infectious agent

agent

1. any power, principle or substance by which something is accomplished, or which is capable of producing a chemical, physical or biological effect such as a disease.

2. of disease; any factor whose excessive presence or relative absence is essential for the occurrence of a disease.

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adrenergic neuron blocking agent

one that inhibits the release of norepinephrine from postganglionic adrenergic nerve endings.

alkylating agent

a cytotoxic agent, e.g. a nitrogen mustard, which is highly reactive and can donate an alkyl group to another compound. Alkylating agents inhibit cell division by reacting with DNA and are used as antineoplastic agents.

anesthetic agent

substance capable of producing reversible general or local anesthesia.

anticholinergic agent

cholinergic blocking agent.

agent change

change in an animal's chemical or antigenic configuration can alter its pathogenicity. For example, a case of nitrate-nitrite poisoning in a cow can become a case of nitrite poisoning after conversion of the nitrate in the rumen. Mutation and antigenic drift are other types of change that vary agent pathogenicity.

chelating agent

a compound that combines with metals to form weakly dissociated complexes in which the metal is part of a ring, and is used to extract certain elements from a system.

chemical agent

substance that produces change by virtue of its chemical composition and its effects on living tissues and organisms.

cholinergic blocking agent

one that blocks the action of acetylcholine at nicotinic or muscarinic receptors of nerves or effector organs.

determinant agent

only some agents are determinants of diseases in that they always cause disease, and the same disease, and the disease does not occur without the agent. Many agents require the intervention of other factors, such as anaerobicity of tissue, hepatic insufficiency or physiological stress before they can establish their pathogenicity.

ganglionic blocking agent

one that blocks cholinergic transmission at autonomic ganglionic synapses.

immobilizing agent

see neuromuscular blockade.

infectious agent

an organism able to live in or on the tissue of a living animal; may not necessarily cause disease.

agent interaction

is the interaction between precipitating and predisposing causes of disease.

oxidizing agent

a substance that acts as an electron acceptor in a chemical oxidation-reduction reaction.

agent properties

are the properties which determine the pathogenicity of the agent, the solubility and acidity or biodegradability of a chemical, the virulence, adhesiveness, resistance to antibacterial agents of bacteria and viruses and so on.

reducing agent

a substance that acts as an electron donor in a chemical oxidation-reduction reaction.

surface-active agent

a substance that exerts a change on the surface properties of a liquid, especially one, such as a detergent, that reduces its surface tension. Called also surfactant.

therapeutic agent

a substance capable of producing a curative effect in a disease state.

agent without disease

exemplified by the orphan viruses. The agent is of a type that causes disease, but none is associated with the presence of the particular agent.

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infectious agent

Pathogen, see there