| Addison-Biermer disease | <haematology> A form of anaemia (low red blood cell counts) that results when the bone marrow fails to produce adequate numbers of red blood cells due to a deficiency in vitamin B12. Intrinsic factor, necessary for normal B12 absorption, may be the underlying cause for B12 deficiency if is not produced in the gastric glands (in the stomach). Origin: Gr. Haima = blood (27 Sep 1997) |
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| addisonian | Relating to or described by Thomas Addison; usually used in relation to pernicious anaemia (05 Mar 2000) |
| addisonian anaemia | <haematology> A form of anaemia (low red blood cell counts) that results when the bone marrow fails to produce adequate numbers of red blood cells due to a deficiency in vitamin B12. Intrinsic factor, necessary for normal B12 absorption, may be the underlying cause for B12 deficiency if is not produced in the gastric glands (in the stomach). Origin: Gr. Haima = blood (27 Sep 1997) |
| addisonian crisis | <endocrinology> An abrupt life-threatening state which is caused by insufficient production of cortisol by the adrenal gland. A typical finding in Addison's disease. Individuals who have been taking corticosteroids (glucocorticoids) for a prolonged period of time (weeks to months) are at risk for acute adrenal crisis if the medication is stopped abruptly. For this reason, corticosteroid medication are withdrawn slowly on a diminishing dosing schedule. Symptoms include low blood pressure (shock), weakness, headache, vomiting, fever chills, tachycardia and sweating. Treatment includes blood pressure support and intravenous hydrocortisone. See: addison's disease (15 Jan 1998) |
| addisonian syndrome | Adrenocortical insufficiency usually as the result of idiopathic atrophy or destruction of both adrenal glands by tuberculosis, an autoimmune process, or other diseases; characterised by fatigue, decreased blood pressure, weight loss, increased melanin pigmentation of the skin and mucous membranes, anorexia, and nausea or vomiting; without appropriate replacement therapy, it can progress to acute adrenocortical insufficiency. Synonym: Addison's disease, addisonian syndrome, hyposupradrenalism, morbus Addisonii. (05 Mar 2000) |
| addition | 1. The act of adding two or more things together; opposed to subtraction or diminution. "This endless addition or addibility of numbers." 2. Anything added; increase; augmentation; as, a piazza is an addition to a building. 3. <mathematics> That part of arithmetic which treats of adding numbers. 4. A dot at the right side of a note as an indication that its sound is to be lengthened one half. 5. A title annexed to a man's name, to identify him more precisely; as, John Doe, Esq.; Richard Roe, Gent.; Robert Dale, Mason; Thomas Way, of new York; a mark of distinction; a title. 6. Something added to a coat of arms, as a mark of honor; opposed to abatement. <geometry> Vector addition, that kind of addition of two lines, or vectors, AB and BC, by which their sum is regarded as the line, or vector, AC. Synonym: Increase, accession, augmentation, appendage, adjunct. Origin: F. Addition, L. Additio, fr. Addere to add. Source: Websters Dictionary (01 Mar 1998) |
| addition compound | Strictly, a complex of two or more complete molecules in which each preserves its fundamental structure and no covalent bonds are made or broken (e.g., hydrates of salts, adducts), loosely, association of acids with basic organic compound's (e.g., amines with HCl), more loosely, addition of two molecules without loss of any atom, but forming new covalent bonds (e.g., CH2==CH2 + Br2 → BrCH2-CH2Br). (05 Mar 2000) |
| addition mutation | <molecular biology> A type of mutation that results from insertion or deletion of a single nucleotide into, or from, an open reading frame in the normal DNA sequence. Normally, the genetic code is read in the wrong frame, three nucleotides at a time, and the entire sequence downstream of the mutation, is translated into a polypeptide with a garbled amino acid sequence from the mutated codon onwards. These mutations may be induced by certain types of mutagens or may occur spontaneously and usually result in the generation, downstream, of nonsense, chain termination codons. Synonym: addition mutation, addition-deletion mutation, deletion mutation, reading-frameshift mutation. (21 Jun 2000) |
| addition polymer | <chemistry> A polymer which is formed from the fusion of two monomers which join completely without losing any small molecules. (15 Jan 1998) |
| addition reaction | <chemistry> Any reaction in which two chemicals combine to form a single chemical. (15 Jan 1998) |
| addition-deletion mutation | <molecular biology> A type of mutation that results from insertion or deletion of a single nucleotide into, or from, an open reading frame in the normal DNA sequence. Normally, the genetic code is read in the wrong frame, three nucleotides at a time, and the entire sequence downstream of the mutation, is translated into a polypeptide with a garbled amino acid sequence from the mutated codon onwards. These mutations may be induced by certain types of mutagens or may occur spontaneously and usually result in the generation, downstream, of nonsense, chain termination codons. Synonym: addition mutation, addition-deletion mutation, deletion mutation, reading-frameshift mutation. (21 Jun 2000) |
| additional | Existing or coming by way of addition, added, further. (18 Nov 1997) |
| additive | 1. <chemistry> Characterised by addition. 2. A substance, as a flavouring agent, preservative or vitamin, added to another substance to improve its appearance, increase its nutritional value, etc. (18 Nov 1997) |
| additive effect | <biochemistry, chemistry> An additive effect is the overall biological effect two chemicals acting together and which is the simple sum of the effects of the chemicals acting independently. Compare: antagonism. (15 Jan 1998) |
| additive model | A model in which the combined effect of several factors is the sum of the effects that would be produced by each of the factors in the absence of the others. (05 Mar 2000) |