From: hounddog23x@gmail.com   
      
   Overuse of Antibiotics Is Seen Behind Many Human Ills    
   Wynne Parry, LiveScience Senior Writer    
   Date: 24 August 2011 Time: 04:30 PM ET    
        
   You were not meant to be alone: The human body contains and is covered in an   
   almost unimaginably large number of microbes. But eradicating them as we do,   
   intentionally and unintentionally, with the prolific use of antibiotics may be   
   harming our health,    
   according to one scientist who studies our minuscule companions.    
   "Overuse of antibiotics could be fueling the dramatic increase in conditions   
   such as obesity, type 1 diabetes, inflammatory bowel disease, allergies and   
   asthma, which have more than doubled in many populations," writes Martin   
   Blaser, a professor of    
   microbiology and chairman of the department of medicine at New York University   
   Langone Medical Center.    
   Humans are sometimes called meta-organisms, because of the sheer number and   
   volume of microbes that share our bodies -- living in our guts, on our skin,   
   even in our belly buttons. Evidence is building for the benefits these healthy   
   microbial communities    
   offer us. They help us access nutrients, such as vitamin K, and energy from   
   complex carbohydrates. They deter dangerous infections, and recent evidence   
   indicates they help keep at bay multiple sclerosis and other autoimmune   
   disorders. [5 Wacky Things    
   That Are Good for Your Health]    
      
   Unintended consequences    
   Antibiotics are nothing short of miracle drugs, and they share the credit for   
   extending the life expectancy from 63 for a U.S. citizen born in 1940 to 78   
   for someone born in the U.S. today, noted Blaser in his commentary, published   
   in the Aug. 25 issue    
   of the journal Nature    
   One problem with the overuse of antibiotics has received fairly widespread   
   attention: the selection for drug-resistant bugs. But Blaser points out a   
   lesser-known effect: These medications, along with other changes in how we   
   live, are altering the    
   communities of microbes that share our bodies.    
   For example, one study published in 2010 monitored how three people's gut   
   bacteria responded to two courses of the antibiotic ciproflaxin. The   
   antibiotic, the researchers found, caused rapid and profound changes in the   
   microbe populations, which never    
   fully returned to their initial state. Other research has shown that   
   antibiotic-induced changes, including the arrival of antibiotic-resistant   
   microbes, can last for at least three years.      
   For 26 years, Blaser has worked with the bacterium Helicobacter pylori.   
   Discovered in 1982 by Robin Warren and Barry Marshall, who later shared a   
   Nobel Prize for the discovery, the bacterium is linked to stomach   
   inflammation, ulcers and gastric cancer.    
   Over time it became clear, however, that the bacterium has an ancient   
   relationship with humans and that it is disappearing from our guts -- by the   
   turn of the 21st century, fewer than 6 percent of children in the U.S., Sweden   
   and German were carrying the    
   microbe, according to Blaser.    
   Not surprisingly, gastric cancers and ulcers have become less common. However,   
   diseases of the esophagus, including esophogeal cancer and acid reflux, have   
   increased dramatically at the same time, and it turns out there is an inverse   
   relationship between    
   these diseases and the presence of H. pylori, which seems to protect the   
   esophagus. And people who lack the bacterium are more likely to develop   
   asthma, hay fever or skin allergies as children, Blaser and colleagues found.    
   Signaling to our immune systems    
   It's clear that resident microbes play a role in our health, although   
   scientists are still exploring the scope of their impact on our biological   
   systems such as metabolism and immunity, according to Dennis Kasper, a   
   professor of medicine and microbiology    
   and immunology at Harvard Medical School, who did not contribute to Blaser's   
   commentary.    
   It's well known that antibiotics can enable the bacterium Clostridium   
   difficile, already present in some healthy people, to cause colon-inflaming   
   infections by decimating the other, healthy microbes in humans, Kasper said.    
   However, most evidence so far comes from work done experimentally on mice and   
   other animals. For example, so-called germ-free mice, which lack the normal   
   healthy microbes, are more susceptible to infections by the food poison   
   bacterium Salmonella than    
   mice with the normal bacterial complement, according to Kasper.    
   Research is showing that resident microbes play a complex role in keeping us   
   healthy. For instance, certain gut residents stimulate different sets of   
   T-cells, a type of white blood cell that either promotes or reduces the   
   inflammation associated with an    
   immune response.    
   "We have very complex flora that, in a healthy situation, seems to keep   
   pro-inflammatory and anti-inflammatory T-cells in balance with each other,"   
   Kasper said. An imbalance between these subsets of immune cells can make   
   someone more susceptible to    
   immune-mediated diseases like inflammatory bowel disease and multiple   
   sclerosis or their flare-ups, he said. [Why Are Humans Always So Sick?]    
   In these diseases, the body's immune system attacks part of itself --the   
   intestinal tract in instances of inflammatory bowel disease; the covering on   
   the nerves in cases of multiple sclerosis. So certain bacteria appear to help   
   prevent this.    
   In his lab, Kasper and colleagues are looking at a molecule produced by a gut   
   microbe called Bacteriodes fragilis. This molecule stimulates the   
   inflammation-suppressing T-cells. Working with mice, they have shown that the   
   toll of experimental    
   inflammatory bowel disease and a disease similar to multiple sclerosis can be   
   substantially reduced if this molecule is fed to the animals.    
   "The gut may hold many molecules that have these kinds of effects on the   
   immune system," he said.    
   Restoring our microbes    
   Blaser suggests a more-judicious use of antibiotics, as well as the   
   development of techniques to rapidly identify the problem pathogen and drugs   
   that target only specific pathogens while leaving other microbes unharmed.    
   We may also need to actively replace what we have lost. Probiotics -- microbes   
   consumed for their beneficial qualities -- have promise, although the science   
   is only in its earliest stages, he said.    
   These might be used one day in conjunction with antibiotic treatment to   
   maintain healthy communities, or administered alongside vaccinations to   
   replace communities we have lost, according to Blaser.    
      
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