Don't Stand So Close To Me

We all know that it's gross to be sprayed by another person's sneeze. But just how extensive is the spray? Let's take a look...





And each of those droplets can house any number of bacteria that can get into your mouth and become lodged into your upper respiratory tract to give you their cold. Some can even become dessicated into "droplet nuclei" that are so small that they can go straight into your alveoli (the functional units of your lungs) and cause pneumonia.

So uhm, keep your mouth shut when people open theirs.

[Photos from Dr. V's lecture]

Weird Words 2

For those of you who haven't heard from me in a really long time (which is probably most you) please blame it on second year. My friends and I love to joke about how second year is like first year on steroids (or on crack) which basically means more information in less time. Seriously, we have exams like every two weeks. It's unholy!

But, besides all that, we are finally learning immunology. I was really excited about it (and still am) because it's SO cool. The body's defensive are incredibly extensive and intensive. And just thinking about the number of pathogens we interact with everyday (germs in our food, on our doorknobs, in our sneezes...) it is kind of amazing that we are not ill every second of every day.

Unfortunately, with such strength of character, comes ridiculous complexity. And I seriously mean ridiculous. Our innate immune system is, in part, composed of the "complement pathway." In general, it's basically a whole much of molecules that are in our bodies that can bind to the membrane of bacteria and poke holes in it. Literally. Okay, that makes sense. But the molecules that are involved in the complement cascade make me wonder if scientists and doctors lack the common sense gene. Here is a quote from my lecture notes.

"C1s, which is cleaved to become a new serine protease, cleaves C4 into C4b which binds C2 which is cleaved into C2b, forming the macromolecular C4bC2b complex. This cleaves C3 into C3b. Binding of C3b into the complex forms the enzyme C4bC2bC3b. This C5 convertase activates the lytic pathway by cleaving C5 to C5b, which complexes with C6 into C5bC6 and C7 into C5bC6C7. This complex displays a high affinity binding site for C8. The formation of the C5b678 complex retrieves C9 to form C5b6789."

And that's only the classical pathway! Hmph!

Weird Words

Trichotillomania. It sounds like one of those words people make up to
either impress or confuse other folks. But it is real and in fact, I
had a 20 month old patient with this problem earlier this week. She
was diagnosed with leukemia 6 weeks ago and sometime during her long
1st hospital stay she developed this in reaction to anxiety.

So what is trichotillomania? It is the compulsive pulling on hair that
leads to hair loss. It is found usually in children, is a reaction to
stress or anxiety usually, and most often is short-lived. So how did I
know that was the problem with my patient. I went to see her in Pre-op
and this cute little girl was stroking/pulling on her right eyelashes.
Mom confirmed that she had started it when she was admitted the 1st
time for her leukemia and it recurred whenever she came back to the
hospital. Today she was having a lumbar puncture with injection of
chemotherapy into the CSF. (The leukemia cells can invade the CSF and
chemotherapy does not cross the blood-brain barrier so to kill those
cells you have to inject the chemotherapy agent into the CSF itself).
My totally unreliable memory suddenly ejected the term
trichotillomania. Who would have guessed that that particular,
extremely esoteric word would surface? That is the great thing about
medicine. Even years later some of those weird things that you are
learning are useful.

(Guest story from Dr. MH)