| ornithine cycle | The metabolic pathway isfound in vertebrates and takes place in theliver, in it, urea is synthesised from amino acids and carbon dioxide. (09 Oct 1997) |
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| ornithine d-aminotransferase | <enzyme> An enzyme that will reversibly catalyze the reaction of alpha-ketoglutarate and l-ornithine to form l-glutamate and l-glutamate gamma-saemialdehyde; a deficiency of this enzyme will result in gyrate atrophy of the choroid and retina. Synonym: ornithine transaminase. (05 Mar 2000) |
| ornithine decarboxylase | <enzyme> The enzyme that converts ornithine to putrescine (dibasic amine) by decarboxylation. Rate limiting in the synthesis of the polyamines spermidime and spermine that regulate DNA synthesis. (18 Nov 1997) |
| ornithine transaminase | <enzyme> An enzyme that will reversibly catalyze the reaction of alpha-ketoglutarate and l-ornithine to form l-glutamate and l-glutamate gamma-saemialdehyde; a deficiency of this enzyme will result in gyrate atrophy of the choroid and retina. Synonym: ornithine transaminase. (05 Mar 2000) |
| ornithine transcarbamoylase | <enzyme> An enzyme of the transferase class that catalyses the reaction of carbamoyl phosphate and l-ornithine to yield orthophosphate and l-citrulline. The enzyme occurs in the liver. The reaction is a part of the urea cycle. Genetic deficiency of the enzyme, an x-linked trait, impairs urea formation and produces hyperammonaemia. Chemical name: Carbamoyl-phosphate:L-ornithine carbamoyltransferase Registry number: EC 2.1.3.3 (12 Dec 1998) |
| ornithine-oxo-acid transaminase | <enzyme> A pyridoxal phosphate enzyme that catalyses the formation of glutamate gamma-saemialdehyde and an l-amino acid from l-ornithine and a 2-keto-acid. Chemical name: L-Ornithine:2-oxo-acid aminotransferase Registry number: EC 2.6.1.13 (12 Dec 1998) |
| ornithinuria | Excretion of excessive amounts of ornithine in the urine. (05 Mar 2000) |
| ornitho- | <prefix> A combining form from the Greek word for a bird. Origin: Cf. Ern. (29 Oct 1998) |
| ornithodelphia | Same as Monotremata. Origin: NL, fr. Gr. + the womb. Source: Websters Dictionary (01 Mar 1998) |
| Ornithodoros | A genus of soft ticks (family Argasidae) several species of which are vectors of pathogens of various relapsing fevers. They are characterised by a capitulum hidden below the hood and by disks and mamillae of the integument that are continuous from dorsal to ventral surfaces in a variety of patterns. Origin: G. Ornis (ornith-), bird, + doros, a leather bag (05 Mar 2000) |
| Ornithodoros coriaceus | A species common in the mountainous coastal areas of California; adults readily attack deer, cattle, and humans, and have an irritating, painful, sometimes toxic bite. Transmits epizootic bovine abortion to cattle. Synonym: pajaroello. (05 Mar 2000) |
| Ornithodoros erraticus | A species the small variety of which is the vector of Borrelia crocidurae in Africa, the Near East, and central Asia; the large variety is the vector of B. Hispanica in the Spanish peninsula and adjacent north Africa. (05 Mar 2000) |
| Ornithodoros hermsi | A species that is a rodent parasite and vector of relapsing fever spirochetes, such as Borrelia hermsii, in the western U.S. And Canada. (05 Mar 2000) |
| Ornithodoros lahorensis | A species that possibly transmits Borrelia persica, the agent of Persian relapsing fever. (05 Mar 2000) |
| Ornithodoros moubata complex | A group of four species in Africa; the taxonomy and ecology of this complex is of great significance because its members are vectors of relapsing fever spirochetes; members of the complex include Ornithodoros moubata (various hosts), Ornithodoros compactus (tortoises), Ornithodoros apertus (porcupines), and Ornithodoros porcinus (warthogs); a domestic subspecies of Ornithodoros porcinus, in turn, forms three strains that feed chiefly on humans, fowl, and swine. (05 Mar 2000) |