I’ve heard of PCR before (polymerase chain reaction) where more copies of a DNA sample can be rapidly made. If the problem was that the quantity of blood that Theranos uses is too small, why wasn’t PCR used/ (if it was) why didn’t it work?
Also if I’m completely misunderstanding PCR, if someone could for that too, I’d appreciate it, thank you!
In: 148
I don’t remember the specific claims of the Theranos machine, however *in general* you can use very small amounts of sample (relatively) to measure a lot of things. I work with a lot of immunoassay machines, so that’s what I can talk about.
There are a lot of machines and technologies today that have shrunk the amount of sample needed, and some have shrunk the size of the machine. The Gyrolab uses approximately 1 microliter of blood plasma or serum, or whatever liquid matrix. Roche Cobas units use fairly small amounts, they require somewhere around 100 microliters in the sample cup but take some fraction of that (been a while since I worked with them). Both machines are quite large, though if there was a need to save space you could definitely shrink by some amount.
There are also quite small machines where all the magic happens on a cartridge or plate you load into it, and the machine exists only to read out a signal and/or pump fluids. A lot of work has been done in this area to do multiplexing, which is measuring a lot of different things at the same time using the same sample, but there are limits to how you can do that, and the more you want to measure simultaneously the larger the machine becomes.
So you’re unlikely to ever have a benchtop machine the size of a toaster which can measure the number of things Theranos were saying they could, but you can definitely shrink the current technology down some. But the sample size of a drop of blood is unlikely to ever be possible, as you run up against mathematical limits like the number of molecules of what you want to measure being undetectable at that volume. As it is you can do a lot with a few milliliters of blood, it just has to go to a room full of machines.
I’ve heard of PCR before (polymerase chain reaction) where more copies of a DNA sample can be rapidly made. If the problem was that the quantity of blood that Theranos uses is too small, why wasn’t PCR used/ (if it was) why didn’t it work?
Also if I’m completely misunderstanding PCR, if someone could for that too, I’d appreciate it, thank you!
In: 148
I don’t remember the specific claims of the Theranos machine, however *in general* you can use very small amounts of sample (relatively) to measure a lot of things. I work with a lot of immunoassay machines, so that’s what I can talk about.
There are a lot of machines and technologies today that have shrunk the amount of sample needed, and some have shrunk the size of the machine. The Gyrolab uses approximately 1 microliter of blood plasma or serum, or whatever liquid matrix. Roche Cobas units use fairly small amounts, they require somewhere around 100 microliters in the sample cup but take some fraction of that (been a while since I worked with them). Both machines are quite large, though if there was a need to save space you could definitely shrink by some amount.
There are also quite small machines where all the magic happens on a cartridge or plate you load into it, and the machine exists only to read out a signal and/or pump fluids. A lot of work has been done in this area to do multiplexing, which is measuring a lot of different things at the same time using the same sample, but there are limits to how you can do that, and the more you want to measure simultaneously the larger the machine becomes.
So you’re unlikely to ever have a benchtop machine the size of a toaster which can measure the number of things Theranos were saying they could, but you can definitely shrink the current technology down some. But the sample size of a drop of blood is unlikely to ever be possible, as you run up against mathematical limits like the number of molecules of what you want to measure being undetectable at that volume. As it is you can do a lot with a few milliliters of blood, it just has to go to a room full of machines.
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