Dr. Lamm's weekly review of relevant articles and research

There is an increasing amount of information available about the gut.  Here are a few informative articles you may find valuable.


The Environment Within: Exploring the Role of the Gut Microbiome in Health and Disease

The Environment Within: Exploring the Role of the Gut Microbiome in Health and Disease
Lindsey Konkel, Jayne Danska, Sarkis Mazmanian, Lisa Chadwick, Environ Health Perspect. 2013;121(9):a276-a281.

The human genome codes for approximately 23,000 genes, [1] yet some experts have suggested that the total information coded by the human genome alone is not enough to carry out all of the body's biological functions. [2] A growing number of studies suggest that part of what determines how the human body functions may be not only our own genes, but also the genes of the trillions of microorganisms that reside on and in our bodies.

The genomes of the bacteria and viruses of the human gut alone are thought to encode 3.3 million genes. [3] "The genetic richness and complexity of the bugs we carry is much richer than our own," says Jayne Danska, an immunologist at the Hospital for Sick Children Research Institute in Ontario, Canada. "They serve as a buffer and interpreter of our environment. We are chimeric organisms."

A role for gut microbes in gastrointestinal function has been well documented since researchers first described differences in the fecal bacteria of people with inflammatory bowel disease. [4] The molecular mechanisms responsible for the gut microbiome's impact on metabolism and diseases throughout the body remain largely unknown. However, researchers are beginning to decipher how the microorganisms of the human intestinal tract influence biological functions beyond the gut and play a role in immunological, metabolic, and neurological diseases.

A New Normal
Early research on microbiota focused largely on the commensal bacteria that reside in the human gut. Commensal gut bacteria supply nutrients, help metabolize indigestible compounds, and defend against colonization by nonnative opportunistic pathogens.

But the distinction between "good" microbes that aid health and "bad" pathogenic microbes that cause disease has become blurred in recent years. Researchers have shown that under certain conditions, some types of normal gut bacteria can trigger disease. Sarkis Mazmanian, a microbiologist at the California Institute of Technology, dubbed these elements "pathobionts"; the term "pathogens," in contrast, refers to opportunistic microbes that are not normally part of the gut microbial community. [5]

Disturbances to the microbial equilibrium of the gut may mean that some microbes become overrepresented while others are diminished. "It's like a garden—you're less likely to have weeds growing if you have lush vegetation, but without this vegetation the weeds can potentially take over," Mazmanian says. When the gut moves toward a state of microbial imbalance, normally benign gut microbes may begin to induce inflammation and trigger disease throughout the body, even in the nervous system.
Researchers have long postulated that gut bacteria influence brain function. A century ago, Russian embryologist Elie Metchnikoff surmised that a healthy colonic microbial community could help combat senility and that the friendly bacterial strains found in sour milk and yogurt would increase a person's longevity. [6,7]

In 2011 Mazmanian and colleagues reported that changes in gut microbial composition might have far-ranging effects that extend to the brain. [8] They worked with germ-free ("gnotobiotic") mice, which are born in sterile environments and are not naturally colonized with microbiota.


Belching: A Very Common Set of Symptoms

Belching: A Very Common Set of Symptoms

Dr. David Johnson, Professor of Medicine and Chief of Gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia. GI Common Concerns -- Computer Consult.

Today I want to talk about a very common set of symptoms that every one of us has experienced: belching, air swallowing, and hiccups.[1] We see these referrals from primary care. What do we do with these patients? From a gastroenterologist's perspective, what do these symptoms mean?

Let's start with the issue of belching (eructation).

It is not uncommon for patients to describe occasional belching; in fact, it is physiologic. However, there is a difference between a gastric belch -- the normal physiologic response -- and a supragastric belch.

The gastric belch means that the air in the stomach is vented through transient relaxations of the lower esophageal sphincter. The air comes up, the upper esophageal sphincter relaxes, and the air is vented physiologically, a process that occurs 20-25 times every day. It is a normal reflex response.

However, most people who complain of excessive belching don't have gastric belching. They have supragastric belching, meaning that the source of air in the esophagus is not swallowed air; instead, it is transported in, and then by retrograde propulsion, it is driven back out into the pharynx and eructation occurs.

With esophageal impedance manometry, we are able to define this process much more clearly. We can tell when someone volitionally swallows air. We can see the changes in esophageal peristalsis with a volitional swallow.

In the case of supragastric belching, air is drawn back into the esophagus by a diaphragmatic contraction, which creates negative intrathoracic pressure. Thus, the air is sucked into the esophagus and expelled back out, without being swallowed. This is what occurs in most people who have supragastric belching.


Sitting Too Much May Raise Risk of Colon Cancer

Sitting Too Much May Raise Risk of Colon Cancer
Published: Oct 30, 2013 | Updated: Oct 31, 2013. By Michael Smith, North American Correspondent, MedPage Today, Reviewed by F. Perry Wilson, MD, MSCE; Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner.

Men who spend most of the day sitting might be increasing their chance of colorectal cancer, a researcher said.

In a pooled analysis of participants from two phase III clinical trials, men who were largely sedentary had an increased risk of recurring adenomatous polyps, according to Christine Sardo Molmenti, PhD, ofColumbia University Mailman School of Public Health in New York City.

On the other hand, there was no link between recurrence and sedentary behavior among women, Sardo Molmenti told reporters at the American Association for Cancer Research prevention conference in National Harbor, Md.

The clinical implication, she told MedPage Today, is that "clinicians should be encouraging patients to move, to stand, or really to do anything but stay in a sitting position for a large portion of time."

"There's a lot of value for these light, household activities, where you're not completely at rest, but you're not breaking a sweat to work out," she said.

The report comes the same week that European researchers also targeted sedentary behavior as a player in the development of metabolic syndrome and cardiovascular disease.

Doctors have tended to focus on the benefits of activity, rather than the risks of inactivity, commented Paul Limburg, MD, of the Mayo Clinic in Rochester, Minn., who was not part of the study but who moderated a press conference at which some details were presented.

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