ILLUSTRATIVE PROBLEM DOMAINS AT THE INTERFACE OF COMPUTING AND BIOLOGY 323
More generally, Watkins et al. point out that the goal of nutritional improvement of agriculture—to
produce changes in crops and foods that provide health benefits to all—is difficult to achieve because
modifications of existing foodstuffs are likely to advantage some people while disadvantaging others.
Watkins et al. cite the example of recent attempts to increase the carotenoid content of the food supply—
a move that was thought to have protective value against certain cancers, especially lung cancer. In the
midst of this effort, it was found that high intakes of ß-carotene as a supplement actually increased the
incidence of lung cancer in smokers—and the move was abandoned.
The intellectual underpinning of this effort is thus metabolomics, the quantitative characterization
of the set of metabolites—generally small, nonprotein molecules—involved in the metabolism or a cell,
tissue, or organism over its lifetime. In the context of nutritional genomics, metabolomic studies attempt
to characterize the levels, activities, regulation, and interactions of all metabolites in an individual and
determine how this characterization changes in response to various foods that are consumed. Genomics
is important because genetic makeup is an important influence on the specific nature of the metabolomic
changes that result as a function of food consumption.
9.8 A DIGITAL HUMAN ON WHICH A SURGEON CAN OPERATE VIRTUALLY
A surgical act on a human being is by definition an invasive process, one that inflicts many insults
on the body. Prior to the advent of medical imaging techniques, surgeons relied on their general
knowledge of anatomy to know where and what to cut. Today’s imaging technologies provide the
surgeon with some idea of what to expect when he or she opens the patient.
At the same time, a surgeon in the operating room has no opportunity to practice the operation on
this particular patient. Experience with other patients with similar conditions helps immeasurably, of
course, but it is still not uncommon even in routine surgical operations to find some unexpected
problem or complication that the surgeon must manage. Fortunately, most such problems are minor
and handled easily. Surgeons-in-training operate first on cadavers and move to live patients only after
much practice and under close supervision.
Consider then the advantages that a surgeon might have if he or she were to be able to practice a
difficult operation before doing it on a live patient. That is, a surgeon (or surgeon-in-training) would
practice or train on a digital model of a human patient that incorporates static and dynamic physical
properties of the body in an operating room environment (e.g., under anesthesia, in real gravity) when
it is subject to surgical instruments.
In this environment, the surgeon would likely wear glasses that projected an appropriate image to
his or her retina and use implements that represented real instruments (e.g., a scalpel). Kinetic param-
eters of the instrument (e.g., speed, velocity, orientation) would be monitored and registered onto the
image that the surgeon sees. When “touched” by the instrument, the image would respond appropri-
ately with a change in shape and connectivity (e.g., when a scalpel touches a piece of skin, it might
separate into two parts and a cut would appear). Blood would emerge at realistic rates, and tissue under
the skin would appear.
Even in this very simple example, many challenges can be seen. To name just a few:
- Realistic modeling of body subsystems. From the perspective of a surgeon’s scalpel, the body is
simply a heterogeneous and spatially organized mass of tissue. Of course, this mass of tissue is func-
tionally a collection of subsystems (e.g., organs, muscle tissue, bone) that have different properties.
These subsystems must be separated so that the physiological responses of surgery are appropriately
propagated through them when surgery occurs. - Integration of person-specific information with a generic model of a human being. Because of the labor
involved in constructing a digital model of a human being, it makes sense to consider an approach in
which a model of a generic human being is developed and then adjusted according to person-specific
information of any given patient.