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  #1  
Old 01-06-2013
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Default NBME 5 questions doubt

Hey everybody

I have a couple of doubts regarding the answer key to questions on nbme 5. Plz answer them.. Thanks

. A 26-year-old man comes to the physician because of a 6-month history of losing consciousness when he laughs. He sleeps 12 to 14 hours every night, has vivid dreams
and nightmares, and feels tired during the day. He was recently involved in a motor vehicle collision. Findings on physical examination are unremarkable. Which of the
following is the most likely diagnosis?
A) Absence seizures
B) Complex partial seizures
C) Major depressive disorder
D) Malingering
E) Narcolepsy
F) Post-traumatic stress disorder
G) Sleep apnea
H) Sleep terror disorder

What is the answer to this? The key that I have says its Malingering, but i think its narcolepsy

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Five separate analyses for serum glucose are done using a new method on a single sample. The values obtained are 102,100, 96,101, and 98 mg/dL. These types of
data are used to determine which of the following characteristics of the test?
A) Accuracy
B) Precision
C) Predictive value
D) Sensitivity
E) Specificity

Why is this answer B and not A?

--------------------------------------------------------------

A study is conducted to compare two drugs (X and Y) for treatment of arthritis pain. Fifty subjects are selected for the study: half are assigned to take drug X and half to take
drug Y. One month later, pain relief is assessed. Following a 1-week washout period (no drug), those who took drug X are reassigned to drug Y, and those who took drug Y
are reassigned to drug X. One month later, pain relief is again assessed. Pain relief with the two drugs is then compared across the 50 subjects. Which of the following best
describes this study design?
A) Case-control
B) Case series
C) Crossover
D) Cross-sectional
E) Historical cohort
F) Prospective cohort
G) Randomized clinical trial

The answer to this is C or F?
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  #2  
Old 01-06-2013
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Tay-Sachs disease is an autosomal recessive disorder for which the carrier frequency in individuals of Ashkenazi Jewish descent is about 1 in 30. On the basis of this carrier
frequency, which of the following is the best estimate of the probability that a child born to two parents, both of whom are of Ashkenazi Jewish descent, will be affected by
Tay-Sachs disease?
A) 1 in 15
B) 1 in 60
C) 1 in 450
D) 1 in 900
E) 1 in 1800
F) 1 in 3600

How is the answer F to this question??
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  #3  
Old 01-06-2013
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During bacteriophage T7 infection of a single Escherichia coli cell, 1000 bacteriophage particles are released. One of these particles contains a fragment of the E. coli
chromosome rather than the T7 chromosome. Will this phage be able to inject its DNA into an E. coli cell, and, if so, how many T7 particles will be produced by this cell?
Able to Inject DNA? # of T7 Particles Produced
A) Yes 1000
B) Yes 100
C) Yes 1
D) Yes 0
E) No 0


How is the answer B??
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  #4  
Old 01-06-2013
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1. The key word is "he was recently involved in a motor vehicle collision". And all symptoms are characteristic for PTSD including losing consciousnes. The answer is F.

2. Accuracy means getting a result that is close to the real answer. Precision means getting a similar result every time you try. So that's why B

3. I think that C crossover coz they were giving sequence of treatments for both group. experiment and control. I mean group1: drugX drugY, group2:drugY drugX.

4. mother 1/30 x father 1/30 x 1/4 (because we need to inherit diseased genes from both of parents and chance for this is like 25%) = 1/3600

5.


correct me if i'm wrong
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  #5  
Old 01-06-2013
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Quote:
Originally Posted by cshekar987 View Post
Hey everybody

I have a couple of doubts regarding the answer key to questions on nbme 5. Plz answer them.. Thanks

. A 26-year-old man comes to the physician because of a 6-month history of losing consciousness when he laughs. He sleeps 12 to 14 hours every night, has vivid dreams and nightmares, and feels tired during the day. He was recently involved in a motor vehicle collision. Findings on physical examination are unremarkable. Which of the following is the most likely diagnosis?


A) Absence seizures
B) Complex partial seizures
C) Major depressive disorder
D) Malingering
E) Narcolepsy
F) Post-traumatic stress disorder
G) Sleep apnea
H) Sleep terror disorder

What is the answer to this? The key that I have says its Malingering, but i think its narcolepsy



My answer would be Narcolepsy. Narcolepsy - Disordered regulation of Sleep - wake cycles; primary exessive daytime sleepiness. May include hypnagogic or hypnopompic hallucinations. Patient's nocturnal and narcoleptic sleep episodes starts off with REM sleep. Cataplexy - loss of all muscle tone following strong emotional stimulus.

What are clues?

1. Losing consciousness when he laughs. That makes up Cataplexy.
2. Has vivid dreams and nightmares. That would be nocturnal and narcoleptic sleep episodes that starts off with REM sleep.
3. Feels tired during the day. This would make up exessive daytime sleepiness. Which caused him to have car accident.

Add them up and you got Narcolepsy.

Last edited by Doctor Ali; 01-06-2013 at 09:57 PM.
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  #6  
Old 01-07-2013
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my mistake, you are right.
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  #7  
Old 01-07-2013
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1. I agree Narcolepsy should be the case.

2. The reason it is Precision not Accuracy is because it is the SAME sample being tested over and over again. We are checking how close it comes out each time, ideally the same value should be reproduced since it is the same sample. Accuracy would be comparing this test to another gold standard test and seeing if you are coming up with the same answers.

3. It is a typical crossover study the people are controls for themselves which is the basic point of a crossover study.

4. 1/30 chance mom is a carrier. 1/30 chance daddy is a carrier. Now if mom is a carrier then she has a 1/2 chance of passing it on and same as dad so you get: 1/30 x 1/30 x 1/2 x 1/2 = 1/3600

5. This one I had to look up because I had not heard of it but what I found is basically there is a property or T7 that during lysis it can produce about 100 progeny. Such a specific thing to ask about though.
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