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Immunology Study Suggests the Appendix Has a Use After All

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The appendix has long had a reputation as a redundant organ with no real function. Doctors often remove it even in mild cases of appendicitis to prevent future infection and rupture, which may not always be necessary. But new research on the way innate lymphoid cells (ILCs) protect against infection in people with compromised immune systems may redeem this misunderstood organ. 

“Our study was to investigate the innate lymphoid cells in the gut [of mice] and how they might contribute to the function and protection of the gut,” Gabrielle Belz, of Melbourne’s Walter and Eliza Hall Institute of Medical Research, tells mental_floss. “At the same time, we were interested to know how different immune cells impacted the different parts of the gut.”

ILCs can be found “underlying all the body’s surfaces, including the skin, the lungs, the gut, and the reproductive tract, and play a very important and broad role in protecting the body from infections and responses to environmental insults,” says Belz.  

Belz’s team worked in collaboration with a team headed by Eric Vivier at the Centre d’Immunologie de Marseille-Luminy, France. Together, they set out to explore how ILC3s (one group of ILCs) function during and after a gut infection—particularly how they altered immune protection.

The study, published in Nature Immunology, found that in mice, gut infections begin in the cecum, a small pouch that is considered to be the beginning of the large intestine, and which contains a large patch of ILC3s near its tip. The team infected mice with the murine pathogen Citrobacter rodentium, which establishes first in the cecum. Then they removed the ILC3s, which caused shrinkage of the cecum and inflammation in the colon. Moreover, they uncovered a “layered contribution” of each of the different types of immune cells in the cecum.

“Thus, surprisingly, altering the balance of immune cells significantly affected what was happening in the cecum, suggesting that a similar effect might occur in humans in the appendix,” Belz says. “This highlights that simply disposing of this organ may not always be in our best interests.” 

While the appendix is not required for digestive functions in humans, Belz tells mental_floss, “It does house symbiotic bacteria proposed by Randal Bollinger and Bill Parker at Duke University to be important for overall gut health, but particularly when we get a gut infection resulting in diarrhea.”

Infections of this kind clear the gut not only of fluids and nutrients but also good bacteria. Their research suggests that those ILCs housed in the appendix may be there as a reserve to repopulate the gut with good bacteria after a gut infection.

ILCs are hardier than other immune cells, and thus vital to fighting bacterial infections in people with compromised immune systems, such as those in cancer treatment; they are some of the few immune cells that can survive chemotherapy. 

Belz says that changing the way the appendix is regarded—from vestigial to integral—may also help prevent unnecessary appendix operations. In non-emergency cases of appendicitis, for instance, non-surgical treatments such as antibiotics “can be used to endeavor to calm the inflammation down in the cecum and appendix,” she says. And a healthy appendix may be helping to keep your gut microbiome balanced: Belz has conducted prior research that shows that diet, particularly leafy green and cruciferous vegetables, may help produce ILCs as well. 

More study can also help understand how ILCs play a role in allergic diseases such as asthma, inflammatory bowel disease, and psoriasis. At the very least, Belz says, “It seems likely that [the appendix] is an integral part of the immune system.”

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Lincoln’s Famous Letter of Condolence to a Grieving Mother Was Likely Penned by His Secretary
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Despite his lack of formal schooling, Abraham Lincoln was a famously eloquent writer. One of his most renowned compositions is the so-called “Bixby letter,” a short yet poignant missive the president sent a widow in Boston who was believed to have lost five sons during the Civil War. But as Newsweek reports, new research published in the journal Digital Scholarship in the Humanities [PDF] suggests that Lincoln’s private secretary and assistant, John Hay, actually composed the dispatch.

The letter to Lydia Bixby was written in November 1864 at the request of William Shouler, the adjutant general of Massachusetts, and state governor John Albion Andrew. “I feel how weak and fruitless must be any word of mine which should attempt to beguile you from the grief of a loss so overwhelming,” it read. “But I cannot refrain from tendering you the consolation that may be found in the thanks of the Republic they died to save.”

Unknown to Lincoln, Bixby had actually only lost two sons in battle; the others had deserted the army, were honorably discharged, or died a prisoner of war. Nevertheless, word of the compassionate presidential gesture spread when the Boston Evening Transcript reprinted a copy of the 139-word letter for all to read.

Nobody quite knows what happened to Bixby’s original letter—some say she was a Confederate sympathizer and immediately burnt it—but for years, scholars debated whether Hay was its true author.

During Hay’s lifetime, the former secretary-turned-statesman had reportedly told several people in confidence that he—not Lincoln—had written the renowned composition, TIME reports. The rumor spread after Hay's death, but some experts interpreted the admission to mean that Hay had transcribed the letter, or had copied it from a draft.

To answer the question once and for all, a team of forensic linguists in England used a text analysis technique called n-gram tracing, which identifies the frequency of linguistic sequences in a short piece of writing to determine its true author. They tested 500 texts by Hay and 500 by Lincoln before analyzing the Bixby letter, the researchers explained in a statement quoted by Newsweek.

“Nearly 90 percent of the time, the method identified Hay as the author of the letter, with the analysis being inconclusive in the rest of the cases,” the linguists concluded.

According to Atlas Obscura, the team plans to present its findings at the International Corpus Linguistics Conference, which will take place at England’s University of Birmingham from Monday, July 24 to Friday, July 28.

[h/t Newsweek]

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These Deep-Sea Worms Could Live More Than a Thousand Years

Plunge below the sparkling surface of the Gulf of Mexico, head down into the depths, and there you'll find the ancient ones, growing in clusters of drab tubes like piles of construction equipment. Scientists writing in the journal The Science of Nature report that some of these worms could be more than 1000 years old.

When it comes to marine organisms, the deeper you go, the slower and older life gets. Biologists have found an octopus that guarded her eggs for four and a half years. They've seen clams born during the Ming dynasty and sharks older than the United States. They've seen communities of coral that have been around for millennia.

Previous studies have shown that some species of tube worm can live to be 250 years old. To find out if the same was true for other species—in this case, the Gulf of Mexico's Escarpia laminata—researchers spent years watching them grow. They used a long-lasting dye called Acid Blue to mark six clusters of worms, then let them to go about their wormy business. A year later, they collected all 356 blue-stained tubes and brought them back to the lab to measure their growth.

By calculating the speed of the worms' growth and comparing it to the size of the largest individuals, the scientists could devise a pretty good estimate of the oldest worms' age.

And boy, are they old. The researchers' worm-growth simulation suggested that the most ancient individuals could be more than 9000 years old. This seems incredible, even for tough old tube worms, so the scientists calculated a more conservative maximum age: a mere 1000 years.

A millennium-long lifespan is an extreme and not the average, the paper authors note. "There may indeed be large E. laminata over 1000 years old in nature, but given our research, we are more confident reporting a life span of at least 250 to 300 years," lead author Alanna Durkin of Temple University told New Scientist.

Still, Durkin says, "E. laminata is pushing the bounds of what we thought was possible for longevity."

She's excited by the prospect of finding older creatures yet.

"It's possible that new record-breaking life spans will be discovered in the deep sea,” she says, “since we are finding new species and new habitats almost every time we send down a submersible.”

 

[h/t New Scientist]

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