The welter of molecular transformations of organic compounds that for the basis of living systems. Examples include the synthesis and degradation of proteins, lipids, polysaccharides, and nucleic acids, and the metabolism of various foodstuffs.

Biomarkers are characteristic biological properties that can be detected and measured in parts of the body like the blood or tissue. They may indicate either normal or diseased processes in the body. Biomarkers can be specific cells, molecules, or genes, gene products, enzymes, or hormones. Complex organ functions or general characteristic changes in biological structures can also serve as biomarkers. For example, body temperature is a well-known biomarker for fever. Blood pressure is used to determine the risk of stroke. It is also widely known that cholesterol values are a biomarker and risk indicator for coronary and vascular disease, and that C-reactive protein (CRP) is a marker for inflammation.

Heavy water is deuterium oxide, or D₂O or ²H₂O. It is chemically nearly the same as normal water, H₂O, but the hydrogen atoms are of the heavy isotope deuterium, in which the nucleus contains an neutron in addition to the proton found in the nucleus of any hydrogen atom. It therefore has an molecular weight of 20 a.m.u. compared to 18 for H₂O.

The biochemical steps that predispose to or culminate in a disease; the immediate biochemical fluxes or controlling processes that are responsible for a functional disorder (a clinical outcome). Can be proximal (early) or ultimate (late) in the biochemical genesis of a disease.

The flow of molecules through a series of biochemical steps (i.e. a pathway); expressed as a rate, in units of chemical mass/time.

In biochemistry, the rates at which molecular transformations occur; contrasted to statics, the study of systems at rest or at a single moment in time.

Instrumental method for identifying the chemical constitution of a substance by separating gaseous ions according to their differing mass and charge. In a mass spectrometer, atoms or molecules in a sample are ionized by an electron beam. The ions are accelerated by an electric field and then deflected by a powerful magnet. Different ions are deflected to different degrees depending on the mass and charge, allowing for measurement of abundances of different masses and therefore, isotopic enrichment of a sample.

A series of linked biochemical steps, with a beginning and an end; activity within a pathway takes the form of flux, or flow, of molecules; the network of pathways forms the biochemical repertoire or potential phenotypes of a biological system.

Isotopes of an element have the same atomic number, but different atomic mass. Stable isotopes do not undergo radioactive decay as radio-isotopes do. Elements can exist in both stable and unstable (radioactive) forms. Most elements of biological interest (including C, H, O, N, and S) have two or more stable isotopes, with the lightest of these present in much greater abundance than the others. Among stable isotopes the most useful as biological tracers are the heavy isotopes of hydrogen, carbon and nitrogen. These elements are found in the earth, the atmosphere, and all organisms.

Translational Medicine (TM) is the emerging field which focuses on using what is learned in pre-clinical studies to do smarter things in the clinic (either during drug development or in the course of predicting, preventing, diagnosing, and treating diseases). TM also uses what can be gleaned in clinical studies to sharpen and improve what is done in pre-clinical efforts to discover new medicines.p>

Highly sensitive mass spectrometers have been used to measure small differences in the ratio of isotopes in certain molecules to ascertain, for example, the isotopic enrichment of a stable isotope labeled biological sample.

Personalized Medicine (PM) embodies the concept of getting the right medicines to the right patients at the right doses. Over the last several decades, it has become apparent that patients with what would once have been considered the same illness (based on signs, symptoms, and older laboratory tests) may actually have very different underlying patho-physiology, associated with different likelihoods of disease progression and responses to different therapies. PM successfully optimizes pharmaceutical R&D to discover and advance medicines that build on an awareness of these heterogeneities.

Proof of Concept studies are clinical experiments intended to test the validity of a particular approach (drug target, compound, etc.) to produce benefit in a particular disease. POC studies are intended to increase the belief in an approach, are carried out during either Phase 1b or 2a, and are for internal decision making rather than for regulatory approval.