Official nbme 15 discussion

[abelabbot]

A new NBME 15 is out! Here is the official discussion page. How did you guys feel about this nbme?

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[drchandrasika]

72 year old man with poorly controlled hypertension is brought to the emergency department because of sever abdominal pain for 2 hour.He appears pale and lethargic.His pulse is 24/min ,respiration a are 16/min and blood pressure is 95/60 mmhg.The lungs are clear to auscultation.An S4 is present.Abdominal examination shows guarding,rigidity, and a pulsatile periumbilical mass.Which of the following additional findings is most likely in this patient?
A.ankle brachial indices that are within normal limits
B.aortic regurgitation
C.asymmetric radial pulses
D.blood pressure reading that are higher in upper extremity than in right
E.decreased femoral pulses

Is this an abdominal aortic aneurysm? Or an Aortic dissection? Why do we see decreased femoral pulses in this case

 

[Handinhand]

I believe based upon his vitals this is most likely an abdominal aortic aneurysm dissection/rupture. You get decreased femoral pulses because your femoral artery is distal to your abdomonal aorta, so if that's "blown" blood is not going to perfuse well distal to it.

 

[tantacles]

72 year old man with poorly controlled hypertension is brought to the emergency department because of sever abdominal pain for 2 hour.He appears pale and lethargic.His pulse is 24/min ,respiration a are 16/min and blood pressure is 95/60 mmhg.The lungs are clear to auscultation.An S4 is present.Abdominal examination shows guarding,rigidity, and a pulsatile periumbilical mass.Which of the following additional findings is most likely in this patient?
A.ankle brachial indices that are within normal limits
B.aortic regurgitation
C.asymmetric radial pulses
D.blood pressure reading that are higher in upper extremity than in right
E.decreased femoral pulses

Is this an abdominal aortic aneurysm? Or an Aortic dissection? Why do we see decreased femoral pulses in this case

It's a ruptured AAA, as diggidy mentioned. All of your upper extremity arteries are supplied early by your brachiocephalics. The legs, on the other hand, are supplied by arteries that occur after the split of the abdominal aorta. Thus, a dissection in the abdominal aorta would affect blood flow through those arteries and result in diminished pulses.

 

[drchandrasika]

thank you

 

[abelabbot]

1. 56-year old lady has a 3 week history of progressive difficulty swallowing. When her symptoms began, she felt that bread and larger pieces of meat were getting stuck in her chest before passing through completely, but now she is having difficulty swallowing all foods and some liquids. Physical examination shows normal oral coordination and a nontender abdomen. An x-ray obtained after a barium swallow shows an irregular mass at the gastroesophageal junction. A photomicrograph of a biopsy specimen obtained via esophagogastroduodenoscopy is shown. Chronic infection with which of the following pathogens is the most likely cause of the histologic findings in this patient?
A) Clonorchis sinensis
B) Cytomegalovirus
C) Entamoeba histolytica
D) Helicobacter pylori
E) Mycobacterium tuberculosis

Isn't this CMV because it causes esophagitis? H.Pylori doesn't cause gerd/esophageal carcinoma so thats why I didn't pick that. Please help


2. A 72-year-old woman is admitted to the hospital because of an acute myocardial infarction. She undergoes cardiac catheterization. Angiography shows a left dominant circulation, and 90% narrowing of the artery supplying the diaphragmatic surface and atrioventricular node of the heart. A balloon angioplasty is scheduled during which a stent will be inserted in the narrowed vessel. The catheter and the balloon must be passed through which of the following vessels (stated in order) to reach the narrowed vessel?

Why is this the answer.

B) left coronary, circumflex, posterior interventricular (posterior descending)

Anyone have a better way of explaining?


3.A 62 yr old man has productive cough, night sweats, and temperatures to 100 F. PPD skin test is positive but culture of sputum shows only normal flora after 2 days. A biopsy of an enlarged lymph node is done. Causal organisms are most likely to be present in which of the following cells in the specimen?

a) epithelial cells
b) fibroblasts
c) macrophages
d) neutrophils
e) t lymphocyes

Please give explanation for why the answer is macrophages

 

[Handinhand]

2. A 72-year-old woman is admitted to the hospital because of an acute myocardial infarction. She undergoes cardiac catheterization. Angiography shows a left dominant circulation, and 90% narrowing of the artery supplying the diaphragmatic surface and atrioventricular node of the heart. A balloon angioplasty is scheduled during which a stent will be inserted in the narrowed vessel. The catheter and the balloon must be passed through which of the following vessels (stated in order) to reach the narrowed vessel?

Why is this the answer.

B) left coronary, circumflex, posterior interventricular (posterior descending)

Anyone have a better way of explaining?

It's pretty straight forward. This question wanted you to realize that the structures that are ischemic are fed by the posterior circulation, which in this individual is left dominant (most people are right dominant). The correct answer is simply the path blood must take in this individual's heart to reach those structures.


3.A 62 yr old man has productive cough, night sweats, and temperatures to 100 F. PPD skin test is positive but culture of sputum shows only normal flora after 2 days. A biopsy of an enlarged lymph node is done. Causal organisms are most likely to be present in which of the following cells in the specimen?

a) epithelial cells
b) fibroblasts
c) macrophages
d) neutrophils
e) t lymphocyes

Please give explanation for why the answer is macrophages.

Another straight forward question -- TB lives within the lysosomes of macrophages. This is why pyrazinamide is one of the 4 drugs we use to treat TB, because it locates to the lysosome and is activated by the acidity there.

I also got the first question wrong. First things first though, this is not esophagitis. I believe this is cancer, an esophageal adenocarcinoma to be specific, which is usually the result of GERD induced Barret's esophagus. I couldn't connect that cancer with any of these pathogens though, but I believe the correct answer is H. Pylori. I'll let someone who got it right weigh in for sure though.

My other answers are within the quotes in bold.

 

[abelabbot]

Thanks,
Also the one about the 55 yr old man , difficulty swelling, regurg go undigested food, unusual rumbling sounds in voice that originate in neck, halitosis, 4 cm posterior midline pouch protruding b/w thyropharyngeus and cricopharyngeus portions of the inferior pharyngeal constrictor muscle. These muscle most likely innervated by which nerve? Is it motor fibers from the vagus nerve just because his motor function of swallowing is messed up?

 

[abelabbot]

 

[Handinhand]

It's motor fibers from the vagus nerve because that's the nerve that innervates those muscles...

Also, did you read what I wrote? Your posterior circulation is not consistent for every person -- in some people it's fed by your right coronary artery, and in a few people it's fed by your circumflex artery off the left main. They explicitly told you in the question that he had a left dominant circulation...

 

[abelabbot]

It's motor fibers from the vagus nerve because that's the nerve that innervates those muscles...

Also, did you read what I wrote? Your posterior circulation is not consistent for every person -- in some people it's fed by your right coronary artery, and in a few people it's fed by your circumflex artery off the left main. They explicitly told you in the question that he had a left dominant circulation...

Yes I did, thats why I ended up deleting my original post and inserting a smiley. Didn't see your reply till now. Thank you

 

[drchandrasika]

1) MI,ON ADMISSION,pulse oximetry30%O2. O2 SATURATION95%
3HR Later, SOB, O2 saturation 90%, crackles lg base, 2/6 systolic murmur, pH 7.41, PCO236,PO2 60, CAUSE OF HYPOXEMIA?

decreased alveolar ventilation

decreased erythrocyte transit time in pulmonary capillaries

decreased lymphatic drainage

increased permeability of pulmonary capillaries

increased plasma colloid osmotic pressure

increased pulmonary capillary pressure





2) 64 year old man with 2 month progressive shortness of breath, 98.6 F temperature, 30/min respirations, bp 125/80, clubbing of fingers, total lung capacity decreased, chest x ray shows a coarse reticular pattern. Most likely cause of these findings?

constriction of the terminal bronchioles

destruction of the alveolar walls

increased fibrosis in the intersittium

increased mucus secretion in the bronchioles

loss of elastic support to the walls of the bronchioles


I was stuck between the third and fourth option

3)An 18 year old man comes to the physician because of a 1 year history of progressive headaches. An x-ray of the head shows a cystic tumor above the sella turcica. The serum concentration of which of the following hormones is most likely to be increased in this patient?
a. ADH (vasopressin)
b. Adrenocorticotropic
c. Follicle-stimulating
d. Growth
e. Luteinizing
f. Prolactin
g. Thyroid stimulating

 

[tantacles]

I also got the first question wrong. First things first though, this is not esophagitis. I believe this is cancer, an esophageal adenocarcinoma to be specific, which is usually the result of GERD induced Barret's esophagus. I couldn't connect that cancer with any of these pathogens though, but I believe the correct answer is H. Pylori. I'll let someone who got it right weigh in for sure though.

My other answers are within the quotes in bold.

Agreed. It's cancer of the esophagus. Your main clue is that the condition is progressive - this woman initially had problems swallowing liquids, but it's gotten worse. In addition, it's clear that there's a mass that's impinging on arteries, your second clue. Mass + progression = neoplasm. H. pylori is associated with gastric cancer, so that seemed like the best answer.

 

[drchandrasika]

bump

 

[Handinhand]

Agreed. It's cancer of the esophagus. Your main clue is that the condition is progressive - this woman initially had problems swallowing liquids, but it's gotten worse. In addition, it's clear that there's a mass that's impinging on arteries, your second clue. Mass + progression = neoplasm. H. pylori is associated with gastric cancer, so that seemed like the best answer.

That's my issue though, H. Pylori is associated with GASTRIC carcinoma (intestinal subtype I believe), and even after combing through stuff online I can't seem to connect H. Pylori to esophageal adenocarcinoma (the biopsy looked pretty glandular, so I'm guessing it was adeno). Oh well, seem pretty low yield. I knew exactly what she had, just couldn't connect it to any of those infections.

 

[Handinhand]

2) 64 year old man with 2 month progressive shortness of breath, 98.6 F temperature, 30/min respirations, bp 125/80, clubbing of fingers, total lung capacity decreased, chest x ray shows a coarse reticular pattern. Most likely cause of these findings?

constriction of the terminal bronchioles

destruction of the alveolar walls

increased fibrosis in the intersittium

increased mucus secretion in the bronchioles

loss of elastic support to the walls of the bronchioles

I believe the actual answer was Bronchiectasis, which would be choice D.


3)An 18 year old man comes to the physician because of a 1 year history of progressive headaches. An x-ray of the head shows a cystic tumor above the sella turcica. The serum concentration of which of the following hormones is most likely to be increased in this patient?
a. ADH (vasopressin)
b. Adrenocorticotropic
c. Follicle-stimulating
d. Growth
e. Luteinizing
f. Prolactin
g. Thyroid stimulating

This is a craniopharyngeoma. Slow growing tumor of tissue descended from Rathke's pouch. If they are left to grow, they can eventually compress the pituitary stalk, which can physically block releasing hormones from the hypothalamus from reaching the pituitary. This can result in blocking Dopamine from reaching the anterior pituitary, leading to an overproduction of Prolactin.

Answers in quote.

 

[Handinhand]

So I've gone back and thought about it more, and I have a problem with the external vs internal validity question on this exam.

I understand the difference between the two; internal being a question if the outcomes are the result of the independant variable, or some other circumstance. External being a question if the results are applicable to the general public, i.e, is your sample population representative of the entire population.

Now, I understand why lack of blinding would lead to a flaw of internal validity. What I want to know is why the subjective nature of the survey instrument is not also an internal validity flaw, as it is a flaw of the research study itself, not the individuals who are being researched.

 

[Slava]

Hello Guys sorry but I got problem: A 56 y.o. women with shortness of breath. She is 55 kg, BMI=20. The physician initiate IV bolus antiarrhythmic to aatain initial peak serum conc.=10mg/l. VD=1.81 l/kg. Which one is Loading dose? 1. 100 2. 250 3.500 4.1000 5.1500

 

[Slava]

A 75 y.o. women with 3 month history of enlarging lesion on her face. Examination show 1.5 cm brown-black mottled scaly lesion with irregular borders. Microscopic exam show atypical melanocytes spread along the basilar layer. Which one?
1. Acanthosis nigricans.
2. Actinik keratosis.
3. Compaund nevus
4. Lentigo maligna
5. Sebborrheic keratosis.
Is it 1?

 

[Slava]

One more, maybe I just stupid but got wrong:
A 62y.o man with productive cough, night sweets and t-37 C during the past 2 weeks. A PPD skin test+,but culture if sputum show only normal flora after 2 days. A biopsy of large lymph node is done. Where is casual organism present?
1. Epithelial cells.
2. Macrophage
3. Fibroblast
4. Neutrophils
5. T lymphocytes.

 

[Slava]

A 52 y.o man with 3 days blindness of the left eye. No pain. Fundoscopy of left eye show pale opaque fundus and bright red fovea centralis. Dense scotoma of entire visual field of the left eye. Right eye no abnormalities. If the left eye illuminated, which one is reaction?
1. Constriction because left optic track is binocular
2. Cons. because projection to the Edinger-Westplah nucleus are bilateral.
3. Dilation because posterior commissure is intact
4. Dilation because is right superior cervical ganglion is intact
5. No Cons. because left ciliary nerve is damage
6. No Cons. because the retinal ganglion cells in the left eye has been destroyed.

 

[surgok]

Hello Guys sorry but I got problem: A 56 y.o. women with shortness of breath. She is 55 kg, BMI=20. The physician initiate IV bolus antiarrhythmic to aatain initial peak serum conc.=10mg/l. VD=1.81 l/kg. Which one is Loading dose? 1. 100 2. 250 3.500 4.1000 5.1500

1000

 

[surgok]

A 75 y.o. women with 3 month history of enlarging lesion on her face. Examination show 1.5 cm brown-black mottled scaly lesion with irregular borders. Microscopic exam show atypical melanocytes spread along the basilar layer. Which one?
1. Acanthosis nigricans.
2. Actinik keratosis.
3. Compaund nevus
4. Lentigo maligna
5. Sebborrheic keratosis.
Is it 1?

Lentigo maligna. Lentiginious spread indicates it's spreading laterally along the basement membrane.

 

[surgok]

One more, maybe I just stupid but got wrong:
A 62y.o man with productive cough, night sweets and t-37 C during the past 2 weeks. A PPD skin test+,but culture if sputum show only normal flora after 2 days. A biopsy of large lymph node is done. Where is casual organism present?
1. Epithelial cells.
2. Macrophage
3. Fibroblast
4. Neutrophils
5. T lymphocytes.

Macrophage. TB lives inside the macrophage.

 

[surgok]

A 52 y.o man with 3 days blindness of the left eye. No pain. Fundoscopy of left eye show pale opaque fundus and bright red fovea centralis. Dense scotoma of entire visual field of the left eye. Right eye no abnormalities. If the left eye illuminated, which one is reaction?
1. Constriction because left optic track is binocular
2. Cons. because projection to the Edinger-Westplah nucleus are bilateral.
3. Dilation because posterior commissure is intact
4. Dilation because is right superior cervical ganglion is intact
5. No Cons. because left ciliary nerve is damage
6. No Cons. because the retinal ganglion cells in the left eye has been destroyed.

Left retina is obviously damaged, meaning that L CN2 isn't functioning. You can shine light all day to non-functioning CN2, and it won't produce any response.

 

[Slava]

Left retina is obviously damaged, meaning that L CN2 isn't functioning. You can shine light all day to non-functioning CN2, and it won't produce any response.

Thank you Sugok, you help a lot.

 

[Slava]

1000

Could you please explain, how did you get 1000, sorry?

 

[periaqueductal]

@Slava Loading dose=Vd*peak serum/F
In this case Vd is in L/Kg, so you need to multiply 1.81*55=~100.
F is 1 because it's IV
100*10=1000

 

[Slava]

@Slava Loading dose=Vd*peak serum/F
In this case Vd is in L/Kg, so you need to multiply 1.81*55=~100.
F is 1 because it's IV
100*10=1000

Thank you! I hate math.

 

[Overlord]

Score dropped 15 points from
NBME 16 to 15.

Tests is in 9 days, and I cannot push it back. Awesome.

 

[1dayatatime]

Hi guys, I have some q's. I tried to read through the thread but wow is it long. Would appreciate any feedback. Thanks in advance!

1. Following a stroke, a 68 year old man had a language problem. His speech is fluent but contains many grammatical errors, word substitutions, and neologisms. He is unable to repeat words after the examiner and is apparently unable to comprehend other verbal requests. Which area is damaged?

I understand the answer is angular gyrus/conduction aphasia (which is apparently H -- doesn't look like the arcuate to me either) but UW says conduction aphasia has "good comprehension" - WTF. I saw a lot of posts about this but it's really not clear. I read the wikis for both wernicke's and conduction and yes, it says that conduction has paraphasias but so do some other aphasias so that can't be specific for conduction aphasia. I really think this q SUCKS and just wanted to know how others' thinking process went and how you were led AWAY from wernicke's.

2. 6 year old girl with RTA. In the question about the defect in renal ammoniagenesis, what is the source of ammonia production? Answer was Glutamine. Don't get this.

3. A 37 y/o woman is brought to the ED after husband found her unconscious. Her temp is 98.6, pulse is 128/min, and BP is 70/40 mmHg. physical exam shows cool, pale extremities, jugular venous distention, faint peripheral pulses and crackles over the bottom two thirds of both lung fields. Heart sounds are normal and there are no murmurs. She withdraws to painful stimuli in all four extremities. This pt is likely experiencing what type of shock?

answer is Cardiogenic but why does she have normal heart sounds/no murmurs?

4. 72 year old man with poorly controlled hypertension is brought to the emergency department because of sever abdominal pain for 2 hour.He appears pale andlethargic.His pulse is 24/min ,respiration a are 16/min and blood pressure is 95/60 mmhg.The lungs are clear to auscultation.An S4 is present.Abdominal examination shows guarding,rigidity, and a pulsatile periumbilical mass.Which of the following additional findings is most likely in this patient?
A.ankle brachial indices that are within normal limits
B.aortic regurgitation
C.asymmetric radial pulses
D.blood pressure reading that are higher in LEFT upper extremity than in right
E.decreased femoral pulses

I read Diggidy's explan which makes sense but I wonder why C and D would be wrong -- would D only be right if it hadn't ruptured? And it would be true for both Abdominal as well as thoracic aorta right? What about C?

5. During a series of normal skel mm. twitches, the ATP concentration -- blah blah -- I"m actually wondering if the statement "ATP is hydrolyzed only during relaxation" is true (even tho it's the wrong answer). I feel like it's true. Also is it just 1 atp used total through that one power stroke?

 

[thehundredthone]

1. Following a stroke, a 68 year old man had a language problem. His speech is fluent but contains many grammatical errors, word substitutions, and neologisms. He is unable to repeat words after the examiner and is apparently unable to comprehend other verbal requests. Which area is damaged?

I haven't seen the question but why would the angular gyrus be affected? It does not deal with auditory comprehension, it deals with written comprehension. It would be the supramarginal gyrus at fault. This region deals with auditory comprehenson, and since it's part of the connection between Broca's and Wernicke's areas, a lesion would also cause conduction aphasia.

2. 6 year old girl with RTA. In the question about the defect in renal ammoniagenesis, what is the source of ammonia production? Answer was Glutamine. Don't get this.

Deamination in the tissues releases glutamate, processed by glutamine synthetase to generate glutamine which is a neutral amino acid, and hence can travel in the blood. It goes to the kidney where it is used for ammonia genesis. This is the source of all ammonia in the kidneys (and similarly in the portal blood as well where it enters the urea cycle).

3. A 37 y/o woman is brought to the ED after husband found her unconscious. Her temp is 98.6, pulse is 128/min, and BP is 70/40 mmHg. physical exam shows cool, pale extremities, jugular venous distention, faint peripheral pulses and crackles over the bottom two thirds of both lung fields. Heart sounds are normal and there are no murmurs. She withdraws to painful stimuli in all four extremities. This pt is likely experiencing what type of shock?

answer is Cardiogenic but why does she have normal heart sounds/no murmurs?

Why must someone with cardiogenic shock have abnormal heart sounds or murmurs? She's definitely in shock based on her vitals. JVD and crepitations indicate biventricular failure, i.e. cardiogenic shock. If it were due to tamponade, then yes, there could be muffled heart sounds, but it need not be the only cause, perhaps she had a massive myocardial infarction.

4. 72 year old man with poorly controlled hypertension is brought to the emergency department because of sever abdominal pain for 2 hour.He appears pale andlethargic.His pulse is 24/min ,respiration a are 16/min and blood pressure is 95/60 mmhg.The lungs are clear to auscultation.An S4 is present.Abdominal examination shows guarding,rigidity, and a pulsatile periumbilical mass.Which of the following additional findings is most likely in this patient?
A.ankle brachial indices that are within normal limits
B.aortic regurgitation
C.asymmetric radial pulses
D.blood pressure reading that are higher in LEFT upper extremity than in right
E.decreased femoral pulses

I read Diggidy's explan which makes sense but I wonder why C and D would be wrong -- would D only be right if it hadn't ruptured? And it would be true for both Abdominal as well as thoracic aorta right? What about C?

I think I answered this before. This is a ruptured (hypotension, bradycardia) abdominal (guarding, rigidity, periumbilical mass) aortic aneurysm (pulsatile mass). The lesion is far beyond the subclavian arteries and hence you will not see any changes between the two the upper extremities. Even if it were a distal aortic dissection, there would be no upper extremity signs, more specifically there would be no abdominal signs because the bleeding is into the wall of the vessel, hence blood does not touch the peritoneum.

D is a sign of a type A aortic dissection affecting the proximal arch before, and not involving, the left subclavian vessel. Conversely, in a coarctation, you may see pressures higher in the right upper extremity than the left.

5. During a series of normal skel mm. twitches, the ATP concentration -- blah blah -- I"m actually wondering if the statement "ATP is hydrolyzed only during relaxation" is true (even tho it's the wrong answer). I feel like it's true. Also is it just 1 atp used total through that one power stroke?

Actually, ATP binding, rather than hydrolysis, is required for cross bridge cycling which allows both shortening and lengthening of the muscle. Binding of ATP to myosin releases the actin-myosin bridge. Both contraction and relaxation are active processes requiring ATP. (This also explains rigor mortis, because now that no more ATP can be made available, actin and myosin bind each other preventing the muscle from relaxing or contracting)

ATP hydrolysis into an ADP~Pi complex allows the free myosin to move into position for the next stroke (cocking) and form a cross bridge. Then the energy from the release of the terminal Pi is used to power 1 power stroke for that filament.

 

[Handinhand]

So I've gone back and thought about it more, and I have a problem with the external vs internal validity question on this exam.

I understand the difference between the two; internal being a question if the outcomes are the result of the independant variable, or some other circumstance. External being a question if the results are applicable to the general public, i.e, is your sample population representative of the entire population.

Now, I understand why lack of blinding would lead to a flaw of internal validity. What I want to know is why the subjective nature of the survey instrument is not also an internal validity flaw, as it is a flaw of the research study itself, not the individuals who are being researched.

Anybody mind answering this?

I also have a question about the problem of the osteoporotic women where it wanted you to say whether osteoblast, osteoclast, and RANK-L concentration would be up or down in this women. I understand that the decrease in estrogen is going to lead to increased osteoblast apoptosis, and I understand that a decrease in osteoprotegerin will also occur -- both a result of decreased estrogen. The correct answer I believe states that blast activity will be decreased, and osteoclast and RANK-L concentration will be increased; this I have a problem with. If you have a loss of osteoblasts, how could you possibly have an increased concentration of RANK-L? Osteoprotegerin is also not a gene regulator, but simply a decoy that binds to RANK-L, preventing its activity, so this shouldn't effect concentration either. Wouldn't it be more appropriate to say RANK-L activity is increased in osteoporosis?

 

[1dayatatime]

Thanks for your help thehundredthone. I've seen your old posts too and you are very helpful! Thanks for being available!

I haven't seen the question but why would the angular gyrus be affected? It does not deal with auditory comprehension, it deals with written comprehension. It would be the supramarginal gyrus at fault. This region deals with auditory comprehenson, and since it's part of the connection between Broca's and Wernicke's areas, a lesion would also cause conduction aphasia.

hmm, that was the question stem that i typed out. it doesn't talk about written comprehension. i'm beginning to think the answer IS wernicke's but it pointed to a place right ABOVE the sylvian fissure (although that's the corner you'd find wernicke's at...but it's always been described as "superior temporal gyrus" so i always look BELOW the sylvian fissure. sigh. what a messed up q.

wait a minute, i just came back to this. the SUPRAMARGINAL gryus is the answer (H) right? (or is that the angular?). I picked J bc i thought that was the superior temporal gyrus. Wiki says that supramarginal gyrus can cause "receptive aphasia" (which is wernicke's right?) but then when i clicked "receptive aphasia" it said it was due to lesion in the "superior temporal gyrus" - what's going on? Also i am under the impresion that a lesion in the angular gyrus would cause Gerstmann syndrome which is not what the vignette is describing so it has to be Supramarginal.


Why must someone with cardiogenic shock have abnormal heart sounds or murmurs? She's definitely in shock based on her vitals. JVD and crepitations indicate biventricular failure, i.e. cardiogenic shock. If it were due to tamponade, then yes, there could be muffled heart sounds, but it need not be the only cause, perhaps she had a massive myocardial infarction.

I guess someone in cardiogenic shock doesn't have to have abnormal heart sounds? I guess I didn't think JVD and crepitations was specific for cardiogenic shock as opposed to the other types, wouldn't you have some crepitations in hemorrhagic or anaphylactic?


I think I answered this before. This is a ruptured (hypotension, bradycardia) abdominal (guarding, rigidity, periumbilical mass) aortic aneurysm (pulsatile mass). The lesion is far beyond the subclavian arteries and hence you will not see any changes between the two the upper extremities. Even if it were a distal aortic dissection, there would be no upper extremity signs, more specifically there would be no abdominal signs because the bleeding is into the wall of the vessel, hence blood does not touch the peritoneum.

D is a sign of a type A aortic dissection affecting the proximal arch before, and not involving, the left subclavian vessel. Conversely, in a coarctation, you may see pressures higher in the right upper extremity than the left.

When would you get different radial pulses?

Lastly this is not from this nbme but from nbme 3. I get why the answer is C (K+) but why can't the answer also be Chloride since that also has a negative equil potential?

During an experimental study of the mechanisms of nerve conduction, a researcher isolates a nerve and uses a microelectrode to measure its membrane potential distal to a site of electrical stimulation. The resting potential of the nerve is found to be ˆ’90 mV. The following membrane potentials are then recorded at various points in time after stimulation:

Time After Stimulation (msec) Membrane Potential
0 -90 mV
0.5 +25 mV
1 -100 mV
2 -90 mV

The change in membrane potential from the resting potential occurring between 0.5 and 1 milliseconds is most likely caused by increased permeability to which of the following ions?

A. Ca2+
B. Cl-
C. K+
D. Na+
E. PO4

Sorry Diggidy, I also was confused about that Behav sci q so can't help.

 

[thehundredthone]

In the attachment you've posted, area H is Wernicke's and a lesion there will explain his symptoms.

Chloride potential is negative with respect to the nerve cell, but its potential is close to the resting potential of the membrane, which opposes its movement into the cell. The activation of sodium channels activates potassium channels simultaneously, whereas the chloride channels are not activated the same way. In fact, I found very little literature with respect to voltage gated chloride channels. Hence immediately after depolarization, it is the continued open state of potassium channels that causes hyperpolarisation.

Diggidy, the subjective nature of a survey instrument will not necessarily affect the internal validity of the study, and it isn't necessarily a flaw either, because it can still produce objective results that hold strong statistically for the population that is studied. The issue however is that those results will not necessarily carry over to the general population (which is usually the aim of a study). If subjectivity always affected internal validity, one could not carry out any subjective studies. If you have the time, this article may be mildly helpful.

 

[1dayatatime]

Great explanations -- so what is your impression of the type of aphasia you'd get with supramarginal gyrus lesions?

Yeah i guess it's wernicke's but it's clearly above the sylvian fissure so i guess that picture just sucks...

May I please ask your opinion on this q too (from NBME 4) that i found on another forum? Most online are saying it's increased sensitivity to sedatives and there's even a paper that said there was no diff in Vd's btwn elderly and young 'uns but UWSA said the opposite (it said benzo's metab is decreased in elderly due to INCREASED Vd due to less body water, less fat, less hepatic Blood flow, and increased fat). So I just want to know what you think, thehundredthone. Thanks is advance!


An otherwise healthy 80-year-old man is scheduled for endoscopy for evaluation of rectal bleeding. A standard dose of midazolam is administered intravenously when the patient is admitted to the endoscopy suite. A few minutes later, he develops cyanosis and labored respirations and requires ventilation with an oxygenated resuscitation bag. An age-related increase in which of the following is the most likely cause of these adverse effects?
A)Enterohepatic recycling
B)Metabolite formation
C)Plasma protein binding
D)Sensitivity to sedatives
E)Volume of distribution

http://www.usmleforum.com/files/forum/2010/1/481294.php

 

[chchch20]

Someone posted this q earlier but I didn't see an answer to it:
#7. A 25yo primigravid at 12 weeks passes a small amount of tissue vaginally. Gross exam of the tissue shows an obvious fetus. Micro exam of tissue via D&C shows chorionic villi with focal edema and trophoblastic proliferation. Which of the following is the most likely diagnosis?
A) Choriocarcinoma
B) Complete hydatiform mole
C) Partial hydatiform mole
D) Placenta accreta
E) Placental site trophoblastic tumor

The whole "obvious fetus" thing threw me off...is it supposed to be partial mole?

 

[chchch20]

Also this has been answered but if someone wouldn't mind explaining a little more... if someone has a defect in ammoniagenesis (I'm guessing RTA4) then what is the most likely source of ammonia production in this patient? The answer is glutamine but I thought RTA4 would mean that glutaminase isn't working in which case how is gln serving as a source of ammonia?

 

[1dayatatime]

that was an ectopic pregnancy. go back to the photo and you'll see a tiny human in the ampulla

 

[chchch20]

I think you're thinking of a different question. This one didn't have a picture, just a description of the findings.

Also, my pharm prof this year made a point of telling us that elderly people have increased sensitivity to actions of drugs in the CNS, not just wrt decreased Vd but just intrinsically (can't remember the mechanism sorry).

 

[Slava]

I think you're thinking of a different question. This one didn't have a picture, just a description of the findings.

Also, my pharm prof this year made a point of telling us that elderly people have increased sensitivity to actions of drugs in the CNS, not just wrt decreased Vd but just intrinsically (can't remember the mechanism sorry).

This is Partial Hyd. mole, because (a small amount of tissue, chorionic villi with focal edema and trophoblastic proliferation).

 

[thehundredthone]

Great explanations -- so what is your impression of the type of aphasia you'd get with supramarginal gyrus lesions?

Conduction aphasia or auditory receptive aphasia with poor repetition. Written comprehension will be intact if the angular gyrus is intact.

May I please ask your opinion on this q too (from NBME 4) that i found on another forum? Most online are saying it's increased sensitivity to sedatives and there's even a paper that said there was no diff in Vd's btwn elderly and young 'uns but UWSA said the opposite (it said benzo's metab is decreased in elderly due to INCREASED Vd due to less body water, less fat, less hepatic Blood flow, and increased fat).

There is no consensus on this. The increased volume of distribution has been reported in studies, although some said it was only seen in male patients. Another study said there was no difference. The increased sensitivity has also been consistently reported with no mechanism elucidated except for a possible increase in receptor sensitivity. Unfortunately this is one of those questions where your guess is as good as mine, only the NBME knows which answer they want (NBME 4 doesn't come with extended feedback).

Also this has been answered but if someone wouldn't mind explaining a little more... if someone has a defect in ammoniagenesis (I'm guessing RTA4) then what is the most likely source of ammonia production in this patient? The answer is glutamine but I thought RTA4 would mean that glutaminase isn't working in which case how is gln serving as a source of ammonia?

I'm not sure I understand, I don't know of any relation between RTA4 and glutaminase dysfunction. The problem with renal ammoniagenesis in RTA4 is that of NH4+ formation in the collecting ducts due to decreased H+ inside the tubular cells. NH3 is still formed in the tubular epithelium, there just isn't any H+ in the cells to bind to it and allow it's secretion into the tubule to buffer the H+ which is in the collecting tubule (which is why the urine is usually paradoxically acidic). If you look at this diagram, the last step is where the problem lies in RTA4.

 

[D3sidud3]

I also originally wanted to choose CMV - but then I began to search for intranuclear inclusions and couldn't find any - which led me to pick H. Pylori via POE. Another reason for elimination of this choice was that CMV esophagitis is mostly seen in patients with low CD4 (at least so far in my step 1 questions experience).

But its still not clear to me how H.pylori caused the lesion at the junction, so it'd be great if anyone has an explanation

 

[Enzymes]

Anyone know the answer to the glucosamine question for joint pain?

Side effects arent listed?
Or
What have you heard about using glucosamine?

I don't get this one....

 

[YeahNoMind]

Anyone know the answer to the glucosamine question for joint pain?

Side effects arent listed?
Or
What have you heard about using glucosamine?

I don't get this one....

Glucosamine is a chondroprotective agent. It is a component of healthy cartilage. Therefore, it can be concluded that long-term treatment with glucosamine:

1. reduces pain,
2. improves function/mobility of the joint,
3. reduces OA progression,
4. reduces risk of total joint replacement.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3150191/

 

[Enzymes]

So what is the answer to the question? Is it "what have you heard about using glucosamine to treat arthritis?"

 

[Enzymes]

Can anyone help with this one: A drug that increases phosphoinositide turnover, but does not affect nicotonic synapses?

Atropine, Bechanecol, neostigmine, succinylcholine?

Really confused on this one.

 

[YeahNoMind]

So what is the answer to the question? Is it "what have you heard about using glucosamine to treat arthritis?"

Yes its D. Addresses patient's concern, and uses an open ended, non confrontational question.

 

[rcdamania]

5. Diphtheria vaccine confers protective immunity by inducing formation of antibodies against a preparation composed of which of the following?
A. Killed bacterial cells
B. Live attenuated bacterial cells
C. Purified bacterial peptidoglycan
D. Purified capsular polysaccharide
E. Purified inactivated toxin

Had some trouble with this I thought that the antibodies were made because it was congugated with Hflu (thanks in advance for the helP!)

 

[thehundredthone]

Diphtheria vaccine is a toxoid vaccine. The antibodies are generated against the toxin. The conjugation helps increase the antigenicity of the toxin, it doesn't change component what the antibodies are generated against.

 

[rcdamania]

Diphtheria vaccine is a toxoid vaccine. The antibodies are generated against the toxin. The conjugation helps increase the antigenicity of the toxin, it doesn't change component what the antibodies are generated against.

So is this a toxoid vaccine which means its a purified inactivated toxin?