| 释义 |
alpha-fetoproteinenUK
al·pha-fe·to·pro·tein A0225700 (ăl′fə-fē′tō-prō′tēn, -tē-ĭn)n. Abbr. AFP A glycoprotein that is abundant in the blood plasma of human and other mammalian fetuses and is also present in the serum of people with certain diseases, such as liver cancer. Abnormal levels in maternal serum are associated with certain fetal abnormalities, including Down syndrome and spina bifida.alpha-fetoprotein (ˌælfəˌfiːtəʊˈprəʊtiːn) n (Biochemistry) a protein that forms in the liver of the human fetus. Excessive quantities in the amniotic fluid and maternal blood may indicate spina bifida in the fetus; low levels may point to Down's syndrome. Abbreviation: afp al`pha-fe`to•pro′tein (ˌfi toʊˈproʊ tin, -ti ɪn)
n. a serum protein produced during pregnancy, useful in the prenatal diagnosis of multiple births or birth defects. Abbr.: AFP [1970–75] alpha-fetoproteinenUK
alpha [al´fah] the first letter of the Greek alphabet, α; used to denote the first position in a classification system; as, in names of chemical compounds, to distinguish the first in a series of isomers, or to indicate the position of substituent atoms or groups; also used to distinguish types of radioactive decay, brain waves or rhythms, adrenergic receptors, and secretory cells that stain with acid dyes, such as the alpha cells of the pancreas.alpha-adrenergic blocking agent (alpha-blocker) (alpha-blocking agent) any of a group of drugs that selectively inhibit the activity of receptors" >alpha receptors in the sympathetic nervous system. As with beta-adrenergic blocking agents" >beta-adrenergic blocking agents, alpha-blocking agents compete with the catecholamines" >catecholamines at peripheral autonomic receptor sites. This group includes ergot" >ergot and its derivatives, and phentolamine" >phentolamine.alpha chain disease the most common heavy chain disease, occurring predominantly in young adults in the Mediterranean area, and characterized by plasma cell infiltration of the lamina propria of the small intestine resulting in malabsorption with diarrhea, abdominal pain, and weight loss, or, exceedingly rarely, by pulmonary involvement. The gastrointestinal form is immunoproliferative small intestine disease.alpha-fetoprotein (AFP) a plasma protein produced by the fetal liver, yolk sac, and gastrointestinal tract and also by carcinoma" >hepatocellular carcinoma, germ cell neoplasms, and other cancers in adults; elevated levels may also be seen in benign liver disease such as cirrhosis and viral hepatitis. The serum AFP level is used to monitor the effectiveness of cancer treatment.
During pregnancy some AFP crosses from the amniotic fluid to the mother's blood. If the fetus has a neural tube defect, large amounts of AFP will be found in the amniotic fluid and maternal blood. Blood screening tests for serum AFP can thus be done as a first step in the screening process; if test results are positive, further testing is indicated to diagnose the defect.alpha particles a type of emission produced by the disintegration of a radioactive substance. The atoms of radioactive elements such as uranium and radium are very unstable, continuously breaking apart with explosive violence and emitting particulate and nonparticulate types of radiation. The alpha particles, consisting of two protons and two neutrons, have an electrical charge and form streams of tremendous energy when they are released from the disintegrating atoms. These streams of energy (rays" >alpha rays) can be used in treatment of various malignancies. See also radiation and radiation therapy.alpha-fetoprotein (ăl′fə-fē′tō-prō′tēn, -tē-ĭn)n. Abbr. AFP An antigen produced in the liver of a fetus and that is also present in certain diseases, such as liver cancer. Its level in amniotic fluid can be used to detect certain fetal abnormalities, including Down syndrome and spina bifida.AFP A gene on chromosome 4q11-q13 that encodes alpha-fetoprotein, a major plasma protein produced by the yolk sac and the liver during foetal life. AFP is regarded as the foetal counterpart of serum albumin and binds copper, nickel, fatty acids and bilirubin; hereditary persistance of alpha-fetoprotein may be found in individuals with no obvious pathology.
Molecular pathology
AFP is elevated in foetuses with neural tube defects, including spina bifida and anencephaly. It is elevated in adults with hepatocellular carcinomas and germ cell tumours.alpha-fetoprotein Fetoglobulin Clinical chemistry A 70 kD glycoprotein, synthesized by the embryonic yolk sac, fetal GI tract and liver, which has 40% homology with albumin, which peaks at 13 wks of fetal age; AFP's role in fetal development is unclear; AFP levels are measured in pregnancy to screen for open neural tube defects–incidence, 1-2/1000 births and for Down syndrome, and in adults to detect liver cancer and germ cell tumors Ref range Non-pregnant adults < 30 ng/mL; maternal serum–13-16 wks, < 1.0-4.4 µg/dL; amniotic fluid–13-16 wks, 0.9-4.1 mg/dL AFP levels in fetal serum are 150-fold > amniotic fluid, which in turn are 200-fold > maternal serum; maternal serum levels are 300-400 µg/L in the 3rd trimester; AFP levels in fetal serum and amniotic fluid peak at 13 wks, while the maternal levels peak at 30 wks; AFP in pregnancy is > in twins and higher multiple pregnancies; if the fetal neural tube fails to close completely, large quantities of AFP enter the amniotic fluid, resulting in ↑ levels in the mother's serum; confirmatory tests such as amniocentesis and/or ultrasonography are used to identify neural tube defects is elevated; after the immediate postnatal period, ↑ serum AFP levels occur only with conditions of abnormal cell multiplication; although AFP measurement is not FDA-approved for cancer screening, in practice, it is used to both detect and monitor therapy in liver cell cancer and germ cell tumors of gonadal, retroperitoneal, or mediastinal origin. See Liver cell carcinoma, Triple screen. Alpha-fetoprotein (AFP)A substance produced by a fetus' liver that can be found in the amniotic fluid and in the mother's blood. Abnormally high levels of this substance suggests there may be defects in the fetal neural tube, a structure that will include the brain and spinal cord when completely developed. Abnormally low levels suggest the possibility of Down' syndrome.Mentioned in: Amniocentesis, Liver Cancer, PregnancyFinancialSeeAlphaSee AFP
See AFPThesaurusSeealpha |