agent (a´jent)

1. An active force or substance capable of producing an effect. For agents not listed here, see the specific name. 2. Referring to disease, a factor such as a microorganism, chemical substance, or form of radiation whose presence, excessive presence, or relative absence (as in deficiency diseases) is essential for the occurrence of a disease. [L. ago, pres. p. agens (agent-), to perform]
adrenergic blocking a. a compound that selectively blocks or inhibits responses to sympathetic adrenergic nerve activity (sympatholytic a.) and to epinephrine, norepinephrine, and other adrenergic amines (adrenolytic a.); two distinct classes exist, alpha- and beta-adrenergic receptor blocking a.'s.
a-adrenergic blocking a. an agent that competitively blocks a-adrenergic receptors; used in the treatment of hypertension.alpha-blocker;
beta-adrenergic blocking a. a class of drugs that compete with beta-adrenergic agonists for available receptor sites; some compete for both beta1 and beta2 receptors (e.g., propranolol) while others are primarily either beta1 (e.g., metoprolol) or beta2 blockers; used in the treatment of a variety of cardiovascular diseases where beta-adrenergic blockade is desirable.beta-adrenergic receptor blocking a., beta-adrenoreceptor antagonist, beta-blocker;
adrenergic neuronal blocking a. a drug that prevents the release of norepinephrine from sympathetic nerve terminals; it does not inhibit the responses of the adrenergic receptors to circulating epinephrine, norepinephrine, and other adrenergic amines.
beta-adrenergic receptor blocking a. beta-adrenergic blocking a
alkylating a. a drug or chemical that, via the formation of covalent bonds, forms a derivatized tissue constituent permanently containing part of the drug or chemical compound; frequently carcinogenic and mutagenic.
antianxiety a. a functional category of drugs useful in the treatment of anxiety and able to reduce anxiety at doses which do not cause excessive sedation (e.g., diazepam).anxiolytic (1) , minor tranquilizer;
antifoaming a.'s chemicals that lower surface tension (hence production of foam), used in laboratory evaporations, and also administered with oxygen to relieve the respiratory obstruction aggravated by the foam of edema fluid in pulmonary edema.
antipsychotic a. a functional category of neuroleptic drugs that are helpful in the treatment of psychosis and have a capacity to ameliorate thought disorders (e.g., chlorpromazine, haloperidol). See also neuroleptic (3).antipsychotic (1) , major tranquilizer;
bacteriostatic a. bacteriostat
Bittner a. mammary tumor virus of mice
blister a. vesicant
blocking a. a class of drugs that inhibit (block) a biologic activity or process, such as axonal conduction or transmission, or ions across a cell membrane; frequently called "blockers."
calcium channel-blocking a. a class of drugs that have the ability to inhibit movement of calcium ions across the cell membrane; of particular value in the treatment of cardiovascular disorders because of pharmacologic effects such as depression of mechanical contraction of cardiac and smooth muscle and of both impulse formation and conduction velocity (e.g., nifedipine).calcium antagonist, slow channel-blocking a;
chimpanzee coryza a. (CCA) respiratory syncytial virus
cholinergic a. an a. that mimics the action of the parasympathetic nervous system (e.g., methacholine).
contrast a. contrast medium
delta a. hepatitis delta virus
Eaton a. Mycoplasma pneumoniae
embedding a.'s materials such as celloidin, paraffin, etc. in which specimens of tissue are set before being cut into sections for microscopic examination.
enterokinetic a. an a. used to relieve intestinal atony.
F a. F plasmid
fertility a. F plasmid
foamy a.'s foamy viruses, under virus
ganglionic blocking a. an a. that impairs the passage of impulses in autonomic ganglia.
high osmolar contrast a. (HOCA) ionic water-soluble iodinated contrast media.high osmolar contrast medium;
initiating a. See initiation.
inotropic a.'s drugs that increase the force of contraction of cardiac muscle; examples include digitalis glycosides, amrinone, and epinephrine.
LDH a. lactate dehydrogenase virus
luting a. a fastening material or cement; e.g., plaster or wax to hold casts to an articulator, or material to hold crowns to teeth.
MS-1 a. a strain of hepatitis A virus.
MS-2 a. a strain of hepatitis B virus.
neuroleptic a. any of a family of drugs producing sedation and tranquilization (e.g., chlorpromazine, haloperidol). See also antipsychotic a.neuroleptic (1);
neuromuscular blocking a.'s a group of drugs that prevent motor nerve endings from exciting skeletal muscle. They act either by competing for the neurotransmitter, acetylcholine, (like D-tubocurarine, mivacurium and pancuronium), or by first stimulating the postjunctional muscle membrane and subsequently desensitizing the muscle endplates to the acetylcholine (like succinylcholine or decamethonium); used in surgery to produce paralysis and facilitate manipulation of muscles.
nondepolarizing neuromuscular blocking a. a compound that paralyzes skeletal muscle primarily by inhibiting transmission of nerve impulses at the neuromuscular junction rather than by affecting the membrane potention of motor endplate or muscle fibers.
Norwalk a. a strain of epidemic gastroenteritis virus that appears to be related to the calciviruses. [Norwalk, Ohio, where first implicated in disease]
Pittsburgh pneumonia a. Legionella micdadei
promoting a. See promotion.
psychotropic a. a chemical compound that influences the human psyche.
reovirus-like a. rotavirus
sclerosing a. a compound which acts by irritation of the veinous intimal epithelium; used in the treatment of varicose veins.
slow channel-blocking a. calcium channel-blocking a
sympathetic a. See sympathomimetic amine.
transforming a. mitogen
TRIC a.'s strains of Chlamydia trachomatis that cause trachoma and inclusion conjunctivitis a.'s See Chlamydia trachomatis.


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