June 15, 2017

How Does "Delayed Drowning" Happen?

Source: aghostmaycome (Pixabay)
Each year as summer rolls around, accounts of children "drowning" days after being in water begin creeping into the news.

Just last week, we heard the story of Frankie Delgado, a 4-year-old Texas boy who died a week after a wave knocked him over. Although Frankie appeared to be fine the rest of the day, he began feeling ill the following night.

So what exactly is "secondary drowning"?

Although a relatively rare occurrence compared to "wet drowning" —  which causes roughly 10 deaths each day in the U.S. —  instances of secondary or "delayed" drowning, occurring hours or even days after being in water, have been on the rise as doctors have become better at identifying it.

When we breathe normally, contraction of the diaphragm muscle allows the lungs to expand, which draws air inward, like a vacuum.

The human respiratory system. 
Source: OpenStax College (Wikimedia Commons).
When water is accidentally inhaled, the larynx in the upper airway spasms. This causes the airway to seal shut, but the vacuum still occurs. As the person struggles to breathe more deeply to open the airway, the vacuum becomes stronger. This mechanism is called dry drowning, and this alone can be a cause of death.

The combination of lack of oxygen and too much carbon dioxide can eventually cause the person to become unconscious, which relaxes the laryngospasm and allows water to enter the lungs in what we call wet drowning. (Note that, unlike what you see in the movies, a person drowning cannot call for help.)

However, in secondary drowning, a small intake of water can cause laryngospasms and choking, but does not completely close the airway. The person can appear completely fine. As time passes, however, the inhaled water irritates the lungs, causing inflammation, swelling, and excess fluids to fill the lungs (or "edema"). Progressively, this results in lack of oxygen, blood acidosis (due to inability to rid the body of carbon dioxide), lowered heart rate, and cardiac arrest.

In essence, instead of the person drowning in a lake or backyard pool, the individual drowns from their own bodily fluids.

Again, secondary drowning is a very rare occurrence, but precautions should be taken to prevent death. If you observe that the child struggles to breathe, or is using "extra" muscles to bring oxygen into their lungs, take them to the emergency room. Other common symptoms include coughing several hours after being in the water, despite not being sick. Fever or vomiting, as seen in case of Frankie, can indicate a bacterial infection caused by water in the lungs.

May 28, 2017

Speech at Penn State College of Medicine 2017 Commencement

Speaking at Penn State College of Medicine's Commencement.
Even though I defended my dissertation almost a year ago, I was finally able to participate in the spring Commencement ceremony with my classmates at Penn State College of Medicine last Sunday!

I was honored to give the graduate student address, and I wanted to share the text of my speech below. Even though it's kind of a rough time for a young scientist to start their career now, the goal of my message was to suggest something that all scientists can start doing today to, hopefully, make the world a little more receptive to what we do. Enjoy!


“Wait. What do you do again?” 

Every graduate student has been asked this question at least 20 times. Per year. Usually at family holiday gatherings. 

I’m very humbled to have the opportunity to address my graduate school colleagues, friends, and family this afternoon. But as I sat down to write this speech, I stared at a blank Word document for a while – which is unfortunately still a common occurrence, even after typing a 200-page dissertation. I didn’t quite know how to address so many different people with so many different graduate school experiences. 

What did we all do these last few years?

April 26, 2017

Why Am I Dependent on Caffeine, and How Can I Wean Off?

Hi, I'm Jordan, and I need a daily caffeine fix. (Hi, Jordan!)

Initially, I was drawn to the fun of snatching up seasonal lattes. (That's how they get ya.) Soon after, I appreciated coffee for its smooth taste and irresistible roasty smell. 

But as I started spending more of my time working in a window-less cubicle, I began relying on coffee to not only perk myself up, but also stay perked up throughout the day. Now I need it every morning.

So, am I too far gone? Why do we become dependent on caffeine in the first place? And is it possible to wean off and get back to "normal"?

I NEED IT. Source: quinntheislander (Pixabay)
First of all, it's important to remember that caffeine is a drug — albeit one that 80% of Americans consume daily, in one form or another. By definition, that means that ingesting caffeine causes a physiological change in the body.

In the case of caffeine, a central nervous system stimulant, those physiological changes include increased heart rate, alertness, faster reaction time, and, in larger doses, jitteriness. (And, for fun, I've also previously written about why coffee makes you poop.)

To understand caffeine, we must understand another chemical: adenosine. Adenosine is an inhibitory neurotransmitter, believed to play a role in suppressing arousal and promoting sleep. Levels of adenosine rise throughout the day, which may explain why we become increasingly sleepy the longer we've been awake.

Caffeine doesn't work because it activates the brain; rather, it's more that caffeine inhibits deactivation of the brain. Caffeine and adenosine have similar chemical structures, which means that caffeine can bind to adenosine receptors — essentially blocking them, and thus blocking their sleep-promoting effects. 
Chemical structures of caffeine and adenosine. Source:  ClockworkSoul (Wikimedia Commons)

When people ingest caffeine everyday (or, you know, hourly), the body tries to re-regulate itself by creating MORE adenosine receptors ("c'mon lady, you're supposed to be sleepy at 9pm"). Regular coffee, tea, and soda drinkers, thus, build up tolerance to caffeine over time, because we need more of it to plug up all the new adenosine receptors that keep forming. 

Like withdrawal from other types of drugs, caffeine withdrawal can cause tiredness, irritability, and headaches. In more severe instances, people can even experience nausea and flu-like symptoms. 

Source: chuckyeager (Flickr)
So how long does withdrawal last, and can we actually ever get back to baseline?

A review of 66 studies by American University scientists suggests that withdrawal symptoms pass relatively quickly: you'll feel your crappiest 20-51 hours after your last ingestion of caffeine, and symptoms last between 2 and 9 days, on average. Although harder to study at the cellular level in humans, researchers have found that the number of adenosine receptors in mice returned to normal levels after 8 days of caffeine withdrawal in the forebrain (which, among many other functions, controls sleep behavior). After 15 days, however, adenosine receptor levels were still elevated in the cerebellum (the region of the brain responsible for coordinating muscle activity).

In other words, if you can last a week without a caffeinated concoction (and yes, it might feel like a looooong week), you too can return, for the most part, to your pre-PSL self.

Have you ever given up caffeine for a period of time? How were your withdrawal symptoms? Did you manage to get back to "normal"? Let me know in the comments!

March 8, 2017

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.

February 16, 2017

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!

January 11, 2017

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: