RE: Determining metabolite clearance fraction
From: "GIRARD PASCAL" PASCAL.GIRARD@adm.univ-lyon1.fr
Subject: RE: [NMusers] Determining metabolite clearance fraction
Date: Mon, November 29, 2004 10:56 am
Good afternoon Paul,
Briefly looking at your issue, it seems that there is no information in your data to
allow you estimating FM3 different from 1. So yes you should have FM3=1-FM1+FM2
rather than an additional THETA(9). In addition I suggest using a logistic
transformation for expressing FM1 and FM2 so that the estimated THETAS 3 and 5 would
be allowed to vary from - to + infinity, rather than the strong constraints 0-1
which make life more difficult for the software. Here is an implementation of the
transformation using your coding:
FM1=(EXP(THETA(3))/(1+ EXP(THETA(3)+ EXP(THETA(5)) ; FM1 FRACTIONAL 4OH FORMATION
FM2=(EXP(THETA(5))/(1+ EXP(THETA(3)+ EXP(THETA(5)) ; FM2 FRACTIONAL NDES FORMATION
FM3=1-FM1+FM2
And in $DES simply put:
DADT(2)=A(1)*KA-A(2)*K; EQ FOR PARENT
Hope it helps,
Pascal
=========================================Dr Pascal Girard
EA 3738 Ciblage Thrapeutique en Oncologie
Fac Mdecine Lyon-Sud
BP12
69921 OULLINS Cedex
France
Tel 33 4 78 86 31 53
Fax 33 4 78 86 31 49
e-mail : Pascal.Girard@adm.univ-lyon1.fr