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Medical Dictionary - Dictionary of Medicine and Human Biology

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γ, uppercase Γ
  • The third letter of the Greek alphabet.
  • A unit of magnetic flux density equal to one nanotesla.
  • Gamma ray, usually used as the attributive form of "gamma ray".
  • Of or relating to one of three or more closely related chemical substances, e.g., the gamma chain of hemoglobin, γ-yohimbine — used somewhat arbitrarily to specify ordinal relationship or a particular physical form and especially one that is allotropic, isomeric, or stereoisomeric (as in gamma benzene hexachloride).
  • Third in position in the structure of an organic molecule from a particular group or atom, and also: occurring at or having a structure characterized by such a position, e.g., γ-hydroxy acids.
  • Of streptococci: producing no hemolysis on blood agar plates.
γ-Abu
Abbreviation for γ-aminobutyric acid.

γ-aminobutyric acid (GABA, γ-Abu) (a-me′no-bu-ter′ik)
An amino acid C4H9NO2 that is a neurotransmitter that induces inhibition of postsynaptic neurons—abbreviation GABA. Used in the treatment of a number of disorders ( e.g., epilepsy).

γ-amylase
SYN: exo-1,4-α-d-glucosidase.

(γ)-benzene hexachloride
See lindane.

γ-butyrobetaine (bu-tir′o-be-tan)
A betaine of γ-aminobutyric acid; a precursor of carnitine by hydroxylation of the β-carbon.

γ-cystathionase
SYN: cystathionine γ-lyase.

γ
1. Third letter in the Greek alphabet, gamma. 2. In chemistry, denotes the third in a series, the fourth carbon in an aliphatic acid, or position 2 removed from the α position in the benzene ring. 3. Symbol for 10−4 gauss; surface tension; activity coefficient; microgram. 4. Symbol for photon. For terms having this prefix, see the specific term.

G
Abbreviation or symbol for gravitational units, under unit; gap (3) ; gauss; giga-; d-glucose, as in UDPG; guanosine, as in GDP; glycine; guanine.

G
Symbol for Newtonian constant of gravitation; Gibbs free energy; Gact or G&ddag;, Gibbs energy of activation.

g
Abbreviation for gram; gaseous state.

g
Unit of acceleration based on the acceleration produced by the earth's gravitational attraction, where 1 g = 980.621 cm/sec2 (about 32.1725 ft/sec2) at sea level and 45° latitude. At 30° latitude, g equals 979.329 cm/sec2.

G1
Symbol for gap1 period.

G2
Symbol for gap 2.

Ga
Symbol for gallium.

67Ga
Symbol for gallium-67.

68Ga
Symbol for gallium-68.

GABA
Abbreviation for γ-aminobutyric acid.

G acid
2-Naphthol-6,8-disulfonic acid.

G-actin
See under actin.

GAD
Abbreviation for glutamate decarboxylase.

Gaddum
John H., English pharmacologist, 1900–1965. See G. and Schild test.

gadfly (gad′fli)
See Tabanus.

gadodiamide (gad-o-di′a-mid)
A nonionic structural analog of gadolinium DPTA; used as a paramagnetic contrast medium in magnetic resonance imaging.

gadoleic acid (gad-o-le′ik)
A cis-unsaturated fatty acid from cod liver oil and other sources. SYN: 9-eicosenoic acid.

gadolinium (Gd) (gad-o-lin′e-um)
An element of the lanthanide group, atomic no. 64, atomic wt. 157.25. The paramagnetic properties of this element are used in contrast media for magnetic resonance imaging. [mineral, gadolinite, from Johan Gadolin, Finnish chemist, 1760–1852]

gadopentetate (gad-o-pen′te-tat)
(NMG)2[GdDTPA], dimeglumine diethylenetriaminepentaacetatogadolinate (III);the methylglucamine salt of dianionic gadolinium DPTA, an acyclic chelate; used as a paramagnetic contrast medium in magnetic resonance imaging.

gadoteridol (gad-o-ter′i-dol)
GdHP-DO3A;a gadolinium (III) chelate of 10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid; a nonionic macrocyclic analog of gadolinium DOTA; used as a paramagnetic contrast medium in magnetic resonance imaging.

Gaenslen
Frederick J., U.S. surgeon, 1877–1937. See G. sign.

Gaffky
Georg T.A., German hygienist, 1850–1918. See G. scale, G. table.

GAG
Abbreviation for glycosaminoglycan.

gag
1. To retch; to cause to retch or heave. 2. To prevent from talking. 3. An instrument adjusted between the teeth to keep the mouth from closing during operations in the mouth or throat. Crowe-Davis mouth g. instrument used for opening the mouth, depressing the tongue, maintaining the airway, and transmitting volatile anesthetics during tonsillectomy or other oropharyngeal surgery.

gage (gaj)
SYN: gauge.

gain (gan)
1. Profit; advantage. 2. The ratio of output to input of an amplifying system, generally expressed in decibels in ultrasound. [M.E. gayne, booty, fr. O.Fr., fr. Germanic] primary g. interpersonal, social, or financial advantages from the conversion of emotional stress directly into demonstrably organic illnesses ( e.g., hysterical blindness or paralysis). Cf.:secondary g.. secondary g. interpersonal or social advantages ( e.g., assistance, attention, sympathy) gained indirectly from organic illness. Cf.:primary g.. time-compensated g. SYN: time-g. compensation. time compensation g. (TCG) SYN: time-g. compensation. time-varied g. (TVG) SYN: time-g. compensation.

Gairdner
Sir William T., Scottish physician, 1824–1907. See G. disease.

Gaisböck
Felix, German physician, 1868–1955. See G. syndrome.

gait (gat)
  • Manner of walking.
  • antalgic g. a characteristic g. resulting from pain on weightbearing in which the stance phase of g. is shortened on the affected side.
  • ataxic g. SYN: cerebellar g..
  • calcaneal g. a g. disturbance, characterized by walking on heel, due to paralysis of the calf muscles, seen following poliomyelitis and in some other neurologic diseases.
  • cerebellar g. wide-based g. with lateral veering, unsteadiness, and irregularity of steps; often with a tendency to fall to one or other side, forward or backward. SYN: ataxic g..
  • Charcot g. the g. of hereditary ataxia.
  • circumduction g. SYN: hemiplegic g..
  • equine g. SYN: high-steppage g..
  • festinating g. g. in which the trunk is flexed, legs are flexed at the knees and hips, but stiff, while the steps are short and progressively more rapid; characteristically seen with parkinsonism -1 and other neurologic diseases. SYN: festination.
  • gluteus maximus g. compensatory backward propulsion of trunk to maintain center of gravity over the supporting lower extremity.
  • gluteus medius g. compensatory list of body (or throw of trunk) to the weak gluteal side, to place the center of gravity over the supporting lower extremity.
  • helicopod g. a g., seen in some conversion reactions or hysterical disorders, in which the feet describe half circles. SYN: helicopodia.
  • hemiplegic g. g. in which the leg is stiff, without flexion at knee and ankle, and with each step is rotated away from the body, then towards it, forming a semicircle. SYN: circumduction g., spastic g..
  • high-steppage g. a g. in which the foot is raised high to avoid catching a drooping foot and brought down suddenly in a flapping manner; often seen in peroneal nerve palsy ( i.e., foot-drop) and tabes. SYN: equine g..
  • hysterical g. a variety of bizarre gaits seen with hysteria-conversion reaction; usually the foot is dragged or pushed ahead, instead of lifted, while walking; frequently the foot is held dorsiflexed and inverted.
  • scissor g. g. in which each leg swings medially as well as forward on walking; usually due to bilateral lower extremity spasticity, the result of cerebral palsy.
  • spastic g. SYN: hemiplegic g..
  • steppage g. a g. in which the advancing foot is lifted higher than usual so that it can clear the ground, because it cannot be dorsiflexed. Seen with peroneal neuropathies and other disorders causing foot dorsiflexion weakness. See high-steppage g.. SYN: steppage.
  • toppling g. a g. in which the steps are uncertain and hesitant, and the patient totters and sometimes falls; probably due to a balance disorder; may be seen in elderly patients after a stroke.
  • Trendelenburg g. SYN: Trendelenburg sign.
  • waddling g. rolling g. in which the weight-bearing hip is not stabilized; it bulges outward with each step, while the opposite side of the pelvis drops, resulting in alternating lateral trunk movements; due to gluteus medius muscle weakness, and seen with muscular dystrophies, among other disorders. SYN: waddle.
Gal
Symbol for galactose.

galact-
See galacto-.

galactacrasia (ga-lak′ta-kra′ze-a)
Abnormal composition of mother's milk. [galact- + G. akrasia, bad mixture, fr. a- priv. + krasis, a mixing]

galactagogue (ga-lak′ta-gog)
An agent that promotes the secretion and flow of milk. [galact- + G. agogos, leading]

galactans (ga-lak′tanz)
Polymers of galactose occurring naturally, along with galacturonans and arabans, in pectins; e.g., agar. SYN: galactosans.

galactic (ga-lak′tik)
Pertaining to milk; promoting the flow of milk.

galactidrosis (ga-lak-ti-dro′sis)
Sweating of a milky fluid. [galact- + G. hidros, sweat, + -osis, condition]

galactitol (ga-lak′ti-tol)
A sugar alcohol derived from galactose; g. accumulates in transferase deficiency galactosemia.

galacto-, galact-
Milk. Cf.:lact-. [G. gala]

galactoblast (ga-lak′to-blast)
SYN: colostrum corpuscle. [galacto- + blastos, germ]

galactocele (ga-lak′to-sel)
Retention cyst caused by occlusion of a lactiferous duct. SYN: lactocele. [galacto- + G. kele, tumor]

galactogen (ga-lak′to-jen)
A polysaccharide containing galactose in various forms. [galacto- + G. -gen, producing]

galactokinase (ga-lak-to-ki′nas)
An enzyme (phosphotransferase) that, in the presence of ATP, catalyzes the phosphorylation of d-galactose to d-galactose l-phosphate, the first step in the metabolism of d-galactose; g. is deficient in one form of galactosemia.

galactometer (gal′ak-tom′e-ter)
A form of hydrometer for determining the specific gravity of milk as an indication of its fat content. SYN: lactometer. [galacto- + G. metron, measure]

galactophagous (gal′ak-tof′a-gus)
Subsisting on milk. [galacto- + G. phago, to eat]

galactophore (ga-lak′to-for)
SYN: lactiferous ducts, under duct. [galacto- + G. phoros, bearing]

galactophoritis (ga-lak′to-fo-ri′tis)
Inflammation of the milk ducts. [galacto- + G. phoros, carrying, + -itis, inflammation]

galactophorous (gal-ak-tof′o-rus)
Conveying milk.

galactopoiesis (ga-lak′to-poy-e′sis)
Milk production. [galacto- + G. poiesis, forming]

galactopoietic (ga-lak′to-poy-et′ik)
Pertaining to galactopoiesis.

galactopyranose (ga-lak-to-pir′a-nos)
Galactose in pyranose form.

galactorrhea (ga-lak-to-re′a)
1. Any white discharge from the nipple that is persistent and looks like milk. 2. Continued discharge of milk from the breasts between intervals of nursing or after the child has been weaned. SYN: incontinence of milk, lactorrhea. [galacto- + G. rhoia, a flow]

galactosamine (ga-lak-to-sam′en)
The 2-amino-2-deoxy derivative of galactose, in which the NH2 replaces the 2-OH group; the d-isomer occurs in various mucopolysaccharides, notably of chondroitin sulfuric acid and of B blood group substance; usually found as the N-acetyl derivative.

galactosaminoglycan (ga-lak′tos-am-i-no-gli′kan)
See mucopolysaccharide.

galactosans (ga-lak′to-sanz)
SYN: galactans.

galactoscope (ga-lak′to-skop)
An instrument for judging of the richness and purity of milk by the translucency of a thin layer. SYN: lactoscope. [galacto- + G. skopeo, to examine]

galactose (Gal) (ga-lak′tos)
An aldohexose found (in d form) as a constituent of lactose, cerebrosides, gangliosides, mucoproteins, etc., in galactoside or galactosyl combination; an epimer of d-glucose.

galactosemia (ga-lak-to-se′me-a)
1. [MIM*230400] An inborn error of galactose metabolism due to congenital deficiency of the enzyme galactosyl-1-phosphate uridylyltransferase, resulting in tissue accumulation of galactose 1-phosphate; manifested by nutritional failure, hepatosplenomegaly with cirrhosis, cataracts, mental retardation, galactosuria, aminoaciduria, and albuminuria that regress or disappear if galactose is removed from the diet; autosomal recessive inheritance; caused by mutation in the galactose-1-phosphate uridyltransferase gene (GALT) on 9p. SEE ALSO: galactokinase deficiency. 2. An inborn error in metabolism other than a deficiency in galactosyl-1-phosphate uridylyltransferase (see subentries below). SYN: galactose diabetes. [galactose + G. haima, blood] epimerase deficiency g. an inborn error in metabolism in which there is a deficiency of uridine diphosphate galactose 4-epimerase; galactose 1-phosphate accumulates. galactokinase deficiency g. an autosomal recessive disorder resulting in an accumulation of galactose and galactitol. transferase deficiency g. an autosomal recessive disorder in which there is a deficiency of galactose-1-phosphate uridylyltransferase (see main entry for g.).

galactose-1-phosphate
A phosphorylated derivative of galactose that is key in galactose metabolism; accumulates in certain types of galactosemia. galactose-1-phosphate uridylyltransferase an enzyme catalyzing the reaction of UTP and α-d-galactose 1-phosphate to form UDP galactose and pyrophosphate, the second and most important step in the metabolism of d-galactose; a deficiency of this enzyme results in an accumulation of galactose, g., and galactitol.

galactose-6-sulfatase
An enzyme that eliminates sulfur from the galactose 6-sulfate residues of certain mucopolysaccharides, producing 3,6-anhydrogalactose residues; it is absent in Morquio syndrome type A. SYN: galactose-6-sulfurase.

galactose-6-sulfurase
SYN: galactose-6-sulfatase.

galactoside (ga-lak′to-sid)
A compound in which the H of the OH group on carbon-1 of galactose is replaced by an organic moiety.

galactosis (gal-ak-to′sis)
Formation of milk by the lacteal glands. [galacto- + G. -osis, condition]




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