Lähettäjä: Soijuv Lähetetty: 27.9.2005 8:47
Lihominen ei välttämättä/yksinomaan johdu ruokavaliosta. Lihominen voi johtua suoliston väärästä bakteerikannasta. Gordonin ja Backhedin tutkimuksen mukaan hiiret joilla on tiettyjä bakteereita suolistossaan lihovat vaikka olisivat dieetillä. Suolistobakteerien tappaminen ei ole varteenotettava vaihtoehto. Gordon tutkimusryhmineen pyrkii kehittämään lääkkeen jonka vaikutus kohdistuu rasvan varastointiin vaikuttaviin hormoneihin
I´m Not Fat I´ve Just Got Fat Bacteria
By Jocelyn Selim
May 05, 2005 | Biology & Medicine
An expanding waistline may have less to with what a person eats than what already inside, say microbiologists Jeffrey Gordon and Fredrik Backhed at the Washington University School of Medicine in Saint Louis. Variations in the population of bacteria living in the gut may explain why some people pack on extra pounds while others stay slim.
Gordon and Backhed base their claim on a study of two groups of mice, one exposed to normal intestinal microbes and another raised in a germ-free bubble. The germ-free mice had 42 percent less body fat, even though they were fed one-third more calories. When the animals were inoculated with bacteria from their normal counterparts, the bubble mice increased their body fat by 57 percent in just two weeks.
We know that gut microbes have ways of breaking down otherwise indigestible carbohydrates, increasing the calories available to the animal, but we thought something else must be at work, Gordon says. His team therefore also looked at a hormone that limits fat storage in the body. They found that the gut bacteria secrete a substance that interferes with the hormone, causing even more of the calories to be stored as fat than would happen normally. The result is that microbe-containing mice pork up, even on a moderate diet.
Having or not having certain species in our intestinal bacterial communities may have a profound effect on how efficiently we harvest and store energy from our food, Gordon concludes. Killing off the gut bacteria is not a viable option ?it would trigger opportunistic infections long before it would yield meaningful weight loss ?but Gordon is targeting the fat-promoting hormone itself in hopes of developing a better diet drug.
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Lähettäjä: Soijuv Lähetetty: 1.2.2006 8:54
Voiko lihavuus tarttua? Lihavuuden lisääntymistä räjähdysmäisesti useissa maissa samanaikaisesti, on vaikea selittää yksinomaan ravitsemustekijöillä ja fyysisen harjoittelun puutteella. Adenoviruksilla saattaa olla osansa lihavuuden synnyssä.
Mikäli tutkijat ovat oikeassa, lihavuuden uusi hoito-ohje tulevaisuudessa on: Käsienpesu!
(Suom. huom. Kuulostaa huomattavasti mukavammalta ohjeelta kuin dieettien noudattaminen.)
Can you ?catch? obesity?
Jan. 30, 2006
Courtesy American Physiological Society
and World Science staff
There is a lot of good advice to help us avoid becoming fat, such as eat less and exercise. But if some researchers are right, you may soon be hearing a surprising new piece of advice: wash your hands.
There is growing evidence that some viruses may cause obesity, thus making obesity contagious, said Leah Whigham of the University of Wisconsin, Madison, lead researcher in a new study on the subject.
The idea isn?t new, but it has been controversial among scientists, Whigham said. ?It makes people feel more comfortable to think that obesity stems from lack of control,? she remarked. ?It?s a big mental leap to think you can catch obesity.?
Her study found that a human-infecting virus called AD-37 causes obesity in chickens. Previous studies had linked two three related viruses with obesity in animals or humans, the researchers added.
The study appears in the January issue of the American Journal of Physiology?Regulatory, Integrative and Comparative Physiology.
AD-37 and its kin are adenoviruses, members of a family of viruses that commonly cause upper respiratory tract infections including the common cold.
Whigham said more research is needed to find out if Ad-37 causes obesity in humans. One study was inconclusive, she said, because only a handful of people showed evidence of infection with Ad-37, not enough to draw any conclusions.
Researchers should now identify which, if any, viruses cause human obesity, she added. Further steps could be to devise a screening test to identify people who are infected, and to develop a vaccine.
?If Ad-36 is responsible for a significant portion of human obesity, the logical therapeutic intervention would be to develop a vaccine to prevent future infections,? wrote Frank Greenway of Louisiana State University, Baton Rouge, in an editorial in the same issue of the journal. ?One would want to ensure that all the [subtypes] of human adenoviruses responsible for human obesity were covered in the vaccine.?
Whigham said there has long been evidence that factors other than poor diet or lack of exercise may be at work in an obesity epidemic that has affected many nations.
?The prevalence of obesity has doubled in adults in the United States in the last 30 years and has tripled in children,? the study noted. ?With the exception of infectious diseases, no other chronic disease in history has spread so rapidly,? and the causes have not been clearly identified, she added.
Other diseases once thought to be the product of environmental factors are now known to stem from pathogens, she added. For example, ulcers were once thought to be the result of stress, but researchers eventually implicated H. pylori bacteria as a cause.
?The nearly simultaneous increase in the prevalence of obesity in most countries of the world is difficult to explain by changes in food intake and exercise alone, and suggest that adenoviruses could have contributed,? the researchers wrote in the study. ?The role of adenoviruses in the worldwide epidemic of obesity is a critical question that demands additional research.?
The theory that viruses could play a part in obesity began a few decades ago, the researchers said. That was when Nikhil Dhurandhar, now at Louisiana State University, noticed that chickens in India infected with the avian adenovirus SMAM-1 had significantly more fat than non-infected chickens.
Since then, Ad-36 has been found to be more prevalent in obese humans, Whigham and colleagues noted.
In the new study, the team worked to determine which adenoviruses might be associated with obesity in chickens. The animals were separated into four groups, each of which was exposed to one of three adenoviruses, or no virus.
Chickens inoculated with Ad-37 had significantly more fat compared with the other three groups, which included those infected with Ad-2 or Ad-31, the researchers found.
Voiko lihavuus tarttua? Lihavuuden lisääntymistä räjähdysmäisesti useissa maissa samanaikaisesti, on vaikea selittää yksinomaan ravitsemustekijöillä ja fyysisen harjoittelun puutteella. Adenoviruksilla saattaa olla osansa lihavuuden synnyssä.
Mikäli tutkijat ovat oikeassa, lihavuuden uusi hoito-ohje tulevaisuudessa on: Käsienpesu!
(Suom. huom. Kuulostaa huomattavasti mukavammalta ohjeelta kuin dieettien noudattaminen.)
Can you ?catch? obesity?
Jan. 30, 2006
Courtesy American Physiological Society
and World Science staff
There is a lot of good advice to help us avoid becoming fat, such as eat less and exercise. But if some researchers are right, you may soon be hearing a surprising new piece of advice: wash your hands.
There is growing evidence that some viruses may cause obesity, thus making obesity contagious, said Leah Whigham of the University of Wisconsin, Madison, lead researcher in a new study on the subject.
The idea isn?t new, but it has been controversial among scientists, Whigham said. ?It makes people feel more comfortable to think that obesity stems from lack of control,? she remarked. ?It?s a big mental leap to think you can catch obesity.?
Her study found that a human-infecting virus called AD-37 causes obesity in chickens. Previous studies had linked two three related viruses with obesity in animals or humans, the researchers added.
The study appears in the January issue of the American Journal of Physiology?Regulatory, Integrative and Comparative Physiology.
AD-37 and its kin are adenoviruses, members of a family of viruses that commonly cause upper respiratory tract infections including the common cold.
Whigham said more research is needed to find out if Ad-37 causes obesity in humans. One study was inconclusive, she said, because only a handful of people showed evidence of infection with Ad-37, not enough to draw any conclusions.
Researchers should now identify which, if any, viruses cause human obesity, she added. Further steps could be to devise a screening test to identify people who are infected, and to develop a vaccine.
?If Ad-36 is responsible for a significant portion of human obesity, the logical therapeutic intervention would be to develop a vaccine to prevent future infections,? wrote Frank Greenway of Louisiana State University, Baton Rouge, in an editorial in the same issue of the journal. ?One would want to ensure that all the [subtypes] of human adenoviruses responsible for human obesity were covered in the vaccine.?
Whigham said there has long been evidence that factors other than poor diet or lack of exercise may be at work in an obesity epidemic that has affected many nations.
?The prevalence of obesity has doubled in adults in the United States in the last 30 years and has tripled in children,? the study noted. ?With the exception of infectious diseases, no other chronic disease in history has spread so rapidly,? and the causes have not been clearly identified, she added.
Other diseases once thought to be the product of environmental factors are now known to stem from pathogens, she added. For example, ulcers were once thought to be the result of stress, but researchers eventually implicated H. pylori bacteria as a cause.
?The nearly simultaneous increase in the prevalence of obesity in most countries of the world is difficult to explain by changes in food intake and exercise alone, and suggest that adenoviruses could have contributed,? the researchers wrote in the study. ?The role of adenoviruses in the worldwide epidemic of obesity is a critical question that demands additional research.?
The theory that viruses could play a part in obesity began a few decades ago, the researchers said. That was when Nikhil Dhurandhar, now at Louisiana State University, noticed that chickens in India infected with the avian adenovirus SMAM-1 had significantly more fat than non-infected chickens.
Since then, Ad-36 has been found to be more prevalent in obese humans, Whigham and colleagues noted.
In the new study, the team worked to determine which adenoviruses might be associated with obesity in chickens. The animals were separated into four groups, each of which was exposed to one of three adenoviruses, or no virus.
Chickens inoculated with Ad-37 had significantly more fat compared with the other three groups, which included those infected with Ad-2 or Ad-31, the researchers found.