Canadian Medical Guide > Chemicals and Drugs > Immunologic and Biological Factors > Biological Factors Terms and Definitions

Biological Factors

Medical Definition:	Compounds made by living organisms that contribute to or influence a phenomenon or process. They have biological or physiological activities.
Guide Notes:	"cpds made by living organisms": differentiate from BIOLOGICAL PRODUCTS which are manufactured & usually used in ther; DF: BIOL FACTORS

Biological Factors Categories.

	Anaphylatoxins - The family of peptides C3a, C4a, C5a, and C5a des-arginine produced in the serum during complement activation. They produce smooth muscle contraction, mast cell histamine release, affect platelet aggregation, and act as mediators of the local inflammatory process. The order of anaphylatoxin activity from strongest to weakest is C5a, C3a, C4a, and C5a des-arginine. The latter is the so-called "classical" anaphylatoxin but shows no spasmogenic activity though it contains some chemotactic ability.
	Biological Markers - Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.
	Blood Coagulation Factor Inhibitors - Substances, usually endogenous, that act as inhibitors of blood coagulation. They may affect one or multiple enzymes throughout the process. As a group, they also inhibit enzymes involved in processes other than blood coagulation, such as those from the complement system, fibrinolytic enzyme system, blood cells, and bacteria.
	Chemotactic Factors - Chemical substances that attract or repel cells or organisms. The concept denotes especially those factors released as a result of tissue injury, invasion, or immunologic activity, that attract leukocytes, macrophages, or other cells to the site of infection or insult.
	Coagulase - Any bacterial component or product which causes coagulation in plasma containing an anticoagulant such as citrate, heparin or oxalate. Coagulases are produced by certain staphylococci and by Yersinia pestis. Staphylococci produce two types of coagulase: Staphylocoagulase, a free coagulase that produces true clotting of plasma, and Staphylococcal clumping factor, a bound coagulase in the cell wall that induces clumping of cells in the presence of fibrinogen. (Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2nd ed)
	Hirudin - The active principle in the buccal gland secretion (saliva) of LEECHES. It acts as an antithrombin and as an antithrombotic agent.
	Luciferins - A generic term referring to a substrate which, upon oxidation by the enzyme luciferase, produces bioluminescence. Luciferins isolated from different species may vary greatly in structure, although in many cases identical structures have been found in widely diverse animals. The American firefly, Photinus pyralis, and its substrate have been studied extensively and is used in the assay of adenosine triphosphate. (From Merck Index, 12th ed)
	Mitogens - Substances that stimulate mitosis and lymphocyte transformation. They include not only substances associated with LECTINS, but also substances from streptococci (associated with streptolysin S) and from strains of alpha-toxin-producing staphylococci. (Stedman, 25th ed)
	Pheromones - Chemical substances, excreted by an organism into the environment, that elicit behavioral or physiological responses from other organisms of the same species. Perception of these chemical signals may be olfactory or by contact.
	Siderophores - Low-molecular-weight compounds produced by microorganisms that aid in the transport and sequestration of ferric iron. (The Encyclopedia of Molecular Biology, 1994)
	Toxins - Specific, characterizable, poisonous chemicals, often proteins, with specific biological properties, including immunogenicity, produced by microbes, higher plants, or animals.
	Virulence Factors - Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: TOXINS and surface adhesion molecules that effect the ability of the microorganism to invade and colonize a host. (From Davis et al., Microbiology, 4th ed. p486)

Biological Factors Medical Definitions and Terms

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