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Blood samples and the study
Posted: Wed Apr 25, 2001 5:49 pm
I've got two epi-dogs in the study, and when I discuss the study I'm often asked about the blood samples.
Folks are very interested in what happens to the blood samples when they are received at the lab. And I've been asked how blood can be useful for studies on epilepsy, when blood tests such as CBC's and SuperChem's often turn up nothing.
Thanks for comments from the researchers on this topic.
Posted: Thu Apr 26, 2001 8:57 am
For our research, the blood sample is simply a source of DNA - any cell with a nucleus can be used as a source of DNA, but it's easier to extract from some sources than from others. In the blood samples, it's the white blood cells that we use - they are separated from the serum and red cells, and then DNA is isolated from the nuclei. If we were using a tissue sample, again, we'd be after the DNA that's in the nucleus of the cells, though it takes a somewhat different process to digest the sample and extract the DNA. Blood is easier for most animals to part with than tissue, and provides a large supply of high quality DNA for the research. This is also why we don't work with cheek swabs - while it's easy to collect, the volume is very low. We don't want to get part-way to the answer and run out of DNA on a key dog! When a test is developed, not much DNA is needed to run that one test - for research, however, we are likely to need to run hundreds of experiments, and that takes a larger volume of DNA. A 5-10ml blood sample is relativly easy to obtain, and provides the volume of DNA needed for research.
The lab tests you mentioned look at numbers of cells, levels of biological biproducts, etc., in the blood which can change with disease, exposure to toxins, hard excersize, and other things. Readings out of the normal range, or changes over time, can give a picture of how that individual's body is functioning. On the other hand, the DNA we're looking at does not change - an individual's DNA is the same from the time there IS an individual. Something that has been inherited is "coded" in the DNA, and not changed by accidents or disease. Samples from normal and affected family members are important so that the DNA from closely related normal and affected individuals can be compared. Random unrelated dogs would be likely to have many differences in their DNA, just due to being unrelated - finding the differences that are due to the disease is much more complicated than comparing differences in close relatives.
Hope that helps to clarify things!