Half-life, biological
The biological half-life or elimination half-life of a substance is the time it takes for a substance (for example a metabolite, drug, signalling molecule, radioactive nuclide, or other substance) to lose half of its pharmacologic, physiologic, or radiologic activity, as per the MeSH definition. In a medical context, half-life may also describe the time it takes for the blood plasma concentration of a substance to halve (plasma half-life) its steady-state. The relationship between the biological and plasma half-lives of a substance can be complex depending on the substance in question, due to factors including accumulation in tissues, active metabolites, and receptor interactions.
Biological half-life is an important pharmacokinetic parameter and is usually denoted by the abbreviation \scriptstyle t_\frac{1}{2}.
While a radioactive isotope decays perfectly according to first order kinetics where the rate constant is fixed, the elimination of a substance from a living organism, into the environment, follows more complex kinetics. See the article rate equation.

This is an excerpt from the article Half-life, biological from the Wikipedia free encyclopedia. A list of authors is available at Wikipedia.
The article Half-life, biological at en.wikipedia.org was accessed 13 times in the last 30 days. (as of: 11/10/2013)
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Biological half-life - Wikipedia, the free encyclopedia
The biological half-life or elimination half-life of a substance is the time it takes for a substance (for example a metabolite, drug, signalling molecule, radioactive ...
en.wikipedia.org/wiki/Biological_half-life
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Half-life - definition from Biology-Online.org
Definition and other additional information on Half-life from Biology-Online.org dictionary.
www.biology-online.org/dictionary/Half-life
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Effective half-life - Wikipedia, the free encyclopedia
Effective half-life is a concept used in pharmacokinetics to reflect the rate of accumulation or elimination of a biochemical or pharmacological substance in an  ...
en.wikipedia.org/wiki/Effective_half-life
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Biological Half-life - HyperPhysics
For a number of radioisotopes of particular medical interest, the rate of excretion has been cast in the form of an effective biological half-life. The rate of decrease ...
hyperphysics.phy-astr.gsu.edu/hbase/nuclear/biohalf.html
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biological half-life - The Free Dictionary
However, in certain indications, some of their features can be detrimental: stimulation of the immune system via the antibody effector region; bivalent binding or ...
www.thefreedictionary.com/biological+half-life
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Biological half life - The Free Dictionary
Definition of Biological half life in the Online Dictionary. Meaning of Biological half life. Pronunciation of Biological half life. Translations of Biological half life.
www.thefreedictionary.com/Biological+half+life
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half-life - definition of half-life by the Free Online Dictionary ...
Physics The time required for half the nuclei in a sample of a specific isotopic species to undergo radioactive decay. 2. Biology. a. The time required for half the  ...
www.thefreedictionary.com/half-life
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Biological Half-Life - Medical Dictionary - The Free Dictionary
half-life (haf´līf) the time required for the decay of half of a sample of particles of a radionuclide or elementary particles; symbol t 1/2 or T 1/2.
medical-dictionary.thefreedictionary.com/Biological+Half-Life
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NRC: Glossary -- Biological half-life
Biological half-life. The time required for a biological system, such as that of a human, to eliminate, by natural processes, half of the amount of a substance ( such ...
www.nrc.gov/reading-rm/basic-ref/glossary/biological-half-life.html
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Biological half life - Dictionary.com
Physics. the time required for one half the atoms of a given amount of a radioactive substance to disintegrate. 2. Also called biological half-life. Pharmacology.
dictionary.reference.com/browse/biological+half+life
Search results for "Half-life, biological"
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Half-life, biological in science
[PDF]The Biological Half-Life of Software Engineering Ideas
Philippe Kruchten □ University of British Columbia □ kruchten@ieee.org. The Biological. Half-Life of Software. Engineering Ideas. Philippe Kruchten.
Tritium page - Physics Department - Idaho State University
In addition, due to the relatively long half life and short biological half life, an intake of tritium must be in large amounts to pose a significant health risk. Although ...
a biological alternative to PEGylation for extending the plasma half ...
Jun 10, 2013 ... PASylation: a biological alternative to PEGylation for extending the plasma half-life of pharmaceutically active proteins. Martin Schlapschy1,; Uli Binder2, ... Published by Oxford University Press. This is an Open Access article ...
Biological half-life of cadmium in the urine of inhabitants after ...
We investigated the biological half-life of the urinary cadmium concentration (U- Cd) based on a 24-year follow-up study after cessation of cadmium exposure in ...
The half-life of DNA in bone: measuring decay kinetics in 158 dated ...
Oct 10, 2012 ... 1Ancient DNA Laboratory, School of Biological Sciences and Biotechnology, Murdoch University, 90 South Street, Perth, Western Australia ...
The use of half-lives and associated confidence intervals in ...
The use of half-lives and associated confidence intervals in biological research ... Microbiology and Preventive Medicine, Iowa State University, 50011, Ames, ...
Journal Ranking - Biological Sciences - The University of Auckland ...
The Cited Half-life of a journal is the calculated point (or age) in years, above which 50% of the citations to the journal are ...
Dinosaur Soft Tissue is Original Biological Material | Bob Enyart Live
Famed paleontologist Jack Horner of Montana State University worked the ... Carbon 14 everywhere including in dinosaur bones - the 521-year half-life of DNA ...
[PDF]Biological half-life of normal and truncated human IgG3 in scid mice
half-life of non-truncated, normal serum IgG3 as well as the chimeric antibody was about 7 ... were obtained from Stanford University, Stanford, CA, courtesy of  ...
Biology | College of Agricultural and Life Sciences – University of ...
There are over 1000 students in the Biology Major, about half in the College of Agriculture ... It will prepare you for jobs in laboratories in universities or industry.
Books on the term Half-life, biological
Medical Physics: Imaging
Medical Physics: Imaging
Jean A. Pope, 1999
Tc is the average time taken for half the radioactive material to be removed from the body by both processes together. It is also possible to define a biological half-life Tb as the time taken for biological processes to remove half the available ...
Biological Safety: Principles and Practices (Biological Safety: Principles & Practices)
Biological Safety: Principles and Practices (Biological Safety: Principles & Practices)
Diane O. Fleming and Debra L. Hunt, 2006
Comprehensive coverage of the identification, assessment, and management of biological hazards. • Presents the essentials for a complete biological safety program, with specific advice on management and implementation issues. • Covers the identification, assessment, and management of hazardous biological agents and toxins. • Updates information on ...
ECOTOX: Ecological Modelling and Ecotoxicology
ECOTOX: Ecological Modelling and Ecotoxicology
L.A. Jørgensen, S.N. Nielsen, S.E. Jorgensen, 2012
Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life Biological half-life ...
Effects of Atomic Radiation: A Half-Century of Studies from Hiroshima and Nagasaki
Effects of Atomic Radiation: A Half-Century of Studies from Hiroshima and Nagasaki
William J. Schull, 1995
Presenting a monumental achievement: 50 years of data cataloging the immediate, long-term, and hereditary effects of atomic radiation on the survivors of the Hiroshima and Nagasaki bombs. Authored by one of the key members of the Atomic Bomb Casualty Commission founded in 1947, this unique work documents the critical findings and conclusions of the...
Comprehensive Handbook of Iodine: Nutritional, Biochemical, ...
Comprehensive Handbook of Iodine: Nutritional, Biochemical, ...
Victor R. Preedy, Gerard N. Burrow, Ronald Ross Watson, 2009
These measurements provided sufficient information so that the biological half-life of iodine could be calculated. The average biological half-life of I in 26 euthyroid (normal) subjects was found to be 66.1 ± 6.3 days, which may be statistically ...
The China Study: The Most Comprehensive Study of Nutrition Ever Conducted And the Startling Implications for Diet...
The China Study: The Most Comprehensive Study of Nutrition Ever Conducted And the Startling Implications for Diet...
T. Colin Campbell, Thomas M. Campbell II, Howard Lyman and John Robbins, 2006
Even today, as trendy diets and a weight-loss frenzy sweep the nation, two-thirds of adults are still obese and children are being diagnosed with Type 2 diabetes, typically an “adult” disease, at an alarming rate. If we’re obsessed with being thin more so than ever before, why are Americans stricken with heart disease as much as we were 30 years ag...
Lewis' Dictionary of Toxicology
Lewis' Dictionary of Toxicology
Robert Alan Lewis, 1998
2: radioactive half-life; the time required for half of me atoms of a radioactive element to undergo decay. See also effective half-life, physical half-life, atmospheric half-life. half- life of a specified substance (e.g., a specified air pollutant, vapor, ...
Life After Doomsday
Life After Doomsday
Bruce Clayton, 1992
Bruce Clayton is a well-known survival expert, author of Life After Doomsday, Fallout Survival and Thinking About Survival, coauthor of Survival Books and Urban Alert, and former publisher of The Survivalist Directory. Dr. Clayton is a state-certified instructor of radiological defense techniques and fallout shelter management in California and has...
Counter-Terrorism for Emergency Responders, Second Edition
Counter-Terrorism for Emergency Responders, Second Edition
Robert Burke, 2006
Additionally, radioactive iodine decays quickly (8 day half-life) so it would be difficult for a terrorist to use. Rates at which radioactive isotopes are eliminated from the body are expressed as the biological half-life. That is the time it takes ...
Fusion Protein Technologies for Biopharmaceuticals: Applications and Challenges
Fusion Protein Technologies for Biopharmaceuticals: Applications and Challenges
Stefan R. Schmidt, 2013
The state of the art in biopharmaceutical FUSION PROTEIN DESIGNFusion proteins belong to the most lucrative biotech drugs—with Enbrel® being one of the best-selling biologics worldwide. Enbrel® represents a milestone of modern therapies just as Humulin®, the first therapeutic recombinant protein for human use, approved by the FDA in 1982 and Orthoc...
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Blog posts on the term
Half-life, biological
What is “Biological half-life” ? - LifeSun
Biological half-life The biological half-life or elimination half-life of a substance is the time it takes for a substance to lose half of its pharmacologic, physiologic, or radiologic activity, as per
lifesun.info/what-is-biological-half-life/
P-force com: Biological Half- life How long does it take Tritace to leave the system? Nursing responsibilities for Tritace. ATC CODE: C09AA05. Other medications containing ramipril.
crap!!! how did i miss this jewel of? a game! i Always tought about a game that had city-building and a good combat system in one, but i never found it. until i saw this.
p-force-com.blogspot.com/2013/10/biological-half-life-how-long-does-it.html
Phosphorylation of the Cryptochrome 1 C-terminal Tail Regulates Circadian Period Length
www.jbc.org/content/288/49/35277.abstract
EJNMMI Research | Full text | Synthesis and biological characterisation of 18F-SIG343 and 18F-SIG353, novel and high selectivity ¿2 radiotracers, for tumour imaging properties
Sigma2 (σ2) receptors are highly expressed in cancer cell lines and in tumours. Two novel selective 18F-phthalimido σ2 ligands, 18F-SIG343 and 18F-SIG353, were prepared and characterised for their potential tumour imaging properties.
www.ejnmmires.com/content/3/1/80
Biological evolution is simply slow motion creationism | Louis Hissink's Crazy World
Just thought of it, so it's noted here for posterity. Update: Apostrophe added
fgservices1947.wordpress.com/2013/11/10/biological-evolution-is-simply-slow-motion-creationism/
Genome Biology | Full text | Short RNA half-lives in the slow-growing marine cyanobacterium Prochlorococcus
RNA turnover plays an important role in the gene regulation of microorganisms and influences their speed of acclimation to environmental changes. We investigated whole-genome RNA stability of Prochlorococcus, a relatively slow-growing marine cyanobacterium doubling approximately once a day, which is extremely abundant in the oceans.
genomebiology.com/content/11/5/R54
Medical Radiation Resources: 1. What is the 'Effective Half Life'?
medradresource.blogspot.com/2012/11/1-what-is-effective-half-life.html
Journal of Biological Engineering | Full text | The Bacillus BioBrick Box: generation and evaluation of essential genetic building blocks for standardized work with Bacillus subtilis
Standardized and well-characterized genetic building blocks are a prerequisite for the convenient and reproducible assembly of novel genetic modules and devices. While numerous standardized parts exist for Escherichia coli, such tools are still missing for the Gram-positive model organism Bacillus subtilis. The goal of this study was to develop and thoroughly evaluate such a genetic toolbox.
www.jbioleng.org/content/7/1/29
Biology Direct | Full text | How stands the Tree of Life a century and a half after The Origin?
We examine the Tree of Life (TOL) as an evolutionary hypothesis and a heuristic. The original TOL hypothesis has failed but a new
www.biologydirect.com/content/6/1/32
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