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The Phantom Burster Model for Pancreatic Beta Cells
The CellML code.
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<title>The Phantom Burster Model For Pancreatic Beta-Cells</title>
<author>
<firstname>James</firstname>
<surname>Lawson</surname>
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<shortaffil>Bioengineering Institute, University of Auckland</shortaffil>
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<section id="sec_status">
<title>Model Status</title>
<para>
This model has been rebuilt according to the author's original XPPAUT code, which can be found at http://www.math.fsu.edu/~bertram/software/islet/BJ_04a.ode . The model is still unable to produce the appropriate output, however. This file is known to run in PCEnv.
</para>
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<sect1 id="sec_structure">
<title>Model Structure</title>
<para>
Pancreatic beta-cells have been the subject of both experimental and theoretical studies for several decades. One reason for this interest has been the essential role beta-cells play in glucose homeostasis - they are the only source of insulin that most cells require in order to take up and metabolise glucose, and impairment of beta-cell function contributes to diabetes. A major focus of theoretical work has been beta-cell dynamics, especially in the form of bursting electrical activity. The bursts consist of active phases of Ca<superscript>2+</superscript>-carrying action potentials alternating with silent phases of repolarisation and are accompanied by oscillations in cytosolic Ca<superscript>2+</superscript>, which drive pulses of insulin secretion.
</para>
<para>
Experimentally, electrical activity in beta-cells is studied in two distinct preparations: islets of Langerhans, which are microorgans containing thousands of endocrine cells, and isolated cells. Pancreatic beta-cells exhibit bursting oscillations with a wide range of periods. Whereas periods in isolated cells are generally either a few seconds or a few minutes, in intact islets of Langerhans they are intermediate (10-60 seconds). In their 2000 publication, Richard Bertram, Joseph Previte, Arthur Sherman, Tracie A. Kinard and Leslie S. Satin develop a mathematical model for beta-cell electrical activity capable of generating this wide range of bursting oscillations. Unlike previously published models, bursting is driven by the interaction of two slow processes (I<subscript>s1</subscript> and I<subscript>s2</subscript> in <xref linkend="fig_cell_diagram" /> below), one with a relatively small time constant (1-5 seconds) and the other with a much larger time constant (1-2 minutes). Bursting on the intermediate time scale is generated without the need for a slow process having an intermediate time constant, hence phantom bursting. This mathematical model has been translated into a CellML description which can be downloaded in various formats as described in <xref linkend="sec_download_this_model" />.
</para>
<para>
The complete original paper reference is cited below:
</para>
<para>
<ulink url="http://www.biophysj.org/cgi/content/abstract/79/6/2880">The Phantom Burster Model for Pancreatic beta-Cells</ulink>, Richard Bertram, Joseph Previte, Arthur Sherman, Tracie A. Kinard and Leslie S. Satin, 2000, <ulink url="http://www.biophysj.org/">
<emphasis>Biophysical Journal</emphasis>
</ulink>, 79, 2880-2892. (<ulink url="http://www.biophysj.org/cgi/content/full/79/6/2880">Full text</ulink> and <ulink url="http://www.biophysj.org/cgi/reprint/79/6/2880.pdf">PDF</ulink> versions of the article are available for Journal Members on the Biophysical Journal website.) <ulink url="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11106596&dopt=Abstract">PubMed ID: 11106596</ulink>
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<caption>Schematic diagram of the pancreatic beta-cell plasma membrane showing the ionic currents captured by the phantom burster model.</caption>
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<title>The Phantom Burster Model For Pancreatic Beta-Cells</title>
<author>
<firstname>James</firstname>
<surname>Lawson</surname>
<affiliation>
<shortaffil>Bioengineering Institute, University of Auckland</shortaffil>
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<section id="sec_status">
<title>Model Status</title>
<para>
This model has been rebuilt according to the author's original XPPAUT code, which can be found at http://www.math.fsu.edu/~bertram/software/islet/BJ_04a.ode . The model is still unable to produce the appropriate output, however. This file is known to run in PCEnv.
</para>
</section>
<sect1 id="sec_structure">
<title>Model Structure</title>
<para>
Pancreatic beta-cells have been the subject of both experimental and theoretical studies for several decades. One reason for this interest has been the essential role beta-cells play in glucose homeostasis - they are the only source of insulin that most cells require in order to take up and metabolise glucose, and impairment of beta-cell function contributes to diabetes. A major focus of theoretical work has been beta-cell dynamics, especially in the form of bursting electrical activity. The bursts consist of active phases of Ca<superscript>2+</superscript>-carrying action potentials alternating with silent phases of repolarisation and are accompanied by oscillations in cytosolic Ca<superscript>2+</superscript>, which drive pulses of insulin secretion.
</para>
<para>
Experimentally, electrical activity in beta-cells is studied in two distinct preparations: islets of Langerhans, which are microorgans containing thousands of endocrine cells, and isolated cells. Pancreatic beta-cells exhibit bursting oscillations with a wide range of periods. Whereas periods in isolated cells are generally either a few seconds or a few minutes, in intact islets of Langerhans they are intermediate (10-60 seconds). In their 2000 publication, Richard Bertram, Joseph Previte, Arthur Sherman, Tracie A. Kinard and Leslie S. Satin develop a mathematical model for beta-cell electrical activity capable of generating this wide range of bursting oscillations. Unlike previously published models, bursting is driven by the interaction of two slow processes (I<subscript>s1</subscript> and I<subscript>s2</subscript> in <xref linkend="fig_cell_diagram" /> below), one with a relatively small time constant (1-5 seconds) and the other with a much larger time constant (1-2 minutes). Bursting on the intermediate time scale is generated without the need for a slow process having an intermediate time constant, hence phantom bursting. This mathematical model has been translated into a CellML description which can be downloaded in various formats as described in <xref linkend="sec_download_this_model" />.
</para>
<para>
The complete original paper reference is cited below:
</para>
<para>
<ulink url="http://www.biophysj.org/cgi/content/abstract/79/6/2880">The Phantom Burster Model for Pancreatic beta-Cells</ulink>, Richard Bertram, Joseph Previte, Arthur Sherman, Tracie A. Kinard and Leslie S. Satin, 2000, <ulink url="http://www.biophysj.org/">
<emphasis>Biophysical Journal</emphasis>
</ulink>, 79, 2880-2892. (<ulink url="http://www.biophysj.org/cgi/content/full/79/6/2880">Full text</ulink> and <ulink url="http://www.biophysj.org/cgi/reprint/79/6/2880.pdf">PDF</ulink> versions of the article are available for Journal Members on the Biophysical Journal website.) <ulink url="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11106596&dopt=Abstract">PubMed ID: 11106596</ulink>
</para>
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<caption>Schematic diagram of the pancreatic beta-cell plasma membrane showing the ionic currents captured by the phantom burster model.</caption>
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