Errors in First Aid for the USMLE (2007): Microbiology

March 24, 2007

As always, comments are welcome. I’m sorry to say that I did not do a good job reviewing the section on viruses as this is my weakest subject.


  1. P.137, Bugs with exotoxins
    1. Bordetella pertussis does not stimulate adenylate cyclase, it instead inhibits GTPase. This differentiates its action from that of cholera toxin and the LT toxin of E.coli, whose actions stimulate adenylate cyclase.
  2. P.140, Intracellular bugs
    1. For facultative intracellular, I offer the following:

i. My Liege, Your Niece Lists Frank, Bruce and Sam.

ii. Mycobacterium, Leigonella, Yersinia, Neisseria, Listeria, Francisella, Brucella, Salmonella.

  1. P.144, Lactose-fermenting enteric bacteria
    1. After including Serratia, change the mnemonic from “lactose is KEE” to:

i. “Test lactose with MacConKEE’S”.

ii. Citrobacter, Klebsiella, E.coli, Enterobacter, Serratia.

  1. P.145, Bugs causing diarrhea
    1. O157:H7 should refer to Enterohemorrhagic E.coli (EHEC), not Enteroinvasive E.coli.
  2. P.150
    1. The heading “Microbiology-Mycology” is on the wrong page, and should be on P.151.
  3. P.152, Pneumocystis carinii
    1. This microbe is now referred to as Pneumocystis jeroveci.
  4. P.154, Medically important helminths
    1. There should be some mention that Schistosomiasis can cause granulomas in the bladder and has a role in Squamous cell carcinoma of the bladder.
  5. P.163, HIV diagnosis
    1. A test with high sensitivity has low false-positives, not high. A sensitive test with high false-positives indicates that there is low prevalence of the tested disease in the population. It is more appropriate to use NPV for this type of statement.
    2. A test with high specificity has low false-negatives, not high. A specific test with high false-negatives indicates that there is a low prevalence of the tested disease in the population. It is more appropriate to use PPV for this type of statement.

i. You may not think that these distinctions are important, but they are. Sensitivity and specificity are qualities of a test and do not change depending on the population tested, but a test conducted in Africa (where prevalence of HIV is high) versus the same test conducted in the US (where the prevalence is low) will have different PPVs and NPVs, i.e., different numbers of false-positive and false-negative results.

  1. P.164, Prions
    1. Fatal Familial Insomnia should be included in this list of Prion diseases.
  2. P.169, Bactericidal antibiotics
    1. I think that Rifampin, daptomycin, the combination treatment SMX/TMP and the polymyxins should be included in the list of cidal drugs
  3. P.169, Methicillin….
    1. “Don’t need MeNDing: Methicillin, Nafcillin, Dicloxacillin”
  4. P.170, Cephalosporins
    1. The MTT group responsible for the disulfiram-like reaction is only found in 2nd generation cephalosporins cefotetan and cefamandole. I think it’s worth changing to “(in 2nd generation cephalosporins with a methylthiotetrazole group, e.g. cefamandole and cefotetan)”.
  5. P.172, Macrolides
    1. I think it’s worth mentioning that Erythromycin is a potent inhibitor of P450, that Azithromycin is used in prophylaxis of MAC, and that their clinical use is for atypical pneumonias.
  6. P.172, Clindamycin
    1. Lincomycin is listed on P.171 as one of the 50S inhibitors, but it is not mentioned that this drug belongs to the same family as Clindamycin. I think this should be changed to “Clindamycin, Lincomycin
  7. P.173, Trimethoprim
    1. I think that the following grouping is interesting:

i. Methotrexate – inhibits human Dihydrofolate reductase

ii. Trimethoprim – inhibits microbial Dihydrofolate reductase

iii. Pyrimethamine – inhibits parasitic Dihydrofolate reductase

  1. P.176, Antifungal therapy
    1. The antimicrobials were listed as being either cidal or static, but this is not done for the antifungal drugs. I think this should be included with each description.

i. Polyenes (Amp B and Nystatin) – cidal

ii. Azoles – static

iii. Flucytosine – cidal

iv. Caspofungin – cidal

v. Terbinafine – static

vi. Griseofulvin – static

Errors in First Aid for the USMLE (2007): Miscellaneous

March 23, 2007

I’m working on the Microbiology section now and it will be up shortly. In the meantime, I’m compiling all of the errors/suggestions/figures into Word documents so that you don’t have to keep clicking around here (you can all thank Jarrad for this).

Each section will be updated seperately, but for those following along, it’s a pain in the ass to recheck. Here are the most recent additions:


  1. P.204, Paraneoplastic effects of tumors:
    1. Hepatocellular CA is also capable of expressing erythropoietin as a PNP syndrome.
  2. P.218, Sympathomimetics
    1. Clonidine and a-methyldopa are centrally acting alpha-2 agonists. They are listed here as simply “alpha”.
  3. P.230, High-Yield Clinical Vignettes
    1. The sixth vignette concerning Temporal Arteritis belongs in the Musculoskeletal section as this topic is not covered in Cardiovascular.
  4. P.231, Auscultation of the heart
    1. Pulmonic Area: Pulmonic stenosis is a systolic murmur, not diastolic as listed
    2. Tricuspid Area: ASD is a soft midsystolic murmur on the upper left sternal border, not a diastolic murmur as listed (Merck, 18th, p.2407)
    3. You might as well label the Left sternal border as Erb’s Point.
  5. P.242, Eisenmenger’s syndrome
    1. “As pulmonary resistance [up arrow], RV hypertrophies, the shunt reverses…”
  6. P.243, Coarctation of the Aorta
    1. “Infantile type: …of ductus arteriosus (preductal). Rapidly fatal.”
  7. P.249, Bacterial endocarditis
    1. “(round white spots on retina surrounded by hemorrhage)” should be placed after “Roth’s spots” and not after “Osler’s nodes”.
  8. P.263, Adrenal Steroids
    1. 3B-hydroxysteroid dehydrogenase is listed as 33-hydroxysteroid dehydrogenase.
  9. P.284, Salivary secretion
    1. Serous on the Sides (Parotids)
    2. Mucous in the Middle (sublingual)
  10. P.290, Stomach cancer
    1. Virchow’s node – involvement of left supraclavicular node by mets from stomach.
  11. P.293, Colorectal cancer
    1. “’Apple core’ lesion seen on barium enema x-ray.”
    2. I think it’s worth mentioning that colonic adenocarcinoma is most commonly found in the Ascending colon.
  12. P.293, Cirrhosis and portal hypertension
    1. Because of the role that cirrhosis plays in increased levels of estrogen and the effects that these estrogen levels have, I think the following symptoms should be grouped:
      1. Hyperestrinism
        1. Spider nevi
        2. Gynecomastia
        3. Loss of Sexual hair
        4. Testicular atrophy
        5. “liver palms”
  13. P.297, Carcinoid
    1. There should be some mention that the “Classic symptoms” refer to carcinoid syndrome, and that this occurs only after metastasis of the carcinoid tumor to the liver.
  14. P.298, H2 blockers
    1. Cimetidine and Ranitidine [down arrow] CR clearance.
  15. P.298, Bismuth, sucralfate
    1. I think it’s worth mentioning that bismuth is directly toxic to H.pylori.
  16. P.300, Pro-kinetic agents
    1. Metoclopramide’s anti-emetic effects are due to central D2-antagonism while it’s peripheral pro-kinetic effects are due to its M1 agonism. I think this should be mentioned.
  17. P.315, Histocytosis X
    1. There is no mention of Birbeck granules on EM in this section, despite the fat that on P. 439, this is the classical finding for Histocytosis X.
  18. P.327, Osteopetrosis
    1. “chalk stick” fractures are characteristic of Osteopetrosis but are not mentioned here. They are instead mentioned on P.328 under Paget’s disease.
  19. P.328, Polymyositis/dermatomyositis
    1. Under dermatomyositis, I think it’s worth mentioning the Gottron papules over the knuckles and the heliotrope rash.
  20. P.332, Primary bone disorders
    1. Osteosarcoma is listed as the “Most common [primary] malignant tumor of bone.” As stated on P.312, multiple myeloma is the most common primary malignant tumor of bone. I think that “(excluding multiple myeloma)” should be added.
  21. P.335, Arachidonic acid products
    1. “Neutrophils arrive B4 others” to help remember that LTB4 is neutrophil chemoattractant.
    2. “LTC4 Contracts”
  22. P.367, Herniation Syndromes and Uncal Herniation
    1. By far, the best figures to illustrate each of these sections can be found in Fix’s High-Yield Neuroanatomy. His descriptions are confusing and would have to be changed, but please consider Fig. 2-2 and Fig. 2-3 for the next edition.
  23. P.401, Wilm’s Tumor
    1. Hemihypertrophy is seen in Beckwith-Weidman syndrome with deletion of the WT2 gene, not in Wilm’s tumor with WT1 deletion.
  24. P.401, Transitional cell carcinoma
    1. Schistosomiasis is responsible for bladder wall irritation, leading to squamous metaplasia and then squamous cell carcinoma. It is less often responsible for Transitional cell carcinoma.
  25. P.433, Pancoast tumor
    1. There is no mention that Pancoast tumors can invade the lower portion of the brachial plexus (nerves T1 and T2). I think this should be mentioned as vignettes commonly have paresthesias in these dermatomes.
  26. P.439, Classic Findings
    1. C-ANCA, P-ANCA – polyarteritis nodosa is listed. This contradicts P.333. This should be changed to “microscopic polyangiitis”.
  27. P.450, Most Common Associations
    1. H. Influenzae type B is no longer the primary cause of bacterial meningitis in kids and E.coli is not the primary cause of bacterial meningitis in newborns. The causes are in the correct order on P.165. Group B strep in newborns, S. Pneumoniae in children.
  28. High-Yield Images, Image 12
    1. Left ventricular hypertrophy typically involves an expansion of the cardiac outline on both the right and left of the mediastinum. Right ventricular hypertrophy typically expands the cardiac outline left of the mediastinum alone. This picture looks like the “boot shape” of RVH.

Errors in First Aid for the USMLE (2007): Reproductive

March 21, 2007

As always, comments are welcome


  1. P. 414, Reproductive Pathology
    1. There is no section for vaginal pathology. I think the following should be added:
      1. Vaginal Carcinomas
        1. Squamous Cell CA – typically an extension from the cervix
        2. Clear Cell CA – seen in women exposed to DES
        3. Sarcoma Botryoides – rhabdomyosarcoma variant. “bunch of grapes”
  2. P.417, Polycystic ovarian syndrome
    1. One of the ways to treat PCOD is with clomiphene, which is neither an OCP or a gonadotropin analog. In women with PCOD that want to conceive, clomiphene is used. In women that do not want to conceive, oral contraceptive pills are used. I think that clomiphene should be included in the treatments.
  3. P.417, Ovarian non-germ cell tumors
    1. Serous cystadenocarcinoma is responsible for 50% of ovarian carcinomas, not 50% of ovarian tumors.
  4. P.418, Breast tumors
    1. I think “commonly found in the upper outer quadrant” should be included in the general description of malignant tumors.
    2. Invasive lobular – often multiple, bilateral. Cells in Indian file.
    3. Paget’s disease of the breast – ….suggest underlying ductal carcinoma.
  5. P.418, Common breast conditions
    1. Cystic – fluid filled. “Blue dome
    2. Fat Necrosis, …..Pendulous breasts
  6. P.419, Cryptorchidism
    1. I think the following should be included:
      1. Leydig cells spared – [up arrow] FSH, [up arrow] LH
      2. Increased risk for seminoma, embryonal germ cell tumors.
  7. P.419, Testicular germ cell tumors
    1. Seminoma – radiosensitive
    2. Yolk sac (endodermal sinus) tumor – infancy and early childhood
  8. P.420, Clomiphene
    1. Under clinical use, I think it should include “induce ovulation in PCOD”

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Errors in First Aid for the USMLE (2007): Psychiatry

March 21, 2007

As always, comments are welcome


  1. P.379, Other anxiety disorders
    1. “Anxiety disorder – emotional symptoms (anxious, depressed mood) causing impairment following an identifiable psychosocial stressor within the last three months (e.g. divorce, moving….”
  2. P.379, Malingering
    1. I think it’s worth adding: “Patient avoids treatment and complaints cease after gain.” This is in contrast to factitious disorder where the patient undergoes treatment ( e.g. surgery) and the complaints recur (grid abdomen).
  3. P.381, Eating disorders
    1. A useful distinction between anorexics and bulimics is that anorexics have incredible control over their eating, while bulimics have no control over their eating. Anorexics are often perfectionists while bulimics are often shoplifters.
  4. P.381, Substance Abuse
    1. Substance abuse does not require dependence as stated.
  5. P.387, Monoamine oxidase (MAO) inhibitors
    1. Atypical depression is characterized by mood reactivity (the ability to feel good when something positive happens) and reversed vegetative symptoms (such as overeating and oversleeping). It is not characterized as accompanying “psychotic of phobic features” as described.

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Errors in First Aid for the USMLE (2007): Heme/Onc

March 21, 2007

As always, comments are welcome.

  1. P.302, High-Yield Clinical Vignettes
    1. The patient presenting with macrocytic megaloblastic anemia that receives folate (when a B12 deficiency is to blame) is not at risk of masking signs of neural damage. The neural damage is either present or not. This should be changed to:
      1. “Masks signs of anemia while allowing neural damage to progress with vitamin B12 deficiency.”
  2. P.303, Basophil
    1. Bosiphilic stippling is scene in RBCs, not Basophils. “Basophilic stippling is seen in TAIL” should be moved to p.307 with the other “RBC forms.”
  3. P.307, Blood groups
    1. I think it’s worth mentioning that the Rh+ and Rh- is referring to the D-antigen.
  4. P.308, Anemia
    1. “Macrocytic” should include “hypochromic”.
    2. The category for “Microcytic hyperchromic” is missing and should list Hereditary Spherocytosis and Hemolytic Anemia.
  5. P.311, Lymphomas, Hodgkin’s
    1. I do not understand why this is listed as “more common in men except for nodular sclerosing type” since nodular sclerosing type is the most common form of Hodgkin’s lymphoma.
  6. P.313, Leukemias
    1. I think it is worth mentioning here that ALL is the most common childhood malignancy and pointing out the association between basophilia and CML.
  7. P.320, Etoposide
    1. This is listed here as G2-phase specific. It’s activity is both in S and G2-phase and this is correctly illustrated in the figure “Cancer drugs – cell cycle” on page 318.
  8. P.320, Tamoxifen, Raloxifene
    1. These drugs have different activities but are described together, and this leads to confusion. Tamoxifen is a receptor antagonist in breast and a partial agonist in the endometrium, but it is not an agonist in bone nor is it clinically useful in preventing osteoporosis. Raloxifene is an agonist in bone and an antagonist in breast and endometrial tissue and is useful in preventing osteoporosis. To recap:
      1. tamoxifene has no activity in bone and is not used for osteoporosis.
    2. I think this section should be rewritten to:
      1. Tamoxifene: receptor antagonist in breast, partial agonist in bone, no bone activity. Useful in treating breast cancer. Increased risk of endometrial CA.
      2. Raloxifene: receptor antagonist in breast and endometrium, receptor agonist in bone. Useful in treating breast cancer and preventing osteoporosis. No increased risk of endometrial CA.

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Errors in First Aid for the USMLE (2007): Gastrointestinal System

February 27, 2007

As always … corrections, suggestions and additions are welcome in the comments.


  1. P.280, Abdominal layers
    1. Not necessary, but I’m just begging you to change this image. In contrast to a typical cross-section on CT, this image is flipped over its axis. This means that with left body on right page, we are looking from head-to-toe and not toe-to-head (as in a CT) and the anterior abdominal wall is placed below the spine on the page instead of above (as in a CT). The simplest solution is to remove all the labels, flip the image across its horizontal axis (as opposed to rotation which would place the IVC and Aorta incorrectly), and then reapply the labels.
  2. P.281, Femoral triangle
    1. The Femoral nerve is not labeled correctly as a nerve. Instead, the “Femoral a.” and “Femoral v.” labels are both pointing to the Femoral nerve. The Femoral artery and Femoral vein are not labeled. This image is also missing the “Empty space and lymphatics” of the femoral triangle.
  3. P.282, Inguinal canal
    1. The “Deep inguinal ring” label is not labeling anything. I think a bar pointing to the ring should be added.
    2. The label “Medial umbilical ligaments” is pointing to one (of two) of the medial umbilical ligaments and (incorrectly) to the median umbilical ligament. The labeling should change appropriately.
    3. The labels “Deep inguinal ring” and “External inguinal ring” are not consistent with the next page, and I think the small changes to “Internal (deep) inguinal ring” and External (superficial) Inguinal ring” would clear up any confusion and bring it in line with the descriptions on the following page.
  4. P.284, Salivary secretion
    1. I think a fourth bullet point with “Lingual lipase begins TAG digestion; activated at low pH on reaching stomach” should be added. This offers a contrast to the activation and action of alpha-amylase.
  5. P.285, GI hormones
    1. I think it’s worth mentioning that Gastrin’s effects are inhibited by Somatostatin. According to Costanzo (BRS Phys), it is a pH of 3 (not 1.5 ) which is the checkpoint for the gastrin/acid-secretion feedback loop between the antrum and the body of the stomach.
      1. Vagal stimulation of gastric acid secretion is due to ACh (as listed on P.284), but no mention is made that vagal stimulation of gastrin secretion from G cells is due to Gastrin Releasing Peptide (GRP). Because this explains why anti-muscarinics do not prevent the secretion of gastrin, I think it should be mentioned.
    2. Cholecystokinin should include “(CCK)” since this abbreviation is not stated elsewhere and is used within the same row of the table. It is also worth mentioning that CCK potentiates Secretin’s effect on pancreatic HCO3- secretion.
    3. Secretin’s effect on increased bile production is not mentioned.
    4. I think it’s worth adding the second-messenger systems used by each hormone. Since Gs, Gi and Gq were previously covered (P.214) I think it’s helpful enough to list the following next to each hormone:
      1. Gastrin (Gq)
      2. CCK (Gq)
      3. Secretin (Gs)
      4. Somatostatin (Gi)
      5. GIP (Gs)
      6. VIP (Gs)
      7. NO (cGMP)
  6. P.286, Regulation of gastric acid secretion
    1. The pattern established by this figure is that each drug with a line towards a receptor is inhibitory for that receptor. This is not the case for Misoprostol, which is a PG analog and stimulatory at the receptor. To avoid any confusion, I think that + and – signs are more appropriate here.
  7. P.294, Alcoholic hepatitis
    1. Changing the mnemonic from “You’re toASTed with alcoholic hepatitis” to “ToASTed, Sam GOT alcoholic hepatitis” helps you remember that SGOT is also known as AST (which is easy to forget).
  8. P.296, Primary sclerosing cholangitis
    1. I had no idea what an ERCP was, nor would I expect most other second-years to know it. If it’s going to be mentioned, I think it should be spelled out to “endoscopic retrograde cholangiopancreatogram (ERCP)”
  9. P.296, Reye’s syndrome
    1. In the way that acute pancreatitis is associated with gallstones and ethanol (for example), Reye’s is not associated “with viral infection … and salicyclates;” it is associated with the combination. It’s subtle but important. I think “and” should be changed to “treated with“.

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Errors in First Aid for the USMLE (2007): Neurology

February 27, 2007

As always… all suggestions, additions, corrections are welcome.


  1. P.345, Basal ganglia
    1. I think this image is confusing and could benefit from a few additions. Specifically, I think it should be made clear that neurons from the SNc are synapsing on neurons in the Striatum. The Striatal neurons are currently labeled as “Putamen” which would lead to confusion if a test stem referenced the “striatal neurons” that are the sites of Huntington’s lesions.
    2. I think it is appropriate in this section to repeat that Dopamine is inhibitory through its D2 receptor (currently unmentioned) and stimulatory through its D1 receptor.
    3. The light and dark shading of the pathways is not very intuitive, and I think a return to + and – signs might be worthwhile.
  2. P.349, Spinal tract anatomy and functions
    1. Under 3rd-order neuron, “sensory cortex” is listed for the Dorsal column-medial lemniscus tract. The third order neuron is actually that neuron originating in the thalamus (receiving the 2nd-order neuron as described) and then projecting to the sensory cortex. It is the 4th order neuron (within the sensory cortex) that is the end-point of this tract and responsible for any conscious experience. “sensory cortex” should be changed to “ascends from VPL of thalamus to sensory cortex.”
    2. This same criticism applies to “sensory cortex” listed for Spinothalamic tract.
  3. P.357, Visual field defects
    1. The 6th bullet for “Left hemianopia with macular sparing” should include the “(PCA)” since this is the most commonly cited cause. The image should also include a bar across the fibers in the posterior part of the optic radiation. As it stands, “6” is the only number in the figure without a bar marking the site of the disruption.
  4. P.359, Aphasia
    1. Just for the repetition, I think the following should be added here:
      1. Broca’s (44,45)
      2. Wernicke’s (22)
  5. P.363, Primary brain tumors
    1. Childhood peak incidence
      1. F. Pilocytic (low grade): this tumor is correctly described as being found most often in the posterior fossa, however, it is drawn in the anterior fossa and supratentorial. Further, the image of the brain is backwards from what is traditionally shown, which may have led to some confusion during the illustration.
  6. P.364, Tabes dorsalis
    1. Because space is not an issue here and the term has not been used recently, I think it might be worth extending “DTRs” to “deep tendon reflexes”.
  7. P.365, Brown-Sequard syndrome
    1. First bullet point is followed by “not shown”. Similarly, the fifth bullet point is also not shown on the diagram. I do not understand this, since the territory of “Ipsilateral UMN signs” is identical to the territory of “Ipsilateral loss of tactile, vibration, proprioception sense”. It seems the labeling could read “1,2” instead of just “2”. My point is similar for bullet points “4,5” instead of “4” when describing the territories of “Ipsilateral loss of all sensation at level of lesion” and “LMN signs at level of lesion”.
  8. P.366, Facial lesions
    1. Instead of the current mnemonic “ALexander Bell with STD: AIDS, Lyme, Sarcoid, Tumors, Diabetes” I suggest the shorter “BLASTeD: Bell’s palsy from Lyme, AIDS, Sarcoid, Tumors, Diabetes”. A small change, but somewhat easier to remember. Or, if you like, “Bell-LASTeD“.
  9. P.367, Parkinson’s disease drugs
    1. When describing bromocriptine, I think it’s important to say that it is not simply a “partial dopamine agonist”. It is instead a selective dopamine agonist at the D2 receptor, and has its action not in stimulating the direct pathway of the basal ganglia, but instead suppresses the indirect pathway.
  10. P.370, Anesthetics – general principles
    1. The line beginning “Drugs with [up arrow] solubility…” could use a little changing. I suggest beginning with the reciprocal relationship between MAC and potency, followed by the conclusion. I also believe that MAC is not Minimal Anesthetic Concentration but Minimal Alveolar Concentration. The distinction is important as the two are not the same.
      1. MAC = Minimal Alveolar Concentration. Potency = 1/MAC. [up arrow] solubility = [up arrow] potency = [down arrow] MAC.
  11. P.371, Intravenous anesthetics
    1. I propose an alternative for the mnemonic “B.B. King on OPIATES PROPOses FOOLishly” for memorizing Barbiturates, Benzodiazepines, Ketamine, Opiates and Propofol.
      1. KOPs keep them BEhind BARs: Ketamine, Opiates, Propofol, BEnzodiazepines, BARbiturates.
        1. Bonus: …where they are put to sleep by IV anesthetics.
  12. P.371, Local anesthetics
    1. In the second bullet point, when dealing with the order of nerve blockade, the small myelinated/unmyelinated fibers of the ANS could be included “temperature > ANS > touch”

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Errors in First Aid for the USMLE (2007): Renal System

February 19, 2007

As always, this comes from an email sent to the First Aid team. If you find any errors, please include them in the comments.

Renal (all references from Merck Manual and Robbins Basic Pathology)

  1. P.396, Hormones acting on kidney
    1. Atrial Natriuretic Factor (ANF) is listed as Atrial Natriuretic Peptide (ANP) on the preceding page. I think one term should be used consistently.
  2. P.401, Kidney stones
    1. To help remember which stones are largely radiolucent:
      1. I can’t C U on XRay.” for Cystine and Uric acid stones.
  3. P.405, Mannitol
    1. Mannitol can be used clinically to decrease intracranial pressure (as listed). If given too rapidly, it can also cause an increase in intracranial pressure. I think this should be listed as well under the toxicities.
  4. P.405, Ethacrynic acid
    1. “Similar to furosemide; can be used in hyperuricemia, acute gout (never use to treat gout)” is not correct. This should instead say, “can cause hyperuricemia, acute gout (never use to treat gout).”
  5. P.406, ACE inhibitors
    1. One of the clinical uses for these drugs is to decrease proteinuria. In toxic doses, it can also cause proteinuria. I think this should be mentioned under clinical uses.

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Errors in First Aid for the USMLE (2007): Musculoskeletal System

February 19, 2007

As always, this comes from an email sent to the First Aid team. Please add any errors or suggestions in the comments section.

Musculoskeletal (all references from Merck Manual and Robbins Basic Pathology)

  1. P.326, Smooth muscle contraction
    1. This diagram shows Myosin light-chain phosphatase (MLCP) acting before contraction. Every other reference I have found details SMC contraction in the following steps
      1. Calcium binds calmodulin
      2. Calcium-calmodulin activates Myosin light chain kinase (MLCK)
      3. MLCK phosphorylates myosin, allowing a crossbridge to form
      4. Contraction follows
      5. MLCP dephosphorylates myosin, allowing for relaxation.
    2. I think this diagram should be changed in the following way:
      1. “Cross-bridge formation with contraction
      2. After the action of MLCP, “contraction” should be changed to ” relaxation.”
  2. P.327, Rheumatoid arthritis
    1. In RA, the DIP is completely spared. A small point, but the image of the Swan-neck deformity should be pointing to the involved joint (hyper-extended PIP) and not the DIP (normal).
  3. P.327, Osteopetrosis
    1. In addition to be called “marble bone disease,” this condition is frequently referred to as “Albers-Schonberg” disease. I think this should be mentioned.
    2. Osteopetrosis also presents with hepatosplenomegaly (secondary hematopoiesis due to loss of bone marrow) and cranial nerve palsies. I think both of these should be mentioned.
  4. P.327, Osteitis fibrosa cystica
    1. This disease is also often referred to as “von Recklinghausen’s disease of bone.”
    2. In the same way that alkaline phosphatase is raised in states of high osteoblastic activity, Tartrate-Resistant Acid Phosphatase (TRAP) levels are raised in states of high osteoclastic activity. I think it is worth mentioning both of these correlates in this section.
  5. P.328, Polyostotic fibrous dysplasia
    1. This disease is often referred to as McCune-Albright. I think the text should be changed to “(McCune-) Albright Syndrome”
  6. P.329, Gout
    1. I think it would be helpful to include “glucose-6-phosphatase deficiency (von Gierke’s)“.
  7. P.330, Scleroderma
    1. After the first bullet point, I think it should say, “Associated with anti-Scl-70 antibody against topoisomerase“.
  8. P.331, Skin disorders
    1. Atopic dermatitis has pruritic eruptions within skin flexures, not on flexor surfaces i.e. you would expect to see them within the elbow crease and around the neck instead of on the surface of the bicep and forearm.
    2. Seborrheic keratosis should include the common vignette descriptions of “ stuck-on appearance” and “greasy.”
  9. P.332, Primary bone disorders
    1. A constant feature of osteoid osteoma (in contrast to osteoblastoma and osteoma) is complaint of pain at the site of the lesion. I think that this should be briefly mentioned: “pt. complains of pain”
    2. A feature of Giant Cell tumor of bone is the complaint of arthritis in a young person (20-40 yoa). I think this should be briefly mentioned: “young pt. complains of ‘arthritis'”.
    3. Osteosarcoma has a bimodal peak in incidence, once in 10-20 year olds associated with Retinoblastoma, and once in the elderly following Paget’s disease of bone. Without this distinction, it makes no sense so list Paget’s disease here because this rarely (if ever) occurs in patients younger than 40. I think this should be changed to:
      1. “Most common primary malignant tumor of bone. Peak incidence in men 10-20 years old (associated with familial retinoblastoma). Smaller second peak in elderly (associated with Paget’s disease of bone, bone infarcts, radiation). Commonly found….”
    4. A feature of Ewing Sarcoma is the complaint of pain and warmth over the site of the lesion. I think this should be briefly mentioned.
  10. P.333, Other ANCA-associated vasculitides
    1. In the same way that the “Lesions are of different ages” in PAN, I think it is worth mentioning that the lesions are all of the same age in microscopic polyangiitis.
  11. P.335, NSAIDS
    1. I do not understand why there is no mention of Aspirin in this section.
  12. P.337, Immunosuppresive agents: sites of action
    1. I do not understand why Tacrolimus (FK506) and Cyclosporine (CSA) are shown as having completely non-overlapping sites of action since they inhibit the exact same pathway at the exact same step (one by binding cyclophilin, the other by binding FKBP).

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Errors in First Aid for the USMLE (2007): Endocrine System

February 19, 2007

As always, this comes from an email sent to the First Aid team. If you find any problems here or things that I’ve missed, please note them in the comments.

Endocrine (all references from Merck Manual, Robbins Basic Pathology)

  1. P.267, Cushing’s Syndrome
    1. The left sidebar states that ACTH-producing tumors can be identified after a high dose of dexamethasone as having “[down arrow] cortisol.” This is not the case for ACTH-producing Small Cell Lung Cancers which do not respond to feedback inhibition of cortisol or its analogues. Instead, these tumors have the same profile in the Dex test as Cortisone-producing tumors described in the sidebar. The sidebar should be changed:
      1. Healthy — [down arrow] cortisol after low dose
      2. ACTH-producing Pituitary tumor — [up arrow] after low dose; [down arrow] after high dose
      3. Cortisone-producing tumor — [up arrow] after low and high doses, unilateral adrenal atrophy (or hyperplasia)
      4. Ectopic ACTH-producing tumor — [up arrow] after low and high doses, bilateral adrenal hyperplasia
      5. Iatrogenic Cortisol administration — [up arrow] after low and high doses, bilateral adrenal atrophy
  2. P.269, Subacute thryoiditis (de Quervian’s)
    1. No mention made that this condition involves granulomatous inflammation of the thyroid, a major characteristic.
  3. P.269, Thyroid Cancer
    1. I think this section should be retitled “Thyroid Tumor” and the following bullet point added first to highlight that the majority of nodes are not malignant:
      1. 90% Benign, adenoma – “hot” on scintigram, Hurthle cells

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