(From Wikipedia, the free encyclopedia)
IC50, the half maximal inhibitory concentration, represents the concentration of an inhibitor that is required for 50% inhibition of things like an enzyme, a cell, a cell receptor or a microorganism.
It's commonly used as a measure of drug effectiveness. Another measure of drug efficacy is EC50 which represents the concentration of a compound that is required to obtain 50% of the maximum effect. (Ex. EC100 would be the minimum concentration of a compound to obtain 100% of its effect).
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ED50
（From Wikipedia, the free encyclopedia）
ED 50 (European Datum 1950) is a geodetic datum which was defined after World War II for the international connection of geodetic networks.
Some of the important battles of World War II were fought on the borders of Germany, the Netherlands, Belgium and France, and the mapping of these countries had incompatible latitude and longitude positioning. This led to the setting up of ED50 as a consistent mapping datum for much of Western Europe. It was, and still is, used in much of Western Europe apart from Great Britain, Ireland, Sweden and Switzerland, which have their own datums.
It was based on the international Ellipsoid of 1909 resp. 1924 ("Hayford"-Ellipsoid) ( radius of the Earth's equator 6378,388 km, flattening 1:297) and widely used all over the world up to the 1980s, when GRS80 and WGS84 were established.
Many national coordinate systems of Gauss-Krüger are defined by ED50 and oriented by means of Geodetic Astronomy. Up to now it has been used in data bases of gravity field, cadastre, small surveying networks in Europe and America, and by some developing countries with no modern baselines.
The geodetic datum of ED50 is centred at the Frauenkirche of Munich in Southern Germany, where the approximate centre of the Western Europe national networks was situated in the years of the cold war. ED50 was also part of the fundamentals of the NATO coordinates (Gauss Krüger and UTM) up to the 1980s.
Datum shift between ED50 and WGS84
The longitude and latitude lines on the two datums are the same in the Archangel region of north-west Russia. As one moves westwards across Europe, the longitude lines on ED50 gradually become further west than their WGS84 equivalents, and are around 100 metres west in Spain and Portugal. Moving southwards, the latitude lines on ED50 gradually become further south than the WGS84 lines, and are around 100 m south in the Mediterranean Sea. (NB. If the lines are further west, the longitude value of any given point becomes more easterly. Similarly, if the lines are south, the values become northerly.)
The datum shift for the Universal Transverse Mercator grid is different. The eastings vary between 0 m in Eastern Europe and 100 m in the far west of the continent, roughly similar to the longitude shift, but the northings are about 200 m different across Europe, with the ED50 UTM northing lines south of the WGS84 UTM northing lines, as UTM northings are measured from the Equator, and the theoretical ED50 Equator is about 200 m south of the WGS84 one.
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LD50
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For other uses, see LD50 (disambiguation).
An LD50 test being administeredIn toxicology, the LD50 or colloquially semilethal dose of a particular substance is a measure of how much constitutes a lethal dose. The test was created by J.W. Trevan in 1927. In animal testing studies, and those of other organisms, the dose administered that kills half the test population is referred to as the LD50, for "Lethal Dose, 50%".
Animal-rights and animal-welfare groups have campaigned against LD50 testing on animals in particular, citing it as cruel and unnecessary, and in the case of some substances, causing the animals to die slow, painful deaths. Several countries, including the UK, have taken steps to ban the oral LD50, and the Organization for Economic Co-operation and Development (OECD) abolished the requirement for the oral test in 2001 (see Test Guideline 401, Trends in Pharmacological Sciences Vol 22, February 22, 2001).
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ASTM American Standard of Testing and Materialsls
AFNOR French Association of Standardization
bioindicator a bioindicator indicates biological or animal species which, because of their ecological characteristics, constitute the early index of biotic or abiotic modifications of the environment due to human activities (ex: lichen).
Biomarquor a biomarquor is a parameter (bio)chimic whose measurement reflects the interaction between a biological system and an environmental agent.
DIN Deutsches Institut für Normung
ECx Concentration having an effect on x% of the population compared to control
EC50 " Effect Concentration 50% " or concentration having 50% of effect compared to control
IC50 " Inhibition Concentration 50% " or concentration inhibiting of 50% a parameter like the growth or luminescence compared to control
ISO International Standardization Organization
LCx concentration having caused the death of X% of the population tested compared to control
LC50 concentration having caused the death of 50% of the population tested compared to control
LD50 " Lethal Proportions 50% " or proportions having caused the death of 50% of the population tested.
LOEC " Low Observed Effect Concentration " or concentration with a very weak observable effect. It is about the lowest concentration for which the effect is different from that of controls. It is the first concentration tested after the NOEC.
NOEC " No Observed Effect Concentration " or concentration without observable effect. It is about the highest concentration tested for which the effect is significantly not different from controls
OECD Organisation for Economic Cooperation and Developement
Toxicity Self capacity of a substance to cause harmful effects on living organisms
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其实IC50的计算包括很多方法，有正态概率转换法，有寇氏法，有序贯法，还有最为准确的加权直线法。不同的方法都对实验设计有不同要求的，要根据具体情况而使用。
但是对于您的实验来说，应当具体情况具体分析，因为不同方法的要求有所差异，对于我来说寇氏改良法比较适合，而IC50计算软件尽管方便，但是没有人提供该软件的确切理论依据，我不敢使用。还有，个人认为做直线回归求IC50不太好，因为实验结果并非总是如您所料，有时候很难做出一条满意的直线来。
转载请注明：转载自《散人笔记》[http://www.eryi.org/blog/]
