| ICD-O | International Classification of Disease for Oncology |
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| ICD-9 | International Classification of Disease, 9th Revision |
| ICD9CM | International Classification of Diseases 9th Revision Clinical Modification |
| ICD-9 CM | International Classification of Diseases, Ninth Revision, Clinical Modification |
| ICD-9 | International Classification of Disease, ninth revision |
| natural mutation | A mutation which occurs by itself without first being affected by a mutagen, for example during the process of DNA replication. Spontaneous mutations arise at a remarkably constant rate. The rate that spontaneous mutations arise has been used as an evolutionary clock to estimate how closely related two (or more) separate species are to each other. (09 Oct 1997) |
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| natural passive immunity | Immunity conferred by the mother on the foetus or newborn. (14 Nov 1997) |
| natural pigment | A naturally occurring coloured compound; absorbs light in the visible range of the electromagnetic spectrum. Compare: structural colour. Synonym: biochrome. (05 Mar 2000) |
| natural products | Naturally occurring compounds that are end products of secondary metabolism; often, they are unique compounds for particular organisms or classes of organisms. (05 Mar 2000) |
| natural selection | The hypothesis that genotype environment interactions occurring at the phenotypic level lead to differential reproductive success of individuals and hence to modification of the gene pool of a population. (18 Nov 1997) |
| immunity, natural | The capacity of a normal organism to remain unaffected by microorganisms and their toxins. It results from non-specific mechanisms such as genetic endowment, naturally occurring antiviral and bactericidal substances, phagocytosis, and constitutional factors such as body temperature, oxygen tension, and age. (12 Dec 1998) |
| killer cells, natural | Cells responsible for spontaneous cytotoxicity of a variety of tumour cells without prior immunization. These natural killer cells are found in non-immune humans and experimental animals and are thought by some to be the same as killer cells (killing by antibody-dependent cell cytotoxicity), but they can also kill in the absence of antibody. (12 Dec 1998) |
| adansonian classification | The classification of organisms based on giving equal weight to every character of the organism; this principle has its greatest application in numerical taxonomy. Origin: M. Adanson (05 Mar 2000) |
| Angle's classification of malocclusion | A classification of different types of malocclusion, based on the mesiodistal relationship of the permanent molars upon their eruption and locking, and comprised of three classes; Class I: normal relationship of the jaws, wherein the mesiobuccal cusp of the maxillary first molar occludes in the buccal groove of the mandibular first permanent molar; Class II: distal relationship of the mandible, wherein the distobuccal cusp of the maxillary first permanent molar occludes in the buccal groove of the mandibular first molar, and further classified as Division 1, labioversion of maxillary incisor teeth, and Division 2, linguoversion of maxillary central incisors, both of which may be unilateral conditions; Class III: mesial relationship of the mandible, wherein the mesiobuccal cusp of the maxillary first molar occludes in the embrasure between the mandibular first and second permanent molars, further classified as a unilateral condition. (05 Mar 2000) |
| aortic dissection: classification | <radiology> DeBakey: I ascending aorta to arch with or without descending aorta (30%), II ascending aorta only (20%), III descending aorta to thoracic aorta (50%), Stanford: A involvement of ascending aorta (regardless of origin), B aortic arch and distal aorta see also: aetiology mnemomics: 1 A.D. (DeBakey), A = Ascending (12 Dec 1998) |
| Arneth classification | A classification of the polymorphonuclear neutrophils according to the number of their nuclear lobes. See: Arneth stages. (05 Mar 2000) |
| artificial classification | <zoology> Classification based on convenient or conspicuous diagnostic characters without attention to characters indicating relationship, often a classification based on a single arbitrarily chosen character, rather than an evaluation of the totality of characters. (09 Jan 1998) |
| Black's classification | A classification of cavities of the teeth based upon the tooth surface(s) involved. (05 Mar 2000) |
| Caldwell-Moloy classification | A classification of the variations in the female pelvis; namely gynecoid, android, anthropoid, and platypelloid pelvis, based on the type of the posterior and anterior segments of the inlet. (05 Mar 2000) |
| Galton's system of classification of fingerprints | A system of classification based on the variations in the patterns of the ridges, which are grouped into arches, loops, and whorls (A.L.W. Or arch-loop-whorl system). "Arches are formed when the ridges run from one side to the other of the bulb of the digit, without making any backward turn, but no twist; whorls, when there is a turn through at least one complete circle; they are also considered to include all duplex spirals." The abbreviations used in making a record of fingerprint's are: a, arch; l, loop; w, whorl; i, loop with an inner (thumb side) slope; o, loop with an outer (little-finger side) slope. The ten digits are registered in four groups as follows, distinguished by capital letters: A, the fore, middle, and ring fingers of the right hand; B, the fore, middle, and ring fingers of the left hand; C, the thumb and little finger of the right hand; D, the thumb and little finger of the left hand. See: dermatoglyphics. (05 Mar 2000) |