Slug Slime Inspires Super-Sticky Surgical Sealant

Wyss Institute at Harvard University
Wyss Institute at Harvard University

Some damp things, like sweaty thighs, only want to stick together. Others, like wet organs, are far less cooperative. But now scientists have devised a clever way to make them play nice: a two-part glue inspired by slug mucus. The team reported their results in the journal Science.

Surgical adhesive has a big job. It has to be safe, and it has to be able to stick to living tissue, even when that tissue is slick and wet with blood. So far, engineers have had a hard time finding glues that meet all these criteria.

That may be because, previously, they hadn't spent enough time lying on their bellies in the backyard. Ordinary slug mucus is a marvel of chemistry and physics. It's a liquid crystal, neither liquid nor solid. It protects the slug from pathogens, helps it glide along the ground, and can give off chemical messages to other slugs nearby.

And that's just the basic package. Individual slug species also brew special slime blends to suit their own needs. One European species, the dusky arion (Arion subfuscus), copes with threats by mucus-gluing itself to a surface and simply refusing to budge. Its slime is absorbent, strong, and super-sticky. In short, it's a surgeon's dream.

Previous studies of A. subfuscus mucus found that the slime derives its power from its unusual, two-layered structure, with a tough matrix covered with positively charged proteins.

To recreate this magical goo, experts in bio-engineering teamed up with material scientists and heart surgeons. They created their own version of the slime: a rugged hydrogel matrix beneath a sticky layer of large, positively charged molecules.

The researchers put the new glue through an impressive battery of product tests, trying it out on wet and dry pig parts, including skin, cartilage, hearts, arteries, and livers. They used it in rats that had recently undergone surgery, on mice with liver hemorrhages, and on pig hearts. In each case, the glue outperformed existing medical adhesives while causing no damage to surrounding tissue.

In a statement, co-author Adam Celiz, now at Imperial College London, said the slug glue has "wide-ranging applications."

"We can make these adhesives out of biodegradable materials, so they decompose once they've served their purpose. We could even combine this technology with soft robotics to make sticky robots, or with pharmaceuticals to make a new vehicle for drug delivery."

Donald Ingber is founding director of Harvard's Wyss Institute for Biologically Inspired Engineering, where some of the study researchers are based. He was not involved with this study, but praised the team for their ingenuity: "Nature has frequently already found elegant solutions to common problems; it's a matter of knowing where to look and recognizing a good idea when you see one."

Feeling Stressed? Playing Tetris Could Help Relieve Your Anxiety

iStock/Radachynskyi
iStock/Radachynskyi

When Nintendo released their handheld Game Boy system in the U.S. and Japan in 1989, the first game most users experimented with was Tetris. Bundled with the system, the clever puzzler—which prompts players to line up a descending array of tiles to create horizontal lines—was the video game equivalent of an addictive drug. Some players described seeing the shapes in their dreams. The game was in the hands of 35 million portable players; by 2010, it had sold 100 million smartphone downloads.

Now, there’s evidence that Tetris players may have a solution to anxiety in the palms of their hands. According to a paper published in the journal Emotion, Tetris has the capability to relieve stress and troubling thoughts by providing a form of distraction.

As part of a larger study about the benefits of distraction, researchers at the University of California, Riverside conducted an experiment on 309 college students who were told to expect some anxiety-provoking news: They were told someone would be offering an evaluation of their physical attractiveness. While they waited for their results, a third of the subjects played a slow-moving, beginner-level version of Tetris; another group played a high-speed variation; and a third played an adaptive version, which automatically adjusted the speed of the game based on the player’s abilities.

Tetris games that were too slow or too fast bored or frustrated players, respectively. But the game that provided a moderate challenge helped reduce the subjects’ perception of their stress levels. They reported a quarter-point higher level of positive emotions on a five-point scale and a half-point reduction of negative emotions. The students still worried about the results of the attractiveness evaluation, but they experienced fewer negative feelings about it.

The key, according to the study, is that the students were experiencing “flow,” a state of mind in which you’re so engrossed in an activity that you lose your sense of self-awareness. While Tetris may be one of the best ways to quickly fall into flow, anything that consumes your attention—playing music, drawing, cooking—is likely to work.

The next time you have to wait for potentially life-altering news, you may find that a Tetris session will help you cope.

[h/t NPR]

9 Fascinating Facts About the Vagus Nerve

The vagus nerve is so named because it “wanders” like a vagabond, sending out sensory fibers from your brainstem to your visceral organs. The vagus nerve, the longest of the cranial nerves, controls your inner nerve center—the parasympathetic nervous system. And it oversees a vast range of crucial functions, communicating motor and sensory impulses to every organ in your body. New research has revealed that it may also be the missing link to treating chronic inflammation, and the beginning of an exciting new field of treatment for serious, incurable diseases. Here are nine facts about this powerful nerve bundle.

1. THE VAGUS NERVE PREVENTS INFLAMMATION.

A certain amount of inflammation after injury or illness is normal. But an overabundance is linked to many diseases and conditions, from sepsis to the autoimmune condition rheumatoid arthritis. The vagus nerve operates a vast network of fibers stationed like spies around all your organs. When it gets a signal for incipient inflammation—the presence of cytokines or a substance called tumor necrosis factor (TNF)—it alerts the brain and draws out anti-inflammatory neurotransmitters that regulate the body’s immune response.

2. IT HELPS YOU MAKE MEMORIES.

A University of Virginia study in rats showed that stimulating their vagus nerves strengthened their memory. The action released the neurotransmitter norepinephrine into the amygdala, which consolidated memories. Related studies were done in humans, suggesting promising treatments for conditions like Alzheimer’s disease.

3. IT HELPS YOU BREATHE.

The neurotransmitter acetylcholine, elicited by the vagus nerve, tells your lungs to breathe. It’s one of the reasons that Botox—often used cosmetically—can be potentially dangerous, because it interrupts your acetylcholine production. You can, however, also stimulate your vagus nerve by doing abdominal breathing or holding your breath for four to eight counts.

4. IT'S INTIMATELY INVOLVED WITH YOUR HEART.

The vagus nerve is responsible for controlling the heart rate via electrical impulses to specialized muscle tissue—the heart’s natural pacemaker—in the right atrium, where acetylcholine release slows the pulse. By measuring the time between your individual heart beats, and then plotting this on a chart over time, doctors can determine your heart rate variability, or HRV. This data can offer clues about the resilience of your heart and vagus nerve.

5. IT INITIATES YOUR BODY'S RELAXATION RESPONSE.

When your ever-vigilant sympathetic nervous system revs up the fight or flight responses—pouring the stress hormone cortisol and adrenaline into your body—the vagus nerve tells your body to chill out by releasing acetylcholine. The vagus nerve’s tendrils extend to many organs, acting like fiber-optic cables that send instructions to release enzymes and proteins like prolactin, vasopressin, and oxytocin, which calm you down. People with a stronger vagus response may be more likely to recover more quickly after stress, injury, or illness.

6. IT TRANSLATES BETWEEN YOUR GUT AND YOUR BRAIN.

Your gut uses the vagus nerve like a walkie-talkie to tell your brain how you’re feeling via electric impulses called “action potentials". Your gut feelings are very real.

7. OVERSTIMULATION OF THE VAGUS NERVE IS THE MOST COMMON CAUSE OF FAINTING.

If you tremble or get queasy at the sight of blood or while getting a flu shot, you’re not weak. You’re experiencing “vagal syncope.” Your body, responding to stress, overstimulates the vagus nerve, causing your blood pressure and heart rate to drop. During extreme syncope, blood flow is restricted to your brain, and you lose consciousness. But most of the time you just have to sit or lie down for the symptoms to subside.

8. ELECTRICAL STIMULATION OF THE VAGUS NERVE REDUCES INFLAMMATION AND MAY INHIBIT IT ALTOGETHER.

Neurosurgeon Kevin Tracey was the first to show that stimulating the vagus nerve can significantly reduce inflammation. Results on rats were so successful, he reproduced the experiment in humans with stunning results. The creation of implants to stimulate the vagus nerve via electronic implants showed a drastic reduction, and even remission, in rheumatoid arthritis—which has no known cure and is often treated with the toxic drugs—hemorrhagic shock, and other equally serious inflammatory syndromes.

9. VAGUS NERVE STIMULATION HAS CREATED A NEW FIELD OF MEDICINE.

Spurred on by the success of vagal nerve stimulation to treat inflammation and epilepsy, a burgeoning field of medical study, known as bioelectronics, may be the future of medicine. Using implants that deliver electric impulses to various body parts, scientists and doctors hope to treat illness with fewer medications and fewer side effects.

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