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In pharmacology, the international unit (IU) is a unit of measurement for the effect or biological activity of a substance, for the purpose of easier comparison across similar forms of substances. International units are used to quantify vitamins and biologics ( hormones , some medications , vaccines , blood products and similar biologically ...
The enzyme unit, or international unit for enzyme (symbol U, sometimes also IU) is a unit of enzyme's catalytic activity. [ 1 ] 1 U (μmol/min) is defined as the amount of the enzyme that catalyzes the conversion of one micro mole of substrate per minute under the specified conditions of the assay method .
International units (IU) are based on measured biological activity or effect, or for some substances, a specified equivalent mass. [ citation needed ] Enzyme activity ( kat ) is commonly used for e.g. liver function tests like AST , ALT , LD and γ-GT in Sweden.
The specific activity of an enzyme is another common unit. This is the activity of an enzyme per milligram of total protein (expressed in μmol min −1 mg −1).Specific activity gives a measurement of enzyme purity in the mixture.
High levels of rheumatoid factor (in general, above 20 IU/mL, 1:40, or over the 95th percentile; there is some variation among labs) occur in rheumatoid arthritis (present in 80%) and Sjögren's syndrome (present in 50-70% of primary forms of disease). [11] The higher the level of RF the greater the probability of destructive articular disease.
Virus quantification is counting or calculating the number of virus particles (virions) in a sample to determine the virus concentration. It is used in both research and development (R&D) in academic and commercial laboratories as well as in production situations where the quantity of virus at various steps is an important variable that must be monitored.
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Viral load is reported as copies of HIV RNA in a millilitre (mL) of blood. Changes in viral load are usually reported as a log change (in powers of 10). For example, a three log increase in viral load (3 log10) is an increase of 10 3 or 1,000 times the previously reported level, while a drop from 500,000 to 500 copies would be a three-log-drop ...