天津市男性专科问龙济(武清龙济男性地址) (今日更新中)

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 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.

LOS ANGELES, June 4 (Xinhua) -- Pregnant women who eat high-fat diet may be more likely to have a higher rate of stillbirth, a new study suggests.Researchers at Oregon Health & Science University (OHSH) came to the conclusion after observing 24 pregnant Japanese macaques that ate either a diet comprising 32 percent calories from fat or a control diet with 14 percent fat calories for at least four years.The researchers found the monkeys that ate a high-fat diet experienced a significant decrease in blood flow from the uterus to the placenta, a reduction of 38 percent to 56 percent, and a rise in placental inflammation.This was the case regardless of whether the monkeys were obese or slender. The risk of stillbirth was further compounded, however, when the monkeys were obese with hyper-insulinemia, or pre-diabetes.A large order of McDonald's french fries are shown May 22, 2008. McDonald's has switched to cooking oils free of trans fats in all of its restaurants in the United States and Canada, Chief Executive Jim Skinner said on may 23Eating a high-fat diet decreases blood flow from the mother to the placenta, the temporary organ that nourishes the unborn fetus, thus raising the risk of stillbirth, the researchers explained.Because the placental structure of the Japanese macaque is very similar to that in humans, cause and effect can be better established, the researchers said.Additional studies are needed to determine exactly how a high- fat diet decreases placental blood flow, the researchers noted.This is the first study to explain exactly how a fatty diet contributes to stillbirth, the researchers said in the study appearing in the June edition of the journal Endocrinology.The researchers hope their work will inform expectant moms and their physicians about the inherent dangers of a high-calorie, high- fat diet."This study demonstrates that maternal diet during pregnancy has a profound influence on both placental and fetal development," said Antonio Frias, M.D., principal investigator and assistant professor of obstetrics and gynecology (perinatology/maternal-fetal medicine) in the OHSU School of Medicine."The high-calorie, high-fat diet common in our society has negative effects on placental function and may be a significant contributor to adverse pregnancy outcomes, such as stillbirth."Previous studies have shown that nearly all adverse outcomes during pregnancy -- abnormal fetal growth, preeclampsia, preterm labor and stillbirth -- are in some way associated with an abnormally developed, or damaged, placenta, the temporary organ that nourishes the unborn fetus.In addition, maternal obesity has been associated with placental inflammation and dysfunction and an increased risk of stillbirth.Taking these findings into account, the researchers hypothesized that eating a diet high in fat during pregnancy also may increase the risk of placental inflammation and the risk of stillbirth.The researchers said they plan to conduct further studies on the impact of dietary changes and diet supplementation on improving outcomes in both monkeys and humans.

BEIJING, June 10 (Xinhua) -- The nation's drug watchdog on Friday publicized a draft national standard of sulfur dioxide residue in Chinese herbal medicine, which is open for public opinion until Sept. 9 this year.The maximum amount of sulfur dioxide residue is 400 mg in one kg of each of 11 specified kinds of herbal medicine, such as Chinese yams, Gastrodia elata and Codonopsis pilosola, according to the draft standard unveiled by the State Food and Drug Administration (SFDA).The standard provides a 150-mg-per-kg limit for all other kinds of herbal medicine.Fumigation with sulfur is used as a way of drying some herbal medicine by growers, and currently have no alternative that is both cheap and convenient.The SFDA said it doesn't favor the drying herbal medicine through fumigation with sulfur and urges research efforts to invent new alternatives.According to the World Health Organization, the tolerable maximum amount of sulfur dioxide that a human body can take in one day is 0.7 mg per kg, which means that an adult of 60 kg should not take in more than 42 mg of sulfur dioxide a day.Long-term exposure to high amounts of sulfur dioxide can cause damage to human body, especially the respiratory system, according to experts. 

来源：资阳报