| TCH | tanned-cell hemagglutination; thiophen-2-carboxylic acid hydrazide; total circulating hemoglobin; tu... |
|---|---|
| TCR | T-cell reactivity; T-cell receptor; T-cell rosette; thalamocortical relay; total cytoplasmic ribosom... |
| TEF | Tracheo-Esophageal Fistula ? Tx 1. Infant Warmer ... |
| BD | barbital-dependent; barbiturate dependence; base deficit; base of prism down; basophilic degeneratio... |
| CAGE | cut down, annoyed by criticism, guilty about drinking, eye-opener drinks (a test for alcoholism) |
| down promoter mutation | <molecular biology> A mutation (a change in base pair sequence) in a promoter region, this results in lower gene expression (less transcription of the gene occurs). (09 Oct 1997) |
|---|---|
| down-regulation | <physiology> Development of a refractory or tolerant state consequent upon repeated administration of a pharmacologically or physiologically active substance. It is the process that decreases ligand and receptor interactions or reduces the responsiveness of a cell to a stimulus following first exposure. This is often accompanied by an initial decrease in affinity of receptors for the agent and a subsequent reduction in the number of available receptors expressed on the surface which can result from internalisation of the ligand:receptor complex or from decreased expression of the receptor. Classically the concept referred to hormone receptors but contemporary usage includes other cell surface receptors. (03 Jul 1999) |
| Down's syndrome | <genetics, syndrome> A congenital disorder in which a person is born with three copies of chromosome 21 (trisomy 21). Clinical features include moderate to severe mental retardation, slanting eyes, a broad short skull, broad hands and short fingers. Other congenital abnormalities include heart defects, oesophageal atresia and an increased incidence of acute lymphocytic leukaemia. Trisomy 21 can be detected in the first few months of pregnancy by amniocentesis. Risk factors include prior child with Down's syndrome and mothers who become pregnant after age 40. This disorder was formerly known as mongolism. Incidence: 1 in 1000 births. (09 Oct 1997) |
| down syndrome | <radiology> Trisomy 21, mongolism, atlantoaxial subluxation, Wormian bones, absent/small paranasal sinuses, endocardial cushion (AV canal) defects, aberrant right subclavian artery, 2 ossification centres for manubrium (90%), 11 or 13 ribs, duodenal atresia / stenosis, tracheo-oesophageal fistula, Hirschsprung disease (12 Dec 1998) |
| let-down reflex | <neurology, paediatrics> An involuntary reflex during breast feeding which causes the milk to flow freely. See: milk-ejection reflex (22 Sep 2002) |
| absolute terminal innervation ratio | The number of motor endplates divided by the number of terminal axons related to them. (05 Mar 2000) |
| accommodative convergence-accommodation ratio | The amount of convergence (measured in prism diopters of convergence) divided by the amount of accommodation (measured in diopters) required to direct both eyes upon an object. (05 Mar 2000) |
| A/G ratio | <abbreviation> Albumin-globulin ratio. (05 Mar 2000) |
| albumin-globulin ratio | The ratio of albumin to globulin in the serum or in the urine in kidney disease; the normal ratio in the serum is approximately 1.55. (05 Mar 2000) |
| ALT:AST ratio | The ratio of serum alanine aminotransferase to serum aspartate aminotransferase; elevated serum levels of both enzymes characterise hepatic disease; when both levels are abnormally elevated and the ALT:AST ratio is greater than 1.0, severe hepatic necrosis or alcoholic hepatic disease is likely; when the ratio is less than 1.0, an acute non-alcoholic hepatic condition is favoured. (05 Mar 2000) |
| amylase-creatinine clearance ratio | A test for the diagnosis of acute pancreatitis; it is determined by measuring amylase and creatinine in serum and urine in apparently healthy individuals the renal clearance of amylase is less than 5% that of creatinine; in acute pancreatitis the ratio is said to be greater than 0.05 or 5%. (05 Mar 2000) |
| aspect ratio | <radiobiology> In toroidal geometry, the ratio of the major diameter (total width of the torus) to the minor diameter (width of a slice taken through one side of the ring). In inertial-confinement fusion, aspect ratio refers to the ratio of a fuel pellet's radius to its wall thickness. (09 Oct 1997) |
| at/gc ratio | <molecular biology> The ratio of adenine-thymine base pairs to guanine-cytosine base pairs on a DNA molecule. (09 Oct 1997) |
| basic reproductive rate, ratio | <epidemiology> See Reproductive Ratio. (05 Dec 1998) |
| body-weight ratio | Body weight (in grams) divided by stature (in centimeters). (05 Mar 2000) |