Enzyme Kinetics in Ordinary Life

From the New England Journal of Medicine:

A 68-year-old man presented with unilateral ptosis [i.e., one droopy eyelid] and no other symptoms […] Myasthenia gravis was suspected, and the ice-pack test was performed with the placement of an instant cold pack over the left eye. After 2 minutes, the ptosis was substantially diminished (>5 mm), indicating a positive test […] The inhibition of acetylcholinesterase activity at a reduced muscle temperature is thought to underlie the observed clinical improvement.

A bit of background:

  • Neurons secrete a neurotransmitter called acetylcholine onto muscle cells which binds to the muscle cells’ acetylcholine receptors. This leads to muscle contraction and is the way neurons cause muscles to contract. Acetylcholinesterase is an enzyme present in the junction between neuron and muscle cell, which speeds up the breakdown of acetylcholine so that its effect on the muscle isn’t too long-lasting.
  • In the disease known as myasthenia gravis, the body produces antibodies which bind to the muscle’s acetylcholine receptors, blocking acetylcholine from binding. The result is muscle weakness (one manifestation is droopy eyelids), as the nerves’ ability to stimulate muscle contraction is diminished.
  • Enzymes, including acetylcholinesterase, work less efficiently at lower temperatures, because at lower temperature molecules move slower, so are less likely to bump into the enzyme, and they are less likely to bump into the enzyme with sufficient energy to bring the reaction to completion.
  • One way to treat myasthenia gravis is by administering a drug which inhibits acetylcholinesterase, so that it cannot break down acetylcholine as quick, therefore leaving acetylcholine to act for longer. Now, decreasing temperature also has the same effect, which is why myasthenia gravis is alleviated in the presence of cold. (Note: inhibition of acetylcholinesterase is not the only reason for low temperature helping myasthenia gravis – there’s a couple others – just one major one).

I’m sharing this because I was really impressed by a basic principle of biochemistry (that low temperature reduces enzyme efficiency) having such a simple visual demonstration.

Links

  • This past week featured World Down Syndrome Day (to represent trisomy 21, it fittingly falls on 3/21). At Down Syndrome Uprising, I’ve found an old but cool article about pre-modern depictions of Down Syndrome in art.
  • Over at his blog Eastern Christian Books, Adam DeVille criticizes Rod Dreher’s Benedict Option. I love the quote near the end from Schmemann about how to live a monastic life (some of the things Wittgenstein did actually overlap remarkably well with Schmemann’s suggestions).
  • On YouTube, Vox has a video about the Hubble Deep Field image. I had seen the photo before, but I didn’t realize that it shows galaxies in different stages of development. Very cool. But some of the YouTube comments illustrate the tendency I’ve noticed among some atheists to deify the cosmos, e.g., “If you think about it, all we are is atoms. And these faraway galaxies are basically atoms too. And so is everything in between, and beyond. We may all feel separated, but we are all connected. We are one. We are all the universe.”

Ss. Patrick and Augustine on Language and Education

Happy St. Patrick’s day! Below are two passages, one from St. Patrick and the other from St. Augustine. Both of their remarks on the difficulty of expressing our thoughts (Patrick: “I can’t express myself with the brief words I would like in my heart and soul” and Augustine: “dwelling long in the tedious processes of syllables which come far beneath the standard of our ideas”) come in a discussion of preaching or catechesis. St. Patrick’s work seems to be a general letter of exhortation to recognize God’s greatness and St. Augustine’s is a set of instructions on how to catechize. This makes sense: trying to explain the reasons for a fact to someone else often leaves you fumbling with words to express what is self-evident in your mind (once in high school a classmate noted how this happens when explaining the limit surface area-to-volume ratio sets on cell size). Given how “much our articulate speech may differ from the vivacity of our intelligence,” it does seem reasonable to wonder how speech even has the ability to help us learn. According to Thomas Aquinas, words themselves do not provide knowledge but prompt the learner to derive conclusions from their own innate first principles, in a similar way to how the doctor only provides medicine for consumption, but it is the body which takes the medicine where it needs to go and brings it to take its effect. The role the student plays is significant. We often forget that when we are presenting students with new arguments, not only do they have to see how successive steps follow logically, but they also need to see why the argument had to go in this direction and not in any other direction (e.g., in a math proof, students often ask “why couldn’t you do this instead?”). This obviously fits with Aristotle’s account of certain knowledge: “We suppose ourselves to possess unqualified scientific knowledge of a thing, as opposed to knowing it in the accidental way in which the sophist knows, when we think that we know the cause on which the fact depends, as the cause of that fact and of no other, and, further, that the fact could not be other than it is” (Posterior Analytics, 1.2).

This is why I have long thought to write, but up to now I have hesitated, because I feared what people would say. This is because I did not learn as others did, who drank in equally well both the law and the sacred writings, and never had to change their way of speaking since childhood, but always grew better and better at it. For me, however, my speech and words have been translated into a foreign language, as it can be easily seen from my writings the standard of the instruction and learning I have had. As it is said: ‘The wise person is known through speech, and also understanding and knowledge and the teaching of truth [Sir 4:29].’ However, even though there’s truth in my excuse, it gets me nowhere. Now, in my old age, I want to do what I was unable to do in my youth. My sins then prevented me from really taking in what I read. But who believes me, even were I to repeat what I said previously? I was taken prisoner as a youth, particularly young in the matter of being able to speak, and before I knew what I should seek and what I should avoid. That is why, today, I blush and am afraid to expose my lack of experience, because I can’t express myself with the brief words I would like in my heart and soul.
—St. Patrick, Confessio, 9-10. Patrick’s remaining writings (the Confessio and the Epistola) are available for free online.

Now if the cause of our sadness lies in the circumstance that our hearer does not apprehend what we mean, so that we have to come down in a certain fashion from the elevation of our own conceptions, and are under the necessity of dwelling long in the tedious processes of syllables which come far beneath the standard of our ideas, and have anxiously to consider how that which we ourselves take in with a most rapid draught of mental apprehension is to be given forth by the mouth of flesh in the long and perplexed intricacies of its method of enunciation; and if the great dissimilarity thus felt (between our utterance and our thought) makes it distasteful to us to speak, and a pleasure to us to keep silence, then let us ponder what has been set before us by Him who has “showed us an example that we should follow His steps.” For however much our articulate speech may differ from the vivacity of our intelligence, much greater is the difference of the flesh of mortality from the equality of God.
—St. Augustine, On the Catechising of the Uninstructed, 10.15.

Links

  • Apparently there is a ‘philosophy-opera’ out now by Kate Soper called “Ipsa Dixit,” which artistically illustrates Aristotle’s Poetics, Metaphysics, and more. Many clips of it can be found on Soper’s Vimeo page.
  • Dr. Alan Cann on the past and the future of microbiology, including some interesting comments about the strong link between the brain and gut flora, and an especially important one about CRISPR:
  • Many people would argue that CRISPR has been the great leap forward of the last decade, but I’m not so sure. To me it’s just another tool, following on directly from cloning and PCR. When people involved the first human genome CRISPR trials tell you they are “a huge undertaking and not very scalable”, they may have a point. As the NHS crumbles in the UK, what hope will there ever be for rolling out such expensive technologies worldwide?

  • Though this may be little-known today, from the 1950s to the 1970s a significant number of scientific and medical journals published summaries of their articles in the constructed language Interlingua. The choice that many editors made of Interlingua over Esperanto provoked some controversy, although one reason Interlingua was favored was because it was already readily intelligible to Romance language speakers. Read a little about it in this article by Dr. Jonathan Thon.
  • A brief paper about the history of metformin. It is humbling that a compound which is not that far removed from a component of a plant (goat’s rue) which was used in medieval and early modern times to treat various diseases, including (it seems) diabetes, and whose precise mechanism of action is still unknown is a highly safe and popular way of treating type 2 diabetes.
  • Excel has a (sometimes) annoying habit of converting input to a format that the entered data resembles. This cannot be turned off globally, and so certain gene names often get mangled by Excel: e.g., the gene SEPT7 becomes 07-Sep. One study found that nearly 20% of papers in a sample of published articles from genetics journals contained some form of mangled gene names. Read about it and a possible solution here.