Å

DEFINITION:

Symbol for "angstrom."

ai

DEFINITION:

Check back. Definition to be added.

Å

DEFINITION:

Symbol for "angstrom."

5'-cap

DEFINITION:

A structure consisting of a 7-methylguanosine (m⁷G) residue attached backwards (i.e., 5' to 5') by a triphosphate linkage to the 5' end of primary mRNA transcripts in eukaryotes. In addition, the first and, in some cases, second nucleotide of the mRNA are methylated at the 2' position of the ribose residue. The 5' cap protects the mRNA from attack by 5' exonucleases and also functions in the recognition of the mRNA by ribosomes.

a helix

DEFINITION:

A secondary structure occurring in many proteins; it is a right-handed helix with 3.6 amino acid residues per turn stabilized by hydrogen bonds between the imino hydrogen of each peptide bond and the carbonyl oxygen of the peptide bond four residues further along the polypeptide chain.

ß-endorphin

DEFINITION:

The C-terminal 30-amino acid residue and is found in the adenohypophysis, hypothalamus, and other sites in the brain; one function appears to be mediation of pain perception.

5,6-dimethylbenzimidazole

DEFINITION:

A derivative of benzimidazole doubly methylated on the benzene ring; it is an unusual base that together with a ribose 3'-phosphate moiety forms the nucleotide portion of the vitamin B₁₂ molecule.

a level

DEFINITION:

Significance level.

&#223

DEFINITION:

Also ß. Beta, the second letter of the Greek alphabet; symbol for the ß chain of hemoglobin and the probability of Type II error.

7 transmembrane domain

DEFINITION:

The seventh region (domain) of the transmembrane V2R. See schematic drawing of the V2R.

a-adrenergic receptor

DEFINITION:

An adrenergic receptor that responds to norepinephrine and to such blocking agents as phenoxybenzamine hydrochloride and phentolamine. Called also alpha receptors.

β

DEFINITION:

Also β. Beta, the second letter of the Greek alphabet; symbol for the β chain of hemoglobin and the probability of Type II error.

amino acids

DEFINITION:

See definition for "amino acid."

a-amino acid

DEFINITION:

One in which the amino and carboxyl groups are both attached to the same carbon atom.

&#951

DEFINITION:

Symbol

ß

DEFINITION:

Beta, the second letter of the Greek alphabet; symbol for the ß chain of hemoglobin.

a-amino-3-indolepropionic acid

DEFINITION:

Tryptophan.

1-desamino-8-D-arginine vasopressin

DEFINITION:

1-desamino-8-D-arginine vasopressin (DDAVP or dDAVP or desmopressin) is a vasopressin analogue which has a potent antidiuretic potency (V₂ receptor stimulation), prolonged duration of action and diminished pressor effects (V₁ receptor stimulation). The natural hormone in man is ADH (antidiuretic hormone), also called vasopressin or arginine-vasopressin. ADH is a nonapeptide (molecular weight 1099) with pressor and antidiuretic actions.


The pressor effect is mediated by the V₁ receptor stimulation which is localized mainly on the small muscle of the blood vessels and which stimulation induce " vasoconstriction ."

The decrease in urine volume after ADH administration is mediated by the stimulation by ADH of the V₂ receptor, localized on the collecting tubule of the kidney. Patients with central diabetes insipidus are usually treated with dDAVP which stimulates only the V₂ receptor. (Definition provided by G. Decaux, PhD, Hopital Erasme, Brussels.)

ß-adrenergic receptor

DEFINITION:

An adrenergic receptor that responds to epinephrine and to such blocking agents as propranolol; they are of two types: ß₁ (lipolysis and cardiostimulation) and ß₂ (bronchodilation and vasodilation). Called also beta receptors .

a-globulins

DEFINITION:

See alpha globulins.

10-fold

DEFINITION:

1. Comprising ten parts or members.


2. Ten times as great or as much.

ß-galactosidase

DEFINITION:

Any of a group of enzymes of the hydrolase class that catalyze the cleavage of terminal, ß-linked, nonreducing galactose residues from a variety of substrates, including ganglioside GM₁, lactosylceramides, lactose, and various glycoproteins and oligosaccharides.

a-hemolytic

DEFINITION:

Pertaining to alpha hemolysis.

17-KS

DEFINITION:

17-ketosteroid.

ß-globulins

DEFINITION:

Globulins of plasma that have an electrophoretic mobility in neutral or alkaline solutions intermediate between that of the alpha and the gamma globulins.

a-keratin

DEFINITION:

Keratin in the form of an a helix; it is the usual form for nail and hair keratins and thus is sometimes used synonymously with hard keratin.

1H-imidazole-4-ethanamine

DEFINITION:

Chemical name for histamine .

ß-glycosidase complex

DEFINITION:

The enzyme complex comprising lactase and glycosylceramidase (phlorhizin hydrolase) activities, occurring in the brush border membrane of the intestinal mucosa and hydrolyzing lactose as well as cellobiose and cellotriose; it is a single polypeptide, processed from a larger precursor, with two catalytic sites for the two enzyme activities.

a-ketoglutarate

DEFINITION:

An anionic form of a-ketoglutaric acid.

2 X 2 contingency table

DEFINITION:

A contingency table having two rows and two columns.

ß-hydroxybutyric acid

DEFINITION:

Butyric acid substituted at the ß, or 3, position, one of the ketone bodies produced in the liver and occurring at high levels in the blood and urine in ketosis. Called also 3-hydroxybutyric acid.

a-ketoglutaric acid

DEFINITION:

2-oxopentanedioic acid, 2-oxoglutaric acid, an intermediate in the tricarboxylic acid cycle; a-ketoglutarate is also produced from glutamate in amino group transfer reactions and by oxidative deamination.

2-oxoglutaric acid

DEFINITION:

See a-ketoglutaric acid.

ß-ketobutyric acid

DEFINITION:

Acetoacetic acid.

a1-globulins

DEFINITION:

The faster of the serum globulins with the most rapid electrophoretic migration, the other (slower) being the a₂-globulins.

3',5'-AMP

DEFINITION:

Abbreviation for cyclic adenosine monophosphate.

ß1-adrenergic receptor

DEFINITION:

See ß-adrenergic receptors.

a2-globulin

DEFINITION:

The slower of the serum globulins with the most rapid electrophoretic migration, the other (faster) being the a₁-globulins.

3',5'-GMP

DEFINITION:

Cyclic guanosine monophosphate.

σ

DEFINITION:

Sigma, the eighteenth letter of the Greek alphabet; symbol for "standard deviation."

a2-macroglobulin

DEFINITION:

See alpha₂-macroglobulin.

3-hydroxybutyric acid

DEFINITION:

ß-hydroxybutyric acid.

■

DEFINITION:

Symbol for "variance."

ai2

DEFINITION:

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4-fold

DEFINITION:

1. Comprising four parts or members.


2. Four times as great or as much.

2n

DEFINITION:

Indicating diploid chromosome number.

ai

DEFINITION:

Check back. Definition to be added.