| active succinate | The condensation product of succinic acid and CoA; one of the intermediates of the tricarboxylic acid cycle and a precursor in the synthesis of haem. Synonym: active succinate, succinyl-CoA. (05 Mar 2000) |
|---|---|
| active sulfate | 3'-phosphoadenosine 5'-phosphosulfate;an intermediate in the formation of urinary ethereal sulfates, notable for containing a "high energy" sulfate bond; the 3'-OH of adenosine is replaced by -OPO3H2, the 5'-OH by -OP(O2H)-OSO3H. Synonym: active sulfate. Acronym: PAPS (05 Mar 2000) |
| active transport | <biochemistry, chemistry> Transport of ions, nutrients or other molecules into a cell against a concentration gradient, this requires the expenditure of energy through ATP hydrolysis. (06 May 1997) |
| active treatment | A therapeutic substance or course intended to ameliorate the basic disease problem, as opposed to supportive or palliative treatment. Compare: causal treatment. (05 Mar 2000) |
| active vasoconstriction | Reduced caliber of a vessel caused by increased tonus in the smooth muscle in its walls. (05 Mar 2000) |
| active vasodilation | Vasodilation caused by decrease in tonus of smooth muscle in the wall of a vessel. (05 Mar 2000) |
| artificial active immunity | See: acquired immunity. (05 Mar 2000) |
| biological transport, active | The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy. (12 Dec 1998) |
| chronic active hepatitis | <pathology> This is a form of continuing liver inflammation that results in liver cell death. Causes include viral infection (hepatitis D, hepatitis B, hepatitis C), autoimmune disease, drug ingestion or metabolic causes. Chronic active hepatitis will lead to hepatic failure and death in a small percentage of these patients. (27 Sep 1997) |
| chronic active inflammation | The coexistence of chronic inflammation and superimposed acute inflammation. (05 Mar 2000) |
| chronic active liver disease | Any of several types of hepatitis persisting for more than six months, often progressing to cirrhosis. Synonym: chronic active liver disease. (05 Mar 2000) |
| specific active immunity | See: acquired immunity. (05 Mar 2000) |
| surface-active | Indicating the property of certain agents of altering the physicochemical nature of surfaces and interfaces, bringing about lowering of interfacial tension; they usually possess both lipophilic and hydrophilic groups. See: surfactant. (05 Mar 2000) |
| surface-active agent | Agents that modify interfacial tension of water; usually substances that have one lipophilic and one hydrophilic group in the molecule; includes soaps, detergents, emulsifiers, dispersing and wetting agents, and several groups of antiseptics. (12 Dec 1998) |
| surface active compound | <biochemistry> Usually, in biological systems, means a detergent like molecule that is amphipathic and that will bind to the plasma membrane or to a surface with which cells come in contact, altering its properties from hydrophobic to hydrophilic or vice versa. (18 Nov 1997) |