Bond Chemistry

Today, I watched Skyfall, the new Bond film. It's a fantastic film, with gorgeous actors, actresses, cars and explosions abound. I would do a post critiquing it and examining the themes throughout, but that's not what this blog is for, and it'd just be a drop in the online ocean of fan-made reviews of films they've just seen.

So instead, I thought I'd look into the sciencey medically bit that intrigued me. The main villain is revealed to have bitten a cyanide pill in the past, which failed to kill him; he now has very few teeth and  has to wear a false set. When he takes them off, the muscles in his face seem to sag, and the lower half of his eyeball is revealed, as if someone had pulled down on the skin around his cheek, seemingly because his dentures also include supports for his maxilla or something.

But what I thought I knew about cyanide was that it works by inhibition of one of the enzymes used in respiration. Could it really eat away at the inside of your mouth? The first clue was in the name of the actual chemical inside cyanide pills, hydrogen cyanide. This tells you that it is a compound of the formula HX, where X is some negative ion (here, it is cyanide). These kind of compounds dissociate in solution to form H+ ions and X- ions. They're also known as acids. In this case, the "X" is cyanide, which forms CN- ions; this is what inhibits the respiratory enzyme.

It is conceivable that, because it is an acid, it could erode the teeth and bone away (acid erosion of teeth is permanent, at least). For this to happen, you would need an acid of a very low pH, and in sufficient quantities that it can react with enough teeth.

Now for some wild assumptions and quick calculations:
The fatal dose of cyanide, according to Health Canada, is about 1.52mg/kg bw. So for the sake of argument, we will say that he took as close to the fatal dose as possible without it being fatal. Celebritiesheightandweight.com helpfully informs us that Javier Bardem, the actor playing Silva, weighs 84 kg. Therefore in order to be just non-lethal, the pill would have to contain 127.68mg of cyanide ions. The Mr of CN is 26, so the lethal amount of HCN is 0.004910769231 moles.
The pill was stored in his 2nd molar, which we will model as a 9mm*9mm*7mm cuboid (assuming it is on the upper jaw); therefore its volume is 0.000567dm^3. The pill would have had to have taken up much of this space in order to be easily accessible, so we can say that the pill has the same dimensions as the molar. Therefore the concentration of HCN (which used to be known as prussic acid, on an unrelated note), is 8.660968661moldm^-3.
Hydrogen cyanide's pKa is 9.2. Therefore its acid dissociation constant is 10^(-9.2). This is [H+][CN-]/[HCN]. Given that the concentrations of H+ ions and CN- ions are the same (because they dissociate in a 1:1 ratio), and given the concentration of HCN, it is possible to work out the concentration of H+ ions:

[H+][CN-]/[HCN] = 10^(-9.2)
[H+] = [CN-], therefore ([H+]^2)/[HCN] = 10^(-9.2)
[HCN] = 8.660968661, therefore [H+]^2 = 8.660968661*10^(-9.2)
Therefore [H+] = sqrt(8.660968661*10^(-9.2))
[H+] = 7.392362131*10^(-5)

Therefore pH (= -log[H+]) = 4.131216766

= 4.13 to 2 decimal places

Wikipedia says that there is a paper saying that solutions with pH<5.0-5.7 cause dental erosion. Therefore, Silva's pill may well have damaged his teeth. However, it seems unlikely that it could have destroyed so much of his jaw and face: the pH of wine, for instance, is around 3-4. So the acidic effect of the cyanide pill would actually be less than if you just squirted the inside of your mouth with some sauvignon blanc.

Pathology project news again

The medlink team have got back in touch; the paper I wrote last year is going to be published in their collection! Woooooooo!
...Not quite a peer-reviewed journal, but I'll take what I can get.

Prayer as an element of medicine

         James records in his gospel that “the prayer of faith shall save the sick” ¹, and according to the U.S. Centre for disease control and prevention, 45% of adults use prayer for personal health reasons in the modern age.² Unfortunately, it is very difficult to measure the power of prayer as a part of the treatment of someone, for quite a number of reasons: firstly, because some religious groups claim that praying as part of a scientific study is artificial, so the prayers will not be answered. There are also various confounding variables, such as ability to pray (according to some, prayer is a skill to be learned )³ and fervour of prayer (this may affect the effectiveness of prayer)⁴. Another reason that it is difficult to study is that it receives very little funding; according to the Washington Post, “about $5 million is spent worldwide on such research”⁵. Critics of scientific study of prayer argue that part of the point of prayer is that it is not always answered, and that god is not a mechanism that responds in a way that is predictable, or even measurable, by humans. For these reasons, and because in such a religiously charged subject, some studies are bound to be biased, research into prayer is still very much being refined, and there are conflicting results at the moment.

There have been three main types of prayer studied scientifically to gauge their efficacy. The most obvious one is second person prayer, which is performed by someone who knows the person they are praying about. Second person prayers directly ask a higher power for the person to be helped, as do third person prayers, which are performed by a stranger. First person prayer not only includes the petition to god but also can include self-meditation beforehand, and is a separate type of prayer.

Fat acceptance

On the subject of ethics, here's an interesting topic. There is a movement, now largely online, to end discrimination and prejudice against fat people, and whose proponents say that you can be healthy regardless of how big your waist is. According to the group, the health issues associated with obesity are exaggerated because of society's bias against fat people.

Gillon's 4 principles of medical ethics

Doctors are often asked to make decisions which have no immediately obvious "right" or "wrong" outcome. Of course, as a doctor, you sign up to do this, and you won't always need help; occasionally though, there are situations that really give one pause for thought, and when a systematic approach is necessary to ensure you have covered all bases.

The most common of these approaches (to my knowledge) is Gillon's 4 principles. The way to use this framework is to work through all of the effects of a decision relating to 4 given principles, and use that as a basis to decide what is the best thing to do. The areas to consider are: beneficence (what good can come of it), non maleficence (what harm could be avoided), autonomy (does it give everyone a choice), and justice (does it do good for the greater community). If it is impossible to decide having done this because all sides of the argument seem to be equal, then more weight is given to autonomy, because there is truly no moral difference between deciding one thing or another, so taking choice away would make any decision unnecessarily immoral.

Androgenic effects of steroids and why they can be less than great

Yesterday I wrote a brief explanation of the anabolic effects of certain types of steroids, and mentioned the fact that they make you "more manly". The post was also almost an advertisement for the drugs, which was unintentional; I just haven't got on to why you probably shouldn't take them yet.

Anabolic steroids

So I've recently started going to the gym, and looking around, there's a fairly standard range of body shapes. Clearly, there's some selection bias, given that people who go to the gym are generally fitter than the average person on the street, but you get the idea.
Then you see people who look like this, who are so far outside the normal range that they can't possibly be achieving those results naturally.
I'm sure that some of them really are doing it through nothing but hard work and a good diet, but steroid abuse exists in a big way, particularly in professional bodybuilding.