Category: Science Communication

I’ve felt bad all week. Well, not really all week. And not really bad. I’ve felt a teeny bit guilty for joking that economic sciences is not really a “science”. The “soft” sciences (social sciences, economic sciences, psychology, to name a few) are too often ridiculed by practitioners of the “harder” sciences. I’ve done it too. Last week in fact, as I’ve just said.

Most of the “soft” scientists I know don’t really mind too much (yes, I have soft science friends, I *can’t* be an elitist), and they laugh along. But still, I wanted to bring a bit of nuance and perhaps a tiny apology,

(sorry)

especially since this years’ Nobel Prize for Economic Science was awarded for integrating climate change an technological innovations into long-run macroeconomic analysis. Two subjects that are kind-of STEM-related.
Therefore, no matter how you might be willing to rank them, something can be considered science (from the Latin word scientia – “knowledge”) if the scientific method is applied.

What’s this scientific method?

The scientific method is a way to approach a problem or question by following this – or any similar – flowchart:

Very briefly and with an example, these are the steps you’d follow:

1. Observation
   This can be anything you observe.
   Example: People seem a lot friendlier here in [town A]. When I pass people on the street, people smile at me more than they did when I was in [town B].*
2. Question
   From that observation, you can formulate a well-defined question, a problem you would like to know the answer to. Science is simply the pursuit of knowledge, you know.
   Example: Are people more friendly in [town A] than in [town B]? (if friendly is defined as “smiling at people on the street”)
3. Hypothesis
   You probably have a little bit of data (from your observations) that allow you to formulate the answer you would expect. This possible answer is something you can test: is what you assumed true or false?
   Example: People in [town A] smile more on to passers-by than in [town B]
4. Experiment
   Now it is time to collect your data.
   Example: I’d go to [town A], walk around in the center for – say – 30 minutes and count how many people I pass on the street (and actually make eye contact with) and how many people smiled at me. I’d then do the same for [town B].
   
5. Analysis
   When you have collected all your data, sit down and perform some analysis. Usually, statistics are the thing to apply.
   Example: I’d calculate the ratio of smiling people in each town, let’s say 17 out of 59 (29%) of people smiled at me in [town A], while 34 out of 81 (42%) people smiled in [town B].
   
6. Conclusion
   Example: I reject my hypothesis; people in [town A] are not friendlier than people in [town B].
   This last step is checking if my hypothesis was correct (it wasn’t). Rejecting the hypothesis means I can go back and change my hypothesis and start again. If my hypothesis was correct, yay – I’ve done science!

Well, in reality, there is even more to it (both for rejecting and accepting an hypothesis).
In this example, there are many faults. Was my definition of “friendliness” correct? Were there factors I didn’t account for, like a bit of spinach between my teeth that caused more people to smile (or laugh) at me? More importantly, if I repeat the experiment, do I get the same result**? Was my experiment well designed; maybe there are better ways to test this same hypothesis?

Back and forth and back and forth and back and forth again.

Science is a very iterative process. Hypotheses are constantly being reformulated and retested. It is actually impossible to be 100% a hypothesis is true. The real science is when you try every which way to disprove your hypothesis. It is after a lot of back and forth and iteration, that a theory about something can be formulated. But you should know that in the scientific lingo, a theory has nothing to do with guesswork. It is the result of several repeats of observations and experiments that are generally accepted as reliable accounts of the world around us. ***

Scientist vs. engineer

I’d also like to note that science and engineering are quite different things. A scientist wants to know how things work while an engineer kind of just wants to make things work.
For example: engineers built the large hadron collider; scientists use it to study elementary particles.
Though it should be said that a lot of scientists have a bit of engineering in them, and vice versa, so this is probably a giant simpification.

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* I just know that this is just because I look funny.
** Typically, at least three repeats showing the same conclusion are necessary to accept a hypothesis.
*** More about scientific theory here: https://www.gotscience.org/2015/10/theory-vs-hypothesis-vs-law-explained/

Last weekend, I attended the Centenary conference commemorating the 100-year anniversary of the publication of On Growth And Form by D’Arcy Wentworth Thompson. You might have heard me mention this book and its centenary at some point?

It was not just your usual conference. While most conferences centre around a certain field or topic, this one explored the influence of D’Arcy and his book on many different fields It was the most interesting mix of people and topics at any meeting I’ve been at, it succeeded in bringing scientists, mathematicians, computer scientists, historians, artists, architects, musicians and knitters in the same room.

Also, the sessions were not organised topically, but pretty much random, which meant that even if you were just interested in a few talks (on paper), you ended up hearing the wide variety of topics that have something to do with D’Arcy. Personally, I thought this was a very clever choice of the organisers (kudos to them), and I enjoyed hearing about art, architecture, history, and yes, knitting, instead of boring ol’ science for a change.

I also feel like I made some type of personal achievement. I was accepted to give a talk on the Physics of Cancer, which you might remember as the topic of my two FameLab contributions. For each of these, I had written a little song. So, in a crazy phase of over-confidence, I decided to incorporate these songs into my talk. And, why not, I also incorporated Star Wars references, weird cartoon cell drawings and pretty dodgy doodles I had drawn myself.

The response was amazing. I’ve given talks at conferences before but never have I received such positive feedback. Not only because they found the songs entertaining (I can assure you no-one fell asleep during my presentation) but I was also complimented on the clarity and accessibility of my talk (the very mixed audience, remember) and my optimistic approach to a “heavy” topic. If possible, I will from now on take this approach for every talk.

Finally, I have a new favourite D’Arcy quote (it’s quite convenient to have three days full of inspirational quotes to muse about):

“(…) things are interesting only in so far as they relate to themselves to other things; only then you can put two and two together and tell stories about them.”

Closely followed by this one, actually:

“Facts are pointless unless they illustrate greater principles.”

(The comics snippets and the second quote are from the graphic novel “Transformations“.)

Two weeks ago, I told you that physics and cancer are, perhaps counterintuitively, intermingled and that this relationship has biological and clinical implications. I outlined how mechanical forces act on cells and tissue, and perhaps are responsible for one of the many ways of cancer progression.

In this post, I’d like to tell you about how being able to detect mechanical properties of tissue can help with diagnosing diseases. So while the previous post was more about how physics can influence the biology of a tissue, this time I’d like to focus on how biology can dictate physical properties of a tissue.

A very important issue to point out, before going into the differences between healthy tissue/cells and cancer, is the size scale we are considering. Depending on whether we are talking about cells (µm size range) or tissues (100s of µm to mm), we can make quite opposite conclusions: several studies have shown that tumour cells are softer than healthy cells (of the same tissue type), while tumour tissue is stiffer than healthy tissue.

First the cells. Experiments such as Atomic Force Microscopy (which I mention because I have used it myself) show that especially metastatic tumour cells are softer than healthy cells. If we consider what cells do during metastasis, this actually makes sense. (Metastasis is the process where cells migrate away from the initial tumour and spread to other parts of the body.) A softer cell is able to squeeze through other cells, and through the wall of a blood vessel, allowing it to travel to elsewhere in the body. This different mechanical property allows it to behave in its particular way. Knowing this property allows us to predict the aggressiveness (or invasiveness) of a certain cancer. If the tumour has cells that are much softer than other, it is usually a more aggressive type of cancer.

This difference in mechanical properties not only makes sense if we consider the behaviour of the cells, it can also help make prognoses and decide on what type of treatments to use.

Next, on a larger scale, tumours are stiffer than healthy tissue. This is exactly what we feel when we are “looking for lumps”. A bit of tissue feels different, namely stiffer, than what it should be. The reason tumours are stiffer is not actually due to the (softer) cells it contains, but due to what sits in between the cells: the extracellular matrix. The extracellular matrix is a very structured meshwork of structural proteins that acts as a scaffold for the cells: it provides the tissue with structural integrity, cell organisation and mechanical strength. For example, there are a lot of extracellular matrix proteins in our skin, which is why it is, well, our skin (hurray for circular reasoning): a sturdy barrier between the outside and the inside of our body. In healthy tissue, the extracellular matrix is usually very well organised. The fibers making up the matrix are regularly cross-linked and have and neatly organised. However, the matrix in tumourous tissue is chaotic. In essence, was “built” too quickly. In this fast-growing bit of tissue, the scaffolding had to be assembled fast to support the rapidly dividing cells. As a result, the fibres are not well organised and the crosslinking is random. It is as if the scaffolding of a building was built too quickly, so rather than nicely structured, there are random beams sticking out in all directions. As a result, pushing down on the matrix does not compress it as much, and it feels stiffer.

At a tissue level, these differences in mechanical properties are very useful for diagnosing cancer. Because of different mechanical properties, we can feel lumps, but we can also image it using techniques such as ultrasound, MRI and other imaging techniques. Due to different physical properties, the cancerous tissues interacts differently with whatever wave (light, sound, …) we are using to try and detect it. Thank you physics!

To wrap this up: the physics of cancer is important, and useful, and interesting, and cool and definitely worth researching. And this is why interdisciplinary research is not only a fancy buzzword, it can also increase our understanding certain phenomena and come up with better diagnoses and treatments by approaching the problem from a completely different perspective.

This subject was the topic of my second FameLab performance (Scottish regionals), which ended in a little song (to the tune of “What a Wonderful World” by Sam Cooke), in which I wanted to highlight the importance of interdisciplinary research and how studying diseases from a physics perspective can only be productive:

You know, cancer’s about biology
And perhaps a bit of chemistry
But I’m telling you there’s physics too
There’s physics happening inside you
With one subject you can never be sure
Put them together, and we might find a cure
And what a wonderful world that would be…

Some references I used to verify that my thoughts on this subject were not completely unsubstantiated:

• Baker EL, Lu J, Yu D, Bonnecaze RT, Zaman MH. Cancer Cell Stiffness: Integrated Roles of Three-Dimensional Matrix Stiffness and Transforming Potential. Biophysical Journal. 2010;99(7):2048-2057. doi:10.1016/j.bpj.2010.07.051.
• Suresh S. Biomechanics and biophysics of cancer cells. Acta biomaterialia. 2007;3(4):413-438. doi:10.1016/j.actbio.2007.04.002.
• Kumar S, Weaver VM. Mechanics, malignancy, and metastasis: The force journey of a tumor cell. Cancer metastasis reviews. 2009;28(1-2):113-127. doi:10.1007/s10555-008-9173-4.
• Plodinec M, Loparic M, Monnier CA, Oberman EC, Zanetti-Dallenback R, Oertle P, Hyotyla JT, Aebi U, Bentires-Alj M, Lim RYH, Schoenenberger C-A. The nanomechanical signature of breast cancer. Nature Nanotechnology. 2012; (7):7 57–765. doi:10.1038/nnano.2012.167

If you are confused by the title, that’s okay. Usually, when we read something about cancer, it is about something biology-related, for example about specific mutations or the environmental conditions that increase cancer risk. A lot of research is happening with regards to the biology and biochemistry of cancer: which tumour suppressor genes are mutated in certain cancers, what are the effects cancer has on someone’s health, what drugs can we use to treat a cancer, … ? But, perhaps surprisingly, studying the physics of cancer also has its merit. Why, it’s a whole field in itself!

So I’d like to talk a little bit about this topic, the physics of cancer, and in this first part, I will focus on how physical forces can change the behaviour of cells (and how this might be involved with disease).

Cells not only sense their biological environment, they also feel their physical environment. They sense the stiffness of the cells and protein structures around them, they sense how other cells are pushing and pulling on them, and then they react to it. And these mechanisms could actually be quite important for the development and progression of cancer.

Recent research showed that the cells surrounding a tumour are under mechanical stress because of the growth of the tumour. As a tumour grows, it pushes on its environment. So the – initially healthy – cells in its direct surroundings, feel a pressure. In this specific study, they showed that this pressure caused the cells to start a mechanical response pathway leading to the upregulation of a protein β-catenin. This protein is involved in activating certain pathways involved in cell proliferation.

Which is exactly what its upregulation leads to in cancer. In the case of colorectal cancer (which I am particularly interested in), a mutation of Apc (adenomatous polyposis coli, in case you were wondering) also leads to an accumulation of β-catenin amongst other things. The APC protein has been linked to many functions, but the best known is its involvement in forming a complex that binds to β-catenin and tagging it for destruction. That way the proteins involved in protein recycling know that the β-catenin proteins can be cut up. But when APC is mutated, β-catenin gets tagged and starts piling up and doing some of its jobs a little bit too well, including inducing proliferation pathways.

So back to the study, if healthy cells are experiencing a constant pressure (due to a big bad tumour growing into their space, or – as they tested in the study – artificially caused pressure), they start acting more “cancer-like”. This suggests that mechanical activation of a tumorigenic pathway, in this case, the β-catenin pathway, is a potential method for transforming cells.
This is just one example of how physics and cancer are potentially related. As a side note, I myself am also interested in how cells respond the mechanical stresses, which prompted me to do an experiment where I placed weights on top of cells.

This subject was the topic of my first FameLab performance, which ended in a little song (to the tune of “Friday I’m in Love” by the Cure). It’s sung from the perspective of a cell that is stuck next to a growing tumour:

Hello there, I am a cell.
Feeling healthy, fit and well.
Life is good, yes, life is swell.
But my neighbour’s got it worse.

Something about him does not belong.
The way he pushes is just wrong.
They say in him the force is strong,
they say he’s got the force.

He takes up so much space.
And is always getting up in my face.
It’s putting me in a stressful space.

You could say he’s left his mark.
It’s like swimming with a shark.
He’s pushing me towards the dark,
the dark side of the Force,
the dark side of the Force.

Oh, have a mentioned that I like Star Wars?