上海恢复脊髓神经的最好方法(上海肺纯磨玻璃结节6mm如何治疗) (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.

MOSCOW, June 27 (Xinhua) -- Russia successfully launched a Cosmos class military satellite on Monday, said spokesman of the Russian Space Forces Alexei Zolotukhin.A Soyuz-U carrier rocket carrying the military satellite blasted off from the Plesetsk Plesetsk space center in northern Russia at 20:00 Moscow time (1600 GMT), Zolotukhin said."The rocket put the Cosmos series military satellite into the designated orbit at 20:08 Moscow time (1608 GMT)," he added.The spokesman also said the launch of the Soyuz-U carrier rocket "was the first time for this type of rockets" in this year.The launch carried out by a team from the Russian Space Forces was supervised by Space Forces Commander Oleg Ostapenko.The satellite, Cosmos-2472, is a new member to a Russian network of about 60-70 military reconnaissance satellites.

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.

RIO DE JANEIRO, Aug. 31 (Xinhua) -- The Brazilian city of Rio de Janeiroe may have an unprecedented dengue fever epidemic next summer, its mayor warned on Wednesday.The increasing number of dengue fever cases in the past few months shows similarities to the months predecing the 2002 and 2008 epidemics, Mayor Eduardo Paes said."Everything points to a new cycle of the disease, certainly the worst epidemic in Rio's history," he said.In 2008, Rio registered some 250,000 cases of dengue fever, with 174 people confirmed dead from the disease. In 2002, Rio had some 290,000 dengue fever cases and 91 people died.In efforts to halt the spread of the disease, Paes has declared a state of alert and is determined to take a series of measures to eliminate the habitat of the Aedes aegypti mosquito, which transmits dengue fever through its bite.Paes also announced an increase in the number of health care units for dengue fever patients. The total cost of a dengue prevention and combat program, which is expected to last until April 2012, will reach 42 million reais (26.25 million U.S. dollars).There is no vaccine against dengue fever, but Brazilian scientists are currently working on one which will immunize against four types of the disease.

来源：资阳报