Sci-Ed Update 322

Discoveries about poop, mosquitoes love/hate me, mitochondria don't damage DNA, placebo discovery, flushing brain waste, why don't bacteria consume us alive, and more!

Jul 25, 2024

About 170 billion cells are in the brain, and as they go about their regular tasks, they produce waste — a lot of it. To stay healthy, the brain needs to wash away all that debris. But how exactly it does this has remained a mystery.
Now, two teams of scientists have published three papers that offer a detailed description of the brain's waste-removal system. Their insights could help researchers better understand, treat and perhaps prevent a broad range of brain disorders.
The papers, all published in the journal Nature, suggest that during sleep, slow electrical waves push the fluid around cells from deep in the brain to its surface. There, a sophisticated interface allows the waste products in that fluid to be absorbed into the bloodstream, which takes them to the liver and kidneys to be removed from the body.

Scientists Discover Brain Circuit That Could Explain How Placebos Ease Pain

Placebos offer the tempting possibility of pain relief without drugs or surgery, largely relying instead on expectations that pain will go away.
As intangible and elusive as that sounds, the placebo effect is a very real thing, which scientists have now traced to specific neural circuits in the brain in a recent experiment based on mice.
What's more, in the process the team of researchers led by Chong Chen, an anesthesiologist at the University of North Carolina (UNC) Chapel Hill, also discovered that a part of the brainstem not previously known to be involved in pain processing actually is.

Mitochondria May Have Been Wrongly Accused in DNA Damage

Normal metabolic activity produces reactive oxygen species (ROS) that, if not eliminated, can damage cellular components. As a result, ROS from overactive mitochondria are frequently cited as a source of DNA damage. Despite this longstanding belief, few studies have explicitly demonstrated this linkage.
Tobias Dansen, a redox biologist at the University Medical Center Utrecht, admits that even during his graduate studies, he believed that ROS produced by mitochondria could damage DNA. This idea began changing as he attended more meetings and met biochemists studying redox biology. “You start to realize that actually, to get from the mitochondria into the nucleus and damage the DNA, you have to pass a lot of stuff,” he said, adding that because of ROS’s reactivity, it would likely get caught along the way.
Dansen and his graduate student and study coauthor, Daan van Soest, put this assumption to the test. In a paper published in Nature Communications, the team demonstrated that hydrogen peroxide, a ROS produced by mitochondria, does not diffuse to the nucleus.¹ Considering the presence of DNA bases mutated by hydroxy radicals in tumors, the findings support a nuclear source of ROS yet to be identified.

You’re Surrounded by Bacteria That Are Waiting for You to Die

You are filled with bacteria, and you are covered in them. And a whole lot of them are just waiting for you to drop dead.
As soon as you die, they’ll swoop in. This week, we learned exactly how microbes chow down on us. A brave and strong-stomached team of scientists spent months watching dead bodies decompose, tracking all the bacteria, fungi, and worms, day by day. Forensic scientists can use this timeline, published in Science, to help determine time—and even place—of death. (More on that in a previous Gory Details.)
The microbes in your intestines get first dibs, the scientists found. As soon as you die, they’ll start decomposing you from the inside out. Meanwhile, other bacteria on your skin or in the soil beneath you start mounting an attack from the outside in. As Michael Byrne at Motherboard so nicely summed it up, “Earth is just waiting for you to drop dead.”
That’s a little unsettling, if you think about it. And it begs the question: What keeps all those bacteria from decomposing you alive?
That’s silly, you say. I’m alive. Only dead things decompose.
Yes, but why?

Why Do Mosquitoes Love Me?

Though mosquitoes kill millions of people every year through the diseases they transmit, they are not indiscriminate when it comes to choosing their hosts. Researchers shed light on why mosquitos are attracted to certain people over others.

'Stones' of Undigested Fruit, Hair, And Even Gum Can Hide in Your Gut For Years

In the first Harry Potter novel, Professor Severus Snape hopes to embarrass Harry by quizzing him on the topic of bezoars. According to Snape, they are stony masses found in the stomach of a goat that can act as an antidote for most poisons. Later in the series, bezoars come to the rescue of a poisoned Ron Weasley.
The name bezoar is a derivative of both the Persian and Arabic languages, translating as "antidote" and "against poisons" – which is probably where J.K. Rowling got her inspiration. But many Harry Potter readers may not have realised that bezoars aren't just a product of Rowling's imagination.
And while it's true they can be found in the stomachs of goats and other animals, humans can also develop bezoars – albeit rarely – in their stomachs, intestines, gullets and even windpipes.
Bezoars range in size and weight. In July 2024, a 16-inch mass of hair, weighing two pounds, was surgically removed from a 24-year-old woman's stomach in Manabi, Ecuador. In March 2024, doctors in Newcastle removed a 6-inch hairball from the stomach of a seven-year-old girl. According to reports, it covered 80 percent of her bowel.

Your Poop Schedule Says a Lot About Your Overall Health, Study Suggests

A new study published Tuesday in Cell Reports Medicine reveals that bowel movement frequency significantly influences physiology and long-term health, with the best outcomes linked with passing stools once or twice a day.
Previous research has suggested associations between constipation and diarrhea with higher risks of infections and neurodegenerative conditions, respectively.
But since these findings were observed in sick patients, it remained unclear whether irregular bathroom visits were the cause or result of their conditions.
"I do hope that this work will kind of open clinicians' minds a bit to the potential risks of not managing bowel movement frequencies," senior author Sean Gibbons at the Institute for Systems Biology told AFP, explaining that doctors often view irregular movements as merely a "nuisance."
Gibbons and his team collected clinical, lifestyle, and biological data – including blood chemistry, gut microbiome, genetics and more – from over 1,400 healthy adult volunteers with no signs of active disease.

The Poop Episode | Using Fecal Changes to Monitor Health

In The Poop Episode, host Kevin Patton applies stories from his experience monitoring digestive health in zoo and circus animals to human anatomy and physiology. We explore the frequency of defecation, and how to read poop for common health issues. This is the episode that tells you how to get an elephant to poop on command!

Kevin Patton comment→ This episode includes how to incorporate poop into your course to enhance learning. Believe it or not.

To listen to this episode, click on the play button above ⏵ (if present) or this link→ theAPprofessor.org/podcast-episode-121.html

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