adaptive immunity and wound healing, whereas the sluggish and prolonged elevation” of stress hormones “is likely to impair immune function.” 【1009】 |
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