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ex-Member
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Join Date: Sep 2006
Posts: 110
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ex-Member
Join Date: Sep 2006
Posts: 110
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Quote:
Originally Posted by aftermathman
this is not my field so I am interested in your views here.
Oxford Bio claim :
"ProSavin delivers to the patient’s brain three genes required to convert cells that normally do not produce dopamine into cells that do, thereby replacing the dopamine synthesising cells lost during the course of the disease. ProSavin is based on a novel LentiVector system carrying the genes AADC (aromatic amino acid dopa decarboxylase), TH (tyrosine hydroxylase) and CH1 (GTP-cyclohydrolase 1). These genes are able to reprogramme transduced cells to manufacture and secrete dopamine".
Accepting your point re. lack of proof of the claim of efficacy vs L-dopa, I am interested in your views as to the potential of this product.
I am also interested in why Oxford and others would view this as worth the cost of testing.
Please try to keep the explanation simple, I am a mere techie and the world of gene therapy can easily go over my head.
Thanks for your help,
Aftermathman.
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At first I thought this was very interesting because it was doing something very new and claiming proven efficacy for it. However, after checking further details elsewhere it is not all it seems.
I'll try to explain what it is attempting to do in English rather than biochemical gobbledeegook. If I don't succeed please let me know.
DOPAMINE
Parkinson's Disease is primarily due to a lack of dopamine.
Dopamine is produced naturally in the brain in the dopamine producing cells (called the dopaminergic neurons).
They have claimed that the lack of dopamine is due to a lack of these cells, yet no research has ever shown this.
Dopamine is naturally produced in the brain by the following means :
L-tyrosine >>> L-dopa >>> dopamine
So the brain is taking L-tyrosine, turning it in to L-dopa and then turning it in to dopamine.
ENZYMES
An enzyme is a chemical substance turns one substance in to another substance in the body.
So one enzyme turns L-tyrosine in to L-dopa. This is the enzyme they refer to as TH (tyrosine hydroxylase). Incidentally, that name is forty years out of date !
A secoond enzyme turns L-dopa in to dopamine. This is the enzyme they refer to as aromatic amino acid dopa decarboxylase. Incidentally that name is an incorrect mixture of the old name and the present name.
There is no third enzyme involved in dopamine formation as they have suggested.
GENES
Enzymes are made from genes. Each enzyme has a specific gene that makes it. A gene is chemical substance that normally naturally occurs, and is in the body from birth.
So as they claim that there are three enzymes needed to make dopamine, they are providing, by injection in to the brain, three genes to make those enzymes. By this means they hope that those enzymes will make more dopamine.
FLAWS
There are several flaws in their facts and their theory :
Parkinson's Disease isn't due to a massive lack of dopamine producing cells.
Parkinson's Disease isn't (usually) a genetic disorder. So replacing the genes has no rational basis, as there is no deficincy to begin with. People with PD have plenty of these genes already.
They've got the enzyme names and number completely wrong.
By artificially stimulating the activity of these enzymes will result in an opposite after effect.
They take no account of all the other substances that the brain needs in order to produce dopamine.
Their supposedly successful clinical trials have not even begun. They are still applying for permission to carry out the clinical trials. I checked their web site, that soon makes it obvious that nobody has even used, let alone improved using their method. They really are stretching the facts concerning this.
VERDICT
"I am also interested in why Oxford and others would view this as worth the cost of testing."
A huge range of methods and substances are under investigation for use in Parkinson's Disease. Most of them, this one included, could be correct except that the theory they have based it on contains fundamental errors. Also in medicine what may work in the short term is often counterproductive in the long term. What many researchers unfortunately do is to concentrate on the initial beneficial effects and completely disregard what will happen over time - which is usually the opposite effect ! Also, contrary to common belief, most research is arranged by people who have never studied human biochemistry, or whose knowledge of it you could write on one piece of paper (or a lot less). This causes them to make obviousy false assumptions. I have been in discussions with supposed "world experts" in Parkinson's Disease only to find that they didn't even know basics. The errors that have been made with this product make it obvious to me that they do not even know the bicohemistry involved.
I suspect that we will continue to hear more about this but that it will gradually fade away because in practice they will find that any beneficial effects will not be long term and will end up being counterproductive.
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