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A biomarker, or biological marker, generally refers to a measurable indicator of some biological state or condition. The term occasionally also refers to a substance whose presence indicates the existence of living organisms.
Biomarkers are often measured and evaluated to examine normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. Biomarkers are used in many scientific fields.
The use of the term "biomarker" has been dated back to as early as 1980. In 1998, the National Institutes of Health Biomarkers Definitions Working Group defined a biomarker as “a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.”
In medicine, a biomarker can be a traceable substance that is introduced into an organism as a means to examine organ function or other aspects of health. For example, rubidium chloride is used as a radioactive isotope to evaluate perfusion of heart muscle. It can also be a substance whose detection indicates a particular disease state, for example, the presence of an antibody may indicate an infection. More specifically, a biomarker indicates a change in expression or state of a protein that correlates with the risk or progression of a disease, or with the susceptibility of the disease to a given treatment.
Biochemical biomarkers are often used in clinical trials, where they are derived from bodily fluids that are easily available to the early phase researchers. A useful way of finding genetic causes of diseases such as schizophrenia has been the use of a special kind of biomarker called an endophenotype.
Other biomarkers can be based on measures of the electrical activity of the brain (using Electroencephalography or Magnetoencephalography), or volumetric measures of certain brain regions (using Magnetic resonance imaging) or saliva testing of natural metabolites, such as saliva nitrite, a surrogate marker for nitric oxide.
One example of a commonly used biomarker in medicine is prostate-specific antigen (PSA). This marker can be measured as a proxy of prostate size with rapid changes potentially indicating cancer.
In cell biology, a biomarker is a molecule that allows the detection and isolation of a particular cell type (for example, the protein Oct-4 is used as a biomarker to identify embryonic stem cells).
In genetics, a biomarker (identified as genetic marker) is a DNA sequence that causes disease or is associated with susceptibility to disease. They can be used to create genetic maps of whatever organism is being studied.
Geology and astrobiology
A biomarker can be any kind of molecule indicating the existence, past or present, of living organisms. In the fields of geology and astrobiology, biomarkers, versus geomarkers, are also known as biosignatures. The term biomarker is also used to describe biological involvement in the generation of petroleum.
Biomarkers are used to indicate an exposure to or the effect of xenobiotics which are present in the environment and in organisms. The biomarker may be an external substance itself (e.g. asbestos particles or NNK from tobacco), or a variant of the external substance processed by the body (a metabolite) that usually can be quantified. (See also: Bioindicator.)
- Biomarker discovery
- Biomarkers (journal)
- Biomarker insights - a journal
- Molecular marker
- Saliva testing
- Aronson, Jeffrey (2005). "Biomarkers and surrogate endpoints". British Journal of Clinical Pharmacology 59 (5): 491–494. doi:10.1111/j.1365-2125.2005.02435.x. PMC 1884846. Retrieved 17 July 2013.
- Strimbu, Kyle; Jorge, Tavel (2010). "What are Biomarkers?". Current Opinion in HIV and AIDS 5 (6): 463–466. doi:10.1097/COH.0b013e32833ed177. PMC 3078627. PMID 20978388. Retrieved 17 July 2013.
- "Biomarkers and surrogate endpoints: preferred definitions and conceptual framework.". Clinical Pharmacology & Therapeutics 69 (3): 89–95. 2001. doi:10.1067/mcp.2001.113989. PMID 11240971. Retrieved 17 July 2013.
- Biomarkers for Psychiatric Disorders. Publisher: Springer U.S. doi:10.1007/978-0-387-79251-4 Copyright: 2009 ISBN 978-0-387-79250-7 (Print) 978-0-387-79251-4 (Online)
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