new: mike tutors and offers personalized advice for the usmle (click here for more info)

Thursday, May 10, 2007

The Day Before the Exam Is High Yield for the USMLE

Sounds weird but I think its true. The day before the exam you are at a set point to achieve for the day of the exam. The height of this set point is in direct relation to the amount and quality of effort you have put into the exam. The day before, you might be tempted to try to push that set point higher. I instead suggest to work on keeping the set point from dropping any lower, that is make it your duty to keep your set point stable. Don't harm your score by a little pre-test jiggers.

Make sure not to panic about any details you may not be able to remember. This exam won't be testing details as much as it will test your concepts. For example, the day(s) before the exam you might close your eyes and try to recall all you know. Some people report having a feeling of emptiness but do not panic; No one will be asking you to give a lecture on any of this stuff but only to circle the best answer. Please, DO NOT FREAK YOURSELF OUT THE DAY BEFORE THE EXAM as that is low low yield and this is a high yield blog.

This is not to say you should go into denial about tomorrow. Forcing yourself to not think about the exam on the day before is about as or more stressful as studying another day. I tried to keep my day before the exam as stress free as possible so that I could be relaxed and most importantly confident on test day. In order to keep yourself focused on the exam I have a simple solution and here it is. The day before I would do NBME questions that you have already answered and have figured out the correct answers. This will work to keep the concepts of the most important practice questions fresh but also it should further build up your self confidence as you'll probably score much more correct this time around.

Also note that I do not suggest that you do practice questions over and over again throughout your study period just to falsely build up your self confidence - to me (but many disagree and do fine their way) doing Q-bank more than once for whatever reason is a waste - how about you move on to USMLE World? All I'm saying is that a boost of self confidence the day before the exam is just what a 1st time boards test taker needs.

Sunday, May 6, 2007

The Tuberculous Granuloma is High Yield for the USMLE

Ahh the Granuloma - a great example of topic that overlaps multiple subjects and any topic that brushes borders with the likes of pathology, immunology and microbiology make for great questions. Here are 5 steps to the granuloma in perfect 3rd grader doodle form:

Step 1:
Inhale the red, ACID FAST rod

M. tuberculosis is only acid fast why?

B/c of the MYCOLIC ACID in the cell wall resists decolorization with acid-alcohol and so it remains red which is the color of the initial stain, carbol fuchsin.

What else stains acid fast? Nocardia which is “partially acid fast”

Step 2: Phagocytosis by alveolar macrophages

Circulating monocytes roll on the vascular endothelium (d/t selectins) and adhere to it (d/t ICAMs) and then transmigrate into the affected area where they are called tissue macrophages.

Macrophages are the main players in the formation of a granuloma

Step 3: Antigen Presentation

Step 4: T Cell Activation

CD4 T Cells are involved

The TH1 subtype

No CD4 T Cells? No Granuloma. AIDS patients who loose their CD4 t-cells well before loosing their CD8 T Cells will make very weak if any granulomas.

Step 5: Macrophage Activation

Did I mention what the main player of a granuloma is? Oh yea, its the macrophage.

The Caseous Granuloma

Note that the caseous necrosis is cottage cheese like and is due to the destruction of the M. TB organism's cell wall's mycolic acids (mycolic acids are lipids).

Saturday, May 5, 2007

Fundamentals of Biochemistry are High Yield for the USMLE

Sorry for the infrequent posting as of late but I've been traveling. Here's a great link if you are having trouble picturing the various molecular events not only in biochem and cell biology but also micro and immuno. It contains many animations that really helps you picture this stuff.

The page is called Max Animations

I especially suggest the lac operon, HIV virus lifecycle but there are tons of animations there so I just though I would point out this potentially useful link for you.

Thursday, May 3, 2007

Viruses are High Yield for the USMLE Step 1

I suggest when trying to memorize viral structures make a priority list. Common viruses and ones that also overlap with pathology are the ones to focus on here since they can be asked about in many different ways.

Knowing DNA vs RNA is the most important distinguishing feature. Furthermore, f you know if its DS or SS you'll probably get the points.

Enveloped vs Naked: If you can memorize enveloped vs. naked for each virus then god bless, but I like this:
Envelopes are made of a lipid bilayer which are prone to destruction by the environment whereas naked viruses are more resistant to environmental stresses.

A 46 year old female who has genital warts (d/t HPV) takes a shower in her home during which time the virus sheds on the floor. Later her child presents with a wart on his toe.
This all happened since this virus had its tough nucleocapsid for protection and not a wimpy envelope. Take home message is if the virus is capable of fomite transmission it is probably naked.

Play odds, especially for rare viruses with less of a chance of being asked. I walked into the exam knowing that if I saw an RNA virus that looked deadly or pretty rare I would guess that it is SS (-) linear w/envelope.

Here is my list of High Yield Viruses and why I think they have a great chance of being asked
  • Herpesviruses - DS linear DNA
    • this family includes so many viruses that overlap with pathology I list it first since I think this is most important.
  • All the viruses that cause hepatits - see First Aid for them since these are important!
    • Note that Hep B carries the reverse transcriptase enzyme with it just like the retroviruses do.
  • HIV - SS (+) linear RNA
    • If you don't get at least 1 question on AIDs I will give you my blog. Seeing if you know virus structure is a possible secondary question.
  • Papovavirus - DS (-) linear
    • besides HPV causing cervical cancer don't forget about molluscum contagiosum which causes the umbilicated wart (center of wart is depressed like an "innie" belly button).
  • Paramyxoviruses - SS (-) linear RNA with helical capsid symmetry
    • this family is responsible for causing croup (parainflunza virus), bronchiolitis (d/t RSV), measles and mumps.
  • Parvovirus - SS linear DNA
    • It, along with Hepadnavirus, is exception to the rule that all DNA viruses are linear.
    • It overlaps with pathology since it causes aplastic anemia in patients with sickle cell disease
      • Pt might give you a history of having recent contact with a kid who had a slapped cheek appearance.
      • Blood labs will give you a low RBC count with low reticulocytes (less than or equal to 3% of hematocrit - I wouldn't freak out about not knowing how to correct a reticulocyte count).
  • Influenza virus (an orthomyxovirus) - SS (-) linear segmented RNA
    • the NBME and practice questions I've seen love the fact that this genome is segmented since:
      • Genetic shift - if our influenza virus recombines with a pig's or chickens genome we get pandemics - we're all screwed (small minor mutations lead to drifts causing an epidemic in a much smaller area w/ much less people). involved)
      • If you digest the genome and view it with northern blotting you will see each of these (7 or 8) segments as separate bands.

Friday, April 27, 2007

Motivation is High Yield for the USMLE Step 1

Not that any med student goes into medicine for the money BUT if you happen to find yourself stuck inside studying for the boards all day, maybe feeling a little down, then this might cheer you up some.

Dr. X of ValueMD points out that a browse through Physician Salaries might just be the boost you need to go the extra mile.

Make sure to study the heart and anesthetics really well (you'll see what I mean)!

If you read this and immediately start day dreaming about the car you'll get or the kind of place you plan on living in then I want you to shut down your computer and open up a review book right this minute.

So stay motivated and keep your head in the game.

Thursday, April 26, 2007

Vitamin K is High Yield for the USMLE Step 1

  • Vit. K is needed for the γ-carboxylation of clotting factors 2, 7, 9 and 10
    • This gives them a Ca binding site
    • This explains why the vit. K dependent factors are the same factors that are dependent on calcium
  • Deficiency:

o Primary problem is an inability to γ-carboxylate factors 2, 7, 9 and 10

      • therefore, factors ARE made but can NOT be activated by Ca
    • Involves several factors, including factor 7 which:
      • has the shortest t½ of all the clotting factors
        • therefore, factor 7 is the first factor unable to be activated
      • Since factor 7 is specific to the extrinsic pathway the extrinsic pathway is affected first
      • Since the prothrombin time (PT) is a measure of the extrinsic pathway, it is the value expected to be elevated first
        • Leads to ↑↑PT (AND eventually ↑PTT) – therefore, PT is most sensitive since its ↑’d 1st
        • Bleeding time, a measure of platelet function, is normal since platelets are not affected
    • Deficiency can be seen in the following patients:
      • Newborns born at home
        • Breast milk has low levels of vit K
        • All babies in the US are given vit. K shots @ birth in the hospital to prevent hemorrhagic disease of the newborn
      • Pts on broad spectrum antibiotics
        • Bacteria in colon synthesize much of our vit. K
      • Pts w/ steatorrhea
        • Loss of fat in the stools also leads to a loss of the fat soluble vitamins, including vit. K
      • Vitamin E toxicity
        • Inhibits vitamin K dependent carboxylation of clotting factors
  • Treatment
    • Vitamin K Injection
    • If bleeding is serious then give fresh frozen plasma

Monday, April 23, 2007

Testable Anemias That Do Not Always Make It To The Books

Here are some anemias that aren't always thought of in the same breath as many other anemias.

  • Vitamin C deficiency - since vitamin C enhances non-heme iron absorption in the gut, a vitamin C deficiency can cause a iron deficiency (microcytic and hypochromic) anemia.
  • Vitamin E (alpha-tocopherol) deficiency - Vit. E prevents the peroxidation of lipid cell membranes by free oxygen radicals since vit. E is an anti-oxidant. When deficient in vit. E, one sign is acanthocytes in the peripheral blood smear. When these spiny RBCs burst it causes a hemolytic anemia
    • Similarly, in abetalipoprotinemia, an autosomal recessive disorder of lipid absorption may manifest with acanthocytosis in part because vitamin E (a fat soluble vitamin) is also not being absorbed.
  • Orotic Aciduria - megaloblastic anemia unresponsive to folate or B12. A number of wordy enzymes may be deficient but the essential problem here is pyrimidine synthesis and so DNA synthesis is subsequently impaired.
    • This is very similar to B12 and folate deficiencies since in both of these cases, DNA synthesis is also impaired.

Friday, April 20, 2007

Lymphatic Drainage is High Yield for the USMLE

Here's some basic information about lymphatic drainage:

Pretty simple, which is how I like it. Apo B48 is on chylomicrons which carry the dietary lipids. I remember this by its the apolipoprotein that is in the food before (B4) you ate (8). Okay, its not really before you ate it its after you ate it, but I think it gets the point across that ApoB48 is for the lipids that you eat and so is therefore found on chylomicrons. Since lipid soluble vitamins are absorbed with your dietary lipids, chylomicrons also contain fat soluble vitamins.

The right lymphatic duct also drains into venous blood but instead of the left internal jugular/subclavian vein, its into the right ones.

So it was just a quick doodle and explanation today about these straight forward points. I'm sure you can think of a lot of other integrated info about lymphatic system which I encourage you to share in the comments section.

Thursday, April 19, 2007

Targeting Your Weakest Area(s) is HY for the USMLE

This one seems pretty obvious but its not always as easy as it seems. Instead of preaching how you should do it, I'll just tell you what I did.

With about 2 weeks before my exam I took a timed NBME exam (link in the sidebar to the right). The results are broken down by subject and your performance is shown as a shaded area in each subject and organ system. For example:

___________________P E R F O R M A N C E____________
SUBJECT ________Lower___ Borderline______Higher

This student obviously needs a lot of work in Behavioral science. That student was me. Much of my other subjects were further to the right and overlapped. If the bars overlap then they should be interpreted as similar.

Now, I think we can all agree that Pathology and pharmacology seem like much more important
subjects for the exam, and they are. But my theory was that if I'm doing pretty good in most and pretty bad in some then it would be much higher yield for me to focus on my weaknesses. It hurts too because nothing satisfies your soul more than reading the same stuff you already know over again 2 weeks before test day. It builds up your confidence (indeedimportant) but also it may induce you to overlook a gaping hole in your knowledge bank as it did for me.

Face your fears today: A good strategy would be to look at the table of contents or quickly flip the pages of first aid. Your body will let you know when you're at the right page. For me, I get a tight feeling in my stomach and hold my breath on inspiration (not long enough to cause a respiratory acidosis though) while my heart pounds through my chest (apex beat is found at the left 5th intercostal space). Bingo! Weakness area found.

As painful as it was to drop pathology and pharmacology, for me it was the right choice. I focused on behavioral and it paid off since behavioral science overlaps pathology and pharm on my actual performance profile from the USMLE.

Take home message is this:
A weak area brings your score down
Fixing your weak area can bring your score up much easier and higher than strengthening other already strong areas to compensate.

Wednesday, April 18, 2007

Burkitt's Lymphoma is High Yield for the USMLE Step 1

Burkitt Lymphoma
a form of non-Hodgkin's lymphoma

Associated with Epstein Barr Virus and is commonly located in the jaw of Africans (the classic patient)

Classic Translocation = t(8;14) which moves the c-myc gene on chromosome 8 right next to the Immunoglobulin (Ig) Heavy Chain.

Here is a joke for you. I hope you find it hilarious. Okay, a giggle will do. Tell it to someone else, embrace the awkwardness that ensues and that should tattoo it to your brain for a while.

How come Mick ate one for?

-----Here is what the joke really means----
come Mick = c-myc
ate = 8 - since c-myc is on chromosome 8
one = 1
for = 4

To get heavy!
heavy = Ig Heavy chain which is on chromosome 14

And here's a little doodle to drive it on home:

That big guy there is Mick (myc) who has just ate (8) one (1). For (4) what? To get heavy.
c-myc is on chromosome 8
Ig Heavy chain is on chromosome 14

Believe me, this joke is much funnier if you're telling it to yourself when you are looking at a question on it.

Here is what some practice questions I've seen ask and is mentioned in various review therefore I made sure I knew this for my exam although I had to look it up again for this post.

The function of c-myc: c-myc is a proto-oncogene which codes a protein that regulates nuclear transcription. When it is moved next to the gene for the Ig heavy chain it becomes constantly active since the body is constantly making Ig heavy chains. At this point it is now called an oncogene. c-myc now causes the B-cells to constantly reproduce themselves over and over again. This results in a high grade lymphoma

This is in contrast to B-cell follicular lymphomas in which BCL-2 (a gene which promotes apoptosis). When BCL-2, a tumor suppressor gene, is translocated it becomes functionally inactive and so B-cells can't undergo apoptosis the same anymore. This is an example of low grade tumor.

So I think this is how you should think about it: Burkitt's lymphoma is when B-cells actively divide whereas in B-cell follicular lymphomas, B-cells don't die.

Also, here's the classic"Starry Sky Appearance"

I just want to point out here what that refers to. The dark purple areas are really just a bunch of neoplastic B-cells that are dividing much more rapidly now that c-myc is always active. ("Dark is Dividing") The stars are the lighter areas which are much fewer in number - these are the macrophages. I'm not sure what they are doing there, but I do know that they are NOT the problem. Perhaps they are trying to help out in getting rid of the tumor.

That's what I think is really important for this tumor that seems to be a pretty hot topic for the exam.