infinite horizon impactor trouble shooting

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Jscience
Jscience's picture
infinite horizon impactor trouble shooting

Has anyone teated out animals impacted with a spiked graph?
Wondering if i can use them.

Omai
Omai's picture
Try looking at this paper:

Try looking at this paper:

http://www.jneurosci.org/cgi/content/full/25/19/4694

Also, this company (Precision System and Instruments) makes an Infinite Horizon Impactor.

Here is their tech support email-
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or
eval(unescape('%64%6f%63%75%6d%65%6e%74%2e%77%72%69%74%65%28%27%3c%61%20%68%72%65%66%3d%22%6d%61%69%6c%74%6f%3a%69%6e%66%6f%40%70%72%65%73%79%73%69%6e%2e%63%6f%6d%22%3e%69%6e%66%6f%40%70%72%65%73%79%73%69%6e%2e%63%6f%6d%3c%2f%61%3e%27%29%3b'))

Hopefully they can answer your question.
Omai

TWanke
TWanke's picture
My lab is looking to start

My lab is looking to start using the contusion model more frequently, and we are in the market for a new impactor.  I have read Rabchevsky's article in Neurotrama comparing to the IH impactor to the NYU impactor with a creatine treatment for SCI.  It seems that significant trends were found using the IH impactor that were not found using the NYU impactor.  Therefore it seems that the IH may be more sensitive.  I was hoping someone might be able to offer some professional advice on the decision.  Which is the best for comparing an experimental drug?  Which is easier to use?  And finally, is there a way to get an IH impactor used or for cheaper than $19,500?
Any advice would be wonderful!

MarkH356
MarkH356's picture
 This reply may be a bit late

 This reply may be a bit late, but have a read of the recent paper by Kim et al (J. Neurotrauma. 2009 vol. 26 (8) pp. 1395-1404) where they discuss the various impactor devices available. 

They key factor for comparing drug treatments is to start with injuries that are the same size in different animals (i.e. the lowest variance you can get). That way you can feel more confident that differences observed in your treated animals are due to the treatment and not to differences in the size of the initial injuries.
For contusion type injury devices, it is the depth of penetration of the impactor into the tissue that most determines the extent of the lesion size. This can vary considerably for simple weight drop devices (NYU Impactor) and force feedback devices (Infinite Horizons) and is dependent on the resistance to compression of the tissue being impacted. Because the spinal cord is inside a fairly rigid container (vertebral column), differences in the size of the laminectomy site through which the impact is made can have a huge effect on the depth of penetration into the tissue. A small laminectomy relative to the diameter of the impactor tip means more hydraulic resistance = less penetration. A larger laminectomy site means less hydraulic resistance = deeper penetration. The IH impactor is good (albeit a bit expensive), but you need to be very consistent with the size of your laminectomies and importantly secure the vertebral column well so it doesn't move when the impact strikes (i.e. secure clamps onto vertebral spines either side of the impact site).

Read also the paper by Bilgen (Neurorehabilitation and neural repair, 2005 vol. 19 (3) pp. 219-26). This device has position control (you can choose the depth of penetration aswell as the impact velocity, thus variances in laminectomy size have much less influence. Down side is you need to build your own impactor, but the upside is it is very inexpensive (around $4-5K USD all up). We have also used one of these devices and found very reproducible initial lesion sizes (Ek et al, PlosOne, 2010 vol. 5 (8))