Biomedical Engineering

As a biomedical engineering student, we covered a lot of anatomy and physiology back in school, including a class on dental implants and a pig dissection. None of those things ever grossed me out or made me uncomfortable. The only chapter that ever made me cringe (and fortunately we didn't go into too much detail about it) was eyes. Something about the eyeball just creeps me out, and as someone who wears contacts and has extra-sensitive eyes, I am frequently at the eye doctors and considering Lasik (even though the idea of it makes me nauseous).

The eye is a pretty amazing and complex organ. They heal quickly and with proper care most corneal scratches repair in 48 hours or less. Humans blink about 12 times a minute, with the average blink lasting 1/20 of a second. And seeing is such an important part of everyday life that it requires about half the brain to get involved.

The reason I bring this all up is because scientists at the University of Nottingham have recently discovered an undetected layer in the cornea which could help surgeons dramatically improve the outcomes for patients undergoing corneal grafts and transplants. The cornea is the clean 'window' at the front of the eye that allows light to enter the eye. It is about 500 microns thick, incredibly tough, and strong enough to withstand one and a half to two bars of pressure. The cornea was originally thought to only have five layers. This new layer, named Dua's Layer (after the scientist who discovered it), is 15 microns thick and sits at the back of the cornea.

The discovery was made by Professor Harminder Dua and his colleagues by injecting air into the corneas of eyes that had been donated for research and using an electron microscope to scan each separate layer.

Dua notes, "From a clinical perspective, there are many diseases that affect the back of the cornea which clinicians across the world are already beginning to relate to the presence, absence or tear in this layer."

Did you know that Newborns don't produce tears. They make crying sounds, but the tears don't start flowing until they are about 4-13 weeks old." ^{Image Credit: myrna.info.}

Not only will the discovery mean that anatomy text books will have to be rewritten, but it means that now doctors can provide better outcomes for patients undergoing eye surgery and those with a disease of the cornea. One disease in particular, acute Hydrops, is a bulging of the cornea caused by fluid buildup and occurs in patients in a conical deformity of the cornea, which is caused by a tear in the Dua layer. This causes water from the inside of the eye to rush in and results in water logging.

Coffee. It can change your day. For many there is a psychological and well as physiological addition to the drug. In 2008 the annual world average of coffee consumption was 1.3 kg per person. I've avoided talking about coffee on this blog because there are so many studies that show conflicting results, but I think now's a good time to put out some of the ideas.

^{Image Credit: Precision Nutrition}

Most recently, the National Cancer Institute did a study with more than 400,000 volunteers ages 50 to 71, who were free of major diseases at the start of the study in 1995. They found that men who reported drinking two or three cups of coffee were 10 percent less likely to have died than those who didn't drink coffee, while women drinking the same amount had a 13 percent less risk of dying during the study. Now, these seems like some sketchy stats to me, and even the researchers admitted that it's not clear exactly what coffee had to do with their longevity; however the correlation is striking.

The list of adverse effects of caffeine should really cause most people to avoid coffee. These effects include causing palpitations and headaches, impairing fertility, increasing levels of cortisol (stress hormone), increasing calcium loss from our bones, and reducing sleep quality.

However more and more studies are linking coffee to medical benefits such as lowering your risk of liver disease, preventing the return of breast cancer, reduction in the risk of developing Type 2 diabetes, basal cell carcinoma (the most common skin cancer), prostate cancer, and oral cancer. Some of these studies separate the caffeine from the coffee substance.

Another notable benefit of coffee is an association with reduced risk of dementia and Alzheimer's disease.

^{Image Credit: Ilovecoffeebook.com}

So besides being delicious, there are many benefits to drinking coffee. It's important to note that some of these studies focused on the coffee compound, and others focused on the caffeine, and risks to drinking too much coffee do exists. No one can deny the popularity of drinking a cup (or two) a day and there is probably a good reason for that. So, how do you like your coffee?

3D printing has been weekly news for the past couple of months. It is revolutionizing products and industries as we know them. Additive manufacturing (aka 3D printing) is the process of making three-dimensional solid objects from a digital model. It is achieved by using additive process, where an object is created by laying down successive layers of material. This differs from traditional machining techniques which are subtractive processes.

^{Image Credit: Dezeen.com}

3D printing has been getting a bad rep in the past couple of weeks after stories of a fully functional 3D printer gun were released. Sure, that's one thing (along with the millions of others things) that the printers can be used for, but they can also be used to help people. In the field of biomedicine, 3D printers are paving the way for building fully functional components that can be used to replace defective human organs. For example, Princeton University has deigned and printed a bionic ear that can hear better than human ears. The printed ear intertwines embedded electronics by printing cells and nanoparticles, and then combining a small coil antenna with cartilage to create the ear.

Another amazing feat of 3D printing has been creating a splint for a baby who had severe tracheobronchomalacia, a condition that causes a collapse of the windpipe, blocking the body's flow of air. The splint was molded from a scan of the baby's windpipe and after it was printed the stent was sewn around the baby's airway, which helped open up his bronchus and aided his breathing.

Image Credit: Mashable.com

Other ways that 3D printing can help health care include cutting down the kidney transplant list, regulating diabetes by creating new organs, grafting skin for burn victims, addressing dental health needs, and printing medicine.

Working off of the medical mystery post last week and an "emergency" trip to the dentist this week, I thought I would follow up with some more information on your pearly whites. I've talked about teeth before and the link between being a redhead and being scared of the dentist but what are some everyday things that could cause damage to your teeth?

No More Sucking

^{(But how can you say no to him?) Image Credit: South Riding Family Dentistry}

While I'm sure this doesn't apply to my readers (I hope), it may apply to your kids. Once a child has their permanent teeth, thumb sucking could cause changes that affect tooth and jaw structures, including misalignment of the teeth. Misalignment could cause difficulty chewing and breathing problems, so tell your kids to quit sucking (you know what I mean).

Don't Crush

Teeth are designed to crunch through things, not against something so no more crunching ice. The cold temperature and hardness of the ice can cause serious damage to your teeth.

Brush…Gently

We all have to brush (and use foaming toothpaste) as part of good oral hygiene, but brushing your teeth too hard can wear down enamel, irritate your gums, and make your teeth more sensitive to temperature. Dentists recommend using a soft bristled toothbrush that's recommended by the ADA (it'll say so on the packaging).

Your Teeth are Not Tools!

We're all guilty of this. Actually I broke this rule this morning when I ripped a tag off with my teeth. Using your teeth to rip open a package or break off a string can cause your teeth to crack. Teeth are also not placeholders for pencils, glasses, etc. Holding something between your teeth may cause them to shift, crack, or ruin existing dental work. Same goes for biting nails. Pretty much don't chew or bite something unless it's food.

^{(Besides, nail biting is a little gross….) Image Credit: Stopnailbitingtips.com}

Say No to Acid

Soda and citrus fruits are often very acidic. Soda corrodes the enamel on your teeth, and it's even worse if you sip over a long period of time. The longer sugar stays in your mouth, the worse it is. Sugar is consumed by acid-producing bacteria in your mouth. The acids eat away at tooth enamel. Avoid foods like jelly candies, which stick in your teeth longer than other foods and bathe them in sugar. Dried fruit such as raisins are no better. Reach for fresh fruit instead. Acid can cause decay around the gum lines and loss of enamel; same with citrus fruits, especially lemons, which can erode the enamel away to the point where the surface of your teeth have a rough texture.

It's been a while since a great mystery has been solved for you all here. But have no fear - I have a good one today that has affected everyone at some point. Ready? Why does everything taste bad after you brush your teeth?

^{Image Credit: champagnedentalblog.com}

We've all been there; you're ready for work and you grab a glass of OJ on your way out the door and it tastes awful!

Turns out, this is due to sodium laureth sulfast, also known as sodium lauryl ether sulfate (SLES) or sodium lauryl sulfate (SLS)-- depending on which toothpaste you use. These chemicals are added to toothpaste to create foam and make the paste easier to spread around your mouth by lowering the surface tension of a liquid.

^{Image Credit: Magic foods}

In addition to making it easier to brush your teeth, these sulfates mess with your taste buds. They suppress the receptors that perceive sweetness, making orange juice gross. The sulfates also break up the phospholipids on your tongue. These fatty molecules inhibit our receptors for bitterness, so when they're broken down by the sulfates in the toothpaste, bitter tastes get enhanced.

^{Image Credit: library.thinkquest.org}

So anything you eat or drink after you brush is going to have less sweetness and more bitterness than it normally would. There are surfactant-free toothpastes which won't foam, but won't ruin your breakfast either.

Do you faint at the sight of blood? This story is particularly relevant to me, since one of my younger cousins passed out after seeing blood in his science class last week. Apparently he's not alone, since 3 to 4 percent of people suffer from blood phobia or a related disorder. Someone who suffers from a blood phobia experiences an increase and sudden decrease in blood pressure and heart rate at the sight of blood. This manifests as dizziness, sweatiness, tunnel vision, nausea, fainting, or some combination of these conditions.

^{Image Credit: The Post College Life}

During this reaction, the vagus nerve overreacts in response to the blood (among other things such as hunger, dehydration, pain, and vomiting) and causes a vasovagal response. The vagus nerve runs from the brain stem through the neck, chest, and abdomen. It is part of the parasympathetic nervous system, which controls the involuntary "rest and digest" functions, such as lowering heart rate and promoting the secretion of gastric juices.

^{Image Credit: uvahealth}

Since passing out at the sight of blood doesn't seem to make sense from an evolutionary perspective, there are many theories that try to explain why this happens for some people. One suggestion is that it is a way of "playing dead" in dangerous situation. This may be very helpful to keep you from bleeding out after being cut. There is also a connection with heredity since 60 percent of blood phobics' first-degree relatives also have the phobia.

^{Image Credit:Toonpool}

If you suffer from this phobia, there are specialists dedicated to helping you get over it. One technique commonly used is to clench their muscles at the sight of blood, which counteracts the drop in blood pressure. The technique has proven very effective in several studies. I'm going to have to pass this technique to my cousin since he joined the wrestling team and there's bound to be a bloody nose on the mat at some point.

(I didn't include any blood pictures, just in case)

Resources

Why Do Some People Faint When They See Blood?

Causes of Fainting