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Topic: Urea cycle

Related Topics

Carbamoyl phosphate

Citrulline

Citric acid cycle

Ornithine

Ammonia

Urea

Blood urea nitrogen

Arginase

Aspartate

Urea Breath Test

Hepatic encephalopathy

Ammonium sulfate

Superoxide dismutase

Amino acid

Polypeptide

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	Urea cycle - Wikipedia, the free encyclopedia
		The urea cycle is a cycle of biochemical reactions occurring in many animal organisms that produces urea from ammonia.
		Urea is much less toxic than ammonia; therefore, organisms that cannot easily and quickly remove ammonia usually have to convert it to some other substance, like urea or uric acid.
		Insufficiency of the urea cycle occurs in some genetic disorders (inborn errors of metabolism), and in liver failure.
	en.wikipedia.org /wiki/Urea_cycle (190 words)

	What is a Urea Cycle Disorder? (Site not responding. Last check: 2007-11-06)
		A urea cycle disorder is a genetic disorder caused by a deficiency of one of the enzymes in the urea cycle which is responsible for removing ammonia from the blood stream.
		In urea cycle disorders, the nitrogen accumulates in the form of ammonia, a highly toxic substance, and is not removed from the body.
		Because many cases of urea cycle disorders remain undiagnosed and/or infants born with the disorders die without a definitive diagnosis, the exact incidence of these cases is unknown and underestimated.
	www.nucdf.org /whatis.htm (1255 words)

	Urea - Wikipedia, the free encyclopedia
		In some animals, the individual atoms of urea come from carbon dioxide, water, aspartate and ammonia in a metabolic pathway known as the urea cycle, an anabolic process.
		Because urea is produced and excreted at a roughly constant rate, high levels of urea in the blood indicate a problem with the removal or, more rarely, the over-production of urea in the body.
		Isotopically-labeled urea (carbon 14 - radioactive, or carbon 13 - stable isotope) is used in the Urea breath test, which is used to detect the presence of Helicobacter pylori (H.
	en.wikipedia.org /wiki/Urea (630 words)

	Lets_Talk
		Urea cylce disorder are genetic disorders caused by a deficiency in one of the enzymes in the urea cycle.
		The urea cycle involves a series of biochemical steps that take place in the liver, in which nitrogen is removed from the blood and converted to urea, which is then eliminated from the body in urine.
		Normally, urea is transferred into the urine and removed from the body, but when one of these urea cycle enzymes is missing or deficient, nitrogen accumulates and is converted to ammonia, a highly toxic substance, instead of urea.
	www.geocities.com /citrullinemia/Lets_Talk.html (639 words)

	The Urea Cycle
		The remainder of the cycle occurs in the cytosol of the cell.
		Urea is formed by the urea cycle by the hydrolysis of arginosuccinate.
		Therefore, the fumarate produced by the urea cycle is eventually converted to another necessary compound aspartate for the urea cycle to continue.
	www.db.uth.tmc.edu /faculty/amoretti/alevine/1521_2000/ureacyc.htm (953 words)

	Urea Cycle Management (Site not responding. Last check: 2007-11-06)
		Urea cycle disorders are estimated to occur in 1 in 30,000 live births.
		Families of patients with urea cycle disorders should receive genetic counseling, as carrier detection and prenatal diagnosis are available for most disorders.
		Individuals with urea cycle disorders may present at any age and may be very acutely ill or have a chronic problem.
	www.meadjohnson.com /metabolics/ureacycle.html (2792 words)

	Urea Cycle Disorder (UCD), Cincinnati Children's Hospital Medical Center (Site not responding. Last check: 2007-11-06)
		A urea cycle disorder (UCD) is an inherited disease caused by the lack of an enzyme needed to break down ammonia in the body.
		Most urea cycle disorders are caused by a lack of a specific enzyme in the urea cycle.
		Urea cycle disorders are genetic, and most appear only if a person inherits a defective gene from both parents.
	www.cincinnatichildrens.org /svc/alpha/l/liver/diseases/urea-cycle.htm (1156 words)

	Urea Cycle
		Aspartic acid is regenerated from fumaric acid produced by the urea cycle.
		Urea is routinely measured in the blood as: Blood Urea Nitrogen (BUN).
		In animals that excrete urea, water is required to dissolve urea in urine.
	www.elmhurst.edu /~chm/vchembook/633ureacycle.html (687 words)

	ARS \| Publication request: In Vivo Urea Cycle Flux Distinguishes and Correlates with Phenotypic Severity in Disorders ...
		We hypothesized that stable isotopically determined in vivo rates of total body urea synthesis and urea cycle-specific nitrogen flux would correlate with both phenotypic severity and carrier status in patients with a variety of different enzymatic deficiencies of the urea cycle.
		Total urea synthesis from all nitrogen sources was determined from [18O]urea labeling, and the utilization of peripheral nitrogen was estimated from the relative isotopic enrichments of [15N]urea and [15N]glutamine during i.v.
		Urea synthesis is altered by alternative route medications and arginine supplementation to the degree that is to be expected from theory.
	ars.usda.gov /research/publications/Publications.htm?seq_no_115=147060 (543 words)

	Newborn Screening Program - Urea Cycle Disorders
		Urea cycle disorders are a group of inherited conditions of amino acid metabolism, each caused by a specific defect in the biosynthesis of one of the normally expressed enzymes of the urea cycle.
		Urea cycle disorders may result in severe hyperammonemia, and infants with this condition require prompt treatment, which may include hemodialysis.
		The urea cycle is a metabolic pathway that converts ammonia and bicarbonate to urea, for the purpose of removing waste nitrogen from the body.
	www.idph.state.il.us /HealthWellness/fs/urea.htm (730 words)

	Nitrogen Metabolism and the Urea Cycle
		The reactions of the urea cycle which occur in the mitochondrion are contained in the red rectangle.
		The essential features of the urea cycle reactions and their metabolic regulation are as follows: Arginine from the diet or from protein breakdown is cleaved by the cytosolic enzyme arginase, generating urea and ornithine.
		In subsequent reactions of the urea cycle a new urea residue is built on the ornithine, regenerating arginine and perpetuating the cycle.
	web.indstate.edu /thcme/mwking/nitrogen-metabolism.html (4052 words)

	BioCarta - Charting Pathways of Life
		In mammals, the nitrogen is converted to urea in the liver through a series of reactions called the urea cycle.
		Urea is released from arginine by the enzyme arginase, bringing the cycle back around to ornithine.
		The general route of entry for amino acids into the urea cycle is through transamination, the transfer of their amino group to alpha-ketoglutarate to form glutamate.
	www.biocarta.com /pathfiles/ureacyclePathway.asp (303 words)

	The Urea Cycle (Site not responding. Last check: 2007-11-06)
		Urea is produced to dispose of excess nitrogen.
		Urea is produced from ammonia in five enzymatic steps.
		Fumarate produced by the urea cycle is an intermediate of the citric acid cycle.
	www-medlib.med.utah.edu /block2/biochem/Lindsley/Nitmet2txt.htm (1553 words)

	UCDC - Information for Physicians
		CPSI is the first enzyme in the urea cycle and is found primarily in the liver.
		Carrier females can also be affected (unlike the other urea cycle disorders) due to switching off on one of the X chromosomes in females.
		Treatment is identical to other urea cycle disorders, with limitation of protein, use of essential amino acid supplements and diversion of ammonia from the urea cycle with sodium benzoate or sodium phenylbutyrate.
	rarediseasesnetwork.epi.usf.edu /ucdc/physicians/definitions.htm (1218 words)

	► Hereditary urea cycle abnormality
		The urea cycle is a metabolic cycle involving incorporation of waste nitrogen from the breakdown of dietary proteins into a form (urea) that can be removed from the body.
		These are genetic diseases caused by a the lack of a gene to make critical enzymes needed for the urea cycle.
		All are genetic diseases associated with lack of a protein/enzyme activity in the urea cycle.
	www.umm.edu /ency/article/000372.htm (362 words)

	[No title]
		Urea Cycle Disorders (UCD) belong to the group of disorders known as inborn errors of metabolism.
		Urea Cycle Management - Urea Cycle Disorders: Background Rebecca S. Wappner Urea cycle disorders are estimated to occur in 1 in 30,000 live births.
		A urea cycle disorder is a genetic disease that affects how protein is broken down in the body.
	www.diseasedirectory.net /Genetic_Disorders/Urea_Cycle/default.aspx (452 words)

	BIOCHEM ISTRY I - AMINO ACID DEGRADATION/UREA CYCLE (Site not responding. Last check: 2007-11-06)
		Ammonia produced is converted to urea via the urea cycle.
		The Urea Cycle was proposed by Hans Krebbs and Kurt Henseleit (in 1932).
		The strategy followed by the cell is to convert carbon frameworks to compounds useful in gluconeogenesis or the citric acid cycle.
	www.sbuniv.edu /~ggray/CHE3364/b1c25out.html (1156 words)

	Dr. Koop - Hereditary urea cycle abnormality
		Patients with urea cycle abnormalities must also be very careful under times of stress, such as infections.
		Most patients with urea cycle disorders require hospitalization at some point in their illness.
		The outcome depends on which of the urea cycle abnormalities a person has, how severe it is, how early it is discovered, and how closely the protein-restricted diet is followed.
	www.drkoop.com /ency/93/000372trt.html (482 words)

	Clinical Trial: Study of Treatment and Metabolism in Patients With Urea Cycle Disorders
		RATIONALE: The urea cycle is the process in which nitrogen is removed from the blood and converted into urea, a waste product found in urine.
		Urea cycle disorders are inherited disorders caused by the lack of an enzyme that removes ammonia from the bloodstream.
		Studying the treatment and metabolism of patients with urea cycle disorders may be helpful in developing new treatments for these disorders.
	clinicaltrials.gov /ct/gui/show/NCT00004307 (332 words)

	Lecture #31: Amino Acid Metabolism and the Urea Cycle (Site not responding. Last check: 2007-11-06)
		This pattern is similar to the TCA cycle where each turn of the cycle regenerates oxaloacetate, and acetate is transferred from acetyl CoA to oxaloacetate to form citrate.
		Second N is acquired via condensation of citrulline's uredio (urea containing) group and aspartate amino group to form argininosuccinate.
		Hydrolysis of arginine to yield UREA and regenerate ornithine.
	www.uaf.edu /chem/451f00D/HW31.htm (248 words)

	UCDC for Patients - Learn More
		N-acetylglutamate is one of the most severe disorders of the urea cycle.
		CPSI is an enzyme in the urea cycle found primarily in the liver.
		Arginase takes the amino acid arginine, which is made by the urea cycle, and breaks it into two molecules, urea and ornithine.
	rarediseasesnetwork.epi.usf.edu /ucdc/learnmore/definitions.htm (1478 words)

	Clinical Manifestations of Inborn Errors of the Urea Cycle and Related Metabolic Disorders during Childhood -- Endo et ... (Site not responding. Last check: 2007-11-06)
		Clinical Manifestations of Inborn Errors of the Urea Cycle and Related Metabolic Disorders during Childhood -- Endo et al.
		cycle, and disorders of the transporters or metabolites of the
		In the urea cycle or in urea cycle–related disorders,
	www.nutrition.org /cgi/content/full/134/6/1605S (2896 words)

	The Urea Cycle (Site not responding. Last check: 2007-11-06)
		Urea is the chief nitrogenous waste of mammals.
		Ammonia is an extremely toxic base and its accumulation in the body would quickly be fatal.
		There are several inherited diseases of the urea cycle caused by mutations in genes encoding one or another of the necessary enzymes.
	users.rcn.com /jkimball.ma.ultranet/BiologyPages/U/UreaCycle.html (487 words)

	Hereditary urea cycle abnormality
		The urea cycle is a metabolic process in which waste (nitrogen) from the breakdown of dietary proteins is incorporated by the liver into a form (called urea) that can be excreted from the body in the urine.
		Abnormality of the urea cycle - hereditary; Urea cycle - hereditary abnormality
		As a result of these disorders, ammonia levels rise as proteins are not properly broken down into urea and removed.
	www.healthscout.com /ency/1/000372.html (381 words)

	triButyrate® and Urea Cycle Disorder Research
		Inborn errors of Urea Synthesis are rare and belong to the larger group of disorders of amino acid metabolism, which are genetically determined and caused by enzyme defects.
		The most well known disorder in the larger group is phenylketonuria (PKU), characterized by an accumulation of the amino acid phenylalanine, which frequently results in mental and psychomotor retardation, if not treated.
		The disorders of inborn errors of Urea Synthesis are less known, but are life threatening conditions associated with hyperammonemia or high plasma glutamine levels, often resulting in coma and death in infants, if not treated immediately.
	www.tributyrate.com /html/urea_cycle_disorder.php (306 words)

	Citrullinemia
		Citrullinemia is a rare inherited disorder caused by deficiency or lack of the enzyme argininosuccinate synthetase (ASS).
		Argininosuccinate synthetase is one of six enzymes that play a role in the breakdown and removal of nitrogen from the body, a process known as the urea cycle.
		The urea cycle disorders are a group of rare disorders affecting the urea cycle, a series of biochemical processes in which nitrogen is converted into urea and removed from the body through the urine.
	my.webmd.com /hw/raising_a_family/nord310.asp (478 words)

	Urea Cycle Disorders / Family Village
		The National Urea Cycle Disorders Foundation is a non-profit organization dedicated to the identification, treatment and cure of urea cycle disorders.
		This is a discussion board for people who care for a transplanted child who was born with a urea cycle disorder (UCD) and families of a UCD-child, who may require a future transplant, that wish to ask questions of people who take care of TRUE Kids.
		Transplanted to Resolve Urea-cycle Enzyme-deficiency TRUE Kids is a gathering place for people who care for a transplanted child who was born with a urea cycle disorder (UCD).
	www.familyvillage.wisc.edu /lib_urea.htm (216 words)

	Urea Cycle Disorders
		Links families, friends and professionals who are dedicated to the identification, treatment and cure of urea cycle disorders, a genetic disorder causing an enzyme deficiency in the urea cycle.
		Opportunity for parents caring for a child with a urea cycle disorder to discuss concerns and ideas.
		Goal is to increase awareness of urea cycle disorders in order to improve diagnosis.
	my.webmd.com /hw/health_guide_atoz/shc29ure.asp (393 words)

	Urea Cycle (Site not responding. Last check: 2007-11-06)
		Fumarate provides a connection with the TCA cycle.There are three possible routes, all of which are things you've seen before:
		Once in the mitochondria, oxaloacetate is easily transaminated back to aspartate to contiue the cycle.
		Urea - not toxic, req's a lot of H
	www.bmb.psu.edu /courses/bmb211/classnotes/UreaCycle.html (248 words)

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