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WASHINGTON, June 16 (Xinhua) -- Cells in the human body are constantly being exposed to stress from environmental chemicals or errors in routine cellular processes. While stress can cause damage, it can also provide the stimulus for undoing the damage. New research by a team of scientists at the University of Rochester has unveiled an important new mechanism that allows cells to recognize when they are under stress and prime the DNA repair machinery to respond to the threat of damage.Their findings will be published Friday in journal Science. Cells in the human body are constantly being exposed to stress from environmental chemicals or errors in routine cellular processes. While stress can cause damage, it can also provide the stimulus for undoing the damage.The scientists, led by biologists Vera Gorbunova and Andrei Seluanov, focused on the most dangerous type of DNA damage -- double strand breaks. Unrepaired, this type of damage can lead to premature aging and cancer. They studied how oxidative stress affects efficiency of DNA repair. Oxidative stress occurs when the body is unable to neutralize the highly-reactive molecules, which are typically produced during routine cellular activities.The research team found that human cells undergoing oxidative stress synthesized more of a protein called SIRT6. By increasing SIRT6 levels, cells were able to stimulate their ability to repair double strand breaks. When the cells were treated with a drug that inactivated SIRT6, DNA repair came to a halt, thus confirming the role of SIRT6 in DNA repair. Gorbunova notes that the SIRT6 protein is structurally related to another protein, SIR2, which has been shown to extend lifespan in multiple model organisms."SIRT6 also affects DNA repair when there is no oxidative stress," explains Gorbunova. "It's just that the effect is magnified when the cells are challenged with even small amounts of oxidative stress."SIRT6 allows the cells to be economical with their resources, priming the repair enzymes only when there is damage that needs to be repaired. Thus SIRT6 may be a master regulator that coordinates stress and DNA repair activities, according to Gorbunova.

SAN FRANCISCO, Sept. 13 (Xinhua) -- Researchers in San Francisco, U.S. have found in a latest study that bisphenol A (BPA) and methylparaben, two chemicals commonly used in consumer products, can interfere with the breast cancer drugs, local media reported on Tuesday.In the study, doctors from California Pacific Medical Center in San Francisco found that healthy breast cells from high-risk patients started to find ways to bypass breast cancer drugs after they were exposed to BPA and methylparaben in the lab.The cells exposed to the two chemicals kept growing and didn't die after they were introduced with Tamoxifen, a current standard drug therapy for female breast cancer and most common used treatment for male breast cancer, Dr. William Goodson, lead author of the study, told San Francisco Chronicle.Goodson said that BPA and methylparaben not only mimic estrogen 's ability to drive cancer, but appear to be even better than the natural hormone in bypassing the ability of drugs to treat it. The finds have been published online in the British medical journal Carcinogenesis.The research shows more evidence of safety issues of BPA, a chemical primarily used to make plastic baby bottles, food containers, household electronics and etc, as well as the less known methylparaben, a chemical preservative used in cosmetics and other personal care products.The researchers noted that the breast cancer rates have been growing by about the same amount in men as in women over the past three decades. Scientists have been looking at environmental causes for the disease and wondering where the hormones are coming from.Goodson said BPA and methylparaben are used so widely and even found in household dust, noting that it is still unknown whether the effects of exposure to the chemicals are reversible.Since 2008, several governments issued reports questioning the negative health effects of BPA, especially raising concerns regarding exposure of fetuses, infants and children. BPA use has been banned in baby bottles in a lot of countries and regions.As for methylparaben, the U.S. Food and Drug Administration said on its website that "at the present time there is no reason for consumers to be concerned about the uses of cosmetics containing parabens (including methylparaben)."

CHONGQING, May 28 (Xinhua) -- Non-infectious chronic diseases have become the major threat to human health in China as deaths from such diseases account for 85 percent of annual total deaths in the country, a report issued Saturday warned.The report said a 2008 national survey on mortality cause in China showed that the figure was up from 53 percent in 1973. Such diseases result in 3.7 million deaths annually.The Disease Prevention and Control Bureau under the Ministry of Health, and the Chinese Center for Disease Control and Prevention conducted the study, which was released at a national forum on prevention and control of chronic diseases in Chongqing.The mortality-cause survey shows that four non-infectious chronic diseases -- Cerebrovascular disease, cancer, respiratory disease and heart disease -- are the four principal causes that led to the largest number of deaths in China.Chronic diseases are the leading cause of mortality in the world, accounting for 60 percent of all deaths, reports the World Health Organization.According to the report, changes in lifestyle is one of the reasons that chronic diseases are increasing. Food with high contents of fat, protein and salt can lead to high blood pressure, high blood-fat and high blood sugar. Meanwhile, more people ride in vehicles instead of walking, meaning they exercise less.Experts at the forum called for more efforts to prevent and treat chronic diseases."It allows no delay," Kong Lingzhi, the vice director of the Disease Prevention and Control Bureau said, underlining the importance of reinforcing public education on chronic disease prevention and control."The earlier patients are aware of chronic diseases and receive proper medical treatment, the more likely they could overcome the diseases," she said.According to Kong, China has set a strategy to cope with chronic diseases in which government assumes the main responsibility, while the focus is on prevention.She said China would work to establish a prevention mechanism that pools the efforts of households, communities, professional institutions, and society at large.

WASHINGTON, July 27 (Xinhua) -- The solar-powered, Jupiter- bound Juno spacecraft was secured into place on top of its rocket Wednesday in preparation for launch next month, the U.S. National Aeronautics and Space Administration (NASA) announced.The launch period for Juno opens Aug. 5 and extends through Aug. 26. For an Aug. 5 liftoff, the launch window opens at 11:34 a.m. EDT (1534 GMT) and remains open through 12:43 EDT (1643 GMT).Juno will arrive at Jupiter in July 2016 and orbit its poles 33 times to learn more about the gas giant's interior, atmosphere and aurora."We're about to start our journey to Jupiter to unlock the secrets of the early solar system," said Scott Bolton, the mission 's principal investigator from the Southwest Research Institute in San Antonio. "After eight years of development, the spacecraft is ready for its important mission."

BEIJING, Aug. 22 (Xinhuanet) -- Researchers have discovered how a human egg captures an incoming sperm for fertilization, paving the way to help couples suffering from infertility, according to media reports on Monday.An international team of researchers found that a sugar chain known as the sialyl-lewis-x sequence (SLeX) makes the outer coat of the egg “sticky,” which has proven to be helpful in binding the egg and the sperm.As a result, this observation has filled in a huge gap in the understanding of fertility and provides hope for ultimately helping couples who currently cannot conceive.Scientists and doctors know that a sperm identifies an egg when proteins on the head of the sperm match and bind to a series of specific sugars in the egg’s outer coating. With a successful match of proteins, the outside surfaces of the sperm and egg then bind together before merging, which is then followed by delivery of sperm’s DNA into egg.To identify this molecules, the researchers used ultra-sensitive mass-spectrometric imaging technology to observe and identify which molecules are most likely to be key in the binding process.They experimented with a range of synthesised sugars in the laboratory and found that it is SLeX that specifically binds sperm to an egg.According to the World Health Organisation, infertility affects about 15 percent of reproductive-aged couples around the world and almost one in every seven couples in Britain has problems conceiving a child for various reasons.