(B)
It could be that certain bacteria causeinflammation that can affect appetite as well as inflammatory bowel conditionslike Crohn’s disease and colitis, the researchers reported in the journal Science. In other words, the germs makeyou overeat, Andrew Gewirtz of Emory University in Atlanta and colleaguesreported. “Previous research has suggested that bacteria can influence how wellenergy is absorbed from food, but these findings demonstrate that intestinal bacteriacan actually influence appetite,” Gewirtz said. “The obesity epidemic is drivenby people eating too much, but why are people eating more?” Gewirtz said theresearch suggests that bacteria may play a role — perhaps a population ofbacteria that thrive because other competing organisms have been wiped out byantibiotics have access to clean water and other factors of modern life. Histeam stumbled on the findings by accident. “We were studying mice that had colitis,”Gewirtz said in a telephone interview. The team suspected some kind of germ wasresponsible, so they transferred mouse embryos into surrogate mothers toprevent them from being infected by their own mothers. Babies are colonized bybacteria and other micro-organisms soon after birth and the makeup of thesecolonies — which persist for life in the skin and bowels — are very similar tothose of the mother. The colitis was better but the baby mice became obese and developedmetabolic syndrome — a cluster of symptoms that include unhealthy cholesterollevels, too much fat around the midsection, high blood pressure and insulinresistance. Insulin resistance means the body does not use insulin effectivelyto break down food and Gewirtz believes this may be the key. The researchersremembered a recent study in which normal, slender mice became obese when fedgut bacteria from fat mice. They worked with that team, including Ruth Ley of CornellUniversity in New York, to see what role the gut bacteria may be playing. “Whatwe think is that the mice are prone to intestinal inflammation,” Gewirtz said.“If you have a lot of inflammatory signals about, insulin won’t work properly.”Weeks of antibiotic therapy helped, and so did diets. “If we limit their foodintake they are mostly OK; they certainly are no longer obese,” he said. “Theyare, however, insulin-resistant.” Gewirtz’s team is now working to see if theycan identify the micro-organisms involved. They are also working to see ifobese people have unique patterns of gut bacteria. Scientists know thathundreds of species of bacteria live in the gut and an average person carriesabout 5 pounds (2 kg) worth. On Wednesday, Chinese scientists reported in thejournal Nature that they found 1,000different species in human intestines. So could you treat, obesity by taking anantibiotic to wipe out the offending germs that are making people overeat? “It isvery hard to replace the bacteria that you have,” Gewirtz said. Studies alreadyshow it is difficult to treat conditions like Crohn’s disease, even with monthsOf antibiotics.
42. What doesthe passage mainly discuss? ( )
A. Influence ofintestinal bacteria on appetite.
B. Eating habitand obesity.
C. Treatment ofcolitis.
D. Antibioticsand obesity.
43. Which of the following is NOTtrue about the baby mice when their embryos had been transferred into surrogatemothers? ( )
A. They had ahigh cholesterol level. B.They suffered from hypertension.
C. They did notuse insulin effectively. D.They had been cured of colitis.
44. How was thediscovery made? ( )
A. By joint effortsof the research team. B.Completely by chance.
C. In a recentstudy. D.Under an antibiotic therapy.
45. What islikely to be one of the reasons why some people overeat? ( )
A. That theyhave a very good appetite.
B. That theyhave unique patterns of gut bacteria.
C. That they areinsulin-resistant.
D. That theysuffer from Crohn’s disease and colitis.
46. All of thefollowing are what scientists want to know EXCEPT ______.( )
A. if they couldtreat obesity by taking an antibiotic
B. if extremelyoverweight people have special patterns of intestinal bacteria
C. if hundredsof species of bacteria live in human intestines
D. if they canidentify the micro-organisms involved in obesity
