THE NUCLEUS Issue 2 Spring 2024

So, there are samples with a known concentration. And we usually have three levels, so there might be a low level, a medium and a high and they'll get run at certain points throughout the day. And we look at how close our measured result is to what it should be. And we have a threshold and if it fails, we stop the testing. So, we do tend to get very good results. It's very rigorous. Joe : One of the things that really interests me about your work is how you read these blood test results. It’s not like there's just a spreadsheet in the DNA that says this is what’s happening with the lungs. How is it that you get this data? Clare : To get those results we have various methods, depending on what it is that you're measuring. So potassium and sodium. are one of our most common tasks. These are electrolytes that are particularly important for water balance in your body. You’ve probably noticed that if you eat a really salty bag of crisps, you feel thirsty. Maybe you know that if you're going to do a marathon, you need to, as well as taking on water, you also need to take on electrolytes. That’s all about keeping these electrolytes at a very tight controlled concentration. And we measure those using ion selective electrodes. You have an electrode that measures hydrogen and sodium ions by measuring the charge that passes across them. And then it's able to calculate the concentration of the sodium in that sample. So that's one of our methods. for a lot of other things, we use what got described as a chemistry test. And they often rely on a chemical reaction between whatever it is you're measuring something it reacts with, and it usually results in a colour change, or it sometimes results in an added particle that causes it to kind of clump together.

And then you can measure the change in transmission of light passing through it. So, for example, say you've got a really high concentration of something. It causes a massive coagulation of these particles and therefore your light transmission goes down. So you get an inverse relationship between your concentration and your light transmission.And then our other common type of test is immunoassay. so this is, often we use this to measure different types of proteins. And this relies on antibody interaction. So you can make antibodies that are very specific. to a tiny portion of that protein that you're looking at. So we can measure testosterone in your blood by using an antibody against a tiny portion of the testosterone molecule.

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