ornithine


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ornithine

 [or´nĭ-thēn]
an amino acid obtained from arginine by splitting of urea; it is an intermediate in urea biosynthesis.
ornithine carbamoyltransferase (ornithine transcarbamylase) an enzyme that catalyzes a reaction occurring in the liver mitochondria as part of the urea cycle.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

or·ni·thine (Orn),

(ōr'ni-thēn, -thin),
2,5-Diaminovaleric acid; the l-isomer is the amino acid formed when l-arginine is hydrolyzed by arginase; not a constituent of proteins, but an important intermediate in the urea cycle; elevated levels seen in certain defects of the urea cycle.
Farlex Partner Medical Dictionary © Farlex 2012

ornithine

(ôr′nə-thēn′)
n.
An amino acid, C5H12N2O2, not found in proteins, formed by hydrolyzing arginine and important in the formation of urea.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

or·ni·thine

(ōr'ni-thēn)
The amino acid formed when l-arginine is hydrolyzed by arginase; an important intermediate in the urea cycle; elevated levels seen in certain defects of the urea cycle.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

or·ni·thine

(Orn) (ōr'ni-thēn)
Amino acid formed when l-arginine is hydrolyzed by arginase; important intermediate in the urea cycle.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
Improved molecular diagnostics for ornithine transcarbamylase deficiency.Am J Hum Genet 1991;48:212-22.
However, some amino acid levels were still higher, notably ornithine, leucine/isoleucine, glutamic acid, and alanine.
Ornithine levels were weakly associated with the levels of rGT (r = 0.33, p < 0.001), but not with ALT or AST.
Arnoux et al., "Long-term outcomes in Ornithine Transcarbamylase deficiency: A series of 90 patients," Orphanet Journal of Rare Diseases, vol.
High-performance liquid chromatography (HPLC) measurement of serum amino acids revealed high levels of glycine (559mmol/L; normal value up to 426 [micro]mol/L), alanine (1090 [micro]mol/L; normal value up to 474 [micro]mol/L), ornithine (132 [micro]mol/L; normal value up to 130 [micro]mol/L), and glutamine (1464 [micro]mol/L; normal value up to 426 [micro]mol/L) and revealed lower plasma levels of citrulline (4 [micro]mol/L; normal value: 9-38) and a higher urine orotic acid at 4.7 mmol/mol and creatinine (normal value: 1.0-3.2 mmol/mol creatinine).
Much more arginine may be used in the ornithine production and this may lead to formation of polyamines which have been previously shown to be closely related to cancer progression.
Arginase activity was also measured by conversion of L-arginine to ornithine in vitro, as previously described [17] and modified by us [18,19].
Plasma amino acid analysis revealed absence of citrulline and argininosuccinic acid, low normal ornithine, and high urinary orotic acid levels consistent with proximal urea cycle defects like Ornithine Transcarbamylase deficiency (OTC), N-acetyl Glutamate Synthase deficiency (NAGS), and Carbomyl Phosphate Synthase 1 deficiency (CPS1).
demonstrated that Pso lesions had increased ornithine decarboxylase (ODC) activity in both lesional and non-lesional skin, compared to healthy controls (7).
Stepwise regression analysis that included age, sex, and body mass index (BMI) further whittled the field down to a panel of seven candidate metabolites: ornithine, arginine, glutamine, histidine, phosphatidylcholine acyl-alkyl C38:2, dodecenoyl carnitine, and octenoyl carnitine.