- Author:
- Catherine Lloyd <c.lloyd@auckland.ac.nz>
- Date:
- 2010-04-20 11:54:28+12:00
- Desc:
- Fixed equations for x, y and z so they better reflect the published paper. Updated the documentation, fixed the broken RDF, and added a curation comment. The odel contains time delays so it will not be fully curated until we have a method for expressing these in CellML.
- Permanent Source URI:
- https://models.physiomeproject.org/workspace/lenbury_pornsawad_2005/rawfile/2e0aac3716a58b444fd8875499a504e352db439d/lenbury_pornsawad_2005.cellml
<?xml version='1.0' encoding='utf-8'?>
<!-- FILE : lenbury_2005.xml
CREATED : 12th July 2007
LAST MODIFIED : 12th July 2007
AUTHOR : Catherine Lloyd
Bioengineering Institute
The University of Auckland
MODEL STATUS : This model conforms to the CellML 1.1 Specification.
DESCRIPTION : This file contains a CellML description of Lenbury and Pornsawad's 2005 delay-differential equation model of the feedback-controlled hypothalamus-pituitary-adrenal axis in humans.
CHANGES:
--><model xmlns="http://www.cellml.org/cellml/1.0#" xmlns:cmeta="http://www.cellml.org/metadata/1.0#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:bqs="http://www.cellml.org/bqs/1.0#" xmlns:cellml="http://www.cellml.org/cellml/1.0#" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:vCard="http://www.w3.org/2001/vcard-rdf/3.0#" cmeta:id="lenbury_2005" name="lenbury_2005">
<documentation xmlns="http://cellml.org/tmp-documentation">
<article>
<articleinfo>
<title>A delay-differential equation model of the feedback-controlled hypothalamus-pituitary-adrenal axis in humans</title>
<author>
<firstname>Catherine</firstname>
<surname>Lloyd</surname>
<affiliation>
<shortaffil>Auckland Bioengineering Institute, The University of Auckland</shortaffil>
</affiliation>
</author>
</articleinfo>
<section id="sec_status">
<title>Model Status</title>
<para>
This CellML model runs in OpenCell but it does not replicate the published results (paramteter values for delta1 2 and 3 have been taken from the legend of figure 3 in the published paper, and initial conditions for x, y and z have been taken from the grpahs in figure 3). The inability of the CellML model to replicate the published results is most likely to be due to the lack of time delays in the CellML model (which currently can not be described). The units are all dimensionless and are therefore consistent, however expressing time as "dimensionless" means that the model cannot be run in COR.
</para>
</section>
<sect1 id="sec_structure">
<title>Model Structure</title>
<para>
ABSTRACT: The present work develops and analyses a model system of delay-differential equations which describes the core dynamics of the stress-responsive hypothalamus-pituitary-adrenal axis. This neuroendocrine ensemble exhibits prominent pulsatile secretory patterns governed by nonlinear and time-delayed feedforward and feedback signal interchanges. Formulation and subsequent bifurcation analysis of the model provide a qualitative and mathematical frame work for a better understanding of the delayed responsive mechanisms as well as the dynamic variations in different pathological situations.
</para>
<informalfigure float="0" id="fig_reaction_diagram">
<mediaobject>
<imageobject>
<objectinfo>
<title>model diagram</title>
</objectinfo>
<imagedata fileref="lenbury_2005.png"/>
</imageobject>
</mediaobject>
<caption>Schematic diagram of the hypothalamus-pituitary-adrenal (HPA) axis. Stimulatory and inhibitory paths are indicated by the arrows and + or - signs respectively. CRH represents corticotropin-releasing hormone and ACTH represents corticotropin.</caption>
</informalfigure>
<para>
The original paper reference is cited below:
</para>
<para>
A delay-differential equation model of the feedback-controlled hypothalamus-pituitary-adrenal axis in humans, Yongwimon Lenbury and Pornsarp Pornsawad, 2005,
<emphasis>Mathematical Medicine and Biology</emphasis>, 22, 15-33. <ulink url="http://www.ncbi.nlm.nih.gov/pubmed/15716298">PubMed ID: 15716298</ulink>
</para>
<para>
It should be noted that in its current form, the CellML description of the this model is unable to perfectly capture the simulation results of the published model, this is due to the time delays which are difficult to describe in the CellML code.
</para>
</sect1>
</article>
</documentation>
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<map_variables variable_2="delta1" variable_1="delta1"/>
<map_variables variable_2="beta" variable_1="beta"/>
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<map_variables variable_2="y" variable_1="y"/>
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<rdf:li>cortisol</rdf:li>
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<rdf:li>adrenal cortex</rdf:li>
<rdf:li>HPA axis</rdf:li>
<rdf:li>hypothalamus</rdf:li>
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Lenbury and Pornsawad's 2005 delay-differential equation model of the feedback-controlled hypothalamus-pituitary-adrenal axis in humans.
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