Biomedical Engineering Reference
In-Depth Information
Prediscovery : understanding the disease and choosing a valid target molecule .
In contrast to the old trial-and-error routines, nowadays the process starts with a clear
understanding of the disease on a molecular level. Based on studies showing associa-
tions between biological mutations and disease states, pharmaceutical researchers
formulate hypotheses about the action mechanisms involved—they study how genes
have changed, how these changes affect the proteins encoded by the genes, how those
proteins interact with each other in living cells, how the affected cells change the
specifi c tissue they are in, and how all these processes combine to affect the patient.
Once scientists develop a good understanding of the underlying causes and
pathways of a disease, a biological target for a potential new medicine is chosen.
A biological target is most often a biomolecule (e.g., a gene or a protein), which is
involved in that particular disease and can be modulated by a drug. For example, the
focus in understanding autoimmune diseases such as cancer and HIV/AIDS is on
discovering the proteins that affect the human immune system. The latest advances
in genetics , genomics , and proteomics (studies of human genes and proteins) are
employed in the process. Complicated experiments in living cells as well as tests on
experimental animals are conducted to demonstrate that a particular target is rele-
vant to the studied disease.
Drug discovery : fi nding promising leads for a drug candidate . Having developed a
good understanding of the disease and its mechanism, scientists start looking for a
drug. They search for a lead compound (an organic or other drug molecule) that
may act on the target to alter the disease course, for example by inhibiting or stimu-
lating the functions of the target biomolecule. If successful, the lead compound can
ultimately become a new medicine.
Scientists turn to nature (plants, animals, or microorganisms) to fi nd interesting
compounds for fi ghting the disease. Microbes or bacteria, cells, tissues, and sub-
stances naturally produced by living organisms, or existing biological molecules can
be used as a starting point, and then modifi ed. An increasingly promising and fl ex-
ible set of possibilities is furnished by the advancements in biotechnology , whereby
scientists can genetically engineer living systems to produce disease-fi ghting bio-
logical molecules. 5 Rich drug source options are also provided by combinatorial
chemistry , or the rapid actual or virtual synthesis of a large number of different but
structurally related molecules. It enables the quick generation of new molecules to
augment the chemical diversity of known molecule libraries. The method of high -
throughput screening is the most common way for screening the already existing
vast libraries to fi nd those compounds that can modify the chosen target without
affecting any off-target molecules. Advances in biorobotics, bioinformatics, and
5 If the medical drugs are created by biological processes, rather than being chemically synthe-
sized, they are referred to as biopharmaceuticals or biologics . Recombinant DNA technology
( rDNA ), whereby scientists are bringing together genetic material from multiple sources to create
sequences that may not otherwise be found in biological organisms (e.g., joining plant DNA with
bacterial DNA), is often the technology used to derive them. Pioneered by Genentech, this is the
main method for obtaining insulin nowadays, having replaced the animal sources previously used
in the process. The technology has found many other applications—e.g., in HIV diagnosis, for the
creation of growth hormones or blood-clotting proteins.
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