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an agent or element that contributes to the production of a result.
factor I see coagulation factors.
factor II see coagulation factors.
factor III see coagulation factors.
factor IV see coagulation factors.
factor V see coagulation factors.
factor VI see coagulation factors.
factor VII see coagulation factors.
factor VIII see coagulation factors.
factor IX see coagulation factors.
factor X see coagulation factors.
factor XI see coagulation factors.
factor XII see coagulation factors.
factor XIII see coagulation factors.
angiogenesis factor a substance that causes the growth of new blood vessels, found in tissues with high metabolic requirements such as cancers and the retina. It is also released by hypoxic macrophages at the edges or outer surface of a wound and initiates revascularization in wound healing.
antihemophilic factor (AHF)
2. a preparation of factor VIII administered intravenously for the prevention or treatment of hemorrhage in patients with hemophilia A and the treatment of von Willebrand disease, hypofibrinogenemia, and coagulation factor XIII deficiency. Included are preparations derived from human plasma (antihemophilic factor, cryoprecipitated antihemophilic factor) or porcine plasma (antihemophilic factor [porcine]) and those produced by recombinant technology antihemophilic factor [recombinant]).
antihemorrhagic factor vitamin K.
antinuclear factor (ANF) antinuclear antibody.
antirachitic factor vitamin D.
atrial natriuretic factor (ANF) a hormone produced in the cardiac atrium; an inhibitor of renin secretion and thus of the production of angiotensin, and a stimulator of aldosterone release. Its effect is increased excretion of water and sodium and a lowering of blood pressure.
factor B a complement component that participates in the alternative complement pathway.
blastogenic factor lymphocyte-transforming factor.
carative f's in the theory of human caring, a set of ten factors that offer a descriptive topology of interventions including (1) a humanistic-altruistic system of values; (2) faith-hope; (3) sensitivity to self and others; (4) a helping-trusting, human care relationship; (5) the expression of positive and negative feelings; (6) a creative problem-solving caring process; (7) transpersonal teaching and learning; (8) a supportive, protective, and/or corrective mental, physical, societal, and spiritual environment; (9) human needs assistance; and (10) existential-phenomenological-spiritual forces.
citrovorum factor folinic acid.
clotting f's coagulation factors.
C3 nephritic factor (C3 NeF) an autoantibody that stabilizes the alternative complement pathway C3 convertase, preventing its inactivation by factor h, resulting in complete consumption of plasma C3; it is found in the serum of many patients with type II membranoproliferative glomerulonephritis.
coagulation f's see coagulation factors.
colony-stimulating factor (CSF) any of a number of glycoproteins responsible for the proliferation, differentiation, and functional activation of hematopoietic progenitor cells; specific factors are named for the cell lines that they stimulate. Used to promote bone marrow proliferation in aplastic anemia, following cytotoxic chemotherapy, or following bone marrow transplantation. Types include granulocyte, granulocyte-macrophage, and macrophage colony-stimulating factors.
factor D a factor that when activated serves as a serine esterase in the alternative complement pathway.
decay accelerating factor (DAF) a protein of most blood as well as endothelial and epithelial cells, CD55 (see CD antigen); it protects the cell membranes from attack by autologous complement.
endothelial-derived relaxant factor (endothelial-derived relaxing factor) (endothelium-derived relaxing factor (EDRF)) nitric oxide.
extrinsic factor cyanocobalamin.
F factor (fertility factor) F plasmid.
Fitzgerald factor high-molecular-weight kininogen.
Fletcher factor prekallikrein.
granulocyte colony-stimulating factor (G-CSF) a colony-stimulating factor that stimulates production of neutrophils from precursor cells.
granulocyte-macrophage colony-stimulating factor (GM-CSF) a colony-stimulating factor that binds to stem cells and most myelocytes and stimulates their differentiation into granulocytes and macrophages.
growth factor any substance that promotes skeletal or somatic growth; usually a mineral, hormone, or vitamin.
factor H a complement system regulatory protein that inhibits the alternative pathway of complement activation.
hematopoietic growth f's a group of substances with the ability to support hematopoietic colony formation in vitro, including erythropoietin, interleukin-3, and colony-stimulating factors. All except erythropoietin stimulate mature cells, have overlapping capabilities to affect progenitor cells of several blood cell lines, and also affect cells outside the hematopoietic system.
histamine-releasing factor (HRF) a lymphokine, believed to be produced by macrophages and B lymphocytes, that induces the release of histamine by IgE-bound basophils. It occurs in late phase allergic reaction, six or more hours after contact with the antigen, in sensitive individuals.
homologous restriction factor (HRF) a regulatory protein that binds to the membrane attack complex in autologous cells, inhibiting the final stages of complement activation.
factor I a plasma enzyme that regulates both classical and alternative pathways of complement activation by inactivating their C3 convertases.
immunoglobulin-binding factor (IBF) a lymphokine having the ability to bind IgG complexed with antigen and prevent complement activation.
insulinlike growth f's (IGF) insulinlike substances in serum that do not react with insulin antibodies; they are growth hormone–dependent and possess all the growth-promoting properties of the somatomedins.
intensification factor in radiology, the comparative increase in light transmission when films are exposed in the presence of intensifying screens compared to that in the absence of screens.
intrinsic factor a glycoprotein secreted by the parietal cells of the gastric glands, necessary for the absorption of cyanocobalamin (vitamin B12). Its absence results in pernicious anemia.
LE factor an immunoglobulin that reacts with leukocyte nuclei, found in the serum in systemic lupus erythematosus.
lymph node permeability factor (LNPF) a substance from normal lymph nodes that produces vascular permeability.
lymphocyte mitogenic factor (LMF) (lymphocyte-transforming factor) a substance that is released by lymphocytes stimulated by specific antigen and causes nonstimulated lymphocytes to undergo blast transformation and cell division; called also blastogenic factor.
macrophage-activating factor (MAF) interferon-α.
macrophage colony-stimulating factor (M-CSF) a colony-stimulating factor secreted by macrophages, stimulated endothelial cells, and most tissues, that stimulates the production of macrophages from precursor cells and maintains the viability of mature macrophages in vitro.
macrophage chemotactic factor (MCF) a lymphokine that attracts macrophages to the invasion site.
macrophage-derived growth factor a substance released by macrophages below the surface of a wound that induces the proliferation of fibroblasts.
macrophage inhibition factor (macrophage inhibitory factor) migration inhibitory factor.
migration inhibition factor (migration inhibitory factor) a lymphokine that inhibits macrophage migration.
minification factor in radiology, the gain in light achieved by a reduction in size of the output phosphor from the input phosphor size.
osteoclast-activating factor (OAF) a lymphokine that stimulates bone resorption; it may be involved in the bone resorption associated with multiple myeloma and other hematologic neoplasms or inflammatory disorders such as rheumatoid arthritis and periodontal disease.
factor P properdin.
platelet f's see platelet factors.
platelet-activating factor (PAF) a substance released by basophils and mast cells in immediate hypersensitivity reactions, and by macrophages and neutrophils in other inflammatory reactions; it leads to bronchoconstriction, platelet aggregation, and release of vasoactive substances from platelets.
platelet-derived growth factor a substance contained in platelets and capable of inducing proliferation of vascular endothelial cells, vascular smooth muscle cells, fibroblasts, and glial cells; its action contributes to the repair of damaged vascular walls.
R factor R plasmid.
releasing f's factors elaborated in one structure (as in the hypothalamus) that effect the release of hormones from another structure (as from the anterior pituitary gland), including corticotropin-releasing factor, melanocyte-stimulating hormone–releasing factor, and prolactin-releasing factor. Applied to substances of unknown chemical structure, while substances of established chemical identity are called releasing hormones.
resistance factor R f.
Rh factor a type of agglutinogen found on some erythrocytes; see also rh factor.
rheumatoid factor (RF) antibodies directed against antigenic determinants on IgG molecules, found in the serum of about 80 per cent of patients with classic or definite rheumatoid arthritis; but in only about 20 per cent of patients with juvenile rheumatoid arthritis; rheumatoid factors may be IgM, IgG, or IgA antibodies, although serologic tests measure only IgM. Rheumatoid factors also occur in other connective tissue diseases and infectious diseases.
risk factor an agent or situation that is known to make an individual or population more susceptible to the development of a specific negative condition.
risk factor (omaha) an environmental, psychosocial, or physiologic event or health related behavior that increases the client's exposure or vulnerability to the development of a client problem; the nurse's knowledge base of risk factors is used to identify potential problem modifiers in the Problem Classification scheme of the omaha system.
sun protection factor (SPF) a numerical rating of the amount of protection afforded by a sunscreen; the higher the number, the more protection is provided.
tissue factor factor III, one of the coagulation factors.
transfer factor (TF) a factor occurring in sensitized lymphocytes that can transfer delayed hypersensitivity to a formerly nonreactive individual; see also transfer factor.
tumor necrosis factor (TNF) either of two lymphokines produced primarily by cells of the immune system, capable of causing in vivo hemorrhagic necrosis of certain tumor cells but not normal cells. They also destroy cells associated with the inflammatory response. They have been used as experimental anticancer agents but can also induce shock when bacterial endotoxins cause their release. Tumor necrosis factor α, formerly called cachectin, contains 157 amino acids and is produced by macrophages, eosinophils, and NK cells. Tumor necrosis factor β is lymphotoxin and contains 171 amino acids.
vascular endothelial growth factor (VEGF) (vascular permeability factor (VPF)) a peptide factor that stimulates the proliferation of cells of the endothelium of blood vessels; it promotes tissue vascularization and is important in blood vessel formation in tumors.
von Willebrand's factor (vWF) a glycoprotein synthesized in endothelial cells and megakaryocytes that circulates complexed to coagulation factor VIII. It is involved in adhesion of platelets to damaged epithelial surfaces and may participate in platelet aggregation. Deficiency results in the prolonged bleeding time seen in von Willebrand's disease.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
1. the classical complement pathway (initiated usually by binding of C1 to IgG or IgM antibody to C1) is a complex of three subunits: C1q, C1r, and C1s. After C1q is bound, C1r (an overbar indicates enzymatic activity) cleaves C1s to C1s. C1s cleaves both C4 into C4a and C4b as well as C2 into C2a and C2b. C2b combines with C4b to form C4b2b, which is a C3 convertase. C3 convertase cleaves C3 into C3a and C3b. C3b joins C4bC2b to form a C5 convertase (also known as C4b2b3b), which cleaves C5 into C5a and C5b. After C5b has been bound to the cell surface, the remainder of the complement components (C6-C9) as well as C5b form the membrane attack complex (MAC). MAC causes a hole in the cell membrane.
2. in the alternative complement pathway, surface-bound C3b binds factor B, which is cleaved by factor D into Ba and Bb. C3bBb is an unstable C3 convertase unless properdin (P) binds to it to form C3bBbP. The stable C3 convertase generates more C3b. When a complex of C3bBbC3b is formed, this is the alternative pathway C5 convertase. From C5b through C9, the classical and alternative pathways are the same.
3. In the lectin-binding pathway, mannose-binding protein initiates the pathway, which then uses components of the classical complement pathway. Some of the "a" components of both pathways have various biologic activities, that is, C3a is an anaphylatoxin.
Farlex Partner Medical Dictionary © Farlex 2012
factor BComplement C3 proactivator, a protein of the alternate complement pathway
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.