Tuesday, September 30, 2014

WILTIMS #190: Raise shields!

Today was a very lab/practical heavy day, so I didn't learn much in the way of interesting factoids, but rather reinforced things from previous days. But in preparation/procrastination for tomorrow, I did learn something:

TIL: One of the ways of describing the bacterial colony feature of elevation, or the raised/flattened appearance of the colony, is the term umbonate. Umbonate comes from the latin root umbo which describes a "boss," or raised bump on a shield. This is the same ultimate root as the modern word emboss, which took a detour through French before becoming part of the English lexicon.

A boss on a shield

Monday, September 29, 2014

WILTIMS #189: Nutritional facts

TIL: Kwashiorkor, which literally means "first-second" disease, or disease of the displaced child. The name describes how it is seen in the first child in a family when a second child is born. Suddenly there isn't enough food for everyone and the older child is often the one left to suffer through malnutrition.

Malnourished children can look merely unremarkably thin due to the masking effect of swelling (edema) from diminished albumin production. Albumin is the most important protein for controlling the osmotic pressure of blood. Its low rate of production would cause more water to leak out of the circulation into the surrounding tissues.

Flag sign of malnutrition
Relatedly, malnutrition can also manifest as a "flag sign" from lack of protein. This is when long hair changes color and/or texture for the period of the malnutrition, leading to a broad stripe in the hair.

Pseudomonas is naturally resistant to most antibiotics by living in the soil, which contains many other organisms that have learned to combat these organisms just like we have over the eons.

Haemophilus influenzae does not cause influenza (the flu virus does). H. influenzae does cause similar symptoms, though. 

Legionnaires disease, and the bacterium found to cause it, is named for a conference of the American Legion at which the first outbreak was reported.

Thursday, September 25, 2014

WILTIMS #188: The Importance of TB-ing Dermis

TB-associate lesions in a
 3000-3500 year old egyptian mummy
We have entered that part of the year where, thanks to our affiliation with a predominantly Jewish institution, we get three four-day weekends in the next month. To make up for this, it seems like our classes have tried to put as much material as possible in our reduced class time. Unless I'm feeling unusually motivated, all of this means there will be a few fewer posts in the coming month. But today's is good enough to make up for the next couple days:

TIL: Though we've only been exposed to viruses like ebola and HIV for the last half-century, we have, as a species, been battling bacterial infections like tuberculosis (TB) since ancient times. Leprosy has been explicitly mentioned in historical and religious texts, and TB has been diagnosed both macro- and microscopically in mummified remains from ancient Egypt. Only now, 3-4,000 years later are we finally turning the tide.

Armadillo PSA: There's no
armor for leprosy; get tested.
Mycobacterium leprae, the bacterium that causes leprosy, is the slowest growing pathogen known. It doubles every 14 days (that's in comparison to every 20 minutes for E. coli). It also only grows in humans, mouse footpads and armadillos. Because M. leprae prefers the cooler tissues of the body (similar to the normal temperature of armadillos) it often causes lesions on the skin and in peripheral nerves. Untreated, this disease is gruesome. And because of the resilient ancient stigma associated with it, there has been a campaign to rename it Hansen's disease so that people will come get treatment before suffering the more deadly and debilitating consequences of the infection.

Lady Windermere syndrome is caused by an opportunistic infection of mucous buildup in the lungs by Mycobacterium avium-intracellulare. The name comes from an Oscar Wilde character who was a very proper English lady. Though, as defensive librarians have pointed out, her character was never actually sick in her eponymous play, the reference hints at the cause in real people. A proper lady is not supposed to cough in front of company, and the only otherwise healthy people who develop this syndrome are older women who, it is hypothesized, learned to always suppress their cough reflex and thus built up collections of mucus in their lungs for this obscure bacterium to grow in.

M. marinum a fresh and salt-water bacterium that causes "fish tank granuloma."

Tuesday, September 23, 2014

WILTIMS #187: Pre-med-achu, I choose you!

This evening I had the fun and freaky opportunity to learn how to interview applicants to our medical school. Our school uses the Multiple Mini-Interview (MMI) format which allows for students to sometimes participate in interviewing the applicants for future classes. Each interviewee completes eight, six-minute interviews on any of a number of usually ethical prompts with members of the school's academic community. This MMI system reduces bias and has been shown to be a fairer and truer judge of communication skills and predictor of clinical excellence than the old one-on-one long-form interviews. It was a nice break from dealing with our own comparatively petty second-year problems, to remember how stressful it was interviewing for the privilege of having our current problems.

TIL: When giving an oral patient summary, it's just as important to give pertinent negative diagnostic findings as pertinent positive ones. On the flip-side, it's important to omit positive as well as negative findings when they are not pertinent to the case at hand. The trick with this being that you have to know what is and is not likely to be pertinent, accepting your medical inexpertise as compared to the person to whom you are presenting the patient. Of course if your mentor wants to know any information that you didn't report, they can always ask.

WILTIMS #186: Shooting starter colonies

Listeria comet
TIL: Listeria comets are super cool (if you don't have them streaking through your intestinal epithelium). This bacterium likes to live inside the cells of the lining of the gut. It uses a potent one-two punch of toxins to burst through the vesicles that cells use to scoop up and destroy offensive organisms. Once in the cell, listeria hijacks some of the cell's scaffolding machinery and redirects it to quickly polymerize in the direction of the cell membrane. This streak is called a listeria comet and it's so strong that it can puncture the adjacent cell's membrane. From there, the bacterium needs only to reactivate its toxic tools to degrade the lipid layers surrounding it and start the process all over again.

This process allows listeria to spread completely unseen by the body's adaptive immune response, by never needing to exit its cellular hiding place to spread or replicate.

Next, C. difficile infections are almost entirely caused by antibiotics. And by that I don't mean that we are injecting people with bacteria or anything, but rather that a side effect of even the most appropriate antibiotic usage can be a gastrointestinal infection from this annoying (and sometimes deadly) bug. It's weird looking back at incidence rates from before and after widespread antibiotic use, because the correlation is very apparent. In fact, scientists originally hypothesized that the antibiotics themselves were the cause of the diarrhea sometimes seen upon their administration.

C. diff is commonly found in small numbers in a large percentage of the population, but it can never really get a foothold thanks to our existing gut microbiota. The problem arises when we wipe out the healthy bacteria while treating some other infection elsewhere in the body with antibiotics. This gives c. diff the chance it needs to assume a bigger and more pathogenic role in the intestines. 

Lastly, most STDs grew in prevalence from the 60s through the 70s. Then the rates of new infections stopped abruptly in 1980. The reason? Fear of the growing AIDS epidemic forced people into practicing safer sex.

Saturday, September 20, 2014

WILTIMS #185: Revenge of the outcasts!

After seven hours of three horrific tests yesterday, we started up again bright and early this morning. Thankfully, in my humble opinion, we are starting the actual microbiology portion of our microbiology course, having wrapped up the immunology section. So, to celebrate the end of ridiculous detail (I'm looking at you, cytokines!), this post will be about a fairly broad idea.

Why do bacteria cause diseases? This may seem obvious, but hear me out. Viral diseases make sense: viruses depend on infecting and lysing cells for reproduction. But bacteria can live without our cellular machinery, so why evoke the wrath of the immune system by picking a fight with the local cells?

Well, first of all, many bacteria don't! These are the commensal bacteria that make up 90% of the cells in "our" bodies*. We love these guys because they do a couple important things for us. Some bacteria help us digest and/or absorb things that we can't easily digest and/or absorb on our own. But more importantly, all commensal bacteria help us out by outcompeting pathogenic bacteria from their niches. And this is the big hint as to why other bacteria need to cause disease.

Essentially, these other bacteria know (evolutionarily, not literally) that they can't win when playing by the same rules as those other extremely well adapted commensal bacteria. So, they change the rules. What do these bugs need to flourish? Water, nutrients, and hopefully a route to move on to other organisms. A great way to get these things is to make the body bring it to you through the well-intentioned but often overzealous actions of the immune system.

In broad terms, the immune system frequently starts it's fight by bringing in reinforcements in the form of immune cells riding a wave of fluid through leaky blood vessels. This fluid gives the bacteria the water it's hoping for, while the damaged cells of the surrounding tissue leak nutrients providing a great environment for the critters to multiply and thrive. If they flare up big enough to cause coughing, sneezing, diarrhea, sores, bleeding, or death, then they can spread to other people and start the cycle anew.

So bacteria often cause disease because all the peaceful positions are usually taken and you either die by the system or break the system in order to survive. 

TIL: Streptococci like to grow in chains, pneumococci in pairs, staphylococci like clusters, and enterococci can do pairs or small clusters.

* They make up 90% of the number of cells not the volume of cells; most prokaryotic cells are very small compared to those of eukaryotes. To give perspective, some bacteria can live inside our cells and some eukaryotic organelles, like mitochondria and chloroplasts, are thought to be very old intracellular commensal organisms that were so symbiotic that we essentially annexed them.

Saturday, September 13, 2014

WILTIMS #184: It's actually lupus!

Apparently, today is one of two days during our preclinical years that we are taught by the dermatology department. In case you are somehow unfamiliar with the weird place that dermatology holds in the medical specialty hierarchy, the head of dermatology had this to say about training in that specialty: "Dermatology is very hard to get into, but your life is very easy after that." [everyone laughs], not at his message, but at his candor.

When you ask the average person what the most prestigious medical specialty is, you are likely to hear some impressive sounding area of medicine like neurosurgery. Dermatology is, in fact, the most competitive and highest paid specialty. Though poking at people's rashes and scraping away moles might not seem like the most desirable work, the lifestyle, hours, and pay have made it, far and away, the most hotly contested field to enter every year.

One of the weird flukes of this arrangement is that, though most would admit one doesn't need to be the top of one's class in med school to treat diseases of the skin, only the most intelligent and talented graduates become dermatologists. This trend was driven home again for me today in a small group session where my module was taught by the senior dermatology resident at our hospital. She was quite the imposing and intelligent instructor. Though only a few years older than us, she was easily an expert on today's topics and absentmindedly bossed around our normally high-and-mighty physician instructor.

TIL: Hemophiliacs are like summer squashes... Stick with me on this one. You know how each individual squash can look dramatically different in size, shape and color from one another regardless of the seed from which it grown? The way they can modify their appearance, even with the same DNA is through epigenetics. Epigenetics is the suppression or augmentation of genetic information through processes like methylation and X-inactivation. This is the same mechanism that diseases like hemophilia use to present with completely different symptoms and severity between directly related family members.

IT'S NEVER LUPUS (at least on House MD)! Ever wonder why lupus is always in the differential diagnosis for the patients on House, even though it almost comedically was never actually lupus causing the symptoms? The reason for this is that lupus has very broad, variable diagnostic criteria. It only requires 4 of the following 11 symptoms to diagnose lupus, often remembered by the mnemonic 
DOPAMINE RASH:
Discoid rash
Oral ulcer
Photosensitivity
Arthritis
Malar rash
Immunologic criterias
Neurological symptoms-(lupus cerebritis)
Elevated ESR
Renal disease
ANA+ve
Serositis
Hematological abnormality

Friday, September 12, 2014

WILTIMS #183: No one needs all 10 fingers anyways

Ow.

You know how the school's nurse practitioner said something to the effect of "whatever you do, don't reinjure that finger."? Totally worth it for that one flag pull. Now I've only hurt my finger (again) my thumb, my rib, my back, and my knee!

TIL: The first cases of antimicrobial resistance for any drug typically are seen within only a couple years of that drug's first use. SO, though MRSA (Methicillin-resistant Staphylococcus aureus) has become a big problem recently, it was probably first seen way back in the 1960s.

Wednesday, September 10, 2014

WILTIMS #182: I'M HELPING!!!

My exhaustion and poor attendance at lecture today are going to make this a short one.

TIL: Part of the reason congestive heart failure is so bad for lower body edema (fluid retention and swelling) is that the kidneys try to help but only make things worse. First of all, the main effect on blood circulation for CHF patients is that the overworked heart can't pump enough blood, so blood collects in the veins (this is where the "congested" in CHF comes from: congested veins of blood). As the blood pools, higher than normal pressure builds up in the capillaries, causing fluid leakage and swelling. No bueno.

Then the kidney tries to help. The kidney is blind to all of the above things happening but notices that there is less blood on the arterial side of the circulation, resulting in low blood pressure. In a normal healthy person, the kidney can fix that! Using a cascade of hormones called the aldosterone-renin-angiotensin axis, the kidney starts retaining sodium and consequently water in the blood it filters. A healthy heart would then increase output and restore normal blood pressure, but a heart in CHF already can't pump all the blood it has pooling in the venous system. So the heart is like, "Can't... pump... anymore..." and the kidneys are like, "HERE, HAVE SOME MOAR BLOOD TO PUMP! YOU'RE WELCOME!" Thanks kidneys.

WILTIMS #181: Stellar

We had our first Foundations of Clinical Medicine (or "How to Be a Doctor") class of the year today. And in the long tradition of wasting time with icebreakers and group building activities, we spent an hour doing a NASA moon crash landing activity. We learned that creativity and action movie logic do not make for a good survival score, that I know way too much about the moon, and that working in groups can make you weaker than had you worked alone (in direct opposition to the likely point of the exercise).

Some important things for when you crash land on the moon:
  1. The moon has no magnetic field (compases won't help you) 
  2. There is no atmosphere on the moon (no lighting matches)
  3. A stellar map is not a "really good" map, but, in fact, a map of the stars
This evening was our school's  club and activities fair at which I was representing three clubs (Cancer Education Awareness Program, Woodfield Cottage Volunteers, and Ultimate Frisbee Club). We joked that the club leadership on campus is very inbred, with nearly every club officer working in the leadership on one or more other clubs. There was a great turnout from the first-year students and new arrivals from the other masters and doctorate programs on campus, which is good because as tradition dictates, all of these clubs will transition to being their responsibility this spring as the second-years progressively lose themselves to preparations for the Step 1 board exam. Given our crazy schedules and often unmanageable volume of work, it amazes me that so many people can find time to volunteer in the community, explore professional interests, and participate in social activities. Perhaps all that stuff we amassed on our med school apps wasn't just for show!

TIL: Crohn's disease and ulcerative colitis are the two main forms of inflammatory bowel diseases. One of the differences between the two include that Crohn's can be found in patches all along the GI tract (or "rooter to tooter" as our pathology resident put it) while colitis is found in one stretch exclusively in the colon. Crohn's also affects all layers of the GI tissue while colitis only disrupts the innermost mucous layer.

Monday, September 8, 2014

WILTIMS #180: Can I have that back, please?

Today was one of only a handful of days that I have left lecture over the past year due to the poor quality of the presentation. My high attendance rate is no small feat given that only around a third of our class attends pathology lectures and maybe a fifth attends microbiology. But by no means does that mean most of my colleagues are slacking off.

Actually, the ones not attending lecture are probably being far more productive. With the ability to play the audio from lecture at 1.5 or double speed, you can get far more done just waiting a day for the recording. Also, half of our topics this year are self-study, meaning that there is no lecture - we are simply expected to teach ourselves the material. And the topics that are lectured on are generally not covered at the level we will be expected to know things for our Step 1 board exam at the end of the year. So, when after leaving class this morning I joined some friends for a study group, we covered more and in more detail than the people we left behind.

"Why does anyone go to lecture at all then?" you might justifiably ask. Some just learn well by listening and would rather listen live. Others like to be able to ask questions of the professors. But I think the bulk of us do it out of habit. After all, why are we paying $50k a year to go to a school where we teach ourselves everything?

TIL At some point in the past I learned but was reminded of today and wanted to share with you because it's a really cool anecdote that: During WWII, penicillin was collected from soldiers' pee so that it could be recycled. The antibiotic was still relatively new and manufacturing couldn't keep up with the demand brought about by all the ailing GIs, so the military took advantage of physiology and penicillin's clearance to save countless more lives.

When penicillin is injected into the blood, it only makes one pass before being almost entirely cleared into the urine by the kidneys. Some of the drug does it's job during that pass and is absorbed and used by the body to kill off bacteria, but the vast majority is just peed out. If you collect the treated soldiers' pee and precipitate out the unused drug, you can very efficiently and sterilely recycle this lifesaving compound to save dozens more lives with the same amount of drug.

Friday, September 5, 2014

WILTIMS #179: Don't Panic

Today, I sensed a disturbance in the force - like a handful of data points cried out and went tragically uncollected. 10 days ago, I transitioned the research project I worked on over the summer so that the two residents I worked with would take over our biweekly data collection while I was in school. But I had a feeling, a spidey-sense even, that the admittedly very busy residents would forget to collect and restock the data cards we have scattered all over the hospital. Apparently I was the last person to collect anything.I think we need a new plan... 

The fun activity for today was our pharmacology problem solving section. For these we break up into small groups and try to figure out which mystery drugs match the vitals signs recorded under various conditions. You work on the puzzle with your team and hope that your team comes to the same conclusions as the other teams. After, you have to justify your answer in front of the class (while being pimped by the professor, regardless of the correctness or completeness of your answer). "Yes, that is what that drug would do under all reasonable conditions, but what about this unreasonable condition?"

Thank the Flying Spaghetti Monster It's Friday! See y'all next week.

TIL: Freaking out during a heart attack will kill you (faster). Activating your sympathetic system increases the workload on your already ischemic heart muscle, which can cause the muscle to fail more rapidly and be more prone to dangerous arrhythmias. Not sure what you should try to feel other than panic during a heart attack though... a macabre curiosity? A stoic determination to make it to phone/hospital?

Folliculitis = inflamed hair follicles
Furuncle = infected hair follicles (aka a boil)
Carbuncle = a cluster of interconnected furuncles (typically caused by a combination of staph infection and diabetes mellitus)

Hashimoto's thyroiditis causes hyperthyroidism then hypothyroidism. This autoimmune reaction causes inflammation of the thyroid, causing it to release more hormones than normal, then as the self-destructive attack continues, the thyroid is damaged to the point of hypothyroidism.

WILTIMS #178: 13 hour day

This was one of the longest days I've had at school (excluding all day/night study days). To give you an idea, here's today's schedule:

06:30 Get up
07:25 Leave house
08:00 Pathology and microbiology doubleheader quiz
09:00 2 hours of microbiology lecture
11:00 Go to student health center for jammed finger
11:30 Prepare for afternoon small group session
12:30 Lunch
13:00 2.5 hour pathology small group session
15:30 Get x-ray of jammed finger
17:00 Free pizza dinner for ethics in medicine club movie night
17:30 Begin watching abortion documentary
19:00 Sneak out for club treasurer meeting (representing 2 clubs)
19:20 Return for end of (super-long) documentary
20:00 Discuss abortion debate and documentary with classmates
20:45 Leave for home with a free leftover pizza

21:15 Watch some tennis and start writing this blog post

First of all, regarding the finger x-rays, I jammed my finger while playing flag football a couple weeks ago and it has just refused to get better. So after talking to finger fracturees from last season, I decided to make a trip to the school's nurse practitioner to make sure nothing serious is going on. She sent me some x-rays to peak at the innards of the inflamed joint. This is all very easy when you are already on a major medical campus, so I had the scans done this afternoon. The radiology tech was really cool and when I asked if I could get a copy of the scan (presumably on a CD) he offered to give me physical film printouts too! So now I have some enormous films of my right ring finger. As far as I can tell, nothing looks broken, but the cartilage and/or joint capsule might have been torn up a bit. Updates to follow once actually qualified medical professionals interpret the images.

The abortion documentary was good conversation starter for the ethics club. It's weird having that debate with a group of people that are not just potential users of abortion services, but also potential practitioners of them. It seems most medical students are loosely pro-choice (and socially liberal in general), if only on the principle of saving lives from unsafe illegal abortions that used to be one of the leading killers of women of childbearing age as recently as the middle of the last century. But very few med students have an intention to actually train to learn the procedure. I think we'd all rather write a prescription for birth control and hope to undercut the need for abortions in the first place. This issue is way more complicated than I'm glibly mentioning here, but I wanted to mention it nonetheless.

TIL: One of the reasons that our appendices occasionally try to explode and kill us is that they are a highly lymphoid tissue, much like your tonsils. The problem with this being that, just as your tonsils might swell when fighting an infection, the walls of the appendix can swell and pinch off the rest of the little dead end tube that makes up this gastrointestinal fold, trapping a growing collection of pus in the lumen of the tube, risking rupture and subsequent septic infection.

Wednesday, September 3, 2014

WILTIMS #177: Bones, ebola, blood, and a bunch of boys

Today was surprisingly fun. We started off with some great lectures by two medical examiners for our county. The first was so deadpan it reminded me of Bones. "Our hospital is a regional trauma center, so people come from other counties to die here," she said, completely deadpan.

For lunch we had a (catered) lunch panel put on by the infectious disease interest group about the ebola outbreak in western Africa. The moral of the story from the dean of the school of public health was that, while ebola is nasty and we should stay informed so that we can calm the public, the flu will kill tens of thousands of americans this year (like every year) and we'd save more lives urging people to get their flu shot than anything we can individually do about the hemorrhagic fever that's making headlines.

In the afternoon we had a microbiology lab, where we got to perform several laboratory tests, including confirming our own blood types (A+ confirmed!). This was the first time we've gotten to stab each other so far in our training. The blood typing was surprisingly easy (if you have serum antibodies for A, B and Rh factor lying around). Just mix a drop of blood with each of the antibody solutions and see if the RBCs clump. Only one person we tested found a different result from what they thought their blood type was. Still not sure how that happens...

Finally, this evening I went to my first volunteering event of the year at the nearby juvenile detention facility. This year, I'm co-president of the club that organizes this and it was fun leading the activity we did today. It's one more thing on my already over-full plate, but well worth the effort to bring a little fun to some really nice if troubled kids.

TIL: Cranial gun shot wounds (GSWs) can appear stellate (star-like) because the tiny distance between the skin and attached bone of the skull can't diffusely distribute the force of the impact resulting in blunt force tearing. Also, entrance wounds are usually rough around the edges because the spinning bullet tears at the tissue as it twists through the skin. This is usually not the case by the time the bullet exits the body (if it does so).

In front-impact car accidents the driver often dies from internal bleeding due to a transected aorta. The location of the tear is often very specific to the site of the insertion of the ligamentum arteriosum. As a random aside, I haven't mentioned that vestigial shunt since over a year ago! Time flies when you're having... let's call it fun.

WILTIMS #176: Vaccines PLUS

Today we started off with a series of lectures on congenital and genetic diseases which, though informative, were not super big on interesting anecdotes. The last lecture was on vaccines and it was actually pretty cool to approach this topic now that I know a little more about the immune system. If you want my views on vaccine safety etc, please see my previous post on the subject, or any of the countless reputable online resources on the subject or [in pharma advertisement voice] talk to your doctor.

Cowpox on the hand of the milkmaid, Sarah Nelmes
First a little set-up from things we learned last year: The most famous example of vaccine development is that of the smallpox vaccine in 1796 by Edward Jenner, with the help of an unconsenting minor, a milkmaid, and Blossom the cow. Jenner (and several other people at the time) noticed that milkmaids that had been exposed to cowpox (similar to smallpox but much less virulent in humans) had little to no reaction to exposure to smallpox. Being the good, if less-than-ethical scientist, Jenner needed to test that this exposure was key to their immunity, so he did the obvious thing and tested it on his gardener's 8 year old boy. After inoculating him with cowpox pus from a milkmaid (who was infected by Blossom), the boy was exposed to smallpox and thankfully never developed the disease.

TIL: The idea behind the cowpox-smallpox vaccine is that, since cowpox is similar to smallpox, but not very good at attacking humans, the immune system will easily combat the disease and store up weapons in the adaptive immune system that can attack either virus equally well in the future.

Attenuated vaccines use the same approach. Scientists take a nasty human pathogen and grow it in cells from another species, like monkeys. The virus/bacterium mutates over many generations until it is better at infecting monkey cells. Hopefully, these changes came at the price of the bug losing its virulence towards humans. This is the equivalent to turning smallpox into cowpox to give the immune system an easy practice target. Attenuated vaccines are generally not used with immunocompromised patients because in very rare cases, the patient can develop the full blown disease if a few of the mutated viruses/bacteria mutate back. This is not a problem with immunologically healthy people.

Adjuvants are another group of compounds about which you may have heard when talking about vaccines. These are substances are added to vaccines to get the immune system to treat your fake threat seriously. Since non-attenuated vaccines are usually composed of just a small piece of a surface protein of the targeted virus/bacterium, the immune system will recognize it as foreign and log it as a possible danger. But the immune system is also smart enough to look around and see that none of the other markers of an infection are present, so it will hold back its biggest weapons for more seemingly serious threats. So scientists add compounds that mimic (or are straight-up copies of) parts of other real threats to trigger a proper immune response that will give the vaccine material the welcome it deserves. These adjuvants often include an aluminum salt or some lipid-like organic molecule.