the immune system is CRAZY

I am ahead of my game right now, I am psyched and don't want to fall behind...so a short post.

I have been geeking out on HLA lately. HLA stands for human leukocyte antigen. This is a set of genes that encode something called the Major Histiocompatibility Complex, which is on cells that present antigens (read - bad stuff) to T cells, so they can trigger mechanisms to destroy said bad things.

There are many different HLA permutations, depending on which types of T cells they want to send messages to (CD4 or CD8). So what is the relevance to me, asks the reader? AUTOIMMUNE diseases. Here, the body turns on itself, in that it recognizes certain cells in the body as foreign and wants to destroy them. Obviously not good, since the body actually needs those cells. A classic exam is type 1 diabetes, where the islet cells on the pancreas that make insulin are destroyed, so uptake of glucose into cells that need it in the body is impaired. These pancreatic cells are destroyed by the body itself! Not some outside interloper. Cool stuff, unless they are your islet cells.

Even more interestingly, certain autoimmune diseases are linked to the same HLA type. Diabetes type 1 is linked to Rheumatoid Arthritis, via HLADR4. There's a whole slew of arthritis oriented disorders linked to HLAB27, including arthritis that you can get after having chlamydia. Even if you treat the chlamydia, you are still at risk for developing this arthritis (called reactive arthritis - used to be called Reiter's arthritis, but they are trying to get away from it because Dr. Reiter was a Nazi doctor, and you know what those dudes were up to).

And with that...back to the thymus.

A cancer you can treat with vitamin A

Quick post today -

Acute myelogenous leukemia. A leukemia is a cancer of the bone or bone marrow. Myelogenous means that the cancer itself produces a lot of myeloid cells, which are neutrophils, macrophages, platelets, eosinophils, basophils, red blood cells. However, because it is a cancer, these cells are not fully developed, and are still in their 'myeloblast' (precursor) stage which is undifferentiated. Acute means onset is quick/sudden.

There is a form of acute myelogenous leukemia (AML for short), that is responsive to VITAMIN A. This very specific cancer (M3 type) has a translocation between chromosomes 15 and 17. You give these patients vitamin A and it forces these myeloblast cells to go from just hanging out in this amorphous undifferentiated state, to develop into regular cells. This way these weird precursor cells develop and stop crowding out all the other cells, like red blood cells. So cool.

However, I just learned that this cancer has something called Auer rods in the myeloblasts (which I knew already) that have peroxidase in them (which I didn't know - think hydrogen peroxide and what it does - that is what peroxidase does). If you treat the cancer, you release this peroxidase into the blood stream and you get something called DIC. Have we made up a plethora of dirty mnemonics around DIC? Clearly.

DIC stands for disseminated intravascular coagulopathy. Here, you clot like crazy. So crazy that you use up all your clotting factors, and start bleeding and not clotting anymore. Good times.

Am homing in on the end of hematology, just have the drugs to do.

the journey continues.

Breasts - more trouble than they're worth?

quick blog today because I am behind in my studies and desperately want to move on from diseased ovaries and breasts to lymphomas and leukemias.

Apparently, women's breasts get all kinds of lumps in them all the time and it's not a big deal. For example, there is something called fibrocystic change that happens in breasts between the ages of 25 and 50. These lumps are sensitive to estrogen and so can fluctuate in size depending on your menstrual cycle, and be painful. No fun. They aren't any kind of precursor to cancer, EXCEPT if you get something called hyperplasia, which means multiplication of cells - this is a cancer buzzword. You wouldn't know if you have hyperplasia unless a biopsy is done and the tissue gets checked out under the microscope.

Maybe I should use this post to talk about a general cancer vs. non-cancer concept. The following is of course wide open to exceptions, qualifications. But here's the deal.

In general.....

If you have a lump in your breast, lymph nodes, etc....and it hurts, it's NOT cancer. Yeah, counterintuitive, right? We think of cancer as this vicious thing (which it is) that will wreck havoc (which it does), and with all that destruction, shouldn't it hurt? Well it does eventually, possibly in the end stages. But painful lymph nodes are due to infections. Painful breast lumps are just part of being a woman - yes, another unbelievable perk.

So if you are feeling around in your neck, jaw, and feel a swollen mass, like a lymph node, you probably have some sort of infection. If you feel one in your breast, you probably bumped it, or you're premenstrual. But if that mass is rock solid and doesn't hurt, then time to see the doctor.

I should probably put a disclaimer in this blog that this information is not meant to diagnose or treat any diseases. I am not held responsible for anything you do as a result of acquiring this info from me.

So there it is.

Mahalo.

reason # 449584794 to stay away from alcohol

Everyone knows that drinking alcohol can screw up your liver. But alcohol isn't snooty. It will hang out with any old organ that is willing to welcome it into its tissues, providing an amusement park of sorts for your favorite wine, beer, whiskey. We all know that the pancreas makes insulin and secretes stuff that helps us digest our food. Pretty important functions, right? Well, give your pancreas a little loving energy, because this is what can happen to it if you booze too much.

Acute pancreatitis. In this disease, the pancreas DIGESTS ITSELF with its own enzymes. Like cannibalism without all the glamor. Here, marooned in a sea of beer, the pancreas has no other choice but to eat itself. Alcohol doesn't deserve all the credit for pancreatitis though, because gall stones can cause it too.

So how do you know you've got it? You will feel abdominal pain, in the epigastric area. Where is the epigastric area? Basically, the space below where your ribs come together. This pain is also felt in the back though. Nausea is also common. If you tell your doctor you are having these symptoms, what else will she look for? She'll check out your serum lipase levels. Lipase is a pancreatic enzyme that breaks down fat. Its serum level is not supposed to be high (why would enzymes to break down fat be at high levels in your blood?), so if it is = pancreas is messed up.

This is some serious serious stuff. You can get blood clots, bleeding, respiratory distress, infection, and organ failure from acute pancreatitis. So it's clearly no joke.

take home - don't drink and digest. If you do, you might lose that whole digesting thing.

Day 14 progresses. I am moving on to the sunny slopes of endocrine land, to study Cushing's and Addison's (what JFK had, and what made him so tan, which helped him win the presidency in 1960 over Nixon).

one of the myriad reasons why acetaminophen (tylenol) should be a controlled substance

yeah, that's right. over the counter, my ass. acetaminophen is a very dangerous drug. it is the number 1 cause of liver failure in this country. I would advise all of you to stay away from it in general.

But liver is not the focus of today's discussion. Instead, the kidneys are in the hot seat, since that is the block I am doing right now (and happily about to finish up for now, once I slog through the diuretics).

Kidneys are under appreciated by the lay public. Really. They get 25% of the cardiac output (what the heart pumps out). Just think about how tiny kidneys are - at the size of your fist, 2 fists get a quarter of your blood. But with great privilege comes great responsibility, in the sense that the kidneys are among the first organs to be affected if you lose blood or can't pump enough blood, like when you are having a heart attack. So what can happen is, you stop getting enough blood to your kidneys, your kidneys stop producing urine, going into something called acute tubular necrosis. Necrosis is definitely what it sounds like.

So you are in acute tubular necrosis, you aren't peeing and you DIE!!!! How? You aren't getting rid of potassium while you are not producing urine, and high potassium can cause your heart to beat irregularly, leading to cardiac standstill. Cardiac standstill means your brain isn't getting O2, and neurons can only survive for a few minutes without O2. So boom. Done.

Back to acetaminophen. If you take a lot of it, it can produce free radicals - these are the things that antioxidants fight - and damage your renal tubules (where filtration happens). Then you decide to take some aspirin too, maybe because you have high blood pressure and you want to thin the blood a little. Aspirin produces a chemical that will dilate blood vessels, but this isn't good because with dilated arteries you don't filter as much. All of this combined freaks your body out, and decides that it wants you to filter more stuff, and a chemical called angiotension 2 causes the arteries in your kidneys to constrict. But the capillaries around your filtering tubes constrict too, depriving them of O2, and they are already hurt from being bombarded by acetaminophen with free radicals. The kidney tubules die, and little pieces of your kidneys slough off into your pee, along with blood and protein. And slowly, like the final scene in LOST, everything fades to white.

ok. too much science. back to drugs.

on this 13th day of studying, I am signing out.

Viridans strep - it's in your mouth

I am learning about bacterial endocarditis right now. This is a disorder of the valvular surfaces in the heart, which acquire soft vegetations of fibrin, inflammatory cells and bacteria (if caused by bacteria, that is). The mitral valve (between left atrium and left ventricle) is most commonly affected, followed by the aortic valve.

Anyway. Viridians streptococci is an organism that isn't super virulent that hangs out in our mouths. Welcome to the exciting and scary world of bacteria and you - a love story. When you have dental procedures, Viridans can get into your bloodstream and travel to your mitral valve, but ONLY if it is already diseased or you have some congenital malformations. You get insidious, so NOT rapid, onset of this type of endocarditis, called subacute bacterial endocarditis.

Symptoms of bacterial endocarditis - you are warned, be vigilant:

fever!!!!!!!!!!

a new murmur

Janeway lesions = small erythematous (red) lesions on the palms of hands or soles of foot

Roth's spots (round white spots in the retina of your eye, surrounded by hemorrhage)

anemia

'Osler's node' (really?) which is tender raised lesions on your finger or toe pads

Splinter hemorrhages on the nail bed.

Treatment?

Antibiotics, obviously, though this person needs to be hospitalized because this is actually very serious. It can lead to valve replacement if it gets severe.

cheerio. back to boards.