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g
Symbol for gram, a unit of measurement of mass in the metric system equal to the mass of a thousandth of a liter of water at 4 degrees centigrade.
The abbreviation for gram is gm.
G (Guanine)
G stands for guanine, one member of the base pair G-C (guanine-cytosine) in the DNA. The other base pair in the DNA is A-T (adenine-thymine).
Each base pair forms a "rung of the DNA ladder." A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the "letters" that spell out the genetic code. In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.
G protein
These molecules have been described as "biological traffic lights." Located inside the cell, G proteins are able respond to signals outside the cell -- light, smell, hormones -- and translate (transduce) these signals into action within the cell.
Alfred G. Gilman and Martin Rodbell shared the 1994 Nobel Prize in Physiology or Medicine for "their discovery of G- proteins and the role of these proteins in signal transduction in cells."
Gait
Manner of walking
Galactorrhea
Galactorrhea is the spontaneous flow of milk from the nipple at a time other than during nursing.
Galactorrhea can be due to "normal" factors such as an unrecognized pregnancy, trauma, surgery, overexercise or one of a number of drugs (including amphetamine, cimetidine, female hormone replacement therapy, hydroxyzine, methyldopa, nicotine, narcotics, reserpine, antidepressants of the so-called tricyclic type, or verapamil).
Galactorrhea can also be due to "abnormal" factors of a pathologic nature such as cirrhosis of the liver, a false pregnancy (pseudocyesis), renal (kidney) failure, disorders of the spinal cord, or a prolactinoma (a benign pituitary tumor that secretes the hormone prolactin which stimulates milk production).
The word "galactorrhea" comes from the Greek "galaktos" meaning "milk" + "rhein" meaning "to flow" = "to flow milk." (The naturally occurring sugar in breast milk is called galactose.)
Galactorrhea is also called witch's milk (or, to use the venerable German name, Hexenmilch) although these terms are sometimes reserved for the milk that commonly flows from the newborn baby's breast or can be expressed from it. This transient phenomenon is due to stimulation of the baby's breasts by the mother's hormones that crossed the placenta during pregnancy. The ability of the baby's breasts to respond in this fashion is a mark of baby's having been born at (or near) full-term; the breasts of a baby whose birth is markedly premature cannot respond with galactorrhea.
Galactose
Sugar found in milk.
Galactosemia
Inherited disorder due to defective metabolism (processing) of the sugar galactose. Galactosemia is one of the diseases in many newborn genetic screening panels. The disease (which can be fatal, if undetected) is treated by avoiding galactose in the diet.
Galeophobia
An abnormally large and persistent fear of sharks. Sufferers from this phobia experience anxiety even though they may be safe on a boat or in an aquarium or on a beach. Hollywood films depicting sharks as calculating, vengeful diabolical monsters have no doubt enkindled the fear of sharks in many persons. So have validated reports of sharks venturing into rivers and lakes.
"Galeophobia" is derived from the Greek words "galeos" (shark with markings resembling those on a weasel) and "phobos" (fear). "Galeophobia" is also sometimes used as alternate term for ailurophobia, fear of cats, because the Greek word "galeos" is derived from "galee," a Greek meaning "polecat" and "weasel."
Gallbladder
A pear-shaped organ that stores bile. It is located below the liver.
Gallbladder absence
This condition, also known as agenesis (failure of development) of the gallbladder, occurs in approximately one out of every 1,000 people.
Gallbladder agenesis is an isolated abnormality in more than two-thirds (70%) of people with agenesis. The person with isolated agenesis of the gallbladder is healthy. No treatment is needed. The prognosis (outlook) is excellent.
Gallbladder agenesis occurs in association with additional malformations in the remaining (30%) of cases which fall into two groups: one (9%) with atresia (failure of opening) of the bile ducts and the other (21%) with normal bile ducts but distant abnormalities such as ventricular septal defect (a hole between the ventricles of the heart), imperforate anus (blind rectum with no anus), malrotation of the gut (failure of the intestines to rotate normally during embryonic development), renal agenesis (absence of a kidney), and syndactyly (fusion of fingers).
Agenesis of the gallbladder is most often a sporadic (unpredictable) occurrence with no clear cause. However, there are families in which the condition has occurred in several members suggesting that there are hereditary forms of gallbladder agenesis. Children with gallbladder agenesis plus distant malformations tend to have trisomy 13 or another chromosomal abnormality that carries a poor prognosis.
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