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DictionarySeefolinic acidEncyclopediaSeefactorcitrovorum factor
factor [fak´ter] an agent or element that contributes to the production of a result.accelerator factor factor V, one of the coagulation factors.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) 1. factor VIII, one of the coagulation factors.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]).antihemophilic factor A factor VIII, one of the coagulation factors.antihemophilic factor B factor IX, one of the coagulation factors.antihemophilic factor C factor XI, one of the coagulation factors.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.Christmas factor factor IX, one of the coagulation factors.citrovorum factor folinic acid.clotting f's coagulation factors" >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 glomerulonephritis" >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 transplantation" >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.fibrin-stabilizing factor (FSF) factor XIII, one of the coagulation factors.Fitzgerald factor high-molecular-weight kininogen.Fletcher factor prekallikrein.granulocyte colony-stimulating factor (G-CSF) a factor" >colony-stimulating factor that stimulates production of neutrophils from precursor cells.granulocyte-macrophage colony-stimulating factor (GM-CSF) a factor" >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.Hageman factor (HF) factor XII, one of the coagulation factors. See illustration. Activation of Hageman factor (factor XII) leads to increased vascular permeability, clotting, and thrombolysis. From Damjanov, 2000.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 complex" >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 factor" >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 hypersensitivity" >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" >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 modifiers" >problem modifiers in the scheme" >Problem Classification scheme of the omaha system." >omaha system.stable factor factor VII, one of the coagulation factors.Stuart factor (Stuart-Prower factor) factor X, one of the coagulation factors.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 response" >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. leucovorin calcium (citrovorum factor, folinic acid) Calcium Folinate (UK), Lederfolin (UK), Refolinon (UK) Pharmacologic class: Water-soluble vitamin Therapeutic class: Vitamin, antidote to folic acid antagonist, antianemic, antineoplastic adjunct Pregnancy risk category C Action Counteracts therapeutic and toxic effects of folic acid antagonists; may enhance therapeutic and toxic effects of fluoropyrimidines used in cancer therapy. Also supplements folic acid in folic acid deficiency. Availability Injection (expressed as base): 10 mg/vial, 50 mg/vial, 100 mg/vial, 200 mg/vial, 350 mg/vial, 500 mg/vial Injection, preservative-free (expressed as base): 10 mg/vial, 50 mg/vial, 200 mg/vial, 350 mg/vial, 500 mg/vial Tablets: 5 mg, 15 mg, 25 mg Indications and dosages ➣ Leucovorin rescue after high-dose methotrexate therapy Adults: 15 mg (approximately 10 mg/m2) P.O., I.M., or I.V. q 6 hours, starting 24 hours after methotrexate infusion begins and continuing until serum methotrexate level drops below 10-8 M. If 24-hour serum creatinine level rises 50% over baseline or if 24-hour methotrexate level exceeds 5 × 10-6 M or 48-hour level exceeds 9 × 10-7 M, increase leucovorin dosage to 100 mg/m2 I.V. q 3 hours and continue hydration and urinary alkalization until methotrexate level drops below 10-8 M. ➣ To reduce toxicity and counteract effects of impaired methotrexate elimination or inadvertent overdose of folic acid antagonist Adults: 15 mg (roughly 10 mg/m2) I.M., I.V., or P.O. q 6 hours until serum methotrexate level drops below 10-8 M. If 24-hour serum creatinine level rises 50% over baseline or if 24-hour methotrexate level exceeds 5 × 10-6 M or 48-hour level exceeds 9 × 10-7 M, increase leucovorin dosage to 100 mg/m2 I.V. q 3 hours and continue hydration and urinary alkalization until methotrexate level drops below 10-8 M. ➣ Advanced colorectal cancer Adults: Usually given in one of the following regimens: 200 mg/m2 slow I.V. injection over at least 3 minutes, followed by I.V. injection of 5-fluorouracil (5-FU); or 20 mg/m2 I.V. injection, followed by I.V. injection of 5-FU. Treatment is repeated daily for 5 days, and may then be repeated at 28-day intervals for two courses and then at 4- to 5-week intervals, as prescribed. ➣ Megaloblastic anemia secondary to folic acid deficiency Adults: Up to 1 mg I.M. daily Dosage adjustment • In leucovorin rescue after high-dose methotrexate therapy: delayed early or late methotrexate elimination (serum methotrexate level still above 0.2 µM at 72 hours and above 0.05 µM [5 × 10-8] at 96 hours after administration) • Evidence of acute renal injury Contraindications • Treatment of pernicious anemia and other megaloblastic anemias caused by vitamin B12 deficiency Precautions Use cautiously in: • anemia (when vitamin B12 deficiency has been ruled out) • patients receiving 5-FU concomitantly • pregnant or breastfeeding patients • children. Administration See Recheck leucovorin dosage in current published protocols before giving as methotrexate rescue. • Give parenterally in patients with GI toxicity, nausea, or vomiting. • Reconstitute leucovorin injection with sterile or bacteriostatic water for injection containing benzyl alcohol. (When giving with 5-FU for colorectal cancer in dosages above 10 mg/m2, reconstitute only with sterile water for injection.) See Don't mix leucovorin injection with 5-FU, because precipitation will occur. See Give I.V. leucovorin slowly (no faster than 160 mg/minute) because of calcium content. Large doses may be infused over 1 to 6 hours as directed. See Don't give intrathecally; drug may be harmful or fatal by this route. • Be aware that P.O. dosages above 25 mg are not recommended.  Adverse reactions Skin: urticaria Other: allergic sensitization reactions, anaphylactoid reactions Interactions Drug-drug. 5-FU: enhanced fluorouracil toxicity Methotrexate, other folic acid antagonists: negated therapeutic and toxic effects of these drugs Phenobarbital, phenytoin, primidone: negated anticonvulsant effect, increased frequency of seizures in susceptible children Patient monitoring See Monitor serum creatinine and methotrexate levels every 24 hours. See Monitor closely for adverse reactions. Continue leucovorin therapy, hydration, and urinary alkalization until serum methotrexate level drops below 10-8 M. See Monitor CBC with white cell differential and platelet count before leucovorin/5-FU therapy starts. Repeat weekly during first two courses and then once each cycle at anticipated white blood cell nadir. • Check electrolyte levels and liver function tests before each treatment for first three cycles. Thereafter, check before every other cycle. • Assess for adequate hydration when giving with 5-FU or high-dose methotrexate. • Watch for hypersensitivity reactions, especially anaphylactoid reactions. Patient teaching • Teach patient about drug and protocol. See Stress importance of taking leucovorin as prescribed with high-dose methotrexate therapy. Emphasize that it's not just a vitamin. • Tell patient to immediately report signs or symptoms of allergic reaction, such as hives. • As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs mentioned above. fo·lin·ic ac·id (fō-lin'ik as'id), 1. The active form of folic acid that acts as a formyl group carrier in transformylation reactions; the calcium salt, leucovorin calcium, has therapeutic use. 2. The term is occasionally applied to other folates. Synonym(s): citrovorum factor, leucovorinfo·lin·ic ac·id (fō-lin'ik as'id) The active form of folic acid, which acts as a formyl group carrier in transformylation reactions; the calcium salt, leucovorin calcium, has therapeutic use.
Synonym(s): citrovorum factor. EncyclopediaSeec & f |