NBME 12 discussion

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titan25

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1 v max 1 enzyme is 300 and 2 nd 30 compare the Km values

km1 is 10 times km 2
km1 is 1/10 km2
we cant compare


2 upregulation of which protects from ARDS is IL 10

3 which anti hypertensive restores back potassium other k sparing

4 a 14 years old brougt to physian because mostly sleeping withdrawn and complaining of abdomen pain 3 weeks , what history will u take first...should we recretion drug history....options school history , devlopmental, family history

5 a drug given in two patients obese and normal given same doses graph ploted with conc on y axis and time on x , slope of normal person is greater
compared to normal person drug x in obese has

greater VD/ lower bioavailability / higher clearance/ shorter absorption

6 pedigree given four genrations AD 1st genration gene seq 4 5 6 changes to 156 cause...is it recombination

7 cytoplasmic enzyme mutated at 127 alanine replaced by serine why reduction of enzyme activity

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I don't think I've seen this one posted...


A 35-year-old woman with HIV infection has a first generalized tonic-clonic seizure. An MRI shows a small, solitary, enhancing lesion in the right frontal lobe. If stereotactic biopsy of this lesion were performed, it would show intense infiltration of lymphocytes, plasma cells, and macrophages and numerous 3 x 7-mm crescent-shaped organisms with central nuclei. The lesion regresses slowly after treatment with sulfonamide and pyrimethamine. Which of the following is the most likely mode of transmission of this infection?

A) Blood transfusion
B) Ingestion
C) Migration across cribiform plate
D) Sexual intercourse
E) Small droplet inhalation - not the answer



I'm guessing this is toxoplasma from ingestion??
 
Yeah, ingestion of toxoplasma eggs (not sure what the proper protozoa term is) in undercooked food or somehow from cat feces is the most likely source.
 
I have a question, I know it's been asked but I would like an explanation please :D

8. Another carbonic anhydrase question. . CA deficiency in erythrocytes only; whats elevated in venous blood?

K+
Ca
Cl - so it seems that this is the correct answer
HCO3 - WRONG
Mg
Na


For some reason I can't wrap my brain around the Chloride shift. I THOUGHT: in the periphery (venous blood?) that chloride shifts INTO the RBC's, and HCO3 shift OUT of the RBC's. In the lungs the reverse of this happens. So with a lack of carbonic anhydrase, you would get an accumulation of HCO3 in the RBC's, and........... oh wait a second, I think I might have just misunderstood the question. I was thinking about the actual red blood CELLS versus the venous blood. Is this where my mistake is? :smuggrin:

Yep. You're correct on the chloride shift -- CA in the RBCs makes bicarb from CO2 and H2O and then the HCO3/Cl antiporter on the RBC membrane trades HCO3 from inside the RBCs for chloride in the venous blood -- thus an inhibition of RBC carbonic anhydrase would increase chloride content in venous blood since it would inhibit the chloride shift.

As a sidenote, you wouldn't really get an accumulation of HCO3 in the RBCs, since you wouldn't make the HCO3 in the first place (that's the action of carbonic anhydrase). You would have a diminished CO2 carrying capacity of the blood, I think, since the majority is usually transported as bicarb (as well as ~20% via carboxyhemoglobin and ~5% dissolved CO2).
 
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A study is conducted to assess whether there is an association between colonic polyposis and subsequent development of colon cancer. A total of 100 patients with colonic polyposis are enrolled and followed for 10 years. Results show that 20 patients developed colonic malignancies during the study period. To estimate the relative risk, it is most appropriate to recruit which of the following control groups for comparison to the study group?

A) Historical control group
B) Subjects with no evidence of colonic polyposis
C) Subjects derived from a GI derived clinic

So I'm assuming the correct answer is B. I understand that, but can someone explain why A is wrong?
 
A study is conducted to assess whether there is an association between colonic polyposis and subsequent development of colon cancer. A total of 100 patients with colonic polyposis are enrolled and followed for 10 years. Results show that 20 patients developed colonic malignancies during the study period. To estimate the relative risk, it is most appropriate to recruit which of the following control groups for comparison to the study group?

A) Historical control group
B) Subjects with no evidence of colonic polyposis
C) Subjects derived from a GI derived clinic

So I'm assuming the correct answer is B. I understand that, but can someone explain why A is wrong?

Would somebody mind explaining the following. I read through all 7 pages but I don't remember reading the answer to these:

1. 18 month old boy 20 minutes after playing gets respiratory distress 98.6 fever, respirations 70/min, decreased air movements and wheezes heard

2. 16 month old girl that refused to move her arm after he brother grabbed her and now her arm is stuck in pronation?

3. Neisseria vaccine. Pili or capsule? (I picked pili which seems stupid)

4. 17 yo boy w/ lung biopsy shown after AML marrow transplant. I think people said T cell but I just don't know why.

5. 25 yo w/ 6 months amenorrhea and increased LH & FSH. Why is it primary ovarian failure?

6. CT of guy w/ AVM that was plowing snow and then. Hypertension or cholesterol plaques?

Thanks in advance :)
 
Would somebody mind explaining the following. I read through all 7 pages but I don't remember reading the answer to these:

1. 18 month old boy 20 minutes after playing gets respiratory distress 98.6 fever, respirations 70/min, decreased air movements and wheezes heard

2. 16 month old girl that refused to move her arm after he brother grabbed her and now her arm is stuck in pronation?

3. Neisseria vaccine. Pili or capsule? (I picked pili which seems stupid)

4. 17 yo boy w/ lung biopsy shown after AML marrow transplant. I think people said T cell but I just don't know why.

5. 25 yo w/ 6 months amenorrhea and increased LH & FSH. Why is it primary ovarian failure?

6. CT of guy w/ AVM that was plowing snow and then. Hypertension or cholesterol plaques?

Thanks in advance :)

Can anybody help out with these PLEASE! I'm really close to my test date. TIA :D
 
Can't remember all the answer choices but here's what I can remember.

18mo-- foreign object aspiration- toddler playing with small toys loves to put things in their mouth...he's afebrile and had sudden onset of respiratory distress

16mo won't move arm after hard yank--she has subluxation of the radial head

I don't remember the Neisseria question or the AML transplant question unless it was referring to rejection. For transplant rejection, think t-cells unless it is Hyperacute (immediate) rejection which is antibody mediated type II HS due to preformed anti-donor antibodies in the recipient. I think there was a question about graft vs host disease which is where an immunocompromised person receives a transplant and the donor's t-cells react against the host's cells causing severe organ dysfunction.

25yo ammenorrhea-- she has increased FSH and LH levels which tell you that her hypothalamus/pituitary is working but she's still not ovulating therefore there has to be a problem with her ovary not getting the message from FSH and LH and primary ovarian failure is the only answer choice that would fit

man snow plowing-- hypertension is primary predisposing factor to bleeds, stroke, ect
 
A study is conducted to assess whether there is an association between colonic polyposis and subsequent development of colon cancer. A total of 100 patients with colonic polyposis are enrolled and followed for 10 years. Results show that 20 patients developed colonic malignancies during the study period. To estimate the relative risk, it is most appropriate to recruit which of the following control groups for comparison to the study group?

A) Historical control group
B) Subjects with no evidence of colonic polyposis
C) Subjects derived from a GI derived clinic

So I'm assuming the correct answer is B. I understand that, but can someone explain why A is wrong?

The study was designed to assess an EXPOSURE (colonic polyposis) and its association with subsequent disease outcome. Therefore it is a cohort study (calculates relative risk). Remember case-control studies assess an OUTCOME. So B jumps out as the answer because the control group is by definition the non-exposed. When you make the control group you'd like them to match your cases group in every way possible (e.g. same average age, race distribution, gender, etc) except for exposure status, in order to minimize bias. This is why randomized control trials are great because they minimize the differences between the cases and controls, thus minimizing bias. Therefore, comparing a cases group of 100 patients starting today to a control group of 100 patients starting 30 years ago would add bias. It would be better to have them start at the same time. Ahhh, I hope I get a lot of epi questions because it's the only thing I'm good at.
 
The study was designed to assess an EXPOSURE (colonic polyposis) and its association with subsequent disease outcome. Therefore it is a cohort study (calculates relative risk). Remember case-control studies assess an OUTCOME. So B jumps out as the answer because the control group is by definition the non-exposed. When you make the control group you'd like them to match your cases group in every way possible (e.g. same average age, race distribution, gender, etc) except for exposure status, in order to minimize bias. This is why randomized control trials are great because they minimize the differences between the cases and controls, thus minimizing bias. Therefore, comparing a cases group of 100 patients starting today to a control group of 100 patients starting 30 years ago would add bias. It would be better to have them start at the same time. Ahhh, I hope I get a lot of epi questions because it's the only thing I'm good at.

Thanks.

I guess what I am/was hung up on is that it sounds like this study was started 10 years ago, and they are now at the end of the 10 year period. So in choosing the controls, it would be best to go back 10 years "historical" to select the controls (which I just assumed would obviously be without colonic polyps). I guess it would be stupid to conduct a study this way though, by choosing your control group after the study is concluded. I think the wording just confused me.
 
I don't think I've seen this one posted...


A 35-year-old woman with HIV infection has a first generalized tonic-clonic seizure. An MRI shows a small, solitary, enhancing lesion in the right frontal lobe. If stereotactic biopsy of this lesion were performed, it would show intense infiltration of lymphocytes, plasma cells, and macrophages and numerous 3 x 7-mm crescent-shaped organisms with central nuclei. The lesion regresses slowly after treatment with sulfonamide and pyrimethamine. Which of the following is the most likely mode of transmission of this infection?

A) Blood transfusion
B) Ingestion
C) Migration across cribiform plate
D) Sexual intercourse
E) Small droplet inhalation - not the answer



I'm guessing this is toxoplasma from ingestion??

YES. I always remember this bug's life cycle because its' ridiculous.

It grows in an intermediate host (rats) and infection makes the rat drawn to the scent of cats rather than repelled by it<--- one of the coolest parasite/protozoa/whatever mechanisms ever. This makes it more likely for the rat to encounter a cat, where it will be eaten and ingested by the more definitive cat host. Humans get the infection by eating some food (unwashed veggies, undercooked meat) that has been in contact with infected cat feces.
 
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Thanks.

I guess what I am/was hung up on is that it sounds like this study was started 10 years ago, and they are now at the end of the 10 year period. So in choosing the controls, it would be best to go back 10 years "historical" to select the controls (which I just assumed would obviously be without colonic polyps). I guess it would be stupid to conduct a study this way though, by choosing your control group after the study is concluded. I think the wording just confused me.

Yeah I think your correct that 'historical control group' isn't wrong per se. It's just that B is more right.
 
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Post the answer choices and I'll help

Thanks for your willingness to help :)
Can't remember all the answer choices but here's what I can remember.

18mo-- foreign object aspiration- toddler playing with small toys loves to put things in their mouth...he's afebrile and had sudden onset of respiratory distress

16mo won't move arm after hard yank--she has subluxation of the radial head

I don't remember the Neisseria question or the AML transplant question unless it was referring to rejection. For transplant rejection, think t-cells unless it is Hyperacute (immediate) rejection which is antibody mediated type II HS due to preformed anti-donor antibodies in the recipient. I think there was a question about graft vs host disease which is where an immunocompromised person receives a transplant and the donor's t-cells react against the host's cells causing severe organ dysfunction.

25yo ammenorrhea-- she has increased FSH and LH levels which tell you that her hypothalamus/pituitary is working but she's still not ovulating therefore there has to be a problem with her ovary not getting the message from FSH and LH and primary ovarian failure is the only answer choice that would fit

man snow plowing-- hypertension is primary predisposing factor to bleeds, stroke, ect

Thanks for your answers. Do either of you remember the question where there was an adolescent mouse and a baby mouse and they asked what immune response differentiated in them? I chose T cells which was the right answer but I have no clue why. TIA :)
 
Thanks for your willingness to help :)


Thanks for your answers. Do either of you remember the question where there was an adolescent mouse and a baby mouse and they asked what immune response differentiated in them? I chose T cells which was the right answer but I have no clue why. TIA :)

I can't remember the exact wording of the question. Someone answered it earlier in the forum. I picked t-cells as well but for different reasoning than the person above. There is probably a better explanation but I thought about what changes occur in immune function/organs from birth to adulthood. The thymus is large at birth and continues to grow until puberty before it regresses and pretty much becomes non-functional. The thymus is the home of the t-cells. The other answer choices wouldn't change much from birth to adolescence or adulthood.
 
what's the deal with NBME 12? Seemed like a lot of questions had very blatant distractors (e.g. guy with cholecystectomy and gout, kid with Duchenne's and broken fibula, woman with MS and opioid OD). I guess I can see why they do it, but the distractors seemed a lot heavier than they are on UW.

Anyway, I dropped about 10 points on this (261 on NBME 11, 252 on NBME 12). I know people say this one is harder, but is that a normal/expected drop? It's a little discouraging after having studied 2 weeks between the tests. I'd be totally and completely happy with a 252 on the real deal, but I'm afraid to see my score drop anymore :scared:
 
Question for the femoral neck fracture: I put profunda femoris because it asked which artery's branches make the bone susceptible to necrosis, and the medial circumflex is a branch of the profunda femoris. But apparently that's wrong. Is the answer just medial circumflex? Hope I don't get tripped up on too many like that on the real test. Score dropped a tad since my last one a week ago, but that seems to not be too unusual here.

I also missed the one about hydroxyurea, which again seems stupid. I know it increases HbF, but I put that the mechanism of improving your symptoms is by decreasing HbS, since high HbS concentrations lead to sickling and the inherent benefit seems intuitively to be from having less HbS rather than more HbF. But apparently that's wrong too. Effin' overthinking sometimes.
 
yup to both, medial circumflex and increase HbF. I too made several silly mistakes, I dread making them on the real one... tomorrow
 
Thanks and good luck tomorrow. I was also curious about the guy with a "moderately enlarged prostate" who was obtunded with uremia. A couple people said they thought it was BPH but there wasn't any real affirmative response. Can someone confirm? The way it was phrased steered me away from BPH. If that's what happens when you get a moderately enlarged prostate, we'd have an epidemic of comatose 70 year olds. But maybe I'm missing something.
 
Thanks and good luck tomorrow. I was also curious about the guy with a "moderately enlarged prostate" who was obtunded with uremia. A couple people said they thought it was BPH but there wasn't any real affirmative response. Can someone confirm? The way it was phrased steered me away from BPH. If that's what happens when you get a moderately enlarged prostate, we'd have an epidemic of comatose 70 year olds. But maybe I'm missing something.

Nasty BPH -> Post-renal azotemia -> renal failure and uremia.
 
Yeah I can see that. I interpreted the "moderately enlarged" to mean that his BPH might give him some mild urinary issues but shouldn't be the reason he's comatose. I would've picked it if they said, I don't know, "insanely large prostate". Figured there must be something extra to have such a dramatic presentation. But I see that I tend to read into the questions too much sometimes.
 
A 25-year-old man is lost in the desert for 1 week with an ample supply of water but no food. Enzymes and molecules below (inc or dec)

F2,6P
G6Pase
PEPCK
PK

I put all dec and got it wrong (I reasoned that ketogenesis was predominant since he was starving for a week). Anyone actually got this question right and know the answer? Read the previous pages and it was mostly speculation.

I thought form 12 was pretty brutal too, lots of distractors that ended up successfully distracting me. My score dropped 10 pts from forms 6, 7, 11.
 
Gluconeogeneic enzymes (PEPCK, fructose 1,6 bisphosphatase, pryvuate carboxylase etc.) would still be increased. It's true that your brain can switch to metabolizing ketone bodies, but you have to keep in mind that your RBCs absolutely require glucose. They can't get energy from another source. Even in extended starvation, gluconeogenesis will be upregulated relative to the fed state.
 
Gluconeogeneic enzymes (PEPCK, fructose 1,6 bisphosphatase, pryvuate carboxylase etc.) would still be increased. It's true that your brain can switch to metabolizing ketone bodies, but you have to keep in mind that your RBCs absolutely require glucose. They can't get energy from another source. Even in extended starvation, gluconeogenesis will be upregulated relative to the fed state.

Thanks. I guess other cycles like alanine transport from muscle (during starvation) and Cori cycle would also need gluconeogenesis (pyruvate to glucose) as well.

I thought I was being really brilliant when I chose that ketogenesis answer, haha really bummed to get it wrong.
 
Can anyone please explain the answers to these? The answers have been stated but I don't think they were explained unless I scrolled too fast.

The question with hearing loss and dysmetria asking to identify the brain region on slice.

The question with the woman with spastic paralysis and treatment options and mechanisms. I went with the renshaw cells option but that was wrong.

Thanks ahead for any help.

I also got killed on this one and had a panic attack as my exam is in 3 days. Was getting 340s to 345s on DIT end exam, free Usmle, and Uworld 2. Then got a 228 on this *******. Glad to hear I'm not alone. That combined with beer helps. 13 tomorrow, hopefully back up in the 240s.
 
Hey what do you guys think of this question?

5. 72 year old woman who is right handed is brought to the ER by her husband 3 hours after the sudden onset of difficulty speaking. She has a history of atrial fibrillation. She is alert. Neurological examination shows moderate weakness of the lower 2-3rds of the face on the right. She understands verbal commands, such as raise your right arm. Her speech is not spontaneous and consists of brief phrases without intonation (prosody). Damage to which of the following labeled structures in the drawing of the brain is most likely cause of the language findings in this patient?

Image of the brain is attached.
 

Attachments

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Hi

I have no clue on this can you explain the answer please

1- asymptomatic 75 y old female come for check up Bp 150/80 2pack smoking for 35 years fundoscopic examination shows copper wiring and arteriovenous kinking heart sound s4 gallop ECG show an axis of 30 degrees what is the clue of this fundoscopic findings??

a- age related macular degeneration (wrong)
b- glucoma
c- HTN retinopathy
d-retinal artery occlusion
e- type Dm
 
Hi

I have no clue on this can you explain the answer please

1- asymptomatic 75 y old female come for check up Bp 150/80 2pack smoking for 35 years fundoscopic examination shows copper wiring and arteriovenous kinking heart sound s4 gallop ECG show an axis of 30 degrees what is the clue of this fundoscopic findings??

a- age related macular degeneration (wrong)
b- glucoma
c- HTN retinopathy
d-retinal artery occlusion
e- type Dm


In our ophtho workshops at school I remember them saying something about how HTN causes the veins to get engorged and juicy and stuff, which creates the "nicking" look whenever they cross over the arteries. Similar pathophys for the copper wiring. But as far as step 1 goes, I think this is one of those things that you should only be expected to recognize by buzzwords.
 
Hey guys not sure if this has been answered but here goes :
1) During an experiment on the effects of ATP on renal function , a kidney is excised from an experimental animal and perfused with a mitochondrial inhibitor. The kidney is then studies with a micropuncture of single nephrons. In which of the following nephron segments is the greatest decrease in sodium resorption most likely?
a) collecting duct
b) distal convoluted tubule
c) prox conv tubules
d) thick ascending loop
e) thin ascending loop
f) thin descending loop

doesnt the prox tubules, TAL, Dct and collecting tubules have ATPase?? I couldnt really narrow it down to any choice on this one.

thanks!
 
The proximal tubules resabsorbs ~66% of the filtrate via secondary active transport. The question is answered just based on percentages. The DCT is provides 5-10% and the TAL provides 15-20% of sodium reabsorption. The greatest decline in sodium reabsorption would come from poisoning the PCT.
 
The proximal tubules resabsorbs ~66% of the filtrate via secondary active transport. The question is answered just based on percentages. The DCT is provides 5-10% and the TAL provides 15-20% of sodium reabsorption. The greatest decline in sodium reabsorption would come from poisoning the PCT.

that makes sense! thanks!
 
my qs:

1. 59 yo woman with pancreatic cancer decline palliative chemo, best answer:
- have you consulted your clergy before choosing this path
- I respect your choice, I'll make you as comfortable as possible
- I think you're making bad decision. why would you choose to die sooner
- I think you're making unwise decision. you never know what kinds of treatment are just around the corner
- i'd like to involve your family in this decision

2. experiment with insulin-stimulated glucose uptake in myocytes, 4 graphs.

3. about the guy with painless mass in testicle. so as I understand he has non-seminoma neoplasm. then the history of scrotum trauma is distractor? because I can't see how trauma would lead to neoplasm development in 1 week

Thanks in advance!
 
my qs:

1. 59 yo woman with pancreatic cancer decline palliative chemo, best answer:
- have you consulted your clergy before choosing this path
- I respect your choice, I'll make you as comfortable as possible
- I think you're making bad decision. why would you choose to die sooner
- I think you're making unwise decision. you never know what kinds of treatment are just around the corner
- i'd like to involve your family in this decision

Thanks in advance!

I don't remember the others.
 
ok, forget about Q #2, it has graphs.

Q #3
Otherwise healthy 22 year old man comes to the physician after noticing a painless mass in his right testicle. He was kicked in the scrotum during soccer practice 1 week ago. Vitals are normal. Phys.examination shows 2 cm hard mass that does not transluminate. His serum a-fetoprotein is increased. What does he have:
a. Hematoma
b. Leydig cell tumor
c. Nonseminoma neoplasm
d. Sertoli cell tumor
e. Spermatocele

I found somewhere earlier that the correct answer is C. Nonseminoma neo. Can it really develop 1 week after trauma?? or the trauma is just distractor?

Thank you, I appreciate your help!
 
the kick in the nuts caused him to exam his balls. most men don't know wtf is going on with themselves as we will see when we start our rotations
 
By the way, the graph that you are talking about got me a little confused at first. If I remember the question correctly, insulin upregulates the glut 4 receptor to be transported to the cell membrane. Thus, vmax should increase, as there is more capacity for glucose transport.
 
the kick in the nuts caused him to exam his balls. most men don't know wtf is going on with themselves as we will see when we start our rotations

Also, this happens to be what patients do. A lot of patients discovering a mass in the scrotum will attribute it to a sporting injury a week ago or whatever.
 
55 y/o with difficulty walking. Hyperreflexia, spasticity. Which drug will decrease spasticity of the pt?
a) activation of g-aminobutyric acid receptors in muscle spindle afferents
b) wrong
c) activation of serotonin receptors in alpha motor neurons
d) inhibition of glycine in golgi tendon afferents
e) inhibition of nicotinic receptors in renshaw cells
f) inhibition of alpha2 receptors in excitatory interneurons

Woman wants to donate money and see results of the donation in 1-2 years. Which should she contribute to?
a. creation of antismoking campaign (wrong)
b. aerobic exercise program
c. fortify water with asprin
d. placing defibrillators in public spaces throughout city
e. HMG co A reductase to all ppl over 50
f. Free relaxation and stress management programs
 
Also, for the NNT calculation, how do we know when the numbers given can just be subtracted rather than calculating 1/ RRcontrol- RR treatment?
 
55 y/o with difficulty walking. Hyperreflexia, spasticity. Which drug will decrease spasticity of the pt?
a) activation of g-aminobutyric acid receptors in muscle spindle afferents
b) wrong
c) activation of serotonin receptors in alpha motor neurons
d) inhibition of glycine in golgi tendon afferents
e) inhibition of nicotinic receptors in renshaw cells
f) inhibition of alpha2 receptors in excitatory interneurons

Woman wants to donate money and see results of the donation in 1-2 years. Which should she contribute to?
a. creation of antismoking campaign (wrong)
b. aerobic exercise program
c. fortify water with asprin
d. placing defibrillators in public spaces throughout city
e. HMG co A reductase to all ppl over 50
f. Free relaxation and stress management programs

1st one is A) Gaba activation.
2) D) You will see results in 1-2 years.
 
What did you guys think of this test? It seemed harder than UWSA's. May be because of the language of the questions...
 
I believe it was T cells because Chlaymdia/Chalmydophila are intracellular bugs

I missed this question. I narrowed it down to B, T and plasma cells and went with B lymphocyte. I did not make the connection of Chlamydia being an intracellular. So as far as categorizing this question. Would you say, i missed it because i need more practice? It seems like a difficult questions. Gracias!
 
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