Sunday, October 11, 2009

Death of Fischer 344

Spent a few Fridays observing Emil, an anesthesiologist turned researcher who is looking at the relationship between estrogen and its neuroprotective benefits. The specific breed of rat he is using is called Fisher 344. I am not sure how they got their name, but I'm sure they didn't come up with it on their own.

So far, we have talked a little about his science, and I have mostly observed him running experiments. Here's how this goes:
  • The morning begins with anesthetizing our rat with Isoflurane.
  • Next, the subject is rolled over with extremities taped down to provide a stable working surface.
  • A femoral artery is cannulated to provide arterial pressures and is used as an injection site for medications.
  • Exposing the trachea, Emil severs the trachea and inserts a large bore catheter, essentially performing a tracheotomy.
  • That done, he finds the exposed carotid arteries, teases the vagus nerve off, and lightly places a silicon ligature on each carotid arteries. The vertebral arteries were already ligated the previous day.
  • Turn over the rat, and it's time to build a "cranial window" to observe the pial artery. He needs to visualize perfusion into the brain so he can observe and measure the effects of cutting off perfusion to the brain and testing doses of estrogen to see how well the arteries "bounce back" after a traumatic insult.
  • To build a cranial window, Emil "scalps" the rat and exposes the skull. With a dremel and some deft hands, he gently cuts a small rectangular window along the suture lines and oh-so-gently removes part of the skull. He literally builds a transparent window filled with sterile saline and is able to visualize cerebral perfusion via the saggital sinus and pial artery using a specilized microscope equiped with camera and video recording capability.
This is a three hour process, by the way. Not to mention the weeks of prep work involved: taking out ovaries, waiting for the natural estrogen effects to wear off, and giving controlled and specific doses of estrogen to finally run the experiements. You can say that each experiment builds up over time resulting in a clear expectation of learning something from each rat. Otherwise: what is the point?

Two fridays in a row we have had the same results. The first friday, we transferred the subject over to the video microscope to begin running experiments and I noticed the brain bulging out of the skull. Emil sees the same thing and says "Oh, this might be bad." As if you can understate rat problems. Dead.
This past friday I made the trip up to John Hopkins again. Same meticulous prep work, same 3-4 hour intense investment. Only this time, we moved the rat over and lost blood pressure. Emil starts troubleshooting the catheter right away and says a couple of "oh no's" as a pre-emptive strike against us. Catheter flushing fine, ventilator functioning and doing its job. Look down again, and rat eyes turn from black to a dusky grey. Emil again with the "Oh, this might be bad." I was not sure for whom he was referring, and did not ask. However, after a few frustrating exhales and futile "rat CPR", we watched as a few meager red blood cells moved sluggishly through veins only with the prompting of sad and depressing rat CPR.

Thus was the death of Fischer 344.

1 comment:

  1. Hey Carl, I'm glad you're writing again, it's fantastic! Stangely what you just described with the rat is similar to what we are doing here with the neurovascular cases! haha. Just kidding! Take care man. D2

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