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Calculating whole body toxin concentration


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#1 Montys

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Posted 05 November 2016 - 05:51 AM

Hi,

 

I want to calculate the whole body amount of a specific toxin by analyzing the excreted toxin in urine. I know that there are assumptions that are necessary like the toxin needs to be in steady state and so on.

 

 

But there are several Problems.

 

  1. First it is best if you use urine to get a 24h urine and if not possible you need to korrekt it by the creatine concentration which we want to do.
  2. I have the more or less normal half life time of the toxin at about 58 days. Well brain e.g. has a longer half life time as compared to blood but the median ist about 58 days. I am not sure if this is right because the data is from the early 70' and 80' so I want take into account different half life times.
  3. The toxin appears in different subforms as inorganic and organic subforms that are differently distributed through out the body. I know that I could use 3 compartment approaches but never did this before.
  4. I found old data that compare the blood to total daily toxin uptake by e.g. 0.25ng/ml blood equals 2.5 µg/day. These data is also very old and I am not sure it is correct.

So I can tell me somebody how this works or give me a link to some good literature?

 

 

Thx so much

 

Montys

 

 

 

 

 

 

 



#2 bob1

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Posted 08 November 2016 - 06:54 AM

Just because data is from the 70's and 80's doesn't mean it isn't valid...I would look at these data and see if they make sense.

 

Check out the Merck Index and see if your drug is in there, check associated references.



#3 Montys

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Posted 18 November 2016 - 10:41 AM

Hi thx for the Merck Index Info but we don't have access to it.

 

 

Sure I would use the half-life values from the 70s the only value for whole body amount of toxin is also very old and there is no data, if the values are calculated by using one compartment models or whatsoever.

 

I have newer values from 24h urine but they didn't calculated the whole body amount. 

 

So right now I am a bit stucked.



#4 bob1

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Posted 18 November 2016 - 11:21 AM

Don't give up on the Merck index - it used to be a book, so a professor or library may well have it on their shelves.

 

You could also try PubChem and ChemXSeer.



#5 Montys

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Posted 22 November 2016 - 08:29 AM

Ok got one from 1996. But there is not much information in it: Position 5801 for Mercury just explains some general stuff. 

 

 

But nothing to calculate the whole body concentration out of the urine concentration. 



#6 bob1

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Posted 22 November 2016 - 09:53 AM

Did you find this paper? It seems to indicate that excretion of mercury in the urine is more or less linear and dependent on the kidney, which is a slow release organ. Having said that, there seems to be a correlation between the excretion rate and the amount of mercury in the blood.



#7 Montys

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Posted 28 November 2016 - 08:59 AM

Thx for the paper. I actually haven't read it before. Problem with this paper is that they used DMSA, this will release mostly mercury stored in the kidneys not the whole body. In addition it is used for acute detoxification, there is no evidence for effectiveness in chronic low dose intoxication 

 

So I don't get the exact intake/elimination ratio out of the paper. I only know that it might be linear but no real numbers except that under acute intoxication with DMSA treatment mercury urine concentrations of 40µg/g creatinine equals 160µg Mercury/d Elimination. 

 

And of course we get information on the model of toxin elimination. 

 

But I think that maybe it is just not possible to calculate back from urine concentration to whole body concentration even though you know the model of elimination and the half life times?



#8 bob1

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Posted 28 November 2016 - 11:22 AM

It's a real possibility that you can't back calculate - I would expect that different tissues would sequester different amounts and release at different rates. However, the rate at which the kidney releases would be the rate limiting factor, so you would have to rely on that, which would in turn be dependent on the blood concentration.






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