Study Aid #8

WILTIMS #100: Doctoring

Centennial post! Thank you to all of my readers. I love writing this blog (though I do forget this sometimes at 2am) and I'm constantly amazed that anyone would come back on a semi-regular basis to read my ramblings. This was the last day before a big week of tests, so I will probably not post anything for a little while. I have to stay in medical school to keep writing about it!

Today we had a midterm in Fundamentals of Clinical Medicine at 8am(!!!). How younger me ever managed to go to school at such an unsavory hour I do not know. We then continued into three straight hours of medical physiology, which was surprisingly intelligible for once. I then ditched the one hour of class in the afternoon - gasp! - to give a presentation at a local middle school about lung cancer and smoking.

Me getting a radiation treatment

As I mentioned in a post eons ago, I am on the executive board of the Cancer Awareness Education Program student club on campus. Our mission is to go to local middle and high schools and give presentations to kids about the dangers of lung cancer and smoking. At the same time, we are conducting research on the effectiveness of such presentations. Unlike D.A.R.E. programs which focus on peer pressure, "just say no!", and the like, our goal is to teach the science behind anti-smoking claims so that kids can decide for themselves not to smoke rather than just being told not to. Of course, we also add a solid dose of scare tactics, via gross pictures, to hammer the message home (my radiation mask and personal cancer stories do wonders too). Here are some of the highlights for your reference:

My mask

• Cancer is the second largest cause of death in the US and lung cancer is far and away the biggest killer of all cancers.
• Even though slightly more people are diagnosed with prostate and breast cancer each year, lung cancer kills more people than prostate, breast, colon and pancreatic cancers combined.
• Over 90% of these lung cancer deaths (and most oral and throat cancers too) are directly caused by smoking.
• Lung cancer is an especially nasty cancer prone to metastasis and has awful, relatively ineffective treatments.
• Smoking, even if it doesn't cause cancer in an individual, always reduces lung function. 
• Whereas healthy lungs will last well over 100 years, a lifelong smoker will start to have difficulty breathing by their 50s and their lungs will start to fail by 75. 
• But by stopping smoking, even after decades, the lungs will return to a normal rate of decay, prolonging the time that they'll work well.
• So don't start, but if you do, it is never too late to quit!

I love doing outreach like this - sharing the wonders of science and medicine with the uninitiated public. I firmly believe that regardless of education or interests, everyone should have a healthily inquisitive mind. And one of the biggest mysteries that everyone confronts on a daily basis is how their own body works. Part of the reason I write this blog and why I wanted to go into medicine in the first place is to share the knowledge that am lucky enough to learn in medical school with my friends, family and someday my patients. It's your body and it's amazing and you should know that!

The word "doctor" is literally Latin for teacher

TIL: The diving reflex is a physiological response to submersion of the face in cold water causing the lowering of the heart rate and vasoconstriction of peripheral circulation. This reflex allows people, especially young children, to survive for an extended time underwater without breathing.

WILTIMS #99: Do it in Latin

Today, on top of some surprisingly lucid lectures, we did something new! We had a physiology small group case study lesson which entails the following: we are given a write-up about a patient and asked to think of possible diagnoses; we decide on further tests we would like to order and justify the need for said tests; we are then given the results of the desired tests (see pic below) and are then asked to come up with a final explanation of what is going on with the patient.

It's almost like were doctors! Except that 80% of people got each question wrong the first time around... Hey, we're only 12.5% of the way through med school, so cut us a break!

Important medical gibberish gleamed from the fake tests we ordered on our fake patient

TIL: "Night repair" beauty products must be used at night because they contain vitamin A, which is extremely light sensitive. If applied during the day, the drug becomes intensely active and can cause chemical burns.

The oxidation of polyunsaturated fatty acids is the main cause of the smell associated with spoiled food.

One possible explanation for elderly people always feeling cold is the decreased sensitivity to sympathetic adrenergic neurotransmitters that control vasoconstriction in non-glabrous skin. Rather confusingly, glabrous skin is non-hairy skin and non-glabrous skin is hairy skin. 

Cor bovinum (literally "cow heart") is a term for the massive left ventricular hypertrophy - thickening of the walls of the left side of the heart. As my professor said today, "If you're going to insult your patient, do it in Latin."

WILTIMS #98: Snow day

So today we had a partial snow day that robbed me of most of my potential material...

So...

Yeah...

Yesterday's post was good though! You should go read that one. Again. There'll be a quiz.

TIL: Female steroid hormones (like estrogen) have 18 carbons, male steroids (like testosterone) have 19, others (like progestins, glucocorticoids and mineralocorticoids) have 21.

Dehydroepiandrosterone (DHEA), a very popular anabolic steroid for doping athletes, is produced naturally by the body just prior to and after birth. It then peaks again in the mid-twenties and steadily declines from then on. DHEA is an androgen (sex hormone) precursor and has numerous beneficial side effects (hence the doping), particularly for the elderly who have severely diminished natural production.

WILTIMS #97: Über-eases and parentheses

Sorry for the long one today, but if you can navigate all the parentheses, I promise you'll learn a thing or two!

Is there such a thing as a good disease? Dis-ease literally means not-good, so it would appear not. But we don't seem to have a better word for an abnormal genetic variation that is actually beneficial. ApoA1 Milano is an aberrant version of apolipoprotein A1, a protein found in high density lipoproteins (HDL ("good" cholesterol)). The very few people that seem have this version of the protein are seemingly immune to atherosclerosis (the hardening of arterial walls, a main cause of coronary artery disease). These real-life X-men have extremely low amounts of HDL floating around their blood vessels and oodles (that's a scientific term) of triglycerides, but show none of the associated ill-effects. If drug companies can find a way to produce this protein cheaply or get the body to produce it through gene therapy, huge strides could be made in combating our #1 killer, heart disease.

TIL: A related protein to ApoA1, ApoB, is the best example of RNA editing. Both ApoB-100 and ApoB-48 are encoded by the same gene. While ApoB-100 is translated in its entirety in the liver, ApoB-48's RNA transcript is changed by one nucleic acid. This small but important edit changes a codon (nucleic acid triplet that codes for one amino acid of a protein) in the middle of the protoprotein to a stop codon, terminating the protein early, effectively creating a totally different protein from the same DNA code.

Xanthomas on the surface of knees

Familial hypercholesterolemia causes xanthomas, relatively benign collections of fat seen in connective tissue.

Statin drugs inhibit HMG reductase, the enzyme that allows your body to synthesize cholesterol. Don't we need some of that? you might ask. We consume more than enough cholesterol in our diets; statins just stop us from adding our own to the mix. But I suppose if you are starving in a desert somewhere you should probably discontinue your statin prescription.

The coronary circulation (blood vessels supplying nutrients to the muscle or the heart) perfuses the heart tissue very oddly. The epicardium (outer surface of the heart) perfuses during systole (during ventricular contraction (when blood is pushed out of the heart)) which makes sense in the rest of the body, but the endocardium (inner surface) perfuses during diastole (when the ventricles are being refilled but no blood is flowing out of the heart). Though this doesn't seem to make sense at first (How do you get more nutrients from blood that isn't flowing?), it should with a little more explanation.

Whereas the outer surface of heart muscle is essentially at ambient pressure in the chest cavity, the inner surface is put under high pressure (specifically the systolic pressure (~120 mmHg)) every time the heart beats. This high pressure is easily withstood by the sturdy coronary arteries, but the veins are weak and collapse, stopping flow through the whole endocardium. Flow is returned after the heart finishes its beat (during diastole), allowing the blood to drain and the tissue to be perfused.

Subliminal semicolon

Looking back at my previous post, I discovered that using a semicolon in a sentence about vitamin D resulted in a subliminal message about biochem:

WILTIMS #96: Foundering in biochem

If you would like to keep my attention in class, never preface a statement with the phrase, "For those of you who are interested in the organic chemistry of this reaction..."

TIL: Tangier disease (also known as hypoalphalipoproteinemia) is an extremely rare autosomal recessive genetic disease caused by a defective ABCA transporter. ABCA normally transports cholesterol and phospholipids out of cells for incorporation into high density lipoproteins (HDL or "good cholesterol"). The lack of HDL in the bloodstream increases the risk for coronary artery disease meanwhile the buildup of cholesterol in tissues causes all sorts of problems depending on the tissue.

The disease gets its name (not the eleven syllable one) from Tangier Island in Chesapeake Bay, where the first few patients were discovered. This is an example of the genetics concept called the founder effect whereby an extremely rare trait from a large population is magnified once it is isolated, such as through the colonization of a previously uninhabited island. Tangier Island's first British colonists brought the diseased allele with them and when two of their great great great great great great great grandkids had children in the 1940s, the disease was finally able to rear its head.

Vascular beds can be either arborizing (tree-like) or anastomosing (interconnecting).

Cholesterol is not a precursor to vitamin D; actually they have the same precursor, but are not interconvertible.