Using Physics to Model Medical/Biological Phenomena

Ygggdrasil

The story was probably referring to the following paper, published last year in the Proceedings of the National Academy of Sciences:

Franco et al. 2011. Molecular vibration-sensing component in Drosophila melanogaster olfaction. Proc Natl Acad Sci USA 108:3797. doi:10.1073/pnas.1012293108

This isn't really "quantum biology" how most people might think of quantum biology. The quantum claim really only holds true in that the vibrations of molecules are governed by quantum mechanics. Furthermore, although the ideas presented in the paper are very interesting, the idea that olfactory receptors may be sensing the vibrations of a molecule remains controversial, and we don't yet fully understand everything that is going on here (see the following correspondences over the paper published here and here).

mazinse

being able to detect difference in isotopes does throw a huge wrench into our current system of experiments. Isotopes are used for A LOT OF PURPOSES because we can detect them in experiments in place of the normal compounds.

atyy

Isotopic effects in chemistry were known quite a bit before last year, eg.
http://pipeline.corante.com/archives...oyd_landis.php

Andy Resnick

Most people (biologists, physicists, chemists, engineers, etc) have told me that I don't know anything about anything :)

But yes, the situation is slowly improving over time- people follow money, and the research money is currently being given out to multi-disciplinary work.

Ygggdrasil

Deuterium is a special case for isotopes because its mass is twice that of hydrogen-1. This has a number of effects on its chemical properties, for example, altering hydrogen bonding strengths and changing the rates of proton transfer reactions. Other isotopes (e.g. using ³²P instead of ³¹P) involves only a very small mass change and would not be expected to affect the chemistry of the phosphorus.

Andy Resnick

I totally agree- biology provides some of the most sophisticated applications of thermodynamics.

Another aspect that hasn't yet been discussed is using biology to model physical systems- the 'converse' of the OP. For example:

http://en.wikipedia.org/wiki/DNA_computing
http://en.wikipedia.org/wiki/Directed_evolution

and some books:

http://www.amazon.com/Geometry-Biolo.../dp/0387989927
http://www.amazon.com/Origins-Order-...rigin+of+order

cepheid

I don't think so. The radio show in question has a website with a webpage for each episode that has links for further information on each story. In this case, the story linked to these tw articles:

http://www.nature.com/news/2011/1106...l/474272a.html
http://www.wired.com/wiredscience/tag/quantum-biology/

both of which are explicitly referred to as being about quantum biology. It also linked to the webpages of these scientists:

http://meche.mit.edu/people/faculty/?id=55
http://www.chem.utoronto.ca/staff/SCHOLES/bio.html
http://www.jenniferbrookes.org/

Now I remember...the third person was talking about whether quantum effects were important in olfaction, and that's where the whole thing about sensory receptors came in. The middle guy was talking about quantum effects in photosynthesis. I don't know what the first guy was talking about.

So I guess I didn't describe the content of the story very well the first time.

Andy Resnick

I recall reading a few papers about this:

http://pubs.rsc.org/en/Content/Artic...04/OB/b409802a

Which is related to the Drosophila papers Ygggdrasil mentioned. Speaking for myself, I draw a distinction between applying quantum mechanics to individual (bio)molecules and (bio)chemical reactions, where it clearly *does* apply, and trying to apply quantum mechanics to higher levels of organization (organelle, cell, tissue, organ, etc), where it likely does not. At least, there has not yet been a biological example that displays quantum effects at the macroscale, analogous to superconductivity.

atyy

I think biologists (in some to be unnamed fields ) do that to each other all the time, sounds like you've been accepted to the club!

To the OP: I do think it is fun to brainstorm and ask questions like "Is number theory useful in biology"? Sometimes you get unexpected answers. But a basic philosophy in physics is to "think physically", which is really the same thing as biologists' "think biologically" - so to start off with the phenomena that have been reliably observed and try to explain it. One doesn't care if the mathematics needed is simple or complex, in fact, the best thing is if you can provide a simple insight to what appears complex. OTOH, as Freeman Dyson said, say you want to make a bicycle - high energy physics is not useful for telling you how to do that. I believe, for example, our ability to cure cancer is still very much in the phase of trial and error. In neurobiology, we know clinically that stroke patients can be rehabilitated to some extent, and that this rehabilitation is in part due to synaptic plasticity. In the lab, the dynamics of synaptic plasticity have been worked out very well for some conditions. There remains a lot to do in understanding if and how the rules worked out for neurons in a dish carry over to the intact animal, and even more to do in using that to improve stroke rehabilitation. A spectacular example of an unintended success is deep brain stimulation for Parkinson's. There was a theory that Parkinson's was due to excessive "inhibition", so one might be able to alleviate it by reducing the "inhibition". Curiously, it was found that this didn't work, but instead *stimulating* the area that produced inhibition did! (Now, maybe the electrical stimulation is in fact reducing the inhibition, but I don't think there is a widely accepted theory of how deep brain stimulation works.)

Here are some videos about DBS
http://www.youtube.com/watch?v=a-8LW...eature=related
http://www.youtube.com/watch?v=j3NjNKm0pio
http://www.youtube.com/watch?v=PP4m3q21Q0M

mazinse

dealing with quantum mechanics at the electron level for biology has been going on for decades, so it's not new. Every biochemists need to learn physical chem and thats where they get their knowledge. now at the nuclear level or even one level below which is the high energy one, thats a little different. Maybe in the areas of radiation cancer therapy that comes in.

Ygggdrasil

With regard to particle physics, one area of particle physics research that has directly impacted biology is the development of synchotron light sources. Synchotrons are a form of particle accelerator that propel particles along a circular path. As these particles inside the accelerator turn along the track, they release x-ray radiation that can be used in x-ray diffraction studies to determine the structures of biological molecules. Synchotron light sources are much better than conventional x-ray generators for biological XRD studies because they produce much more intense radiation (allowing the collection of higher-resolution data) and they generate a wide spectrum of x-ray frequencies, allowing biologists to select specific frequencies for certain sets of experiments (anomalous scattering experiments) that are helpful for determining new biomolecular structures. Nowadays, most of the really important work in this field relies on data collected at synchotron light sources.

Of course, new developments in x-ray lasers may make synchotron light sources obsolete in the next few decades.