A delayed nonlinear PBPK model for genistein dosimetry in rats
Catherine
Lloyd
Auckland Bioengineering Institute, The University of Auckland
Model Status
This CellML version of the model has been checked in COR and OpenCell and the model runs to 'almost' recreate the published results. The only difference is the CellML model is missing the time delays. Although it is possible to express time delays in the CellML language, the software tools PCEnv and COR are currently unable to handle time delays. The units have been checked and are consistent. The author of the original model was involved in the process of translating the model into CellML and his help has been invaluable.
Model Structure
Abstract: Genistein is an endocrine-active compound (EAC) found in soy products. It has been linked to beneficial effects such as mammary tumor growth suppression and adverse endocrine-related effects such as reduced birth weight in rats and humans. In its conjugated form, genistein is excreted in the bile, which is a significant factor in its pharmacokinetics. Experimental data suggest that genistein induces a concentration-dependent suppression of biliary excretion. In this article, we describe a physiologically based pharmacokinetic (PBPK) model that focuses on biliary excretion with the goal of accurately simulating the observed suppression. The mathematical model is a system of nonlinear differential equations with state-dependent delay to describe biliary excretion. The model was analyzed to examine local existence and uniqueness of a solution to the equations. Furthermore, unknown parameters were estimated, and the mathematical model was compared against published experimental data.
model diagram
Schematic diagram of the genistein PBPK model. The upper components represent compartments containing the pure genistein (gen) while the lower components contain genistein that has undergone conjugation in the liver (con). B - plasma, rp - richly perfused tissues, pp - poorly perfused tissues, l - liver, GI - gastrointestinal tract, ROB - rest of body, Ab - bile-delayed compartment. The arrows represent genistein transfer as blood flows between the organs and the systemic circulation, and also genistein elimination in the urine (out of Ccon_ROB); these are all linear with the exception of the conversion of pure to conjugated genistein in the liver which follows Michaelis-Menton kinetics.
A delayed nonlinear PBPK model for genistein dosimetry in rats, Michael G. Zager, Paul M. Schlosser and Hien T. Tran, 2007, Bulletin of Mathematical Biology, 69, 93-117. PubMed ID: 17024552
endocrine
genistein
pharmacokinetics
biliary excretion
The original model author contacted me and gave me an updated equation to calculate "H" (used in the equation to calculate Vinf). This fixed the units issue (inconsistency) and also fixed the model such that it now recreates the published results.
The University of Auckland, Auckland Bioengineering Institute
2007-01
concentration of genistein conjugates in rest-of-body
Ccon_ROB
keyword
Paul
Schlosser
M
c.lloyd@auckland.ac.nz
Hien
Tran
T
A delayed nonlinear PBPK model for genistein dosimetry in rats
69
93
117
Catherine Lloyd
Catherine Lloyd
Catherine
Lloyd
May
amount of genistein conjugates in bile-delayed compartment
Acon_b
The original model author has worked with us to get the CellML version of his model running in PCEnv to replicate the published results.
Zager, Schlosser and Tran's 2007 delayed nonlinear PBPK model for genistein dosimetry.
concentration of pure genistein in plasma
Cgen_B
Bulletin of Mathematical Biology
concentration of pure genistein in gastrointestinal tract lumen
Cgen_GI
2007-07-02T00:00:00+00:00
concentration of pure genistein in liver
Cgen_l
concentration of pure genistein in richly perfused tissues
Cgen_rp
The University of Auckland
Auckland Bioengineering Institute
17024552
concentration of pure genistein in poorly perfused tissues
Cgen_pp
concentration of genistein conjugates in liver
Ccon_l
2007-10-03T13:25:05+13:00
Catherine
Lloyd
May
This is the CellML description of Zager, Schlosser and Tran's 2007 delayed nonlinear PBPK model for genistein dosimetry.
Michael
Zager
G