太原肛门有裂口(太原大便出血肚子疼) (今日更新中)

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, June 6 (Xinhua) -- Apple's chief executive officer Steve Jobs on Monday took a break from his medical leave to introduce the company's new cloud-based service iCloud.Jobs, in his trademark black turtleneck and jeans, got a standing ovation in San Francisco's Moscone Center when he appeared on stage. Someone screamed "I love you," and Jobs said " it always helps and I appreciated it.""ICloud stores your content in the cloud and wirelessly pushes it to all your devices," said Jobs, calling it Apple's "next big insight."According to Apple, iCloud Backup will automatically back up users' iOS devices to iCloud daily over Wi-Fi when they charge their iPhone, iPad or iPod touch. Backup content includes purchased music, apps, camera roll, device settings and app data. It will also automatically upload documents from iWork in the cloud and pushes them to users' all relevant devices.The service will currently be free and replaces the former MobileMe which Apple once charged 99 U.S. dollars per year.Users will get five gigabytes of memory which is not counting purchased apps, music or books. A beta version is available on Monday and the final version will be shipping with iOS 5 this fall, with paid plans for more storage to be announced at that time.For a 24.99-dollar paid music plan named iTunes Match, a user's iTunes library will be scanned and they will gain instant access to those tracks or albums from compatible devices, rather than uploading them. Song files, including those converted from CDs, will also be uploaded to iCloud if they are not matched in iTunes stores but recognized by music labels.Jobs pointed out that iTunes Match paid plan is cheaper than Amazon's offering and Google has not announced a price yet, saying "it's an industry leading effort."The Apple CEO finally showed a photo of the company's new, massive data center in North Carolina to emphasize Apple is ready for iCloud service.Before Jobs, Apple executives introduced Lion, the eighth major release of Mac OS X and iOS 5, the next version of Apple's mobile operating system.Phil Schiller, Apple's marketing chief and Craig Federighi, the OS X software vice president, introduced ten key new features among the 250 ones of the new Mac operating system, including multi-touch features that bring the users experience on iPhone to their computers.Lion will be available to customers in July in Mac App Store. The price is adjusted to 29.99 dollars from 129 dollars Apple used to charge for upgrades.Scott Forstall, head of Apple's iOS software, demoed Apple's new mobile operating system, noting that iOS already has 44 percent of the mobile operating system market.The new version iOS 5 will have more than 200 new features, including a Notification Center that catches missed calls, mail messages and phone messages; and a feature called Reminder that provides virtual Post-it notes using geolocation technology.The new mobile operating system also integrates Twitter with many other iPhone apps and has a Newsstand on which the newspaper and magazines icons will be the actual covers of the publications.Apple said that iOS 5 is coming to the public this fall, which probably means the new iPhone is coming in the fall as well.Apple's new services are unveiled at its annual Worldwide Developers Conference (WWDC). Jobs kicked off the keynote event by saying that Apple had sold out 5,200 tickets to attendees just in two hours.

LOS ANGELES, June 8 (Xinhua) -- NASA's Mars Exploration Rover Opportunity is heading toward "Spirit Point" on the rim of a large crater, a long-term destination that the rover has been trying to reach for nearly three years, the Jet Propulsion Laboratory (JPL) announced on Wednesday.Opportunity has moved toward the crater, Endeavour, since climbing out of Victoria crater in August 2008.Having driven 11 miles (18 kilometers), the rover has about two miles (about three kilometers) to go before reaching the rim of Endeavour, said JPL in Pasadena, Los Angeles.Rover team members last week selected "Spirit Point" as the informal name for the site on the rim where Opportunity will arrive at Endeavour crater. The choice commemorates Opportunity's rover twin, Spirit, which has ended communication and finished its mission."Spirit achieved far more than we ever could have hoped when we designed her," said Steve Squyres of Cornell University, Ithaca, New York, principal investigator for the rovers. "This name will be a reminder that we need to keep pushing as hard as we can to make new discoveries with Opportunity. The exploration of Spirit Point is the next major goal for us to strive for."Endeavour offers the setting for plenty of productive work by Opportunity. The crater is 14 miles (22 kilometers) in diameter -- more than 20 times wider than Victoria crater, which Opportunity examined for two years. Orbital observations indicate that the ridges along its western rim expose rock outcrops older than any Opportunity has seen so far. Spirit Point is at the southern tip of one of those ridges, "Cape York," on the western side of Endeavour.Opportunity and Spirit completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of bonus, extended missions. Both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life.NASA's JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for the NASA Science Mission Directorate, Washington.

WASHINGTON, June 21 (Xinhua) -- Brain cancer patients who are able to exercise live significantly longer than sedentary patients, U.S. scientists at the Duke Cancer Institute have reported.The finding, published online this week in the Journal of Clinical Oncology, adds to recent research that exercise improves how cancer patients feel during and after treatments, and may also extend their lives.The study enrolled 243 patients with advanced recurrent gliomas, lethal brain malignancies that typically result in a median life expectancy of less than six months. The patients who reported participating in regular, brisk exercise -- the equivalent of an energetic walk five days a week for 30 minutes -- had significantly prolonged survival, living a median 21.84 months versus 13.03 months for the most sedentary patients."This provides some initial evidence that we need to look at the effects of exercise interventions, not only to ease symptoms but also to impact progression and survival," said Lee Jones, associate professor in the Duke Cancer Institute and senior author of the study.

SYDNEY, June 29 (Xinhua) -- A type of dried seaweed sold in Asian food supermarkets in Australia has been recalled after it was found to have high levels of iodine dangerous to pregnant women, local media reported on Wednesday.Food Standards Australia New Zealand (FSANZ) has ordered the recall of Wang Dried Kelp Varech Speche, a Korean brand of the dried seaweed, according to Australian Associated Press (AAP).It has been available in Asian grocery stores and restaurants in the Brisbane and Gold Coast areas of Queensland."The product contains high levels of naturally occurring iodine," FSANZ said in a statement."Regular consumption of these products may cause health problems in some people including pregnant and breastfeeding women."FSANZ said consumers concerned about their health should seek medical advice and should return the products to the place of purchase for a full cash refund.

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