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Bat Spit: A Bit of Saliva Reduces Strokes

 
 
Reply Sat 20 Dec, 2008 05:54 pm
http://www.washingtonpost.com/wp-dyn/content/article/2008/12/18/AR2008121801525.html

Bat Saliva-Based Stroke Drug Disappoints in Trial

By Ed Edelson
HealthDay Reporter
Thursday, December 18, 2008; 12:00 AM

THURSDAY, Dec. 18 (HealthDay News) -- An experimental clot-busting drug derived from the saliva of the vampire bat has failed to reduce stroke damage in a major trial.

But hope for the drug, called desmoteplase, remains alive, experts say, because the study may not have been large enough to provide clear results.

"The sample size was underpowered to detect any benefit," said study co-author Dr. Anthony J. Furlan, chairman of neurology at Case Western Reserve University, in Cleveland. "The simplest answer is that stroke is an extremely heterogeneous condition, and it is difficult to predict what the outcomes will be from a smaller size population."

Two earlier and smaller studies showed a benefit when desmoteplase was given intravenously to reopen brain arteries blocked by clots. But there was no significant difference in outcome in the latest trial, called DIAS-2, between stroke victims given desmoteplase and those who got a placebo, said a report to be published online on Dec. 17 in The Lancet Neurology.

But there remains vigorous debate about the best method to use in selecting those stroke patients who will be treated in the next trial, which is in the planning stage, Furlan added.

Desmoteplase was originally spotted in the saliva of the vampire bat, which uses the chemical to keep its victims' blood flowing freely, so it can suck a full meal.

The drug is contending to replace tissue plasminogen activator (tPA), the only current treatment for ischemic strokes, which are caused by blockage of a blood vessel. Most strokes are ischemic strokes; tPA is given by intravenous injection and works quickly to dissolve clots.

"But tPA must be given within three hours of a stroke, so only a small percentage of patients can get the treatment," Furlan noted. "We hope to triple that window to nine hours with desmoteplase."

But the strategy didn't work in DIAS-2, which included 186 people with strokes. A total of 123 patients received either a high or low dose of desmoteplase, while 63 got a placebo.

The death rate was actually higher for those who got the drug -- 11 percent in the low-dose group and 21 percent in the high-dose group, compared to 6 percent for those given a placebo.

So it's back to the drawing board, the researchers said, and one big question is whether the high-tech methods used to select participants in the trial were too sophisticated to be reliable.

DIAS-2 neurologists used either computerized tomography or magnetic resonance scanning to detect what they formally called "mismatches" -- brain areas that have been affected by the stroke but are not yet dead.

"There is a core area of tissue that is dead," Furlan explained. "Around that area are brain cells that are not yet dead, so they can be saved."

That is the theory, anyway. But it's a theory that some of the neurologists involved with the new drug are questioning.

"The current mismatch model is insufficient to identify those patients who would benefit," Furlan said. "We need a more sophisticated mismatch model."

But another school of thought among neurologists is that a simpler, rather than more complex, method of choosing trial participants might be better.

"There is some controversy about the design of the next trial," Furlan said. "Maybe we can select patients simply by determining whether a major artery is blocked, instead of the mismatch. The main way patients would be enrolled is by looking to see if a major artery is blocked out to nine hours, rather than for mismatch."

No firm start date has been set for DIAS-3, said Furlan, who is on the safety committee for the proposed trial.

The trial was funded by German drug company PAION Deutschland GmbH and U.S.-based Forest Laboratories, which had been working together to develop desmoteplase.

More information

Ischemic stroke and is treatment are explained by the U.S. Library of Medicine. http://www.nlm.nih.gov/medlineplus/ency/article/000726.htm

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Butrflynet
 
  1  
Reply Sat 20 Dec, 2008 05:58 pm
Here's Jill Bolte Taylor's talk at a TED conference about her stroke experience:

Quote:
Neuroanatomist Jill Bolte Taylor had an opportunity few brain scientists would wish for: One morning, she realized she was having a massive stroke. As it happened -- as she felt her brain functions slip away one by one, speech, movement, understanding -- she studied and remembered every moment. This is a powerful story about how our brains define us and connect us to the world and to one another.


0 Replies
 
Butrflynet
 
  1  
Reply Sat 20 Dec, 2008 06:03 pm
Jill Bolte Taylor talks about her recovery:



Her website and her book are both valuable resources:

http://www.mystrokeofinsight.com/

http://www.amazon.com/My-Stroke-Insight-Scientists-Personal/dp/1430300612
0 Replies
 
ossobuco
 
  1  
Reply Sat 20 Dec, 2008 06:56 pm
@Butrflynet,
Bumping, as this is pretty interesting, at least re some strokes, the clotting ones.
0 Replies
 
Butrflynet
 
  1  
Reply Sun 21 Dec, 2008 05:45 pm
After watching Jill's description of what was happening to her during the stroke event, I gave a second listen to a piece of music that Dys posted over on Rockhead's music thread. Read the words being said and think about Jill's description of her stroke event. I wonder if this is what Dys was attempting to describe with his song choice.

Lyrics:

Everybody's talking at me.
I don't hear a word they're saying,
Only the echoes of my mind.
People stopping staring,
I can't see their faces,
Only the shadows of their eyes.

I'm going where the sun keeps shining
Thru' the pouring rain,
Going where the weather suits my clothes,
Backing off of the North East wind,
Sailing on summer breeze
And skipping over the ocean like a stone.

I'm going where the sun keeps shining
Thru' the pouring rain,
Going where the weather suits my clothes,
Backing off of the North East wind,
Sailing on summer breeze
And skipping over the ocean like a stone
0 Replies
 
 

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