How Do EpiPens Work?

EpiPen has made a splash in the headlines in recent months. Last summer, the pharmaceutical company Mylan drew widespread criticism when it was revealed that a 500% price hike had been placed on the epinephrine autoinjector. After Congressional investigations, Mylan agreed to introduce a cheaper generic version of the drug, as well as fund programs to help patients afford the costs.

An EpiPen, with its safety cover. Source: Tokyogirl79 (Wikimedia Commons)

But the damage has already been done: since the beginning of 2017, physicians have been prescribing alternatives to EpiPen at a rate 6X higher than in 2016. Without insurance, a generic version called Adrenaclick costs just $10 for a two-pack at CVS.

A young boy with anaphylaxis. 

Source: James Heilman, MD 

So how do EpiPens, and other brands of epinephrine autoinjectors, work in the first place?

Millions of people keep epinephrine autoinjectors on hand due to their risk of anaphylaxis. Anaphylaxis is a serious type of allergic reaction — most commonly to particular foods, animal stings or bites, and medications — that can start within minutes of exposure to the allergen. Symptoms include shortness of breath, throat or tongue swelling, vomiting, lightheadedness, and a drop in blood pressure.

Why such a severe reaction? In response to the the allergen, inflammatory mediators such as histamine cause contraction of smooth muscles (such as the lungs), blood vessel dilation and fluid leakage, and changes in heart rate. A person can die from anaphylaxis if their heart stops beating, or if they are unable to breathe due to swelling of the airway.

EpiPens work by rapidly injecting a dose of epipinephrine (also called adrenaline), which reverses the effects of anaphylaxis.

Epinephrine. Source: Roland Mattern (Wikimedia Commons)

Epinephrine, which plays an important role in our fight-or-flight response, relaxes the smooth muscles of the airways and lungs, and rapidly increases blood pressure by constricting blood vessels. (It's the same hormone that makes us feel like we can run a marathon when, instead, we have to sweat through a public speech to a large, scary audience.) The pen is injected directly into the thigh muscle, as the intramuscular route is faster than subcutaneous administration (like how insulin is delivered).

Have you used an epinephrine autoinjector before? What was the experience like? Let me know in the comments.

Why Does Drinking Milk Ease the Pain of Eating Spicy Food?

I'm pretty wimpy when it comes to eating spicy foods — but if I must indulge in some peppery Chinese food or a plate of hot wings, you'll surely see a glass of milk close to my reach.

You can find me with a plate of hot wings, and a glass of milk.
Source: falovelykids (Pixabay)

Chili peppers contain an active component called capsaicin, which is part of the vanillioid family (the same family that includes the vanilla bean). Capsaicin binds to a receptor called the vanilloid receptor subtype 1 (TRPV1).

While TRPV1 receptors are found in several different organs throughout the body, activation of the TRPV1 receptor on the tongue produces the sensation of heat or abrasion, causing that characteristic burning sensation. Eating a chili pepper does not actually cause a chemical burn — but it certainly feels like it.

So why does milk soothe the savage serrano?

The chemical structure of capsaicin (below) reveals a long hydrocarbon tail, shown in black (carbon) and white (hydrogen):

Chemical structure of capsaicin. (Source: Jacopo Werther/Favourites/Chemistry, Wikimedia Commons)

That hydrocarbon tail means that oily or soapy compounds can act as a detergent to dissolve capsaicin, but water cannot. It's similar to how you can't clean grease off of a cooking pan simply with water, but dish soap will get the job done.

Source: Unsplash (Pixabay)

Milk from mammals contains a protein called casein (the same protein which creates curds in sour milk). Casein is a lipophilic (literally, "fat-loving") protein, which means that it acts as a detergent on capsaicin, thanks to that fatty hydrocarbon tail.

Alcohol also dissolves capsaicin well (wings and beer, anyone?), although its concentration in most alcoholic beverages is often too low to have much of an effect. (On the other hand, casein represents roughly 80% of the protein in cow's milk.)

But remember: it must be mammal's milk! Plant-based milks — such as soy, rice, coconut, or almond — do not contain casein.

Fun fact: Interestingly, in birds, the TRPV1 receptor does not respond to capsaicin, which means that the seeds of chili pepper plants can be dispersed widely. Biologists believe that some species of peppers, such as ghost peppers, have evolved to contain such high levels of capsaicin in order to deter animals from eating them — unless they are also able to help disperse the seeds!

Learn more about the Scoville Scale and how spiciness is quantified here.

Do you have a favorite home remedy for combating the pain of spicy foods? Let me know in the comments!

Does the Mercury in Vaccines Cause Autism? What's the Safest Immunization Schedule for Infants?

With the recent news of President-Elect Trump's talks with Robert F. Kennedy, Jr. to potentially head a new commission on vaccine safety and scientific integrity, many in the scientific and healthcare communities are understandably rattled. Kennedy is a well-known skeptic of vaccine safety, and has previously described the vaccine/autism allegations as such:

“They get the shot, that night they have a fever of a hundred and three, they go to sleep, and three months later their brain is gone. This is a holocaust, what this is doing to our country.”

Source: James Gathany, Judy Schmidt, USCDCP

Mercury is toxic to the human body. It's important, however, to understand how the mercury present in immunizations is different than the mercury in, say, the scary old thermometer in your medicine cabinet.

Thimerosal is a vaccine preservative. Since the early 20th century, small amounts of thimerosal have been used in vaccines to prevent the growth of fungi and bacteria. Thimerosal is mainly composed of ethylmercury. When we hear concerns of mercury toxicity (for example, with the consumption of fish), we are primarily concerned about the compound methylmercury.

Methylmercury (left) and ethylmercury (right). Image source: Wikimedia Commons (public domain)

Ethylmercury is metabolized and excreted by the body much faster than methylmercury (half-life of 1 week vs. 6 weeks), meaning methylmercury is more likely to "build up" in the body. You consume higher, longer-lasting, more concerning doses of mercury when you eat a serving of fish than when you get a vaccine.

Many independent epidemiological studies over the last two decades have concluded that the low doses of thimerosal in vaccines are not harmful to infants, and the compound is not present in routine childhood vaccination schedules in the U.S., E.U., and several other countries. All this said, the current scientific consensus is that there is no compelling evidence linking vaccinations and autism; mercury poisoning does not resemble autism, and rates of autism diagnosis continue to rise despite the removal of thimerosal in many vaccines.

Furthermore, there is no evidence to suggest that the American Academy of Pediatrics' recommended immunization schedule is harmful, or that young children's bodies can't "handle" it. Spacing out vaccines only increases the amount of time by which children are vulnerable to contracting vaccine-preventable diseases. The parents' choice to delay their children's immunizations is what caused the measles outbreak in Disneyland in 2015, with nearly 150 cases.

It's estimated that the MMR (measles, mumps, and rubella) vaccine has saved 17.1 million lives worldwide since 2000. Herd immunity is important for the health of the entire community, as not all children can be vaccinated or will respond satisfactorily to immunizations.

Further reading:

• Centers for Disease Control: Understanding Thimerosal, Mercury, and Vaccine Safety
• Centers for Disease Control: Immunization Schedules for Infants and Children
• Dorea et al.: Toxicity of ethylmercury (and thimerosal): a comparison with methylmercury (J Appl Toxicol 2013; 33:700-11)
• Flaherty: The vaccine-autism connection: a public health crisis caused by unethical medical practices and fraudulent science (Ann Pharmacother 2011; 45:1302-4)

What are Migraines, and What Do They Feel Like?

I am lucky to have never experienced a migraine before. *knocks on wood*

Sasha Wolff (Wikimedia Commons)

But 15% of the world's population suffers from migraines, and those folks will easily rattle off all of the painful symptoms: pulsating pain — sometimes localized to one side of the head — often accompanied by sensitivity to light, sound, or smell. Some also experience nausea. About 1/3 of migraine sufferers perceive auras before the onset of pain, or brief periods of strange visuals, scents, or confusing thoughts.

In more lay terms, Huffington Post columnist Lisa Belkin once described a migraine as feeling "like you are trying to give birth through your forehead."

But what exactly causes migraines, and how are they different from headaches?

It's important to know that although the brain perceives pain from all parts of the body, the brain itself does not feel pain. The brain lacks nociceptors, or specialized sensory nerve fibers that transmit pain signals, which are present in our skin, muscles, and joints.

Headaches, then, are not pain in the brain, but rather activation of nociceptors located in the layers between the brain and the skull: the pia mater and dura mater (collectively, the meninges):

The pia mater (yellow) and dura mater (gray), collectively called the meninges, cushion and 

protect the brain from the skull. OpenStax (Wikimedia Commons)

As you can see from the image above, these layers are highly vascularized, or contain many blood vessels. Common headaches are triggered by fatigue, stress, head injury, or medications which, one way or another, lead to dilation of blood vessels, blood vessel spasms, or inflammation of the meninges.

While the source of pain in migraines is similar to that of headaches, migraines are actually thought to originate in the brain. Many specialists believe auras are caused by sudden increased, then decreased, neural activity in the cortex (outer layer) of the brain.

The activation of these nerves releases a number of proteins, such as serotonin, which can cause inflammation to the meninges as well as dilate blood vessels. A family of migraine medications called triptans work by constricting blood vessels and blocking serotonin. Many people report that "triggers," such as certain foods or changes in the weather, will reliably cause the onset of their migraines, though it is not entirely clear why this happens.

Do you suffer from migraines? Are there specific things that "trigger"  your migraines? What treatments work for you (or don't work)? Let me know in the comments.

What are Hiccups?

What are hiccups?  Possibly the most annoying thing (in my opinion, anyway) that can happen to the body on a semi-regular basis is HICCUPS. They're unexpected, they're rhythmic, and they're darn hard to get rid of.

But what are they in the first place, anyway?

Hiccups can also be...terrifying? (Watch the kitten on the right.)
Pretty nice image to tie in National Cat Day (today), Halloween (Saturday), and the topic of this post, eh? Reddit (anfea2004)

When we breathe normally, air is drawn into the lungs thanks to the contraction of the diaphragm, a sheet of muscle that extends just under the lungs. This contraction is controlled by the firing of the phrenic nerve.

With hiccups, the phrenic nerve becomes irritated, resulting in erratic, involuntary contractions of the diaphragm. The spasm is so strong that it causes us to draw in a quick breath and our vocal cords to close briefly, resulting in the characteristic (read: embarrassing) "HIC!" sound.

Mayo Foundation for Medical Education and Research

So what causes this phrenic nerve irritation? Most commonly, gastric distention caused by bloating, eating too quickly or eating too much, carbonated beverages, swallowing excessive air (like when chewing gum), and even spicy food can tickle the nerve, sending the diaphragm into spontaneous contractions. Rapid changes in temperature (like eating hot food with a cold drink), sudden excitement, or stress can also affect this reflex. People with central nervous system disorders or tumors that affect the phrenic nerve can suffer from intractable hiccups that may require medical attention.

What's the best way to treat hiccups? For more persistent hiccups, medication is available to calm the phrenic nerve, though no single drug has been proven particularly effective.

For your everyday, run-of-the-mill hiccups, grandma's remedies are best. Increasing the partial pressure (volume per area) of carbon dioxide — like holding your breath or breathing into a paper bag — stops hiccups for many people, though the mechanism isn't entirely clear. Some people find success in stimulating another nearby nerve, the vagus nerve, by eating dry bread, a spoonful of peanut butter, or other foods that are a bit harder to swallow.

For me, personally, the most effective treatment is swallowing 10 gulps of water while holding my nose — it's probably a combination of increased carbon dioxide and vagus nerve stimulation that does the trick. (It feels weird, but works like a charm every time.)

The World Record for longest hiccups is held by Charles Osborne. The hiccups began in 1922 just as Osborne went to weigh a hog before slaughtering it. “I was hanging a 350 pound hog for butchering.  I picked it up and then I fell down.  I felt nothing, but the doctor said later that I busted a blood vessel the size of a pin in my brain.”

It's thought that this burst vessel affected an area of the brain that helped inhibit hiccups. Unable to find a cure for 68 years, they finally ceased on their own in 1990. He died just a year later. It's estimated that he experienced 430 million hiccups during this time.

How do you cure your hiccups? Let me know in the comments!

What the Heck is Déjà Vu? Why Do I Get It and Some People Never Do?

Erika Wittlieb (Pixabay)

What is déjà vu?  Many of us know the feeling. You'll be going about your day, minding your own business, folding some laundry...nothing out of the ordinary. Suddenly a sensation of familiarity washes over you, and you're completely aware that it's happening. I've been here before. Except you haven't. Or have I? You might try to think back and pinpoint when you'd experienced this moment before. But just as quickly as the feeling hits you, it's gone again.

Did you predict the future? Were you seeing something from a past life? What the heck is déjà vu, anyway?

Perhaps unsurprisingly, déjà vu (French for "already seen") is, scientifically, pretty poorly understood. There are a few theories, however:

University of Bristol

• Déjà vu may be the result of some sort of "mismatch" in how we're simultaneously sensing and perceiving the world around us. Perhaps we smell something familiar, for example, and our mind is instantly transported to the first time we smelled it. (It's a vague theory, though, and doesn't explain why most déjà vu episodes don't reflect true past events.)
• Déjà vu may be a fleeting malfunctioning between the long- and short-term circuits in the brain. The information our brain takes in about its surroundings may "shortcut" its way straight to long-term memory, bypassing typical storage transfer mechanisms. When we have a moment of déjà vu, it feels as though we're experiencing something from our distant past. 
• A region of the brain called the rhinal cortex, involved in detecting familiarity, may be inexplicably activated without actually activating memory (hippocampal) circuits. That may explain why déjà vu episodes feel so non-specific when we try to figure out where and when we had previously experienced a particular moment. In fact, some patients with epilepsy reliably experience déjà vu at the beginning of a seizure. For these individuals, experimental stimulation of the rhinal cortex — and not so much the hippocampus itself — induces déjà vu.

Déjà vu is estimated to occur in 60-70% of people, and most commonly in those between the ages of 15 and 25 years. (Why? No idea.) Interestingly, I had previously written about déjà vu years ago out of my own curiosity on the matter, having experienced it fairly frequently. I'm now 26, though, and can't remember the last time I had an episode.

Are any of these theories correct? We may never know. After all, an episode of déjà vu is completely unexpected and, for most of us, extremely rare. Empirical research on the topic is next to impossible.

The most parsimonious explanation, then, is likely the following:

What about you?
Do you experience déjà vu?
Let us know
In this anonymous poll!

Why Do We Feel 'Pins and Needles' When our Appendages Fall Asleep?

Medical Treasure

We've all experienced the strange sensation. Maybe it's when your alarm goes off in the morning and you realize you can't feel your arm to shut it off. Or when your legs are folded into a pretzel on the floor while playing Barbie with your kid and you can't stand back up. You give your dead appendages a shake, and suddenly you feel a surge of pins and needles. What causes that feeling?

There's actually a medical term for it  – paresthesia – defined as the tingling sensation caused by pressure or damage to peripheral nerves.

Don't pinch these! Gray's Anatomy
(Wikimedia Commons)

It occurs when there's prolonged pressure on a limb, like your arm positioned awkwardly under your head while sleeping or sitting cross-legged on the floor. The limb "falls asleep," either due to (1) arteries being compressed, thus blocking blood flow of oxygen and glucose to feed the nerves, or (2) directly pinching nerve pathways, causing normal neurotransmission to slow or cease.

Although your limbs may feel lifeless, your brain is receiving a signal of pain, saying "change your position already, idiot!" When you finally free your limb, the sensation of pain intensifies as blood returns to the area and nerves begin firing regularly. The "pins and needles" sensation occurs as certain areas nerve fibers receive blood nutrients and begin re-firing before others. Eventually, after a few seconds, equilibrium is established again.

A common misconception is that blood flow is blocked entirely to the affected limb when it "falls asleep." If that were true, we'd be experiencing a much more serious medical problem. Luckily, the 50,000-60,000 miles-worth of capillaries in our bodies ensure that our other tissues stay satiated and healthy. It would be as though a tourniquet were applied to a limb, and that's simply not what's happening.

Prolonged, regular compression to nerves can result in a more long-term sensation of "pins and needles," such as carpal tunnel syndrome. Consult a doctor if pain, tingling, and numbness is not relieved when you change body position.

Now, I'm going to undo my leg from under me (as I always do when I write) and go for a short walk to wake it back up. OUCH. Sometimes I never learn.

Why Do I Get Hangry (Angry When Hungry)?

Niklas Hellerstedt (Flickr)

Why do we get hangry?  One lovely fall day a few years ago, my now-husband (I'm not sure why he married me after this) almost left me on the side of the road. We had just left a Penn State football game, and I was H-U-N-G-R-Y.

My resulting behavior was far from what you might consider "ladylike," much less "civilized." I won't even re-type the words that were spoken. Eventually, a pit stop for a burger and fries managed to tame my inner beast.

What causes the sensation of "hanger" – the phenomenon of feeling angry and short-tempered when hungry? Coincidentally, fellow The Conversation writer and obesity/nutrition researcher Dr. Amanda Salis recently covered this topic here. Do check out her article for details, as I'll be mostly summarizing below.

Basically, three major factors are thought to contribute to our bad tempers when we're famished:

Glucose metabolism. Mikael Häggström (Wikimedia Commons)

1. When we eat, carbohydrates are broken down into simple sugars, one of which is glucose. Right after a meal, the levels of glucose in our blood are high. Over time, though, blood-glucose levels drop. Eventually, if these levels fall far enough, your brain will perceive it as life-threatening. Unlike other organs, which have an energy back-up, your brain relies solely on glucose as a fuel source and requires a continuous supply. In fact, despite accounting for only 2% of your body's mass, your brain is estimated to use up 20-23% of your body's energy intake throughout the day, even at rest. Low blood glucose, obviously, signals, "imminent death! Act now!"

2. To our other organs, low glucose ramps up hormones that act to increase glucose in the body. Among these are epinephrine and cortisol, which are synthesized in the adrenal glands. These are both stress hormones, released when our body perceives threat, like a lion chasing us or an organic chemistry exam being handed out in class. That's enough to change someone's mood for the worse, right?

3. As it turns out, anger and hunger don't only share many of the same letters, but they're also controlled by similar genes. One of these genes produces a protein called neuropeptide Y, which not only stimulates eating behavior, but also regulates anger and aggression. Long story short, I probably had pretty high levels of neuropeptide Y after that football game.

What about you?
Do you get hangry, too?
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Why Do I Only Remember Certain Things in Certain Places?

Why do I only remember certain things in certain places?  I'm glad you asked, because this happens to me all the time. I'll think about something, get off the couch and go to the kitchen to do whatever I told myself I needed to do, then completely lose my train of thought. Why did I come in here, anyway?

Man Vyi (Wikimedia Commons)

Funny enough, psychologists have actually studied this.

In a 2011 paper, Gabriel Radvansky and colleagues from the University of Notre Dame had participants play a computer game. In a virtual room, they were instructed to pick up an object from a table and take it to another table. The objects varied in color and shape. Importantly, as long as the participant was "carrying" the object, it was invisible to them.

Sometimes the participants' video game characters simply had to cross the room to put the object down. Other times, they had to walk through a virtual doorway to get to the table.

At random times throughout the experiment, participants were asked what object they were currently carrying. Interestingly, walking through a virtual doorway resulted in less accurate and slower responses than when they simply needed to cross a room.

MetroParent

But why? The authors suggest that we keep information in our working memory for as long as we consider it relevant. But when something related to the context of our memory changes — like the room we're in when we think about something — the memory must no longer be important enough for us to remember. Our brains probably think they're helping out by purging that memory for us. This is consistent with the hypothesis that, in general, recently-formed memories are extremely vulnerable to many interfering forces if they have not yet had a chance to consolidate.

To answer the broader question: we associate certain memories with certain places, and that's how we make sense of all the input flooding into our noggins. Our brains have incredible storage capacity, but they can only do so much. (Elephants* never forget, though.)

Do you forget more
When you walk through a door?
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Why Does Coffee Make Me Poop?

Free Stock Photos

Why does coffee make me poop?  Come on, fess up. It happens to the best of us. In fact, I just finished my morning mug, and...anyway, you get the picture.

If a cup of joe makes you go, you're not alone – 29% of people have the "desire to defecate" after drinking coffee, according to this 1990 paper published in the journal Gut. In addition to the survey, the study authors studied bowel motility in 14 subjects before and after drinking caffeinated coffee, decaffeinated coffee, or hot water using a manometry probe (fun!).

Common sense suggests that, like its stimulating effects on the brain, caffeine must also act on the muscles of the colon, resulting in peristalsis (coordinated contraction/relaxation of the GI tract that cause bowel movements). But the results suggested something else.

Peristalsis. Adrignola (Wikimedia Commons)

When asked, 6 subjects who drink coffee and 4 who drank decaf said they felt they could defecate afterward, compared to no subjects who had hot water.

Eight of the 14 subjects who had claimed that coffee typically induces the urge to purge showed increased bowel activity within four minutes of drinking coffee. This continued for at least 30 minutes. But interestingly, a similar increase was seen in those who drank decaf, suggesting that a compound in coffee other than caffeine may be responsible.

Interestingly, 63% of those who claimed that coffee makes them go were women, which may be supported by research suggesting that women are generally more sensitive to distention than men, and are more likely to suffer from irritable bowel syndrome.

What about you?

Does coffee make you wanna poo?

Let us know

In this anonymous poll!*

(*The rhyming was not intended, but hey, it works.)