Practice MMI questions

[alpine]

How is everyone planning to practice for MMI? (i.e. how do you approach the sample aspartame question)

[The Law]

The source was "the web"... What does that even really mean? Can you just trust any source of information? What kind of study was it - a study on one person (case study) or was it a case control, etc? What kind of clinical evidence, and how was this evidence obtained? The biggest problem I had was the fact the source was the web... but there are lots of other things that are unclear and require further explanation/evidence.

 

Haha, I don't have an interview at Mac but those were my thoughts upon reading it.

[nitac]

I also considered the fact that they didn't compare the dose of Aspartame that causes the detrimental effects compared with the dose consumed when used as a sweetener. Vitamin E in excess can be fatal - I would use this as a comparison situation.

[Hall&Oates]

Well, in terms of the logical consistency, I thought it was quite inconsistent because first they talk about multiple sclerosis which is a PNS disease and later in the paragraph they quote Dr. Russell Blaylock (by the way, what are his credentials? And is he a medical doctor or some guy with a PhD in some irrelevant field?) who talks about brain damage, which is about the CNS. Also, I wasn't sure if MS really is an "epidemic" since I don't know any friends or relatives who have it.

 

These were some of my thoughts...

[mbene085]

On the basis of logical consistency (not bringing much scientific knowledge into it), they say that aspartame->methanol->formic acid happens at body temp, not that it happens in the body. If you do know any chemistry, this reaction requires an extreme pH, but the first logical inconsistency is that occurring at body temperature \= actually occurring in the body.

 

They also say formic acid is in the same "class" as cyanide and arsenic. You could ask what class it is that they're referring to. Then they say it exerts its effects by metabolic acidosis - yet they provide the neuronal death explanation at the end (two conflicting etiologies). You could then ask if the aspartame overdose symptoms (depression, anxiety, slurred speech, etc) are associated with metabolic acidosis, which was their original explanation, because they don't seem to be.

 

Now, bringing science into it...arsenic is an element while cyanide and formic acid are organic compounds. Arsenic poisons pyruvate dehydrogenase while cyanide poisons the proton-driven ATP synthetase in mitochondria. Meanwhile, formic acid can and is ingested safely - it is used as a salad dressing by indigenous people in South America (squeezed from fire ants). You can view it as acetic acid (vinegar) minus one methyl group. So I'm not sure how they are 'classed together'.

 

It also sounds like they're suggesting that the formic acid itself causes acidosis - playing off the fact that they both have 'acid' in there somewhere. But metabolic acidosis occurs when your body is driven to produce too many acidic metabolites, generally because it has to undergo alternate metabolic pathways. For formic acid to accomplish this, it would have to be poisoning an important metabolic enzyme. Otherwise, if they're suggesting that ingesting the formic acid itself causes you to go acidotic, the amount that could possibly produced from ingested aspartame definitely couldn't overcome the bicarbonate buffer in your blood.

[A-Stark]

Um, your first two paragraphs contain nothing but explanations from the scientific background.

 

Immediately, it should be clear that the claims are not only substantiated, but also wildly profound in their implications. The article would have readers believe that aspartame is definitively implicated as a cause of serious, degenerative nerurological disorders, an auto-immune disease, and a whole menu of nonspecific largely self-reported symptoms. The explanation for why this evidently dangerous food additive remains on the market is nothing more than the assertion that a grand conspiracy exists between "powerful lobbies" and unscrupulous politicians - an extraordinary claim, to be sure, and one that is conspicuously lacking in correspondingly extraordinary proof.

[mbene085]

Um, your first two paragraphs contain nothing but explanations from the scientific background.

 

Immediately, it should be clear that the claims are not only unsubstantiated...

 

First off, my first two paragraphs are logic-based. My first paragraph states that "happens at body temperature \= happens in the body". Just because the temperature is right doesn't mean that the other conditions are right as well. For example, you could say "In the summertime, the climate in Ontario can support millions of malaria-carrying mosquitoes". That doesn't mean, however, that there are malaria-carrying mosquitoes in Ontario to begin with. It's a logical fallacy to assume that a process can occur when you are only told that one of several conditions has been met. The pH example I threw in as an aside (if you know the chemistry behind it, you know that pH is the non-temperature factor that renders this reaction unlikely in the body).

 

As for the second paragraph - if you read the question in the admissions package, you would see that they want you to probe the statement's logic, as well as "ask about areas you would like to investigate further before drawing a conclusion". I suggested that you could ask what arsenic, cyanide and formic acid have in common - the question vaguely states that they're in the same "class of drugs", without stating what that class is or why that class of drugs would be related to the symptoms and etiologies discussed later in the paragraph. They are implying that formic acid is deadly by classifying it together with well-known arsenic and cyanide. This is again an error in logic - drugs can be classified in many ways, for example by the way they are produced, not just by the way they act. If formic acid and cyanide are both isolated from bacteria, for example, they could be classified together on those grounds.

 

Again, though, without knowing anything of the scientific background on these compounds (and element), you *can* understand that grouping things together without explaining what they have in common doesn't explain anything. They are relying on the reader making the mistake of assuming formic acid is a poison because the other members of this unspecified "class of drugs" are well-known poisons.

 

Your explanation doesn't even touch on the purpose of the question - to explore the holes in their logic, and list areas you'd like to investigate further before drawing your final conclusion. You're saying that the article's claims are unsubstantiated without exploring the gaping holes in their logic, the simplest of which to spot was the fact that they listed 2 completely separate etiologies for aspartame poisoning - (1) metabolic acidosis and (2) neuronal death.

[Orchid]

I think A-stark was just trying to show you can answer the question without mentioning any of those 'sciency' details.

[Hall&Oates]

I think they both made really good legitmate points though (and I do think that the arguments presented by both are not all that scientific if you really get down to the real points they are trying to make). I'm just glad to see that there are so many different ways to approach problems like this and fill up our 8 minutes!