gamma (redirected from Gamma (letter))

gamma /gam·ma/ (gam´ah)

1. third letter of the Greek alphabet, see also ?-.

2. obsolete equivalent for microgram.

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gam·ma (gm)

n.

1. Symbol The third letter of the Greek alphabet.

2. The third item in a series or system of classification.

3. The third position from a designated carbon atom in an organic molecule at which an atom or a radical may be substituted.

4. A unit of magnetic field strength equal to one hundred thousandth (10⁵) of an oersted.

5. A unit of mass equal to one millionth (10⁶) of a gram.

adj.

1. Relating to or being the atom or radical group that is in the third position relative to the functional group of atoms in an organic molecule.

2. Relating to or characterizing a polypeptide chain that is one of five types of heavy chains that may be present in immunoglobins.

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gamma (gyaˑ·m),

n Greek letter represented by γ. See also Greek letters.

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gamma

1. the third letter of the Greek alphabet, G or ?.

2. used in names of chemical compounds to distinguish one of three or more isomers or to indicate the position of substituting atoms or groups.

3. used in sensitometry to denote the straight line of a characteristic curve. The greater the film contrast the higher the gamma.

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gamma benzene hexachloride

see chlorinated hydrocarbons.

gamma delta T lymphocyte

see T lymphocyte.

gamma globulin

a class of plasma proteins composed almost entirely of immunoglobulins, the proteins that function as antibodies. Gamma globulins, immunoglobulins, antibodies and antiserum are often used synonomously and interchangeably. See also antibody.

Commercial preparations of gamma globulin are derived from blood serum of several species and are used for prevention, modification and treatment of various infectious diseases. This type of gamma globulin, which is an immune serum, contains a wide range of antibodies, depending on its method of production, and it provides passive immunity for several weeks. In cattle, its most common use is in the newborn orphan which receives no colostrum. In dogs and cats, it has been used in the prophylaxis, and occasionally treatment, of viral infections.

The production of gamma globulin may be increased in the body by the invasion of harmful microorganisms. An abnormal amount of gamma globulin in the blood, a condition known as hypergammaglobulinemia, may be indicative of a chronic infection or certain malignant blood diseases. There is also a rare inherited condition, agammaglobinemia, in which the body is unable to produce gamma globulin. Animals suffering from this condition are extremely susceptible to infection.

gamma glutamyl transferase (GGT)

see gamma glutamyl transferase.

gamma-aminobutyric acid (GABA)

an amino acid that is one of the principal inhibitory neurotransmitters in the central nervous system. GABA_A receptors open chloride channels and GABAB receptors are linked to potassium channels. Avermectins act by stimulating the presynaptic release of GABA and enhancing its binding to the postsynaptic receptors

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gamma γ Symbol for: 1. Heavy chain of immunoglobulin G–IgG 2. Hemoglobin monomeric chain 3. Photon 4. The 3^rd carbon in an aliphatic organic molecule Genetics A value calculated by the ratio between synonymous DNA mutations, which don't result in a different amino acid being translated from a codon, and nonsynonymous mutations–which result in a different amino acid being encoded Imaging A measure of contrast 1. Film–The slope of the density vs. exposure curve 2. Electronic display terminology–The slope of the brightness distribution curve; a large gamma indicates a steep slope and high contrast