| D | 1. <abbreviation> Symbol for Diopter; for dexter (right), the vitamin D potency of cod liver oil, multiples of which (5D, 100D, etc.) are used to designate the vitamin D potency of irradiated ergosterol (viosterol) or other substances; for deuterium; for dihydrouridine in nucleic acids; for diffusing capacity; for aspartic acid; dihydrouridine; diffusion coefficient (in italics). 2. <chemistry> Denotes a double bond, usually with a superscript to indicate position in a chain (d5); application of heat in a reaction (A B); absence of heat treatment (); distance between two atoms in a molecule; or position of a substituent located on the fourth atom from the carboxyl or other primary functional group (d); change (d); thickness (d); chemical shift in NMR (d). 3. <prefix> Prefix indicating a chemical compound to be dextrorotatory; should be avoided when (+) or (-) could be used. (21 Jun 2000) |
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| d & c | Dilatation and curettage, a minor operation in which the cervix is expanded enough (dilatation) to permit the cervical canal and uterine lining to be scraped with a spoon-shaped instrument called a curette (curettage). (12 Dec 1998) |
| D and C | This gynaecological procedure involves dilating the cervix (opening to the uterus) such that a surgical curette may be passed into the uterus. The surgeon uses the curette to remove the inner lining of the uterus (endometrium). This procedure is often performed to correct dysfunctional uterine bleeding. (27 Sep 1997) |
| D antigen | One of 6 antigens that compose the Rh locus. Antibody induced by D antigen is the most frequent cause of haemolytic disease of the newborn. (05 Mar 2000) |
| D cell | <pathology> (delta cells) Cells of the pancreas, about 5% of the cells present in primate pancreas with small argentaffin positive granules. Their function is unclear, but they may release somatostatin. (18 Nov 1997) |
| d cells | Cells found throughout the gastrointestinal tract and in the pancreas. They secrete somatostatin in both an endocrine and paracrine manner. Somatostatin inhibits gastrin, cholecystokinin, insulin, glucagon, pancreatic enzymes, and gastric hydrochloric acid. A variety of substances which inhibit gastric acid secretion (vasoactive intestinal peptide, calcitonin gene-related peptide, cholecystokinin, beta-adrenergic agonists, and gastric inhibitory peptide) are thought to act by releasing somatostatin. (12 Dec 1998) |
| d check | A comparison of consecutive values for a given test in a patient's laboratory file used to detect abrupt changes, usually generated as a part of computer-based quality control programs. Synonym: d check. (05 Mar 2000) |
| D enzyme | Dextrin transglycosylase or glycosyltransferase;a 4-glycosyltransferase converting maltodextrins into amylose and glucose by transferring parts of 1,4-glucan chains to new 4-positions on glucose or other 1,4-glucans. Synonym: amylomaltase, D enzyme, dextrin glycosyltransferase, dextrin transglycosylase, disproportionating enzyme. (05 Mar 2000) |
| D gene segment | <molecular biology> Diversity gene segment. Part of the gene for the immunoglobin heavy chain, it codes for part of the hypervariable region of the VH domain and is located between the VH and JH segments. There are probably about 20 different D segments. (18 Nov 1997) |
| d loop | <molecular biology> A structure that can sometimes be seen on DNA which forms when a small area of the double-stranded molecule comes apart and becomes two single strands. The result is a structure shaped like the letter D. Single-stranded binding proteins are usually present to hold the strands apart for the purpose of DNA replication. (09 Oct 1997) |
| D mannitol | <chemical> Hexitol related to D mannose. Found in plants, particularly fungi and seaweeds. (18 Nov 1997) |
| D mannose | <chemical> Hexose identical to D glucose except that the orientation of the H and OH on carbon 2 are interchanged (i.e. The 2 epimer of glucose). Found as constituent of polysaccharides and glycoproteins. (18 Nov 1997) |
| d valve | <mechanics> A kind of slide valve. See Slide valve, under Slide. Source: Websters Dictionary (01 Mar 1998) |
| D wave | A positive or negative deflection in the electroretinogram occurring when a light stimulus is removed (off-response). (05 Mar 2000) |
| D&C | <abbreviation> Dilation and curettage. (05 Mar 2000) |