Thursday, January 29, 2009

Train your immune system

Babies Know: A Little Dirt Is Good for You


By JANE E. BRODY
Published: January 26, 2009
Ask mothers why babies are constantly picking things up from the floor or ground and putting them in their mouths, and chances are they’ll say that it’s instinctive — that that’s how babies explore the world. But why the mouth, when sight, hearing, touch and even scent are far better at identifying things?

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Greg Neill
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When my young sons were exploring the streets of Brooklyn, I couldn’t help but wonder how good crushed rock or dried dog droppings could taste when delicious mashed potatoes were routinely rejected.

Since all instinctive behaviors have an evolutionary advantage or they would not have been retained for millions of years, chances are that this one too has helped us survive as a species. And, indeed, accumulating evidence strongly suggests that eating dirt is good for you.

In studies of what is called the hygiene hypothesis, researchers are concluding that organisms like the millions of bacteria, viruses and especially worms that enter the body along with “dirt” spur the development of a healthy immune system. Several continuing studies suggest that worms may help to redirect an immune system that has gone awry and resulted in autoimmune disorders, allergies and asthma.

These studies, along with epidemiological observations, seem to explain why immune system disorders like multiple sclerosis, Type 1 diabetes, inflammatory bowel disease, asthma and allergies have risen significantly in the United States and other developed countries.

Training the Immune System

“What a child is doing when he puts things in his mouth is allowing his immune response to explore his environment,” Mary Ruebush, a microbiology and immunology instructor, wrote in her new book, “Why Dirt Is Good” (Kaplan). “Not only does this allow for ‘practice’ of immune responses, which will be necessary for protection, but it also plays a critical role in teaching the immature immune response what is best ignored.”

One leading researcher, Dr. Joel V. Weinstock, the director of gastroenterology and hepatology at Tufts Medical Center in Boston, said in an interview that the immune system at birth “is like an unprogrammed computer. It needs instruction.”

He said that public health measures like cleaning up contaminated water and food have saved the lives of countless children, but they “also eliminated exposure to many organisms that are probably good for us.”

“Children raised in an ultraclean environment,” he added, “are not being exposed to organisms that help them develop appropriate immune regulatory circuits.”

Studies he has conducted with Dr. David Elliott, a gastroenterologist and immunologist at the University of Iowa, indicate that intestinal worms, which have been all but eliminated in developed countries, are “likely to be the biggest player” in regulating the immune system to respond appropriately, Dr. Elliott said in an interview. He added that bacterial and viral infections seem to influence the immune system in the same way, but not as forcefully.

Most worms are harmless, especially in well-nourished people, Dr. Weinstock said.

“There are very few diseases that people get from worms,” he said. “Humans have adapted to the presence of most of them.”

Worms for Health

In studies in mice, Dr. Weinstock and Dr. Elliott have used worms to both prevent and reverse autoimmune disease. Dr. Elliott said that in Argentina, researchers found that patients with multiple sclerosis who were infected with the human whipworm had milder cases and fewer flare-ups of their disease over a period of four and a half years. At the University of Wisconsin, Madison, Dr. John Fleming, a neurologist, is testing whether the pig whipworm can temper the effects of multiple sclerosis.

In Gambia, the eradication of worms in some villages led to children’s having increased skin reactions to allergens, Dr. Elliott said. And pig whipworms, which reside only briefly in the human intestinal tract, have had “good effects” in treating the inflammatory bowel diseases, Crohn’s disease and ulcerative colitis, he said.

How may worms affect the immune system? Dr. Elliott explained that immune regulation is now known to be more complex than scientists thought when the hygiene hypothesis was first introduced by a British epidemiologist, David P. Strachan, in 1989. Dr. Strachan noted an association between large family size and reduced rates of asthma and allergies. Immunologists now recognize a four-point response system of helper T cells: Th 1, Th 2, Th 17 and regulatory T cells. Th 1 inhibits Th 2 and Th 17; Th 2 inhibits Th 1 and Th 17; and regulatory T cells inhibit all three, Dr. Elliott said.

“A lot of inflammatory diseases — multiple sclerosis, Crohn’s disease, ulcerative colitis and asthma — are due to the activity of Th 17,” he explained. “If you infect mice with worms, Th 17 drops dramatically, and the activity of regulatory T cells is augmented.”

In answer to the question, “Are we too clean?” Dr. Elliott said: “Dirtiness comes with a price. But cleanliness comes with a price, too. We’re not proposing a return to the germ-filled environment of the 1850s. But if we properly understand how organisms in the environment protect us, maybe we can give a vaccine or mimic their effects with some innocuous stimulus.”

Wash in Moderation

Dr. Ruebush, the “Why Dirt Is Good” author, does not suggest a return to filth, either. But she correctly points out that bacteria are everywhere: on us, in us and all around us. Most of these micro-organisms cause no problem, and many, like the ones that normally live in the digestive tract and produce life-sustaining nutrients, are essential to good health.

“The typical human probably harbors some 90 trillion microbes,” she wrote. “The very fact that you have so many microbes of so many different kinds is what keeps you healthy most of the time.”

Dr. Ruebush deplores the current fetish for the hundreds of antibacterial products that convey a false sense of security and may actually foster the development of antibiotic-resistant, disease-causing bacteria. Plain soap and water are all that are needed to become clean, she noted.

“I certainly recommend washing your hands after using the bathroom, before eating, after changing a diaper, before and after handling food,” and whenever they’re visibly soiled, she wrote. When no running water is available and cleaning hands is essential, she suggests an alcohol-based hand sanitizer.

Dr. Weinstock goes even further. “Children should be allowed to go barefoot in the dirt, play in the dirt, and not have to wash their hands when they come in to eat,” he said. He and Dr. Elliott pointed out that children who grow up on farms and are frequently exposed to worms and other organisms from farm animals are much less likely to develop allergies and autoimmune diseases.

Also helpful, he said, is to “let kids have two dogs and a cat,” which will expose them to intestinal worms that can promote a healthy immune system.

    We cannot live alone and it is necessary to interact with other organisms.  Although keeping clean is important to everyone but to keep away from dirt forever is impossible.  There is always a positive side from any negative components.  

The best is be 'moderate'.

     It is essential for us to train our body to built up our best defense system, that is our immune systems, to fight against any potential pathogens or worms. 




Wednesday, January 28, 2009

Obesity (nature vs nurture).....?

Microbe Composition In Gut May Hold Key To One Cause Of Obesity

Web address:
http://www.sciencedaily.com/releases/2009/01/090119210437.htm

Scientists reveal a tantalizing link between differing microbial populations in the human gut and body weight among three distinct groups: normal weight individuals, those who have undergone gastric bypass surgery, and patients suffering the condition of morbid obesity--a serious, often life-threatening condition associated with diabetes, cardiovascular disease, cancer and psychosocial disorders. (Credit: iStockphoto/Lisa Fletcher)

ScienceDaily (Jan. 20, 2009) — Biodesign Institute in collaboration with colleagues at the Mayo Clinic, Arizona, and the University of Arizona, reveal a tantalizing link between differing microbial populations in the human gut and body weight among three distinct groups: normal weight individuals, those who have undergone gastric bypass surgery, and patients suffering the condition of morbid obesity—a serious, often life-threatening condition associated with diabetes, cardiovascular disease, cancer and psychosocial disorders. Obesity affects around 4 million Americans and, each year, some 300,000 die from obesity-related illness.

A collaboration aimed at uncovering the links between the microbial composition of the human gut and morbid obesity began when Dr. John DiBaise, a gastroenterologist at the Mayo Clinic, Arizona, became interested in both the underlying mechanisms of obesity and plausible alternatives to gastric bypass surgery—still the only reliable long-term treatment for the extremely overweight.

DiBaise turned to Bruce Rittmann, Ph.D., an environmental engineer and a member of National Academy of Engineering, whose Center for Environmental Biotechnology uses its expertise to examine microbial populations important for cleaning up pollutants and generating renewable bioenergy. Rittmann invited Rosa Krajmalnik-Brown, assistant professor of civil and environmental engineering, to collaborate and apply her microbial ecology expertise to this project. The three researchers were able to leverage seed funding from the Mayo Clinic and ASU so that they could combine their respective talents. DiBaise recruited 9 middle-aged volunteers in three groups—normal weight, morbidly obese and following gastric bypass surgery—to participate in the study.

The research team's central hypothesis is that differing microbial populations in the gut allow the body to harvest more energy, making people more susceptible to developing obesity. These small differences can, over time, profoundly affect an individual's weight. Supporting this view is the study's confirmation that the microbial composition among obese patients appears significantly altered compared with both normal weight individuals and those who have undergone gastric bypass surgery.

Microbial managerie

To tease out the microbial human gut composition, Husen Zhang, a postdoctoral scholar working with Rittmann and Krajmalnik-Brown, used an advanced DNA sequencing technology and sophisticated ecological tools. The team examined 184,094 gene sequences of microbial 16S rRNA, a molecular structure which provides a characteristic fingerprint for microbial identification. The analysis was conducted with the assistance of University of Arizona's Rod Wing at the Bio5 Institute, using a novel sequencing technique known as 454-pyrosequencing, which allows a significantly larger number and greater diversity of gut microbia to be identified.

The group's latest findings represent the first investigation of gut microbiota from post-gastric-bypass patients to date.

By examining a specific region of the 16S rRNA gene known as V6—PCR amplified from the stool samples of the 9 test subjects—the researchers were able to classify a zoo of microorganisms, which fell into 6 broad categories, with two bacterial phyla, the bacteroidetes and firmicutes, predominanting.

The resulting composition of gut microbiota in the three gastric bypass patients differed substantially and in potentially important ways from obese and normal weight individuals. This means the drastic anatomical changes created by gastric bypass surgery appear to have profound effects on the microorganisms that inhabit the intestine. This change may be part of the reason that gastric-bypass surgery is the most effective means to treat obesity today.

The team's study is the first molecular survey of gut microbial diversity following surgical weight loss, and has helped solidify the link between methane producing microbes and obesity. Specifically, the microbial populations extracted from obese individuals were high in a particular microbial subgroup, hydrogen-producing bacteria known as prevotellaceae. Further, such hydrogen producers appear to coexist with hydrogen-consuming methanogens, found in abundance in obese patients, but absent in both normal weight and gastric bypass samples. Unlike the hydrogen producers, however, these methane-liberating hydrogen consumers are not bacteria. They belong instead to the third great microbial domain—the Archaea, (with Eukarya and Bacteria making up the other two).

Energy managers

During the course of digestion, calories are extracted from food and stored in fat tissue for later use—a process delicately regulated by the multitude of microbial custodians. The intermediary products of the digestive process include hydrogen, carbon dioxide and several short chain fatty acids (SCFAs).

Results suggest a cooperative co-existence in obese individuals between hydrogen-producers and hydrogen consuming methanogens. Rittmann explains how this mutually reinforcing relationship, known as syntrophy, may contribute to obesity:

"Organisms producing hydrogen and acetate create a situation like cars flooding onto the highway. The methanogens, which remove the hydrogen, are like the offramps, allowing the hydrogen cars to get off. That allows more acetate cars to get on, because some hydrogen cars are coming off the highway."

The methanogen offramps, by removing hydrogen, accelerate the efficient fermentation of otherwise indigestible plant polysaccharides and carbohydrates. The effect is to boost production of SCFAs, particularly acetate, which will be taken up by the intestinal epithelium and converted to fat. The result over time may be increasing weight, eventually leading to obesity.

While weight regulation involves a complex interplay of genetic predisposition, exercise, eating habits, and other factors, manipulation of the gut's microflora, particularly the methanogenic Archaea, may provide additional avenues for the treatment of morbid obesity.

The researchers stress that the study is preliminary, but were encouraged by the findings from their small sample. Future investigation is needed to establish the differences in composition of gut microbiota across different age groups and under varying weight-loss regimens involving diet and exercise. Nevertheless, the study's findings point to new avenues for modifying the body's energy harvesting efficiency—perhaps by manipulation of the Bacteria-Archaea nexus.


Dear Students,
In group of 4 members, give comments on the articles (max 200 words). What other major contributory factors?

Ways to control Type 2 Diabetes

Can Diet Alone Control Type 2 Diabetes? No Evidence Yet

Web address:
http://www.sciencedaily.com/releases/2008/07/
080715204819.htm

ScienceDaily (July 16, 2008) — Despite strong evidence that type 2 diabetes can be prevented or at least delayed by a combination of lifestyle changes and good dietary advice, a team of Cochrane Researchers found that there is no indication whether dietary advice alone can prevent the disease.

Type 2 diabetes is very common and the number of people affected is increasing. The disease is linked to obesity, with 80% of individuals who develop the disease being obese. Therefore as the incidence of obesity rises around the world, so too does the incidence of type 2 diabetes. The World Health Organization (WHO) estimates that more than 180 million people worldwide have diabetes. It claims that this number is likely to more than double by 2030.*

When a team of Cochrane Researchers set out to see if dietary advice alone could help a person with type 2 diabetes, they were only able to identify two trials that together involved just 358 people.

"Considering the importance of this disorder, we were disappointed to find such a small amount of relevant data," says lead researcher Lucie Nield, who works in Centre for Food, Physical Activity & Obesity, University of Teesside, Middlesbrough.

The two studies did, however, indicate that dietary advice alone could play an important role. One study randomly assigned people to either a control group or a dietary advice group. After six years 67.7% of people in the control group had diabetes, compared with only 43.8% in the advice group. This was a 33% reduction. In another study 12 months of dietary advice led to significant reductions in many diabetes related factors, such as insulin resistance, fasting C-peptide, fasting proinsulin, fasting blood glucose, fasting triglycerides, and fasting cholesterol and PAI-1.

"These two studies give grounds for believing that dietary advice alone could play an important role in reducing type 2 diabetes, but we do need more well-designed, long-term studies before we can work out the best advice to give," says Nield.


Dear students,
Pls read the above articles and give comments on whether you agree or disagree in max 250 words. Pls indicate your group members' names (4 in groups) in the comments. MARKS WILL BE ALLOCATED.

Tuesday, January 13, 2009

Useful animations

Other than text book, animations are useful in explaining certain topics in biochemistry.

I found a link below from Wiley, which will be useful for student who to grab a deeper understanding of some fundamental concepts of nutrition and metabolism.

http://www.wiley.com/legacy/college/boyer/0470003790/animations/animations.htm


Pls look into the content and evaluate the facts. Make some discussion among yourself.

Have fun!