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Katherine Ralston

Caught on Camera: An Amoeba Eating Human Cells Alive

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Katherine Ralston

Are you squeamish? Does the thought of germs and/or microscopic organisms give you the creeps? You might want to turn back now.

The Entamoeba histolytica amoeba infects 50 million people all over the world, and every year, it kills roughly 100,000 of them. Until recently, researchers weren’t sure how this microbe worked. Now, thanks to postdoctoral researcher Katherine Ralston and her team at the University of Virginia in Charlottesville, we have some unsettling insight into how the amoeba attacks its victims: It eats their cells, bit by bit, until the cells are dead.

This particular infection occurs most commonly in developing nations, after victims ingest contaminated food or water. In some parts of Bangladesh, for example, Ralston says 30 percent of children contract the amoeba at least once before their first birthday. While some victims show no symptoms at all, in others, it can cause severe dysentery and even spread to other organs—like the liver—which can be deadly. So, researchers wanted to know: What exactly happens after these microbes are ingested? How do they go on to cause disease in other parts of the body?

To get an up-close look at the action, researchers, led by Virginia’s William Petri, Jr., mixed the amoeba with human cells and observed its behavior under a microscope. Like a microscopic Pacman, almost immediately upon contact, the parasite started taking bites of and ingesting the human cells. Within about 10 minutes, the cells met their untimely death, and the amoeba moved on to its next victim. Researchers caught the whole thing on video.

Why is this process so shocking? Aside from the cringeworthy fact that a parasite is slowly eating human cells alive, researchers were also surprised because many other microbes take a somewhat less violent approach to eliminating cells, emitting something toxic to poison them. “It was thought they would kill cells like a lot of other microbes kill cells,” Ralston told mental_floss. “Instead you see them gnawing on the cell. This really physical cell death is not typical.”

Even more puzzling: The parasite isn’t using the human cells as a primary source of nourishment. “Once these cells had been killed, they stopped eating and moved on to a new cell,” Ralston says. “If it was about nutrition, they would ingest the rest of the cell as a readily available meal.” So why go through the trouble of ingesting the cells, if not for nourishment? Ralston and her team think this is a way for the parasite to invade the intestine, or perhaps a defense mechanism against immune cells sent to rescue the victim from the parasite.

But researchers needed to be sure that this gnawing process is what actually kills the cells. Could cells survive if they’d only been bitten once or twice? If they knew the cause of cell death, they could move forward developing treatments to prevent it. So they altered the microbe, inhibiting its ability to attach to the cells, and saw that indeed, the cells can endure the carnage, up to a point. “We actually found that with some inhibitors—even if we didn’t completely inhibit nibbling, just reduced it—that it allowed the human cells to live,” Ralston says. “It seems there’s a threshold. If we could block this process, that would be a potential new therapy.”

The findings appear in the April edition of the journal Nature and could lead to new treatments for Entamoeba histolytica, which is currently treatable with one class of drugs. “This changes the paradigm for this infection, “ Ralston says.

Live confocal microscopy time lapse demonstrating that bites of human cell material are internalized by the amoebae. Ingestion of bites occurs while human Jurkat cells are viable and ceases once they are dead. Human cells were pre-labeled with DiI (red; cell membrane), Flou4 (green; intracellular Ca2+); and SYTOX blue (blue; nucleic acid in permeable cells) was present in the media during imaging. Images were collected every 30 seconds and are played back at 1 frame per second


Live confocal microscopy time lapse demonstrating that human cell intracellular calcium elevation follows the ingestion of bites. Human Jurkat cells were pre-labeled with DiD (pink; cell membrane), and Flou4 (green; intracellular Ca2+). Images were collected every 20 seconds and are played back at 1 frame per second.

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Space
SpaceX's Landing Blooper Reel Shows That Even Rocket Scientists Make Mistakes
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SpaceX's Falcon 9 rocket launches.
AFP/Stringer/Getty Images

On March 30, 2017, SpaceX did something no space program had done before: They relaunched an orbital class rocket from Earth that had successfully achieved lift-off just a year earlier. It wasn't the first time Elon Musk's company broke new ground: In December 2015, it nailed the landing on a reusable rocket—the first time that had been done—and five months later landed a rocket on a droneship in the middle of the ocean, which was also unprecedented. These feats marked significant moments in the history of space travel, but they were just a few of the steps in the long, messy journey to achieve them. In SpaceX's new blooper reel, spotted by Ars Technica, you can see just some of the many failures the company has had along the way.

The video demonstrates that failure is an important part of the scientific process. Of course when the science you're working in deals with launching and landing rockets, failure can be a lot more dramatic than it is in a lab. SpaceX has filmed their rockets blowing up in the air, disintegrating in the ocean, and smashing against landing pads, often because of something small like a radar glitch or lack of propellant.

While explosions—or "rapid unscheduled disassemblies," as the video calls them—are never ideal, some are preferable to others. The Falcon 9 explosion that shook buildings for miles last year, for instance, ended up destroying the $200 million Facebook satellite onboard. But even costly hiccups such as that one are important to future successes. As Musk once said, "If things are not failing, you are not innovating enough."

You can watch the fiery compilation below.

[h/t Ars Technica]

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Health
8 Potential Signs of a Panic Attack
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It's not just fear or worry. In fact, many panic attacks don’t look like panic at all. Panic attacks come on rapidly, and often at times that don't seem to make sense. The symptoms of panic disorder vary from person to person and even from attack to attack for the same person. The problems listed below are not unique to panic attacks, but if you're experiencing more than one, it's a good idea to talk to your doctor either way.

1. YOU'RE DIZZY.

Doctors sometimes call the autonomic nervous system (ANS) the "automatic nervous system" because it regulates many vital bodily functions like pumping blood all on its own, without our having to think about it. Panic attacks often manifest through the ANS, leading to increased heart rate or decreased blood pressure, which can in turn lead to feeling lightheaded or faint.

2. YOU'RE LOSING YOURSELF.

Feeling detached from yourself is called depersonalization. Feeling detached from the world, or like it's fake or somehow unreal, is called derealization. Both forms of dissociation are unsettling but common signs that a panic attack has begun.

3. YOU'RE QUEASY.

Our digestive system is often the first body part to realize that something is wrong. Panic sends stress hormones and tension to the gut and disrupts digestion, causing nausea, upset stomach, or heartburn.

4. YOU FEEL NUMB OR TINGLY.

Panic attacks can manifest in truly surprising ways, including pins and needles or numbness in a person's hands or face.

5. YOU'RE SWEATY OR SHIVERING.

The symptoms of a panic attack can look a lot like the flu. But if you don't have a fever and no one else has chattering teeth, it might be your ANS in distress.

6. YOU KNOW THE WORST IS COMING.

While it may sound prophetic or at least bizarre, a sense of impending doom is a very common symptom of panic attacks (and several other conditions). 

7. BREATHING IS DIFFICULT.

The ANS strikes again. In addition to the well-known problems of hyperventilation or shortness of breath, panic attacks can also cause dyspnea, in which a person feels like they can't fill their lungs, and feelings of choking or being smothered.

8. YOU'RE AFRAID OF HAVING A PANIC ATTACK. 

Oddly enough, anxiety about anxiety is itself a symptom of anxiety and panic attacks. Fear of losing control or getting upset can cause people to avoid situations that could be triggering, which can in turn limit their lives. 

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