| AHT | aggregation half time; antihyaluronidase titer; augmented histamine test; autogenous hamster tumor |
|---|---|
| H2 | blockers histamine blockers |
| HA | H antigen; Hakim-Adams [syndrome]; halothane anesthesia; Hartley [guinea pig]; headache; health alli... |
| HAP | Handicapped Aid Program; Hazardous Air Pollutants [List]; hazardous air pollution; health alliance p... |
| HC | hair cell; hairy cell; handicapped; head circumference; head compression; health care; healthy contr... |
| histamine release | The secretion of histamine from mast cell and basophil granules by exocytosis. This can be initiated by a number of factors, all of which involve binding of IgE, cross-linked by antigen, to the mast cell or basophil's fc receptors. Once released, histamine binds to a number of different target cell receptors and exerts a wide variety of effects. (12 Dec 1998) |
|---|---|
| histamine shock | The shock state produced in animals by the injection of histamine; characterised by bronchiolar spasm in the guinea pig and constriction of hepatic veins in the dog. (05 Mar 2000) |
| histamine test | A test for maximal production of gastric acidity or anacidity; after preliminary administration of an antihistamine, histamine acid phosphate is injected subcutaneously in a dose of 0.04 mg/kg of body weight, followed by analysis of gastric contents. Synonym: augmented histamine test. (05 Mar 2000) |
| abortifacient agents | Chemical substances that interrupt pregnancy after implantation. (12 Dec 1998) |
| abortifacient agents, non-steroidal | Non-steroidal chemical compounds with abortifacient activity. (12 Dec 1998) |
| abortifacient agents, steroidal | Steroidal compounds with abortifacient activity. (12 Dec 1998) |
| adrenergic agents | Drugs that act on adrenergic receptors or affect the life cycle of adrenergic transmitters. Included here are adrenergic agonists and antagonists and agents that affect the synthesis, storage, uptake, metabolism, or release of adrenergic transmitters. (12 Dec 1998) |
| alkylating agents | Highly reactive chemicals that introduce alkyl radicals into biologically active molecules and thereby prevent their proper functioning. Many are used as antineoplastic agent, but most are very toxic, with carcinogenic, mutagenic, teratogenic, and immunosuppressant actions. They have also been used as components in poison gases. (12 Dec 1998) |
| anti-allergic agents | Agents that are used to treat allergic reactions. most of these drugs act by preventing the release of inflammatory mediators or inhibiting the actions of released mediators on their target cells. (12 Dec 1998) |
| anti-allergic and respiratory system agents | A collective term for drugs used to treat allergic reactions as well as those drugs that produce an effect on the respiratory system. (12 Dec 1998) |
| anti-anxiety agents | Agents that alleviate anxiety, tension, and neurotic symptoms, promote sedation, and have a calming effect without affecting clarity of consciousness or neurologic conditions. Some are also effective as anticonvulsants, muscle relaxants, or anaesthesia adjuvants. Adrenergic beta-antagonists are commonly used in the symptomatic treatment of anxiety but are not included here. Substances with a benzodiazepine ring structure widely used to treat anxiety and neuroses. Drugs in this class also generally have sedative or weak hypnotic properties and may be effective as muscle relaxants, anticonvulsants, and anaesthesia adjuvants. (12 Dec 1998) |
| anti-arrhythmia agents | Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibres. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade. (12 Dec 1998) |
| anti-asthmatic agents | Drugs that are used to treat asthma. (12 Dec 1998) |
| anticarcinogenic agents | Agents that reduce the frequency or rate of spontaneous or induced tumours independently of the mechanism involved. They differ from antineoplastic agent in that they prevent neoplasms from forming. The anticarcinogenic substances can be divided into three categories. The first consists of compounds that prevent the formation of carcinogens from precursor substances. The second group consists of "blocking agents" which inhibit carcinogenesis by preventing carcinogenic agents from reaching or reacting with critical target sites in the tissues. The third group is the "suppressor agents" which act by suppression of expression of neoplasia in cells previously exposed to carcinogens that would otherwise cause neoplasms. (12 Dec 1998) |
| anticestodal agents | Agents used to treat tapeworm infestations in man or animals. (12 Dec 1998) |