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WASHINGTON, Jan. 2 (Xinhua) -- A systematic review of previous studies suggests that there may be a positive connection between physical activity and children's academic performance, according to a report published Monday in the Archives of Pediatrics & Adolescent Medicine.A group of scientists at the Vrije Universiteit (Free University) Medical Center in the Netherlands reviewed evidence on the relationship between physical activity and academic performance because of concerns that pressure to improve test scores may often mean more instructional time for classroom subjects with less time for physical activity.The authors identified 10 observational and four interventional studies for review, 12 of which were done in the United States, one in Canada and one in South Africa. Sample sizes ranged from 53 to about 12,000 participants between the ages of eight years and 18 years old. Follow-up varied from eight weeks to more than five years."According to the best-evidence synthesis, we found strong evidence of a significant positive relationship between physical activity and academic performance. The findings of one high-quality intervention study and one high-quality observational study suggest that being more physically active is positively related to improved academic performance in children," the report said.Background information in the article suggests that exercise may help cognition by increasing blood and oxygen flow to the brain, increasing levels of norepinephrine and endorphin to decrease stress and improve mood, and increasing growth factors that help create new nerve cells and support synaptic plasticity."More high-quality studies are needed on the dose-response relationship between physical activity and academic performance and on the explanatory mechanisms, using reliable and valid measurement instruments to assess this relationship accurately," the report concluded.

WASHINGTON, Nov. 18 (Xinhua) -- The U.S. Food and Drug Administration (FDA) on Friday revoked its approval of Avastin for treating the breast cancer after concluding that the drug has not been shown to be safe and effective for that use.Avastin will still remain on the market as an approved treatment for certain types of colon, lung, kidney and brain cancer."After reviewing the available studies it is clear that women who take Avastin for metastatic breast cancer risk potentially life-threatening side effects without proof that the use of Avastin will provide a benefit, in terms of delay in tumor growth, that would justify those risks," FDA Commissioner Margaret Hamburg said in a statement. "Nor is there evidence that use of Avastin will either help them live longer or improve their quality of life. "Avastin's risks include severe high blood pressure; bleeding and hemorrhaging; heart attack or heart failure; and the development of perforations in different parts of the body such as the nose, stomach, and intestines.Avastin was approved for metastatic breast cancer in February 2008 under the FDA's accelerated approval program, which allows a drug to be approved based on data that are not sufficiently complete to permit full approval. After the approval, the drug's sponsor, Genentech, completed two additional clinical trials and submitted the data from those studies to the FDA. These data showed only a small effect on tumor growth without evidence that patients lived any longer or had a better quality of life compared to taking standard chemotherapy alone -- not enough to outweigh the risk of taking the drug.FDA's Center for Drug Evaluation and Research, which is responsible for the approval of this drug, ultimately concluded that the results of these additional studies did not justify continued approval and notified Genentech it was proposing to withdraw approval of the indication.Genentech did not agree with the Center's evaluation of the data and, following the procedures set out in FDA regulations, requested a hearing on the Center's withdrawal proposal, with a decision to be made by the Commissioner. That two-day hearing, which took place June 28-29, included recommendations from the FDA 's Oncologic Drugs Advisory Committee, voting 6-0 in favor of withdrawing approval of Avastin's breast cancer indication.

RIO DE JANEIRO, Dec 15 (Xinhua) -- Brazilian President Dilma Rousseff Thursday signed a law banning smoking in public spaces and tobacco advertising at sale places in his country.Smoking in all enclosed public spaces, defined as free access areas used simultaneously by several people, is forbidden in the new law.It also prohibits tobacco advertising such as posters or banners at sale places. Previously the ban was only imposed on TV, radio and billboards advertising.In addition, the law increases the taxes and establishes minimum prices over the tobacco products to discourage buyers, therefore the cigarettes prices are expected to increase 20 percent in 2012 and 55 percent by 2015.Health warnings are also required on both sides of cigarette packs to alert consumers about the consequences of their smoking habit.The law is welcomed by some anti-smoking groups."In addition to protecting the health of its citizens, Brazil has also set an example for the world," said Matthew Myer, president of Campaign for Tobacco-Free Kids.

LOS ANGELES, Oct. 3 (Xinhua) -- An organizer of the World Stem Cell Summit says one of the key problems medical researchers face these days is how to apply their findings in the real world."How do you take the phenomenal scientific research going on in labs and translate it into medical treatments,?" said Bernie Siegel, the founder and co-chair of the summit and executive director of the Genetic Policy Institute, which organized the event."It's a big job to do this, and more than just the science," Siegel said, noting that in a growing field now moving beyond basic lab research, the aim is to connect the people who do the work with those who finance it.The three-day summit, which opened Monday in Pasadena, features more than 150 top international speakers and 50 hours of programming with leaders from science, pharmaceutics, business, policy, ethics, law and other fields.The cell therapy industry, a "nascent" field, has emerged to be a potentially multi-billion business with unlimited potential, Siegel said.Stephen Dalton, a University of Georgia professor, reported that one of the biggest developments in stem cell research in the past year was the realization that cells can be transdifferentiated from one state to another without returning to a pluripotent state.Dalton said the principle was previously supported by a few isolated examples but it was not until 2010 that the idea was widely accepted.Mark Sussman, a professor from San Diego State University, called the identification of lung stem cells from human tissue samples capable of regenerating the highly complex and specialized structures of mature lungs a breakthrough in lung biology and regenerative medicine.He said results presented by the Anversa group in the New England Journal of Medicine demonstrate that human lung stem cells can be expanded in vitro and also retain the capacity to integrate into adult tissue upon introduction into mice.The study, Sussman said, has opened up an entirely new field of possibilities for lung regeneration and potential therapeutic applications for many conditions where treatment options are either very limited or nonexistent.

WASHINGTON, Nov. 7 (Xinhua) -- U.S. researchers have demonstrated for the first time that the brain is a key player in regulating glucose (sugar) metabolism in humans.The findings, published Monday in the online edition of the Journal of Clinical Investigation, suggest that drugs targeting the brain and central nervous system could be a novel approach to treating diabetes."The brain is the body's only organ that needs a constant supply of glucose to survive, so it makes sense that it would have some say over how much glucose is produced," said study leader Meredith Hawkins, professor of medicine and director of the Global Diabetes Initiative at Yeshiva University, in a statement. "This role for the brain was demonstrated in earlier studies in rodents, but there was considerable controversy over whether the results could be applied to humans. We hope this study helps to settle the matter."In an earlier study in rodents, researchers showed that activation of potassium channels in the brain's hypothalamus sends signals to the liver that dampen its production of glucose. Those findings, published in Nature in 2005, challenged the conventional thinking that blood sugar production by the liver (the body's glucose factory) is regulated only by the pancreas (which makes insulin to metabolize glucose). But carefully performed studies on dogs, conducted at Vanderbilt University, failed to replicate the results, suggesting the Einstein findings in rodents might not be relevant to higher mammals, including humans.The current study, involving people, was aimed at resolving this controversy. Ten nondiabetic subjects were given oral diazoxide, a drug that activates potassium channels in the hypothalamus. (The drug is not used to treat diabetes.) Hormone secretion by the pancreas was controlled to ensure that any change in sugar production would only have occurred through the drug's effect on the brain. After the researchers administered the drug, blood tests revealed that patients' livers were producing significantly less glucose than before.Hawkins and her team then repeated this in rats, again giving diazoxide orally, achieving similar results. They confirmed that sufficient amounts of diazoxide crossed the blood-brain barrier to affect potassium channels in the hypothalamus. Additional experiments confirmed that diazoxide was working through the brain. Specifically, the researchers were able to completely block the effects of diazoxide by infusing a specific potassium channel blocker directly into the brain."This study confirms that the brain plays a significant role in regulating glucose production by the liver," said lead author Preeti Kishore, assistant professor of medicine. "We are now investigating whether this 'brain-to-liver' pathway is impaired in people with diabetes. If so, we may be able to restore normal glucose regulation by targeting potassium channels in the brain."

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