Aamc 10 #123

[dougkaye]

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For those of you that have done AAMC 10. This question is strange. It states that H.pylori causes ulcers, and asks what the proof most likely depended on.
The correct answer was:
C. Ulcers can can be produced in healthy individuals by infecting them with H. Pylori

I thought a better answer was A. People with stomach ulcers have antibodies to H. Pylori. The reason why I don't like C is that it is illegal human subject research! For anyone that has worked in the medical field or a lab, it's quite evident that this research, described as the "correct answer" would not be done, plain and simple. You can't infect someone with a pathogen and then test its effects. NO WAY! I don't see how AAMC can have this be the correct answer. I think A. is fine. If you measured the antibody levels of a healthy person versus an ulcer sufferer, you could ETHICALLY find a difference and hence come to a conclusion. Any thoughts?

 

[RogueUnicorn]

the question doesn't ask for legality or ethics, it's just a straight-up science question. interestingly, this very topic comes up with varying frequency, but the fact remains that C is causation and A is correlation. that being said, as a bit of trivia, i believe the man credited with this discovery indeed infected himself with h. pylori to prove the skeptics wrong.

 

[dougkaye]

the question doesn't ask for legality or ethics, it's just a straight-up science question. interestingly, this very topic comes up with varying frequency, but the fact remains that C is causation and A is correlation. that being said, as a bit of trivia, i believe the man credited with this discovery indeed infected himself with h. pylori to prove the skeptics wrong.

It doesn't say self-infection, it says infecting patient(s). Plus I don't see why testing for antibodies isn't an effective way to test for infection. That's not correlation, it's an immunological titer which is what's used to test for lots of infections. Perfectly valid.

 

[dougkaye]

the question doesn't ask for legality or ethics, it's just a straight-up science question. interestingly, this very topic comes up with varying frequency, but the fact remains that C is causation and A is correlation. that being said, as a bit of trivia, i believe the man credited with this discovery indeed infected himself with h. pylori to prove the skeptics wrong.

By the way I just read that over half the world's population has H. pylori (obviously a much larger percentage of people that develop ulcers). So it's all around a pretty bad question. What I mean by that is that you could infect someone with H. pylori and they might never develop ulcers, which destroys AAMC's answer's validity.

 

[RogueUnicorn]

It doesn't say self-infection, it says infecting patient(s). Plus I don't see why testing for antibodies isn't an effective way to test for infection. That's not correlation, it's an immunological titer which is what's used to test for lots of infections. Perfectly valid.

yes, it is a correlation for ULCERS, which is what the question is asking about. we only care about the infection insofar as it relates to ulceration.

the self-infection thing was just trivia. it's the mcat, not irb. you're not being tested on ethics.

By the way I just read that over half the world's population has H. pylori (obviously a much larger percentage of people that develop ulcers). So it's all around a pretty bad question. What I mean by that is that you could infect someone with H. pylori and they might never develop ulcers, which destroys AAMC's answer's validity.

no it's a fine question. you go with the information in the passage and make the best of it.

 

[jphwki82]

For those of you that have done AAMC 10. This question is strange. It states that H.pylori causes ulcers, and asks what the proof most likely depended on.
The correct answer was:
C. Ulcers can can be produced in healthy individuals by infecting them with H. Pylori

I thought a better answer was A. People with stomach ulcers have antibodies to H. Pylori. The reason why I don't like C is that it is illegal human subject research! For anyone that has worked in the medical field or a lab, it's quite evident that this research, described as the "correct answer" would not be done, plain and simple. You can't infect someone with a pathogen and then test its effects. NO WAY! I don't see how AAMC can have this be the correct answer. I think A. is fine. If you measured the antibody levels of a healthy person versus an ulcer sufferer, you could ETHICALLY find a difference and hence come to a conclusion. Any thoughts?

While doing some form of an immunoassay might work to see if someone is infected with a pathogen, such as the rapid strep test. Using antibodies wouldn't work in this case because of the pH in the stomach. Remember that proteins can be natured in acidic environments. C is the best answer because you are directly correlating the colonization of the bacteria in a patient with ulcer formation. Hope this alternative view of looking at the problem helped out with the reasoning.

 

[BerkReviewTeach]

you go with the information in the passage and make the best of it.

That is such a simple, yet totally brilliant insight. Much of the real MCAT is just that. Take what they give you, mix it with some of the basic concepts you've learned, and make the best possible choice you can on each of their questions.

 

[emilymr]

yeah, i just finished checking that answer. That really pissed me off - obviously as a matter of science, the best way to determine causation would be to infect someone. If it was 'proof would depend on' instead of 'depended on' (aka they've already done it), I would've definitely gone with infecting patients.

Oh well, at least it was a practice test. Now I know they assume no morals.

 

[dsoz]

For those of you that have done AAMC 10. This question is strange. It states that H.pylori causes ulcers, and asks what the proof most likely depended on.
The correct answer was:
C. Ulcers can can be produced in healthy individuals by infecting them with H. Pylori

I thought a better answer was A. People with stomach ulcers have antibodies to H. Pylori. The reason why I don't like C is that it is illegal human subject research! For anyone that has worked in the medical field or a lab, it's quite evident that this research, described as the "correct answer" would not be done, plain and simple. You can't infect someone with a pathogen and then test its effects. NO WAY! I don't see how AAMC can have this be the correct answer. I think A. is fine. If you measured the antibody levels of a healthy person versus an ulcer sufferer, you could ETHICALLY find a difference and hence come to a conclusion. Any thoughts?

I don't think that EVERYONE with ulcers have H. pylori (stress induced ulcers, drug induced ulcers) so an antibody titer would show up negative.

Also, if a person used to have H. pilori, and was treated, they should have some antibodies to it still. An antibody titer could show a false positive (depending on which antibody that they are testing for, and the half-life of that particular antibody in the body). This is why I did not choose A.

dsoz