Health and Medical News and Resources

General interest items edited by Janice Flahiff

Unwanted impact of antibiotics broader, more complex than previously known

Antibiotics significantly kill intestinal epithelium, the site of nutrient absorption,  a part of our immune system and a place where other biological functions maintain human health.

Unwanted impact of antibiotics broader, more complex than previously known 

From the 10 February 2015 Oregon State University press release

Researchers at Oregon State University have discovered that antibiotics have an impact on the microorganisms that live in an animal’s gut that’s more broad and complex than previously known.

The findings help to better explain some of the damage these medications can do, and set the stage for new ways to study and offset those impacts.

The work was published online in the journal Gut, in research supported by Oregon State University, the Medical Research Foundation of Oregon and the National Institutes of Health.

Researchers have known for some time that antibiotics can have unwanted side effects, especially in disrupting the natural and beneficial microbiota of the gastrointestinal system. But the new study helps explain in much more detail why that is happening, and also suggests that powerful, long-term antibiotic use can have even more far-reaching effects.

Scientists now suspect that antibiotic use, and especially overuse, can have unwanted effects on everything from the immune system to glucose metabolism, food absorption, obesity, stress and behavior.

The issues are rising in importance, since 40 percent of all adults and 70 percent of all children take one or more antibiotics every year, not to mention their use in billions of food animals. Although when used properly antibiotics can help treat life-threatening bacterial infections, more than 10 percent of people who receive the medications can suffer from adverse side effects.

“Prior to this most people thought antibiotics only depleted microbiota and diminished several important immune functions that take place in the gut,” Morgun said. “Actually that’s only about one-third of the picture. They also kill intestinal epithelium. Destruction of the intestinal epithelium is important because this is the site of nutrient absorption, part of our immune system and it has other biological functions that play a role in human health.”

The research also found that antibiotics and antibiotic-resistant microbes caused significant changes in mitochondrial function, which in turn can lead to more epithelial cell death. That antibiotics have special impacts on the mitochondria of cells is both important and interesting, said Morgun, who was a co-leader of this study with Dr. Natalia Shulzhenko, a researcher in the OSU College of Veterinary Medicine who has an M.D. from Kharkiv Medical University.

Mitochondria plays a major role in cell signaling, growth and energy production, and for good health they need to function properly.

But the relationship of antibiotics to mitochondria may go back a long way. In evolution, mitochondria descended from bacteria, which were some of the earliest life forms, and different bacteria competed with each other for survival. That an antibiotic would still selectively attack the portion of a cell that most closely resembles bacteria may be a throwback to that ingrained sense of competition and the very evolution of life.

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Digestive dysfunction is near the top of the list, with antibiotic use linked to such issues as diarrhea and ulcerative colitis. But new research is also finding links to obesity, food absorption, depression, immune function, sepsis, allergies and asthma.

This research also developed a new bioinformatics approach named “transkingdom network interrogation” to studying microbiota, which could help further speed the study of any alterations of host microbiota interactions and antibiotic impact. This could aid the search for new probiotics to help offset antibiotic effects, and conceivably lead to systems that would diagnose a person’s microbiome, identify deficiencies and then address them in a precise and individual way.

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February 15, 2015 Posted by | Medical and Health Research News | , , , , | Leave a comment

[Press release] Among gut microbes, strains, not just species, matter

From the 29 January 2015 University of Washington press release

First large-scale analysis completed of intra-species genetic variation in gut’s resident organisms

By Leila Gray  |  HSNewsBeat  |  Updated 9:00 AM, 01.29.2015

Posted in: Research

  • Gut microbiomes from different people can contain similar microbial species, but different strains, as this cartoon illustrates.Dana C, Thomas

A large community of microorganisms calls the human digestive tract home.  This dynamic conglomerate of microscopic life forms – the gut microbiome – is vital to how people metabolize various nutrients in their food, how their immune systems react to infection, and how they respond to various medications.  Moreover, imbalances in the microbiome are thought to play a significant role in many human diseases.

The collection of species occupying the gut is known to be quite personalized, and people may differ considerably in the set of species they harbor. Now new research suggests that the differences between people may go even deeper. In a paper published Jan. 29 in Cell, researchers at the University of Washington show that even when people share microbes in common, the exact strains each carries might be very different.

“Knowing more about these strain-level variations,” said Elhanan Borenstein, the senior author of this paper and an associate professor of genome sciences at the University of Washington, “is crucial for understanding the complex relationship between the composition of the community of microbes living in the human gut and its influence on health and disease.”

January 30, 2015 Posted by | Medical and Health Research News | , , , , , , , , , , | Leave a comment

Microbes can influence evolution of their hosts

From the 18 July 2013 article at EurkAlert

Microbes can influence evolution of their hosts

New evidence supporting the hologenome theory of evolution

 IMAGE: This is an illustration of the tree of life created in microbial culture.

Click here for more information. 

You are not just yourself. You are also the thousands of microbes that you carry. In fact, they represent an invisible majority that may be more you than you realize.

These microscopic fellow travelers are collectively called the microbiome. Realization that every species of plant and animal is accompanied by a distinctive microbiome is old news. But evidence of the impact that these microbes have on their hosts continues to grow rapidly in areas ranging from brain development to digestion to defense against infection to producing bodily odors.

Now, contrary to current scientific understanding, it also appears that our microbial companions play an important role in evolution. A new study, published online on July 18 by the journal Science, has provided direct evidence that these microbes can contribute to the origin of new species by reducing the viability of hybrids produced between males and females of different species. [my emphasis]

This study provides the strongest evidence to date for the controversial hologenomic theory of evolution, which proposes that the object of Darwin’s natural selection is not just the individual organism as he proposed, but the organism plus its associated microbial community. (The hologenome encompasses the genome of the host and the genomes of its microscopic symbiotes.)

“It was a high-risk proposition. The expectation in the field was that the origin of species is principally driven by genetic changes in the nucleus. Our study demonstrates that both the nuclear genome and the microbiome must be considered in a unified framework of speciation,” said Associate Professor of Biological Sciences Seth Bordenstein who performed the study with post-doctoral fellow Robert Brucker.

They conducted their research using three species of the jewel wasp Nasonia. These tiny, match-head sized wasps parasitize blowflies and other pest flies, which make them useful for biological control.

“The wasps have a microbiome of 96 different groups of microorganisms,” [My emphasis]said Brucker. Two of the species they used (N. giraulti and N. longicornis) only diverged about 400,000 years ago so they are closely related genetically. This closeness is also reflected in their microbiomes, which are quite similar. The third species (N. vitripennis), on the other hand, diverged about a million years ago so there are greater differences in both its genome and microbiome, he explained.

The mortality of hybrid offspring from the two closely related species was relatively low, about 8 percent, while the mortality rate of hybrid offspring between either of them and N. vitripennis was quite high, better than 90 percent, the researchers established.

“The microbiomes of viable hybrids looked extremely similar to those of their parents, but the microbiomes of those that did not survive looked chaotic and totally different,” Brucker reported.

The researchers showed that the incompatibilities that were killing the hybrids had a microbial basis by raising the wasps in a microbe-free environment. They were surprised to find that the germ-free hybrids survived just as well as purebred larvae. But when they gave the germ-free hybrids gut microbes from regular hybrids, their survival rate plummeted.

“Our results move the controversy of hologenomic evolution from an idea to an observed phenomenon,” said Bordenstein. “The question is no longer whether the hologenome exists, but how common it is?”

 

 

 

July 19, 2013 Posted by | Medical and Health Research News | , , , , | Leave a comment

Gut Microbes at Root of Severe Malnutrition in Kids

Malnourished child

Malnourished child (Photo credit: Wikipedia)

 

From the 30 January 2013 Science Daily article

 

A study of young twins in Malawi, in sub-Saharan Africa, finds that bacteria living in the intestine are an underlying cause of a form of severe acute childhood malnutrition.

The research, led by Washington University School of Medicine in St. Louis and reported Feb. 1 in the journal Science, shows how dysfunctional communities of gut microbes conspire with a poor diet to trigger malnutrition.

Childhood malnutrition is a common problem in Malawi, and while a poor diet clearly plays a critical role, it is not the only factor. Scientists have long puzzled over why some children are afflicted by the condition but not others, even those in the same household who eat the same foods. This has led to the realization that a lack of food alone cannot explain its causes.

The standard treatment is a peanut-based, nutrient-rich therapeutic food, which has helped to reduce deaths from the condition. But the new study shows that the therapeutic food only has a transient effect on the gut microbes. Once the therapeutic food is discontinued, the community of microbes in the intestine and their genes revert to an immature state, in the children and in the mice.

This may explain why many malnourished children gain weight when they are treated with therapeutic food but remain at high risk for stunted growth, neurological problems and even malnutrition and death after treatment is stopped, the researchers say…

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While the food seemed to kick start maturation of the gut microbiomes of the severely malnourished children, its benefits were only temporary. Four weeks after the therapeutic food was discontinued, the gut microbiomes of the malnourished children either failed to progress or even regressed, while those of the healthy co-twins continued to mature on a normal trajectory…

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“There is much more work to do,” Gordon says. “It may be that earlier or longer treatment with existing or next-generation therapeutic foods will enhance our ability to repair or prevent the problems associated with malnutrition.

“We are also exploring whether it is possible to supplement the therapeutic food with beneficial gut bacteria from healthy children, as a treatment to repair the gut microbiome,” he explains. “We hope that these studies will provide a new way of understanding how the gut microbiome and food interact to affect the health and recovery of malnourished children.”

 

 

 

 

January 31, 2013 Posted by | Nutrition | , , , | Leave a comment

   

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