urea cycle

Also found in: Dictionary, Thesaurus, Financial, Encyclopedia, Wikipedia.
Related to urea cycle: Urea cycle disorder


a succession or recurring series of events.
cardiac cycle a complete cardiac movement, or heart beat, including systole, diastole, and the intervening pause.
Cardiac cycle. From Applegate, 2000.
cell cycle the cycle of biochemical and morphological events occurring in a reproducing cell population; it consists of the S phase, occurring toward the end of interphase, in which DNA is synthesized; the G2 phase, a relatively quiescent period; the M phase, consisting of the four phases of mitosis; and the G1 phase of interphase, which lasts until the S phase of the next cycle.
citric acid cycle tricarboxylic acid cycle.
estrous cycle the recurring periods of estrus in adult females of most mammalian species and the correlated changes in the reproductive tract from one period to another.
hair cycle the successive phases of the production and then loss of hair, consisting of anagen, catagen, and telogen.
menstrual cycle see menstrual cycle.
ovarian cycle the sequence of physiologic changes in the ovary involved in ovulation; see also ovulation and reproduction.
reproductive cycle the cycle of physiologic changes in the reproductive organs, from the time of fertilization of the ovum through gestation and childbirth; see also reproduction.
sex cycle (sexual cycle)
1. the physiologic changes that recur regularly in the reproductive organs of nonpregnant female mammals.
2. the period of sexual reproduction in an organism that also reproduces asexually.
tricarboxylic acid cycle the cyclic metabolic mechanism by which the complete oxidation of the acetyl portion of acetyl-coenzyme A is effected; the process is the chief source of mammalian energy, during which carbon chains of sugars, fatty acids, and amino acids are metabolized to yield carbon dioxide, water, and high-energy phosphate bonds. Called also citric acid cycle, Krebs cycle, and TCA cycle.
 Central pathways of metabolism: How the body produces energy from the energy-containing nutrients using the tricarboxylic acid cycle. From Davis and Sherer, 1994.
urea cycle a cyclic series of reactions that produce urea; it is a major route for removal of the ammonia produced in the metabolism of amino acids in the liver and kidney.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

u·re·a cy·cle

the sequence of chemical reactions, occurring primarily in the liver, that results in the production of urea; the key reaction is the hydrolysis of l-arginine by arginase to l-ornithine and urea; l-ornithine is then converted to l-citrulline by a carbamoylation reaction, then to l-argininosuccinate by an amination reaction involving l-aspartic acid; finally, a lyase-dependent step generates arginine and fumarate.
Farlex Partner Medical Dictionary © Farlex 2012

urea cycle

The sequence of chemical reactions occurring in the liver that results in the production of urea. The key reaction is the hydrolysis of arginine by arginase to ornithine and urea.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

urea cycle

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005


Sir Hans Adolph, German biochemist in England and Nobel laureate, 1900-1981.
Krebs cycle - together with oxidative phosphorylation, the main source of energy in the mammalian body and the end toward which carbohydrate, fat, and protein metabolism are directed. Synonym(s): tricarboxylic acid cycle
Krebs-Henseleit cycle - the sequence of chemical reactions, occurring primarily in the liver, that results in the production of urea. Synonym(s): urea cycle
Krebs-Ringer solution - a modification of Ringer solution.
Medical Eponyms © Farlex 2012
References in periodicals archive ?
As a family we are grateful for this opportunity to tell our story and hope that we can and will help other families with arginase deficiency and urea cycle disorders.
However, even if amino acid oxidation is able to maintain neuronal energy levels, the increased amounts of ammonia released during amino acid catabolism could lead to neuronal cell death because all of the enzymes of the urea cycle needed to detoxify ammonia are not present in neurons or glia.
To stimulate the urea cycle, intravenous arginine was initiated at a continuous rate of 600 mg/kg per day, along with 10% dextrose in normal saline at 125 cc/hr [6].
Oyanagi, "Estimated frequency of urea cycle enzymopathies in Japan," American Journal of Medical Genetics, vol.
As Table 5 illustrates, for those with a higher amount of SNPs in the Urea Cycle, there is potential for less than optimal removal of ammonia from those with chronic Lyme disease.
Urea cycle disorders and inherited hyperammonaemias.
Glycerol phenylbutyrate, a nitrogen-binding agent, has been approved for the chronic treatment of adults and children aged 2 years and older with urea cycle disorders, who cannot be managed with a protein-restricted diet or amino acid supplements alone, according to the Food and Drug Administration.
By far the most common of the urea cycle defects is the X-linked recessive disorder, ornithine transcarbamylase deficiency (OTC).
It permits the detection and quantification of many IEMs in a single blood spot for most amino acids, urea cycle disorders, organic acids and fatty acid oxidation defects.
Qatar is also one of the few countries that have introduced liver cell therapy for the treatment of urea cycle disorder -- a rare condition that used to be fatal -- and was successful in using this to treat a baby in 2010, Dr al-Rifai recalled.
Supply of defect glutaric/ methw1 malonic urea cycle.
Several "sets" were sold, and students decided to give 20 percent of their profits to the National Urea Cycle Disorder Foundation (NUCDF)--helping to find a cure for their art teacher's son's disease.