When I'm not incurring the wrath of the Christan right, the paranoid left, conspiracy theorists, free-market disciples and quackery peddlers I do quite an amount of science. In fact, I even use science as a verb - "I science a lot". In January we published a paper in Royal Society Interface on oxygen dynamics in tumour spheroids.
So what does this mean? In cancer, oxygen plays an incredibly important role - cancer can be viewed as defective mutant cells dividing utterly out of control, and as a result tumour regions with poor oxygen occur when the cells grow haphazardly. Poorly oxygenated (or hypoxic) tumour regions become far more resistant to both chemotherapy and radiotherapy, and conversely well oxygenated areas respond better. We're interested in modelling how oxygen diffuses through tumour tissue as a "map" of the underlying oxygen distribution would help better inform treatment strategy - essentially, if one had a map of oxygen, then it follows that you could boost dose or treatment to the regions that needed it most.
To model how oxygen diffuses through tumour tissue, we looked at the simplest possible 3D case, a tumour spheroid - these are "balls" of tumour cells which divide aggressively until they run out of nutrients like oxygen. Picture a tumour spheroid as a clump of cells, growing in a sphere shape with a source of oxygen surrounding it. Oxygen diffuses through the ball, being consumed by the cells. However, at a certain size, all the oxygen is consumed before it reaches the centre most cells, and these cells, starved of oxygen, die out. This leaves a void of dead cells in the centre. The outermost well oxygenated cells are still happily eating oxygen and making clones of themselves, but the inner bunch die off, resulting is something like a hollow ball.
|This pretty little thing is actually a stained cross-section of a DLD1 colorectal tumour spheroid - The centre is starved of oxygen or anoxic and the cells here die off. The cells in red are becoming hypoxic and the green ones are still merrily dividing. |
In the paper just published, we derive a mathematical model which predicts oxygen level at any point in the spheroid, and explicitly predicts the boundaries of a tumour. This model can then be used to estimate the consumption rate of the tumour cells. Consumption rate is important, as cells which are oxygen hungry will devour diffusing oxygen quickly, resulting in more hypoxia and a thinner "shell" - in essence, consumption rate decides the extent of hypoxia to a large degree.
Of course, theory is fun but it's important to validate it - we did that by using a series of DLD1 tumour spheroids, which fit the model very well and allowed us to pull out the estimated consumption rate. Spheroids are in some respects a very simple model of cancer as they're divorced from the complicated vasculature (blood supply) of a real human tumour, but the fundamental principle of oxygen diffusion and consumption is the same throughout, so understanding the relationships between consumption and oxygen status is a good first step.
The whole thing is an interesting combination of physics, mathematics and biology. If you're interested in the detail, the paper is open access and available from Royal Society Interface here
Of course, anecdotal evidence is not evidence, so I had a peek at the literature to see if anyone had studied this from a psychological point of view and hey, presto - climate change denial is associated with a particular set of conservative beliefs and a distaste for any form of regulation. But it isn't solely the preserve of conservatives to deny evidence to fit a pre-existing worldview; liberals can be just as guilty of dismissing solutions like nuclear power based on their own emotional reaction rather than the evidence. This is part of a phenomenon called motivated reasoning, where reality is filtered and selectively taken on board to pacify rather than challenge a preconceived notion.
|Festinger explains motivated reasoning - I couldn't find one of that cliche quote things so I made one myself in ten seconds with that bastion of cutting edge photo manipulation Microsoft paint - because quotes with pictures is internet currency!|
|Helen Lovejoy - Iona material|
On a side note I cannot help but feel I'd have more respect for that particular organisation if they just came out and said they had a religious ideological problem with homosexuality than their continued attempts to scaremonger the general public into supporting their dubious position. I'd still disagree to the hilt, but it would be far more honest than their current carry on.
Right, that's your information overload for now. More focused post coming up soon!