Page 145 - Visions of the Future Chemistry and Life Science

134 P. KOHL ET AL.

8.3.3 The tools
The Physiome Project’s in silico models are based on and validated against
solid experimental data. Much of the ‘input’ data is already available from
many decades of bio-medical research. More will follow and, with the
development of new experimental tools and technologies, the insight into
sub-cellular, genetic and molecular levels of biological activity is becom-
ing increasingly detailed. Virtual biological systems will be produced by
describing in great detail the constituent parts and their interrelation
according to the laws of conservation of energy, mass, and momentum.
Such models can be used to perform in silico experiments, for example
by monitoring the response of a system or its components to a defined
intervention. Model ‘output’ – predictions of biological behaviour – is then
validated against in vitro or in vivo data from the real world.
A confirmation of the modelling-derived predictions would allow the
performance of new in silico experiments, either with a higher degree of
confidence or at a higher level of functional integration. Rejection of model
output would help to pinpoint where the model needs refinement, either by
providing new input data, or by direct model improvement. Subsequently,
the in silico experiment could be repeated with a higher degree of confi-
dence, until the model satisfactorily reflects the tested aspect of reality.
This is a steady iterative process between the virtual organ and the real
thing. Its prime objectives are the development of our understanding of a
biological system like the heart, and the improvement of its in silico
description. Through this multiple iteration, virtual organ models mature
towards a tool that can be used with a high degree of confidence for
research, development or clinical applications by scientists and doctors
who do not need to be specialists in model development or validation.

8.4 The virtual heart 1

8.4.1 Science or fiction?
. . . A patient who recently recovered from a minor heart attack is suffering
from periods of ectopic ventricular beats, originating from what is believed to
be a small area of post-ischaemic fibrosis in the free wall of the left ventricle.

11 This section will contain some of the more technical aspects of bio-mathematical
modelling (in-depth information can be found in Kohl et al. 2000). The subsequent section
on ‘The utility of virtual organs’ will address more general aspects that can be appreciated
without knowledge of the detail presented next.