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nunca
Switzerland
2 Posts |
 Posted - 08/29/2003 : 10:39:44 AM
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Hi,
anybody can explain me how calculate the Id50 with origin?
thank you very much |
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fannon
USA
3 Posts |
Posted - 08/29/2003 : 5:02:14 PM
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| I can give you an example of one way. I'll use the equation y=a*b/(b+x) where a= maximum binding of your drug with no inhibitor, b= the ID50 of your inhibitor and x and y= your data points. After you enter your data choose Analysis, then Non Linear Curve Fitting, then Advanced Fitting Tool. Under function choose New. Select a name for your function. Choose User-Defined. Choose 2 parameters. If you want, check the User Defined Parameter Names and enter your own parameter names as a,b. X is your Independent Variable and y is your Dependent. Then write your equation in the box y=a*b/(b+x). Save it then go to Action and select Fit. Fill in "a" with your maximum binding and a reasonable guess for "b". Click the Vary box for "b". Then click on Iterations. The number you get for b should be your ID50. There are much more complex conditions you might need to consider but this is a simple situation. There may be functions already in Origin for what you need. Hope that helps. |
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easwar
USA
1965 Posts |
Posted - 08/31/2003 : 1:57:43 PM
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Hi Nunca,
If your Id50 value does not directly correspond to a parameter in the equation, once you perform the fit using NLSf (or one of the fit tools like Sigmoidal fit), you can use the Find X/Find Y feature in version 7, which allows you to find the X/Y value from a given Y/X value, once the fitting has been performed.
Please post again with more specifics if you need further help.
Easwar
OriginLab.
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nunca
Switzerland
2 Posts |
Posted - 09/01/2003 : 02:29:33 AM
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Thank you for your explanation but I don't find Iterations..
Bye A+
quote:
I can give you an example of one way. I'll use the equation y=a*b/(b+x) where a= maximum binding of your drug with no inhibitor, b= the ID50 of your inhibitor and x and y= your data points. After you enter your data choose Analysis, then Non Linear Curve Fitting, then Advanced Fitting Tool. Under function choose New. Select a name for your function. Choose User-Defined. Choose 2 parameters. If you want, check the User Defined Parameter Names and enter your own parameter names as a,b. X is your Independent Variable and y is your Dependent. Then write your equation in the box y=a*b/(b+x). Save it then go to Action and select Fit. Fill in "a" with your maximum binding and a reasonable guess for "b". Click the Vary box for "b". Then click on Iterations. The number you get for b should be your ID50. There are much more complex conditions you might need to consider but this is a simple situation. There may be functions already in Origin for what you need. Hope that helps.
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fannon
USA
3 Posts |
Posted - 09/03/2003 : 11:48:53 AM
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| You should find four buttons under the space that you write your equation in, at least in Origin 7. Chi-Sqr, 1 Iter. 100 Iter., and 100 Simplex Iter. Try clicking 100 Iter. That should do it. I don't remember if earlier versions of Origin have the same layout. Good Luck. |
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ID 50