29 June 2008

Rapid Head Injury Treatment : Polyethylene Glycol

Polyethylene glycol (PEG; 2000 MW, 30% by volume) has been shown to mechanically repair damaged cellular membranes and reduce secondary axotomy after traumatic brain and spinal cord injury (TBI and SCI respectively). This repair is achieved following spontaneous reassembly of cell membranes made possible by the action of targeted hydrophilic polymers which first seal the compromised portion of the plasmalemma, and secondarily, allow the lipidic core of the compromised membranes to resolve into each other. _Source
Polyethylene Glycol (PEG) is a group of multi-use polymers of ethylene glycol, classified by molecular weight. Recently, PEG has achieved increasing use in pharmacology via the "PEGylation" process of attaching PEG to a pharmacologic agent to modify its retention time and binding properties to membranes and receptors. PEG also recently made the news as an experimental nano-cage (via Speculist via Will Brown) to hold hemoglobin as a form of artificial blood.

Now it has been discovered that injection of PEG 2000 MW, 30% by volume, if injected early after brain and spinal cord injury, can reduce long term neurologic deficits.
Treated animals received a single subcutaneous injection of PEG. When treated within 2 hours of the injury, injured PEG-treated rats showed statistically significant improvement in their exploratory behavior recorded in the activity box when compared to untreated but brain-injured controls.

A delay of 4 hours reduced this level of achievement, but a statistically significant improvement due to PEG injection was still clearly evident in most outcome measures compared at the various evaluation times. A further delay of 2 more hours, however, eradicated the beneficial effects of PEG injection as revealed using this behavioral assessment.

Thus, there appears to be a critical window of time in which PEG administration after TBI can provide neuroprotection resulting in an enhanced functional recovery. As is often seen in clinically applied acute treatments for trauma, the earlier the intervention can be applied, the better the outcome. __7thSpace
Closed head injury and spinal injury are common occurrences in developed societies, most commonly from motor vehicle accidents and sports injuries. Given the apparent safety and ease of a single subcutaneous injection of PEG, this treatment should considered for approval for use by first responders/EMS, emergency ward physicians, and sports event physicians and paramedics.

Author: Andrew O Koob, Julia M Colby and Richard B Borgens
Credits/Source: Journal of Biological Engineering 2008, 2:9

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5 Comments:

Blogger Will Brown said...

I wonder how effective PEG would be as a routine therapy to prevent accumulation of micro injuries common among boxers (or contact martial arts practioners generally), American football players (Rugby or Australian Rules too), downhill skiers and the like? Athletes who all suffer micro damage to the spinal cord and brain as a routine consequence of their activities. Much too soon to say, I'm sure, but I can't help thinking that specific research into this sort of approach might have much more widespread benefit then otherwise might prove to be the case.

Opposing just the neurosurgeons by the rest of the retail medical profession is much more achievable then is opposing a routine therapy income earner available to any GP or sports medicine clinician. And along the way, maybe a few EMT's will have another tool to do just that little bit more good for people too.

Sunday, 29 June, 2008  
Blogger Snake Oil Baron said...

I am surprised that PEG is being used in these manners. From what I have been told, the monomer, ethylene glycol is nasty on the kidneys since it binds with an enzyme which usually binds with ethanol. The ethylene glycol/enzyme complex forms crystals that damage the kidneys.

Maybe the concentrations are small enough and the depolymerization process is slow enough that the crystals don't form. My old biochemistry teacher used to tell us stories about how animals and kids get into ethylene glycol - a common anti-freeze - because it tastes sweet and that first aid treatment is the administration of booze to compete with the enzyme and prevent crystal formation.

But if the polymerized version is safe and effective in these therapeutic amounts it sounds like there are some clever uses for the stuff.

Sunday, 29 June, 2008  
Blogger al fin said...

Good point, Will. Sports players who suffer a concussion or repetitive head jarring might someday be given a shot of PEG 2000 routinely.

Baron, apparently the polymer holds together quite well. Safety issues seem extremely minor. Another formulation of PEG is used routinely as an oral laxative. Yet other formulations of PEG are used in several injectable medications.

Sunday, 29 June, 2008  
Blogger Snake Oil Baron said...

I guess that with ethylene glycol, as with most things, concentration is everything. Even amino acids can be poisonous if the enzymes needed to convert them or clear excessive amounts are not functioning. It goes to show how surprising chemistry can be, especially in living systems

Monday, 30 June, 2008  
Blogger Julia said...

The doses were a one-time delivery. There were no long-term studies performed on kidney health. But there was a notable difference in general animal well being in the treated vs. non-treated groups.

Also, worth note, there is a big difference in poly-ethylene glycol and ethylene glycol, chemically speaking.

Wednesday, 13 August, 2008  

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