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

January 16, 2007

I was really happy with this section. Under the new divisions, Basic Pathology gets a few pages early to cover neoplasia and inflammation. The majority of Pathology is spread out in the Systems from the second half of the book (which is why so little is covered here).

As always, this is from an email sent to the First Aid team.

Pathology

  1. P.204, Paraneoplastic effects of tumors:
    1. From Robbins Pathology: “Definition: Symptoms not directly related to the spread of the tumor or elaboration of hormones indigenous to the tissue from which the tumor arose.” “Cancer-associated hypercalcemia also results from osteolysis induced by bony metastases; this, however, is not to be considered a paraneoplastic syndrome.” This section in the First Aid lists “bone metastasis (lysed bone)” as a paraneoplastic syndrome causing hypercalcemia. This is not “para” neoplastic or an endocrinopathy like the elaboration of PTH-like peptides from Squamous Cell Lung Cancer.
    2. Hepatocellular CA is also capable of expressing erythropoietin as a PNP syndrome.
  2. P.205, Cancer epidemiology
    1. The way that these percentages are listed makes the pattern non-obvious. I suggest simply rearranging the data.

cancer-incidence-table.jpg

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America Will Never Forget

January 16, 2007

I like it when people surprise me, and sometimes bloggers do that by going off their normal topic to show, other than being intelligent in their own niche, they think intelligently elsewhere. Admit it: it’s encouraging. This from A Farrago Of Gallimaufries (no idea what it means).

While driving home the other day, I saw a giant sign on the side of a building that read, “AMERICA WILL NOT FORGET – Dec. 7, 1941 – Sept. 11, 2001.” Okay, I thought, that’s acceptable, especially since those events were pretty atrocious moments in US history. Let’s review.

  • Dec. 7, 1941
  • Sept. 11, 2001
  • Aug. 6, 1945
  • Aug. 9, 1945
  • Mar. 20, 2003–current

Click here to see how it ends.


Sentence of the Day

January 16, 2007

Best sentence of the day.  Really, I’m tickled.

‘Judge Tries to Unring Bell Hanging Around Neck of Horse Already Out of Barn Being Carried on Ship That Has Sailed.’

Click here to laugh along.

Second best sentence of the day:

It takes a special person to want to do family medicine as you must not only run between the Scylla and Charybdis of your peer’s ridicule but you must also lash yourself to the mast of primary care against the siren call of more lucrative specialties.

Via Panda Bear MD, my new favorite blog.


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

January 14, 2007

As always, comments are welcome.

Pharmacology

  1. P.218, Sympathomimetics
    1. Clonidine and a-methyldopa are centrally acting alpha-2 agonists.  They are listed here as simply “alpha”.
  2. P.223, P-450 interactions
    1. Quinidine is listed as an inducer of P450.  Quinidine is an inhibitor of P450 (BRS 4th ed, P.13)

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

January 14, 2007

Until I write this section, please feel free to add any errors that you’ve found in the comments section.

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

January 14, 2007

As always, this comes from an email sent to the First Aid team.

Immunology

  1. P.191, Complement
    1. “Membrane attache complex” should be “Membrane attack complex.”
  2. P.191, Complement
    1. “Deficiency of C1 esterase inhibitor leads to angioedema (overactive complement).” The angioedema is due to overactive bradykinin as C1 Inh is responsible for inhibiting this pathway. The parenthetical remark should instead be ” (overactive bradykinin pathway).”
  3. P.194, Diseases caused by hypersensitivity
    1. Several texts list auto antibodies as a finding and alternative cause to IDDM (against islet cells) and Hashimoto’s Thyroiditis (against thyroglobulin, thyroid peroxidase), but these are both classified as strictly Type IV hypersensitivity reactions. This is inconsistent with P.196, where auto antibodies to “antimicrosomal elements” are mentioned.
    2. Rheumatoid arthritis is listed as a Type III hypersensitivity disorder. Most medical texts agree that the likely pathogenesis of RA involves CD4+ cells sensitive against the synovium that begin releasing cytokines. The Rheumatoid factor (anti-IgG IgM) is absent in 20% of patients and is a byproduct of the type IV hypersensitivity, not the cause itself. Because Rf does contribute to the vasculitis and subcutaneous nodules characteristic of the disease, RA should be listed as a Type IV with Type III characteristics. SLE represents another mixed hypersensitivity reaction with characteristics of Type II and Type III. I suggest a separate section for mixed hypersensitivity reactions to avoid confusing this issue.

hypersensitivity-table.jpg

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Errors in First Aid for the USMLE (2007)

January 13, 2007

Apologies to anyone that has been reading this post and wondering why I haven’t done any new work on the First Aid.  This section moved here.  Please change any links that lead you to this page so that you can find the updated version of the errors.

Sorry for any confusion, topher.


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

January 13, 2007

The following is from an email sent to the First Aid Team concerning errors/corrections/suggestions to their 2007 edition.

Embryology (reference: HY Embryo by Dudek)

  1. P.122, Embryological derivatives: Under neural crest cells, it lists “cranial nerves.” This is not true. Neural crest cells are responsible for the sensory ganglia of V, VII, IX and X and the parasympathetic ganglia of III, VII (ptery), VII (submand), IX and X. Motor ganglia of all cranial nerves come from the neuroectoderm of the neural tube. The remaining cranial nerve precursors: sensory ganglia of I (surface ectoderm), II (neuroectoderm), VIII (surface ectoderm for both vestibular and cochlear ganglia). Another way to display the CN origins:
    1. Surface ectoderm gives sensory for CN I and CN VIII (both cochlear and vestibular ganglia)
    2. Neuroectoderm gives sensory for CN II.
    3. Neuroectoderm gives motor ganglia for all cranial nerves (III, IV, V, VI, VII, IX, X)

                                                              i.            Sensory for CN II

    1. Neural Crest cells give parasympathetic ganglia for all cranial nerves (III, VII [pterygopalantine and submandibular], IX, X)
  1. P.122, Embryological derivatives
    1. It is mentioned that neural crest cells give rise to odontoblasts but not that they produce dentin . It should also be mentioned under ectoderm that ameloblasts produce the enamel.
  2. P.123, Twinning
    1. Monozygotic ( 65%), Dizygotic (fraternal) or monozygotic (35%).
  3. P.125, Fetal Circulation
    1. I’m sure someone has probably brought this up, but the shading for this diagram is inaccurate. It shows the umbilical vein as carrying less oxygenated blood from the mother to the fetus and more oxygenated blood carried in the umbilical arteries from the fetus to the mother. The fetal circulation cannot be divided into left and right as it can be in the adult (and is in this diagram). The order of oxygenation should be as follows (and represented graphically with gradient shading instead of gray v. white: from most to least

                                                              i.            Most oxygenated blood from L. umbilical vein to end of Ductus venosum

                                                            ii.            Mixing of blood with return from IVC (where it meets ductus venosum) to R. atrium

                                                          iii.            More oxygenated blood following along strong arrow, entering the L. ventricle without much mixing in the R. atrium and R. ventricle with less oxygenated blood from the SVC.

                                                          iv.            Medium oxygenated blood delivered straight to arch of aorta, leaving through R. and L. subclavian aa, L. coronary.

                                                            v.            Less oxygenated blood returning from head into SVC, entering R. ventricle without much mixing with more oxygenated blood from the IVC followed by ejection into Pulmonary trunk through Ductus Arteriosis and into thoracic aorta.

                                                          vi.            Least oxygenated blood leaving via R. and L. umbilical aa.

  1. P.127, Ear development
    1. Eardrum” should be replaced with “tympanic membrane.”
  2. P.128, Cleft lip and cleft palate
    1. In describing the cleft palate, “failure of fusion of the lateral palatine processes, the nasal septum, and/or the median palatine process (formation of [secondary] palate).” I found the bold part very confusing. After describing the primary palate with relation to a cleft lip, why is the term ” median palatine process” used instead of the already introduced “primary palate?” I think that this should be changed, with “primary palate” used instead.
  3. P.128, Diaphragm embryology
    1. I think that the adult derivatives of each part of the diaphragm could be mentioned along with special mention that congenital hiatal hernias are more often through the L. pleuroperitoneal membrane.

                                                              i.            Septum transversum (central tendon)

                                                            ii.            Pleuroperitoneal folds (muscle)

                                                          iii.            Body wall ( muscle)

                                                          iv.            Dorsal mesentery of the esophagus (crura)

  1. P.129, Genital ducts
    1. I suggest adding the following:

                                                              i.            “Mullerian inhibiting hormone (MIH) secreted by the Sertoli cells of the testes suppresses development of the paramesonephric ducts in males. [Up arrow] androgens secreted by the Leydig cells cause development of the mesonephric ducts.”

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Errors in First Aid for the USMLE (2007): Behavioral Science

January 13, 2007

The following is from an email sent to the First Aid Team concerning errors/corrections/suggestions to their 2007 edition.

  1. Behavioral Science (references: HY Biostatistics and HY Behavioral Science)

    1. P.66, Statistical Distribution: I found the (mean>median>mode) v (mean<median<mode) labeling to be unintuitive for right and left skew. To emphasize the idea that the mean is sensitive to skew, the median is insensitive to skew, and the mode is totally uninfluenced by skew, the order should have instead been: (mode< median<mean) and (mean>median>mode). But even this falls somewhat short. The best diagram I have seen is on P.11 of Glasner’s HY Biostatistics. I have attached a quick drawing of it (bottom of page). It is intuitive and requires little (if any) explanation.

    2. P.68, Reportable Diseases: Of the 50+ reportable diseases nationwide (CDC website), I thought the absences of Chlamydia, Hep C, and Lyme disease from this list were significant. Should these be included, the mnemonic would have to change from “Be a smart chicken or you’re gone” to something more straightforward, like the following triplets:
      1. (Hep) ABC, MMR, SSS, TLC, SEX (AIDS, Gonorrhea, Chlamydia)
    3. P.70, Written Advanced Directive: This definition implies that a Living Will can only contain wishes to “withhold or withdrawal life-sustaining treatment.” This is not the case.
      1. Living Will: A document which specifies the life-prolonging measures an individual wants and does not want taken on his/her behalf in the event of a terminal illness or incapacitation.
      2. A Living Will, unlike a DNR/DNI order, can have instructions for both positive and negative measures.
    4. P.74, Sleep stages: Stage 3-4 is described as containing “bed-wetting” while in #6 it says, “Imipramine is used to treat enuresis…” Just to be consistent, I think it should say, “…to treat enuresis ( bed-wetting)…”
    5. P.75, Operant Conditioning: The following three lines are not consistent in their terms/descriptions and I found them to confuse the issue for me. My suggestions follow.
      1. Learning in which a particular action is elicited because it produces a reward.
      2. Positive Reinforcement – desired reward produces action (mouse presses button to get food).
      3. Negative Reinforcement – removal of aversive stimulus [up arrow] behavior (mouse presses button to avoid shock). Do not confuse with punishment. (a definition or example of punishment was never given)
        1. Operant Conditioning – learning in which a consequence produces a behavior.
        2. Positive Reinforcement – introduction of a positive stimulus [up arrow] the behavior (Child cleans room to earn money).
        3. Negative Reinforcement – removal of an aversive stimulus [up arrow] the behavior (Child cleans room to end mother’s complaining). Do not confuse with Punishment.
        4. Punishment – Learning in which a consequence (following the behavior) [down arrow] the behavior (Child is denied dessert for frequently interrupting others. Child now allows others to speak ).
    6. P.76, Immature Ego Defenses: This list is good but is missing a few terms. My suggestions for inclusion and a change to the definition of Isolation:
      1. Somatization – Psychic conflict manifested as physically real bodily symptoms – After hearing bad news, wanting to vomit.
      2. Intellectualism – avoiding/replacing emotion with intellectual detail – cancer patient obsesses over the workings of a CT machine instead of facing poor prognosis.
      3. Isolation (change) – separation of emotion from idea – a child describes his birthday party in a monotone.
      4. Undoing -carrying out symbolic behavior to atone for unacceptable action – A nun making the sign of the cross after cursing.
      5. Passive-Aggression – unconsciously falling short of expectation after creating the expectation – Friend leaves you at campus after promising to give you a ride home.

Mean Median Mode

Right Skew – Left Skew

 

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Errors and Problems in High Yield Cell and Molecular Biology

January 13, 2007

These last two days have been exhilirating and frustrating. Exhilirating because I’m exposing myself to incredible concepts in Cell Biology that make me want to live in a lab for the rest of my life to discover more; frustrating because of the vessel. Dr. Dudek’s High Yield Cell and Molecular Biology (2nd Ed. 2007) is riddled with errors in grammar, spelling, punctuation, etc. As an English marm, I find this incredibly distracting. Further, there are a number of times where the book is not internally consitent (i.e. page 10 contradicts page 20), presents concepts in obfuscating ways (this may just be me being dense), or makes factual errors.

I didn’t schedule the time to spend a few hours each day trying to decipher conflicting statements. Though I found sections of this book amazing, the confusing tradeoffs weren’t worth it. If I were to do it all over again, I would not buy this book.

But if you did buy this book and just searched for “errors in High Yield….” then what follows is what I’ve found. This comes from an email I composed to Dr. Dudek, notifying him of the problems. You have to appreciate an author that gives out their email address like that.

Comments are arranged by Chapter-Page-Section. Important errors are underlined and emboldened. Please escuse my hubris:

Chapters 1-13 (out of 26)

  1. The Cell Membrane
    1. P.6, A.13.17: Abbreviation “DST of the loop of Henle” not explained. I knew this term as Thick Assending Limb and not Distal Straight Tubule.
    2. P.7, B: “across the membrane and [verb?] generally called ion channels.”
    3. P.10, B.2: Title: “Transmitted-gated ion channels” should be “TransmitteR-gated…”
    4. P.11, B.2.c: “..the gate is opened and the influx and Na+ and efflux..” “And” should be replaced with “of”.
    5. P.11, B.2.d: “Purinergic 2x” conflicts with P.16, E: “Purinergic 1,2y” These may be different; I raise it only because both are found on “peripheral terminals of nociceptive neurons.”
    6. P.13 is amazing, by the way.
    7. P.14, C: “..trimer with GDP bound to the [alpha] chain..” The [alpha] should have a “q” after it.
    8. P.15, B: You refer to the actions of both Beta-agonists and Beta-antagonists as having “(positive chronotropism; B1 effect).” This is confusing. As I’ve seen it, these drugs are typically described as being “negatively or positively chronotropic” for antagonists and agonists, respectively.
    9. P.16, C: You have the PLc pathway as producing a “[down arrow/decrease in] IP3 + DAG” when it actually produces an increase in IP3 and DAG.
    10. P.18, P.4: last sentence: “…receptor antagonists and are used to [verb?] opioid toxicity…”
    11. P.21, VII: last sentence: “When LDL … binds to the LDL receptor, receptor-mediated endocytosis [verb?] in the following steps:”
    12. P.21, VII.C: You abbreviation “HNG-CoA reductase” should be “HMG-CoA reductase.”
  2. Cytoplasm and Organelles
    1. P.23, I.E: “…and a DNA-binding region that activate gene…” It should be “activates.”
    2. P.30, C.2: last sentence: “The absence of glucose-6-phosphatase enzyme in skeletal muscle prevents the degradation of glycogen to free glucose,” while certainly correct, is confusing if you don’t already know that this absence is normal, and that no skeletal muscle has this enzyme. Without this context, I would have read this as being a disease state. I think it could be reworded:
      1. “Skeletal muscle lacks glucose-6-phosphatase, thereby committing the stored glycogen to be used by the muscle in glycolysis.”
    3. P.32, Figure 2-2, O: “High magnification of a mitochondria with tubular cristae.” The significance of mitochondrial tubular cristae in steroid-secreting cells was not addressed in this chapter.
  3. Nucleus
    1. Figure 3-2 was really helpful
  4. Protein Synthesis
    1. P.38, II.A: “DNA sequences that flank the gene sequence at the 5′ end of the template strand are called upstream sequences. DNA sequences that flank the gene sequence at the 3′ end of the template strand are called downstream sequences.” This is not correct and conflicts with every mention to follow of upstream/downstream sequences, i.e. P. 95-97.
      1. Template strand: upstream: 3′ of gene
      2. Template strand: downstream: 5′ of gene
      3. Non-template strand: upstream: 5′ of gene
      4. Non-template strand: downstream: 3′ of gene
    2. P.43, Figure 4-3: For some reason the last drawn ribosome has the two subunits separated.
    3. P.44, Figure 4-4, A(3): After giving the translation of each codon-to-amino acid sequence, you omit that UAA codes for STOP. I think that this should be included for completeness.
  5. Chromosomal DNA
    1. P.45, II.B: “…impart a positive charge to the proteins that enhances it binding to…” It should be “..enhances its binding to…”
    2. P.46, II.C: “(an enzyme can pass on DNA double..” This should be “can pass one DNA double”
    3. P.46, II.D: “During metaphase of mitosis, [subject?] can become…”
    4. P.46, III: last sentence: “Microtubules produced the by centrosome…” should be “by the centrosome“.
  6. Numerical Chromosomal Abnormalities
    1. P.54, II.B: You state that chimerism is the “reverse of twinning.” While I understand what you are going for by way of analogy, genetically-speaking, chimerism is not the reverse of twinning and this analogy is potentially confusing.
    2. P. 57, Figure 6-3, (A,B): When describing Patau syndrome, you list “fingers flexed and overlapping” as a key feature. This is a key feature of Edwards syndrome.
    3. P.61, III.I. The notation for each of the multiple myeloma translocations is out of order, i.e. t(14;4), t(14;6), t(14;11) should instead be t(4;14), t(6;14), t(11;14).
    4. P.66, VII.A: last sentence: “…encodes for DNA polymerase eta[?] that is involved…”
    5. P.66, VII.C: missing comma between “hypogonadism” and “microcephaly”
  7. Structural Chromosomal Abnormalities
  8. Chromosome Replications and DNA Synthesis
  9. Meiosis and Genetic Recombination
    1. P.82, Figure 9-2, A: This figure is confusing because the end product shows only a swapped intermediate sequence and does not show how the remainder of the chromosome arms can be switched between the two chromosomes using a Holliday junction. This site has a very good demonstration that might be adapted to fit the space of this page.
  10. The Human Nuclear Genome
    1. P.87, III.F-H: These descriptions are great, but why is there no reference to Figure 12-3 (P.104) which shows how each of these works? Most of the information here is also repeated word-for-word in chapter 12. I think moving Figure 12-3 into this chapter and then (instead of repeating the information) simply referencing III.F-H when the time comes in chapter 12 would help.
    2. P.89, V.C: “Simple variable number tandem repeats (VNTR) polymorphisms called microsatellite DNA or SSR polymorphisms … are typically found in microsatellite DNA.” This is self-referencing and confusing. I don’t know what you mean when you say that microsatellite DNA is typically found in microsatellite DNA.
    3. P.91, Figure 10-2 (F): It was my understanding that two transposons, flanking a gene, carrying out gene transfer required the “cuts” to be on the outermost edges of the transposons, thereby incorporating both transposons with the gene into the new location. This figure shows the gene being transferred without accompanying transposons.
  11. The Human Mitochondrial Genome
  12. Control of Gene Expression
    1. P.07, II.B.3: “CREB (cAMP response element binding protein) binds to the CRE in response to elevated cAMP levels in the cell caused by a protein hormone binding to a G protein-linked receptor and thereby induces gene expression.” I found this sentence very confusing. Because the sequence of events is very linear, I think a more linear sentence is appropriate:
      1. “A cell signal produced by a G protein-linked receptor (resulting in an increase in cAMP) triggers CREB (cAMP response element binding protein) to bind to CRE.
    2. P.100, Figure 12-2 (A): The drawing of the folded Homeodomain protein has the COOH terminus and NH2 terminus switched.
    3. P.101, V.D: “There a[are?] several human genes that [verb?] two or more alternative promoters which…”
    4. P.101, V.D: “Alternative promoters start transcription from different versions; the first exon, which is then spliced into a common set of downstream exons, which produce an isoform of the same molecular weight.” This should say:
      1. “Alternative promoters start transcription from different versions of the first exon, which is then spliced into a common set of downstream exons, and produce isoforms of the same molecular weight.”
    5. P.101,V.D: “…but different amino acid sequences in the NH2-terminal end.” This should say “…but different amino acid sequences in the COOH-terminus.”
    6. P.102, V.G: “…~20% of the total genes on the X chromosome escape inactivation. These ~20% inactivated genes include…” This is contradictory. This should say “These remaining active genes include…”
    7. P.103, VI.D.4: “Glucose and lactose(+)” should be “Glucose(-) and lactose(+).”
    8. P.104, Figure 12-3 (D): “Note that each alternative promoter uses in own first exon” should be “promoter uses its own.” “The size of the dystrophin isoforms are show” should be “shown.”
  13. Mutations of the DNA Sequence
    1. P.107 III: You describe nonsense mutations as producing “non-functional (truncated) proteins” and frameshift (or DNA splicing) mutations as producing “non-functional (“garbled”) proteins.” According to the mechanisms described, both frameshift and DNA splicing mutations can produce “garbled” and truncated proteins.
    2. P.107-108, III.F-G: After stating that Translocational and Unstable Expanding Repeat Mutations have been previously covered (and you reference them), you reprint the text. I think you could save this space.
    3. P.109, IV.A: No examples given of haploinsufficiency but several examples given for gain of function mutations. I would have liked to read about a few of them.
    4. P.110, IV.B: “In order for gain of function mutations to become clinically relevant, the individual needs to be heterozygous (i.e. Rr).” Because homozygotes are not excluded (through inheriting these traits), I think it is more correct to say that:
      1. In order for gain of function mutations to become clinically relevant, the individual needs to have at least one copy of the gene (i.e. Rr or rr).
    5. P.110, IV.B.1: “Pittsburgh variant is a missense mutation in the [alpha]1-antitrypsin protein that produces a gain of function mutation known as the Pittsburgh variant.” This is confusing. I do not know what you mean to say that Pittsburgh variant produces Pittsburgh variant. “…methionine358 in the reactive center acts a bait for…” should be “…acts as bait…”
    6. P.110, V: “Fourth, a polymorphism is the occurrence of two or more alleles at a specific locus in a frequencies greater than can be explained by mutations alone (a polymorphism does not cause a genetic disease).” I found this explanation confusing and it does not mention that it is judged on the characteristics of the population that carries it. I think that the Oxford definition is less confusing:
      1. The occurrence of two or more alleles for a given locus in a population where at least two alleles appear with frequencies of more than 1%.
    7. P.110, V.A.2: When writing about Unequal Sister Chromatid Exchange, you write that: “…cleavage and rejoining of sister chromatids occurs at different positions on the maternal chromosome usually within a region of tandem repeats.” followed by the exact same sentence, changing only “maternal” to “paternal.” I think you should change this into one sentence, reading:
      1. …cleavage and rejoining of sister chromatids occurs at different positions on the (maternal/fraternal) chromosome usually within a region of tandem repeats.”
    8. P.111, V.A.3: When describing replication slippage, you don’t mention that the strand that is slipping either “forward” or “backwards” refers to the parent or daughter strand (respectively). You also don’t mention that the insertions and deletions only affect one arm of the sister chromatid. I think you should expand the description of replication slippage and include something similar to this figure (click to enlarge) that illustrates that the templates are unchanged, therefore there is a 50/50 chance that no insertion or deletion will be passed on.
    9. P.114, Figure 13-1 (G): “PNA splicing” should be “RNA splicing”

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