Weight Loss Microbe

Oct. 4, 2013

By Medical Discovery News

John Donne said, “No man is an island.” Scientists would agree – man is more like a forest. And just like the flora and fauna that call the forest home, each human body houses tons of other species in the form of microbes. In fact, most people have 10 times more microbes in and on them than their own cells! These microscopic organisms live on skin, within the gastrointestinal tract, and inside mouths, helping the human body function and keeping it healthy. Now, new research shows that a certain microbe has huge influence on a person’s weight.

Science is just beginning to understand how the relationship between microbes and human cells, tissues, and organs contributes to good health. The key here is mutualism – the cooperation that benefits both the microbes and the human.

Disruption of the relationship of a person’s microbiome can lead to problems. For example, oral antibiotics can upset the microbiome in the gut, resulting in the discomfort some people experience while taking them. While antibiotics are made to be effective against specific types of bacteria, they also disrupt the normal population of bacteria in the intestinal tract. The types and amount of necessary bacteria here are altered. This results in major changes to the interaction between bacteria and cells lining the gut, much to a person’s dismay and inconvenience.

A recent study shows that a bacterium in the intestines appears to control diet-mediated obesity.  Akkermansia muciniphila is a common resident of the human gut, living in the layer of mucus that coats the surface of the intestinal tract. In a healthy person, this bacterium can be 3-5 percent of all the bacteria present – that’s a lot. The amount of Akkermansia muciniphila in a person’s intestinal tract is highly correlated with their weight. That is, people with low numbers of Akkermansia muciniphila are more likely to be obese and have type II diabetes, and those with high numbers are more likely to have a healthy weight.

To figure out this connection, researchers used mice that were fed either a normal diet or a high fat diet and monitored the number of different bacteria in their guts. As expected, mice fed the high fat diet became obese, but their levels of Akkermansia muciniphila were 100 times lower than mice fed the normal diet. Furthermore, when the obese mice on the high fat diet were also given this bacterium, they lost weight and lowered the incidence of diabetes.

This has some remarkable implications and possibilities for future therapies. This interplay between bacterial populations and the host can prevent some major human health issues, like obesity or diabetes. Perhaps Akkermansia muciniphila will soon be an ingredient in probiotics and yogurts and start a new weight-loss trend.

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Cancer-Fighting Bacteria

Aug. 30, 2013

By Medical Discovery News

Anyone who has experienced the nightmare of food poisoning would probably steer clear of any chance of that. But now, one of the very causes of such illnesses is being tested as a way to treat cancer.

Typically, Listeria monocytogenes infects people when they eat contaminated foods, resulting in 1,600 cases of listeriosis food poisoning each year. The symptoms are fever and muscle aches sometimes along with diarrhea or other gastrointestinal symptoms. It primarily affects the elderly, newborns, or pregnant women, although occasionally people without these risk factors also become ill. In people with compromised immune systems, symptoms can include headaches, stiff necks, confusion, and convulsions. For some, the infection can lead to septicemia, which means that bacteria are in the blood and can lead to a much more rapid deterioration. Listeriosis can also lead to meningitis, a possibly fatal condition in which the bacteria infect the membranes that cover the brain and spinal column. In older adults and people with other serious medical problems, even immediate treatment may not be effective and they can die. 

But a weakened form of the bacterium might be able to deliver radiation directly to cancer cells and effectively kill them. Scientists genetically engineered listeria cells so they were coated with a protein called a monoclonal antibody. Then they attached a radioactive compound called rhenium-188 to the protein. When injected into mice with human cancerous tumors, these modified bacteria cells delivered radioactivity to the tumor cells without harming normal cells. 

The real advantage of this new approach is that it not only targets the primary tumor, but is even better at finding cancer cells that have migrated to other locations in the body. These other metastatic cancer cells are very difficult to target with other therapies. Scientists were unable to find any damage to normal tissues from either the bacteria cells or the radioactive rhenium. Both the bacteria and the rhenium were no longer detectable in the mice one week after the last treatment.

For the experiment, scientists used pancreatic cancer cells. Pancreatic cancer is the most lethal type of cancer, leaving only 4 percent of its victims alive five years after diagnosis. Its location makes diagnosis difficult, and because symptoms often aren’t recognized until the cancer is too advanced to survive, it’s usually too late. If the tumor is confined to the pancreas, then surgery is an option. Chemotherapy and radiation are also used to kill the cancer cells. That’s where this new treatment comes in.

Although this method must be refined to ensure that the bacteria used are as safe as possible and that no dangerous levels of radiation are released and accumulate in the body, it offers hope to the 40,000 people diagnosed with pancreatic cancer each year.

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Rise of Cavities

August 9, 2013

By Medical Discovery News

By 65, 92 percent of Americans have cavities in their permanent teeth, and an average of 3.28 teeth missing or decayed. The answer to why this is may not concern toothpaste ingredients or brushing time, but the lifestyles of ancient humans, as two new studies have discovered.

Humans used to live as hunter-gatherers, meaning they hunted for game and foraged for plants to eat. They were mainly nomadic, following herds to keep their food source. That changed about 10,000 years ago when agriculture was invented. They began to settle down in one place, raising livestock and growing crops for food. The human diet changed as it now included more starch from the grains they harvested.

The breakdown of starch begins with enzymes in the mouth that split the starch into shorter chains of sugars. The process continues in the stomach and the small intestine until the sugar chains are broken down into individual sugar molecules. This leaves a residue of sugar in a film on and between teeth, creating an ideal environment for the growth of bacteria. Two recent studies have documented how this change in diet caused bacteria associated with cavities and periodontal disease to emerge and eventually become widespread.

One group analyzed the bacterial DNA in samples of tarter from ancient teeth to monitor the changes in the types of bacteria that were present. What they found was a record of how humans have wrecked the bacterial ecosystem in their mouths. The increase in starchy foods caused sugar-loving bacteria to flourish.

With new DNA sequencing technologies, scientists isolated bacterial DNA from 34 teeth of Northern Europeans that are 7,000 to 400 years old, including the last hunter-gatherers from Poland and early farmers from Germany. Hunter-gatherers’ teeth harbored fewer types of cavity-causing bacteria, while early farmers’ teeth revealed a sharp increase in bacteria that cause tooth decay and periodontal disease. 

One bacterium, called Streptococcus mutans, contributes to cavities, diabetes, and cardiovascular diseases. In the mid-1800s, Strep mutans became even more dominant in the oral microbiome. This change correlates with the Industrial Revolution, which introduced refined grains and sugars. The simple sugars from these processed foods are the basis for microbial fermentation, which lowers the pH of the mouth and causes damage to tooth enamel.

The second study focused on changes in the DNA of Strep mutans alone from the present then going back in time. They sequenced the genomes of the bacterium from 57 people worldwide, then used some clever genetics modeling to calculate when the Strep mutans started expanding and diversifying. They think that occurred about 10,000 years ago, which correlates to the start of agriculture. 

Both studies show that the oral microbiome changed with the development of agriculture. What neither group has dealt with are the influences of modern behaviors like using toothpaste, adding chlorine and fluoride to drinking water, and more changes to the human diet, particularly the shift to fast food.

 For a link to this story, visit http://www.medicaldiscoverynews.com/shows/351-rise.html.