中山大便拉血是怎么一回事(中山肛门口出来一块肉) (今日更新中)

LOS ANGELES, July 18 (Xinhua) -- U.S. scientists have proven that oncogenes can change normal cells into stem-like cells, paving the way to a safer and more practical approach to treating diseases like multiple sclerosis and cancer with stem cell therapy.In a collaborative study, researchers from the Keck School of Medicine of the University of Southern California (USC), and the Children's Hospital of Orange County (CHOC) in California and Good Samaritan Hospital Medical Center in New York have successfully converted human skin cells into brain cells by suppressing the expression of p53, a protein encoded by a widely studied oncogene. This suggests that p53 mutation helps determine cell fate -- good or bad -- rather than only the outcome of cancer.Oncogenes are generally thought to be genes that, when mutated, change healthy cells into cancerous tumor cells.Study findings were appearing Monday on the website of the American Association for the Advancement of Science (AAAS)."The reality may be more complicated than people think," said Jiang F. Zhong, Ph.D., assistant professor of pathology at the Keck School. "What is a stem cell gene? What is a cancer gene? It may be the same thing.""When you turn off p53, people think the cell becomes cancerous because we tend to focus on the bad thing," Zhong said. "Actually, the cell becomes more plastic and could do good things, too. Let's say the cell is like a person who loses his job (the restriction of p53). He could become a criminal or he could find another job and have a positive effect on society. What pushes him one way or the other, we don't know because the environment is very complicated."Stem cells can divide and differentiate into different types of cells in the body. In humans, embryonic stem cells differentiate into three families, or germ layers, of cells. The reasons why and how certain stem cells differentiate into particular layers are not clearly understood. However, from those layers, tissues and organs develop. The endoderm, for example, leads to formation of the stomach, colon and lungs, while the mesoderm forms blood, bone and heart tissue. In its study, Zhong's team examined human skin cells, which are related to brain and neural cells from the ectoderm.When p53 was suppressed, the skin cells developed into cells that looked exactly like human embryonic stem cells. But, unlike other man-made stem cells that are "pluripotent" and can become any other cells in the body, these cells differentiated only into cells from the same germ layer, ectoderm."IPSCs (induced pluripotent stem cells) can turn into anything, so they are hard to control," Zhong said. "Our cells are staying within the ectoderm lineage."Zhong said he expects that suppressing other oncogenes in other families of cells would have the same effect, which could have critical significance for stem cell therapy. Future research should focus on determining which genes to manipulate, Zhong said.The study is slated to appear in the Proceedings of the National Academy of Sciences later this month, according to AAAS.

SAN FRANCISCO, June 22 (Xinhua) -- Apple Inc. plans to introduce a new iPhone in September featuring faster chip and more advanced camera, U.S. media reported on Wednesday.The new iPhone model, which will closely resemble iPhone 4, will include the A5 processor, a more powerful chip that Apple added to the iPad 2 tablet computer earlier this year, along with an 8-megapixel camera, up from the 5-megapixel model in the iPhone 4, Bloomberg quoted two people familiar with the product as saying.The device will run the iOS 5 operating system Apple previewed at its annual developer conference earlier this month.Aiming at attracting customers in developing countries, Apple is also working to finish a cheaper version of the iPhone which will use chips and displays of similar quality to the current iPhone 4, said the sources.Meanwhile, it was reported that Apple is also testing a new version of the iPad with a higher resolution screen, which, similar to the one currently used on iPhone 4, will be about one- third higher than iPad 2 and feature a more responsive touchscreen.According to a recent projection on smartphone market by the International Data Corp. (IDC), a small market share decline of iPhone is expected as the smartphone market matures and diversifies in 2011.The release of a new iPhone would help Apple gain more market share as smartphones powered by Google's Android system are predicted to grow to more than 40 percent of the market in the second half of this year.

BEIJING, June 28 (Xinhuanet) -- The figure of adults with diabetes has risen to 347 million worldwide, which is more than doubled in the past three decades, according to a study published in the British journal Lancet.The study, which analyzed data compiled from 2.7 million participants aged 25 and over from across the world, shows approximately 138 million in China have diabetes, and 36 million in the United States.Among high-income countries, diabetes rates were the highest in the U.S., Greenland, Malta, New Zealand, and Spain. The Netherlands, Austria, and France boasted the lowest rates, suggested the study published online by The Lancet journal on June 25.Majid Ezzati, a lead author of the study, said on Reuters: “Diabetes is becoming more common almost everywhere in the world.”Danaei added: “Unless we develop better programs for detecting people with elevated blood sugar and helping them to improve their diet and physical activity and control their weight, diabetes will inevitably continue to impose a major burden on health systems around the world.”

WASHINGTON, July 5 (Xinhua) -- The countdown for the final space shuttle launch began Tuesday afternoon, but unfavorable weather may delay shuttle Atlantis' launch attempt on Friday, NASA announced."We are going with a 60 percent chance of KSC (Kennedy Space Center) weather prohibiting launch due to the potential for showers and isolated thunderstorms in the area," shuttle weather officer Kathy Winters told reporters Tuesday at a precountdown status briefing. "I wish I had a better weather briefing for you."Atlantis is scheduled to lift off at 11:26 am (1526 GMT) on Friday from Kennedy Space Center with four U.S. astronauts on board for a 12-day mission to the International Space Station. Overall, the chance of an on-time liftoff is 40 percent, Winters said."We will do everything we can to launch on Friday but if things don't work out so that we can do that we have plenty of options... Saturday and Sunday," said NASA Test Director Jeremy Graeber. Conditions improve for Atlantis launch opportunities on Saturday and Sunday.NASA said it must launch Atlantis by Sunday, otherwise it will have to wait until at least July 16. That's because of an unmanned rocket due to lift off next week, using the same launch support personnel and equipment.NASA's 30-year-old shuttle program is ending due to high operating costs. The Obama administration wants to spur private companies to get into the space taxi business, freeing NASA to focus on deep space exploration and new technology development.When the U.S. space shuttle program officially ends later this year, the Russian space program's Soyuz capsule will be the only method for transporting astronauts to and from the station.

来源：资阳报