urea

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urea

 [u-re´ah]
1. the diamide of carbonic acid found in urine, blood, and lymph, the chief nitrogenous constituent of urine, and the chief nitrogenous end-product of protein metabolism; it is formed in the liver from amino acids and from ammonia compounds.
2. a pharmaceutical preparation of this compound, administered intravenously as an osmotic diuretic to lower intracranial or intraocular pressure, injected transabdominally into the amniotic sac to induce abortion of a second trimester pregnancy, and included in topical preparations to moisten and soften rough, dry skin.



The amount of urea in the urine increases with the quantity of protein in the diet because urea is an endogenous and exogenous waste product: endogenous because some of it is derived from breakdown of body protein as tissues undergo disintegration and repair, and exogenous because some of it is derived from the deamination of amino acids absorbed from the intestinal tract but not utilized by the body. In severe nephritis or other disorders leading to renal failure, the concentration of urea in the blood may be greatly increased, as revealed by measurement of the blood urea nitrogen (BUN).
urea concentration test a test of renal efficiency, based on the fact that urea is absorbed rapidly from the stomach into the blood and is excreted unaltered by the kidneys; 15g of urea is given with 100mL of fluid, and the urine collected after 2 hours is tested for urea concentration.
urea nitrogen the urea concentration of serum or plasma, conventionally specified in terms of nitrogen content and called blood urea nitrogen (BUN), an important indicator of renal function.

u·re·a

(yū-rē'ă),
The chief end product of nitrogen metabolism in mammals, formed in the liver by means of the Krebs-Henseleit cycle and excreted in normal adult human urine in the amount of about 32 g a day (about 85% of the nitrogen excreted from the body). It may be obtained artificially by heating a solution of ammonium cyanate. It occurs as colorless or white prismatic crystals, without odor but with a cooling saline taste, is soluble in water, and forms salts with acids; has been used as a diuretic in kidney function tests, and topically for various dermatitides.
[G. ouron, urine]

urea

(yo͝o-rē′ə)
n.
A water-soluble compound, CO(NH2)2, that is the major nitrogenous end product of protein metabolism and is the chief nitrogenous component of the urine in mammals and certain other animals. Also called carbamide.

u·re·a

(yūr-ē'ă)
The chief end product of nitrogen metabolism in mammals, formed in the liver, by means of the Krebs-Henseleit cycle, and excreted in normal adult human urine in the amount of about 32 g a day (about 89% of the nitrogen excreted from the body); used as a diuretic in kidney function tests and topically for various dermatitides.
[G. ouron, urine]

urea

A substance formed in the liver from the excess of nitrogenous material derived from amino acids and excreted in solution in the urine. Urea can be used as an osmotic diuretic and as a cream for ICTHYOSIS and other hyperkeratotic skin disorders. The drug is on the WHO official list. See also URAEMIA.

urea

an organic molecule that forms the major end product of protein metabolism in mammals, being derived mainly from the ammonia released by the deamination of AMINO ACIDS. Formula: CO(NH2 )2. see ORNITHINE CYCLE.

Urea

A by-product of protein metabolism that is formed in the liver. Because urea contains ammonia, which is toxic to the body, it must be quickly filtered from the blood by the kidneys and excreted in the urine.

hyperosmotic agent

A drug that makes blood plasma hypertonic thus drawing fluid out of the eye and leading to a reduction in intraocular pressure. It is used in solution in the treatment of angle-closure glaucoma and sometimes before surgery to decrease the intraocular pressure. Common agents include glycerin (glycerol), isosorbide, mannitol and urea. See hypertonic solution.

u·re·a

(yūr-ē'ă)
Chief end product of nitrogen metabolism in mammals.
[G. ouron, urine]
References in periodicals archive ?
la), with >60% of the urea remaining in the NBPT treatments at 5[degrees]C and 15[degrees]C at Day 14, and <10% remaining at 25[degrees]C.
The increased urea hydrolysis with increasing temperature is not surprising as it has been found in other studies in the range 5-45[degrees]C (Kumar and Wagenet 1984; Moyo et al.
Urease inhibitors are compounds, which are used to inhibit the urease enzyme activity in soil and slow down the hydrolysis process of urea in soil (Bolan et al., 2004).
The urea amended with CuSO4 can reduce NH3 losses from 24 to 30% in cultivated soil and increased nutrient uptake of plant (Khanif, 1986; Reddy and Sharma, 2000; Leong, 2002).
Over time, residual urea can combine with ethanol to make urethane/EC.
During the development of a spectrophotometric determination of urea with diacetyl monoxime, Douglas and Bremner (1970a) showed that addition of 5 [micro]g/g of silver sulfate, mercuric chloride, or phenylmercuric acetate (Fig.
During the test one has to swallow a capsule containing urea, which is made from an isotope of carbon.
Replacing urea with nitrate salts have recently received wide consideration because of its potential benefits in mitigating enteric methane production (Sophal et al.
Nitrate could be lost through denitrification and leaching, if applied in the form of urea [2].
These results indicate that reducing the rate of urea hydrolysis and inhibiting nitrification with combined use of agrotain, nitropyrin in an alkaline calcareous soil is important to reduce N losses and N2O emission, improve fertilizer use efficiency of applied urea with maximum bioavailability to plants thus increase the yield of Maize crop.
Urea increases the nitrogen availability which in turn improves the protein content (Khan et al., 1999; Rath et al., 2001).
On the basis of the above background, in this work a new synthesis route of low solubility poly carbonyl urea as a slow release fertilizer was developed.