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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 alpha receptors in the sympathetic nervous system. As with beta-adrenergic blocking agents, alpha-blocking agents compete with the catecholamines at peripheral autonomic receptor sites. This group includes ergot and its derivatives, and 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 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 (alpha rays) can be used in treatment of various malignancies. See also radiation and radiation therapy.

α

1. First letter of the Greek alphabet, alpha (α), used as a classifier in the nomenclature of many sciences.
3. In chemistry, denotes the first in a series, a position immediately adjacent to a carboxyl group, the first of a series of closely related compounds, an aromatic substituent on an aliphatic chain, or the direction of a chemical bond away from the viewer.
4. Abbreviation for alpha particle.
5. In chemistry, symbol for angle of optic rotation; degree of dissociation. For terms beginning with this prefix, see the specific term.

[α]


al·pha

(al'fă), The spelling alpha is used in chemical names, the spelling alfa in pharmaceutical names.
First letter of the Greek alphabet, α.

ALPHA

Abbreviation for:
Access to Learning for the Public Health Agenda (Medspeak-UK)
Agenda for Leadership in Programs for Healthcare Accreditation (obsolete)
Antenatal Psychosocial Health Assessment

α

Abbreviation for alpha.

al·pha

(α) (al'fă)
1. First letter of the Greek alphabet; used as a classifier in the nomenclature of many sciences.
3. chemistry Denotes the first in a series, a position immediately adjacent to a carboxyl group, the first of a series of closely related compounds, an aromatic substituent on an aliphatic chain, or the direction of a chemical bond away from the viewer.
4. Alpha (α) particle.
5. chemistry Symbol for angle of optic rotation; degree of dissociation.
References in periodicals archive ?
In several vaccination studies, a mucosal IgA response against alpha toxin, NetB and other immunogenic proteins was reported in chickens partially protected against NE (Caly et al.
Amplification of universal oligonucleotide sequence and alpha toxin gene (Ccta)
In Lane 5, a band at the 43 kDa region was recorded identical and at the same plane of the standard alpha toxin recorded in Lane 3.
Immunization with recombinant alpha toxin protects broiler chicks against experimental challenge with Clostridium perfringens.
Further attempts were made to confirm whether local field strain prevalent in the sampled areas was capable of producing alpha toxins or not on the basis of ccta gene.
All the examined field identified as C.perfringens type "A" (alpha toxin) and gave 402 bp fragment and two examined field identified as C.perfringens type "D"(epsilon toxin) and gave 514 bp fragment as shown in (photo 20).
Similarly, in the present, alpha toxin also causes the lysis of platelet and leukocytes.
A field study of naturally occurring specific antibodies against Clostridium perfringens alpha toxin in Norwegian broiler flocks.
Alpha toxins cause the absence of tissue inflammatory response by potently stimulating platelet aggregation and upregulating adherence molecules on polymorphonuclear leukocytes and endothelial cells.