Friday, July 07, 2006

The mad cows are coming!!!!!

Looks like someone is closing in on a detection method for the silent phase of Creutzfeldt-Jakob disease (CJD, or mad cow disease).

I'm interested in this because I spent some time in Europe in the mid nineties (near the time of the British mad cow scare). Because of that fact, I'm actually not allowed to donate blood. There is no screening system for blood samples, so they just have to exclude sections of the populations that may have contracted the disease. Strangely this didn't actually become an issue till about 2002. I guess they must have issued some policy change at the time. I had given blood before, and it was never mentioned. Then one day, they told me I wasn't eligible to donate. Oh well, it's not the biggest thing in the world. I would like to be able to feel like I'm helping out now and then, but I guess there are other things that I can do. But I did like giving blood because it gave me a chance to work on my fear of needles. It's not a phobia, but like most people, I fear them more then the amount of pain the inflict warrants.
Plus there is the small part of me that is secretly afraid that I may have actually contracted it. Of course that's incredibly unlikely, but if the odds are good enough for the blood people who knows?

Anyway, it looks like the process for detection involves a technique called protein misfolding cyclic amplification (PMCA). Basically, a sample is introduced into an environment with a large concentration of normal copies of the protein. The misfolded prion will go to work on those, converting them and causing chaining of the molecules. To speed up the process they break apart the chain with ultrasound.

The protein most likely behind this is PrPsc (normal form PrPc), the 121-231 domain has been solved via NMR, and the PDB code is 1AG2. The same domain (114-234) was crystalized in complex with an antibody for PDB 1TPX

Some Googling also found some research published in Proteomics. Essentially, they are trying to establish a link between an increase of cystatin C with the CJD. This is important because cystatin C occurs at levels measurable by mass spectrometry. And another previously linked protein usability 14-3-3 , is being questioned.

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