Wednesday, November 3, 2010

Drug 'could reduce stroke damage'

Blocking a molecule which stops brain cells working properly after a stroke could help people recover better.

Californian scientists, writing in the journal Nature, said doing this in mice helped reverse the effects of a stroke.

A treatment based on this approach could be given days later, while conventional treatments need far quicker action.

The Stroke Association said far more testing would be needed on any new drug.

Strokes happen when an area of brain cells is starved of oxygen, due to a blocked or burst blood vessel.

Cells start to die in the affected area, and while nothing can bring these back, scientists know the cells immediately surrounding the damaged area play a crucial role in the ability of the brain to recover and compensate for the damage.

This process of "re-wiring", in which neighbouring brain cells make new connections to replace some of those lost during the stroke, can partly determine the degree of long-term disability some patients will suffer.

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Professor Anthony Rudd of St Thomas' Hospital explains what happens during and after a stroke

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The researchers, from the University of California in Los Angeles, found that a natural process within the surrounding brain cells appeared to be getting in the way of recovery.

"Start Quote

This is an interesting study, however it has only been tested on mice so far, and further research is needed to find out if it could be as effective in humans"

End Quote Dr Sharlin Ahmed Stroke Association

A build-up of a molecule called GABA appeared to dampen down activity in these cells at a time when they should be working hard to make new connections.

When strokes were induced in mice, giving them a drug which blocked the effects of this molecule appeared to improve their ability to recover movement.

Altering the genetic make-up of the mice to be less responsive to GABA produced similar results, adding weight to the theory.

The researchers believe that their work offers the prospect of a new type of drug to boost recovery in stroke patients.

Although trials in humans would still be some way off, the results in mice point to another significant advantage.

At present, strategies to limit stroke damage include giving 'clot-busting' drugs as quickly as possible after a stroke to try to limit the area of the brain affected.

This leads to a race against time to deliver the drug as soon as possible.

The Californian researchers found that blocking GABA produced the best results if done three days after the stroke - in fact, doing it immediately actually worsened stroke damage.

Dr Sharlin Ahmed, from the Stroke Association, said the need to give current treatments quickly, and the fact that not every stroke patient could receive them, meant that there was a "great need" for new ways to improve recovery and limit damage.

She added: "This is an interesting study, however it has only been tested on mice so far, and further research is needed to find out if it could be as effective in humans."



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Scans reveal autism brain secrets

Differences in the brain structure of people carrying an "autism gene" may offer clues to how the condition develops, say US scientists.

Scans revealed children carrying the gene variant appeared to have more nerve cell "connections" within the frontal lobe.

They had fewer connections between this and the rest of the brain, reported Science Translational Medicine journal.

Brain research has just begun to reveal autism's roots, a UK expert said.

One-third of the population carry the CNTNAP2 gene variant, so it does not guarantee that autism will develop, but just slightly increases the risk.

Different pathways

However, scientists at the University of California in Los Angeles believe it may influence the way the brain is "wired".

They used functional magnetic resonance imaging (fMRI) to look for communication between different brain regions, and to measure the strength of these connections.

They scanned the brains of 32 children as they performed learning-related tasks - half had autism, and half did not.

Regardless of their diagnosis, those carrying the CNTNAP2 variant had differences in the connections within the frontal lobe of the brain itself and between the frontal lobe and the rest of the brain.

Dr Ashley Scott-Van Zeeland, who led the research, said: "The front of the brain appears to talk mostly to itself - it doesn't communicate as much with other parts of the brain and lacks long-range connections to the back of the brain."

"Start Quote

The causes of autism are as yet unknown, but we do know there are likely to be many factors involved, so we hope this will contribute to our understanding of this complex condition"

End Quote Carol Povey National Autistic Society

The researchers also spotted differences in the "wiring" between the frontal lobe and the left and right sides of the brain.

In children with the version of the gene not linked to autism risk, the pathways were linked more strongly to the left side of the brain.

In those with the "risk variant", the pathways were different, linking the lobe strongly to both sides of the brain.

This, said the researchers, could explain why the gene variant had been linked to children who are slow in starting to talk.

Dr Scott-Van Zeeland said that if the gene variant did predict language problems, then it might be possible to design therapies which helped to "rebalance" the brain and encourage normal development.

Professor Margaret Esiri, a neuroscientist from Oxford University, said that researchers had so far "barely scratched the surface" of understanding the interplay between genes and brain development.

Her own research closely analyses a scarce supply of donated brains from both autistic and non-autistic adults and children to look for differences in structure and function.

She said: "If you understand these subtle differences, there may be ways of 'tweaking' them earlier in life, and bringing them back into a normal trajectory of development. Of course, this would be many years away."

Carol Povey, from the National Autistic Society, said the study was interesting because it began to link genes thought to be involved in autism to actual changes in brain function.

She said: "The causes of autism are as yet unknown, but we do know there are likely to be many factors involved, so we hope this will contribute to our understanding of this complex condition."



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