中山大便时肛门有血怎么回事(中山大便处血) (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.

BEIJING, July 14 (Xinhuanet) -- European music service Spotify is set to launch in the United States on Thursday, according to media reports.The streaming service will be available in the morning by invitation and through subscription."Spotify is a new way to listen to and manage your music, discover new tracks and share songs and playlists with friends – music whenever you want it, wherever you are," the company said in a statement.Spotify's streaming music and subscription service have long been popular in Europe since its launch in late 2008, and the company has been aiming for a US launch for nearly as long.Spotify has inked agreements with Sony Corp Music Entertainment, EMI Music, and Vivendi SA's Universal Music Group in the last few months. It is expected to close a deal with Warner Music Group by launch or soon after, according to a source.

MOSCOW, Sept. 16 (Xinhua) -- A Russian Soyuz space capsule carrying three astronauts returned to the Earth Friday, the Mission Control Center outside Moscow confirmed.The three astronauts, two Russians and one American from the International Space Station (ISS), who were flown back by a Soyuz TMA-21 spacecraft, were in good condition, search and rescue teams on the ground in Kazakhstan said.Russian TV images showed the three ISS crew members being taken out of the space capsule and seated in armchairs with blankets to re-adapt to the Earth's gravity.According to the Cosmonaut Training Center, the astronauts underwent physical examinations immediately after the landing, which included examinations of hearts, lungs and adrenal glands.Seventeen helicopters and planes had waited for the capsule's landing.Helicopters will carry the astronauts from the landing site to the Kazakh city of Karaganda, from where the two Russian cosmonauts Alexander Samokutyayev and Andrei Borisenko will fly back to Moscow later Friday, while NASA astronaut Ronald Garan will leave directly for the United States for post-mission rehabilitation, the Itar-Tass news agency reported.The return of the three crew members was originally scheduled for Sept. 8, but was postponed by a failed launch of the Progress cargo ship on Aug. 24.The three crew members remaining on board the ISS are scheduled to return in mid-November.

SAN FRANCISCO, July 29 (Xinhua) -- Apple has ousted Nokia as the world's largest smartphone maker as global mobile phone market grew more than 11.3 percent in the second quarter of 2011, according to two separate market research studies.After becoming the largest smartphone vendor in terms of revenue and profits, Apple has become the world's largest smartphone vendor by volume with 18.5 percent market share, said the latest research from Strategy Analytics released on Friday.The Cupertino, California-based company sold 20.3 million iPhones in the second quarter,up 142 percent compared with the same period a year earlier.Samsung's shipments of 19.2 million units grew a huge 520 percent year over year, accounting for 17.5 percent global smartphone market share in the second quarter of 2011.Apple and Samsung overtook long-time volume leader Nokia for the two spots. The Finnish mobile phone giant accounted for 15.2 percent of global smartphone market share in the last quarter, which is less than half of what it was just one year earlier.In the second quarter of 2010, Nokia was the No.1 smartphone maker by volume in the world with 38.1 percent of market share. The industry is now waiting Nokia's pending transition to Windows Phone 7.According to a separate report by International Data Corporation (IDC) released on Thursday, the worldwide mobile phone market grew by 11.3 percent year over year in the second quarter of 2011 despite a decline of the feature phone market for the first time in almost two years.The feature phone market was down by 4 percent in the last quarter, said the IDC Worldwide Mobile Phone Tracker report. It noted that the decline in shipments was mainly in economically mature regions, such as the United States, Japan and Western Europe, as users making rapid transition to smartphones.The shrinking feature phone market had a great impact on some of the world's largest suppliers of mobile phones, such as Nokia, which is losing share in the feature phone category to low-cost suppliers, said the report.For the overall market, global mobile phone vendors shipped 365. 4 million units in the second quarter, compared to 328.4 million units in the same period last year, with Nokia still holding the top spot with a market share of 24.2 percent, followed by Samsung, LG Electronics, Apple and ZTE.But the 11.3 percent growth was lower than IDC's forecast for the quarter and also below the 16.8 percent growth in the first quarter of 2011.IDC said the feature phone forecast isn't expected to be any rosier in the future and the shipment growth of feature phones won 't exceed 1.1 percent in the coming years.

来源：资阳报