Medical Dictionary

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ovoflavin (o-vo-fla′vin)
Riboflavin found in eggs.

ovogenesis (o-vo-jen′e-sis)
SYN: oogenesis.

ovoglobulin (o-vo-glob′u-lin)
Globulin in the white of egg.

ovoid (o′voyd)
1. An oval or egg-shaped form. 2. Resembling an egg. SYN: oviform. [ovo- + G. eidos, resemblance] fetal o. the form of the fetus in utero; its length is about one-half of the length of the extended fetus. Manchester o. an egg-shaped radium applicator for placement in the lateral vaginal fornices. [University of Manchester, England]

ovolarviparous (o′vo-lar-vip′a-rus)
Denoting certain nematodes and other invertebrates in which the eggs are hatched within the female, and the larvae developed or protected within the uterus until the correct time for their emergence. [ovo- + L. larva, a mask, + pario, to bear]

ovomucin (o-vo-mu′sin)
A glycoprotein in the white of egg.

ovomucoid (o-vo-mu′koyd)
A mucoprotein obtained from the white of egg.

ovoplasm (o′vo-plazm)
Protoplasm of an unfertilized egg.

ovoprotogen (o-vo-pro′to-jen)
SYN: lipoic acid.

ovosiston (o-vo-sis′ton)
An oral contraceptive that consists of a mixture of a progestin and an estrogen.

ovotestis (o′vo-tes′tis)
Gonad in which both testicular and ovarian components are present; a form of hermaphroditism.

ovotransferrin (o′vo-trans-far′in)
SYN: conalbumin.

ovovitellin (o′vo-vi-tel′in)
SYN: vitellin. [ovo- + L. vitellus, yolk]

ovoviviparous (o′vo-vi-vip′a-rus)
Denoting those fish, amphibians, and reptiles that produce eggs that hatch within the body of the parent. [ovo- + L. viviparus, bringing forth alive, fr. vivus, alive, + pario, to bear]

ovular (ov′u-lar, o′vu-)
Relating to an ovule.

ovulation (ov′u-la′shun, o′vu-)
Release of an ovum from the ovarian follicle. anestrous o. discharge of ova occurring in animals without estrus. paracyclic o. obsolete term for o. occurring in the menstrual cycle at any time other than the normally anticipated time.

ovulatory (ov′u-la-to-re, o′vu-)
Relating to ovulation.

ovule (ov′ul, o′vu-)
1. The ovum of a mammal, especially while still in the ovarian follicle. 2. A small beadlike structure bearing a fancied resemblance to an o.. SYN: ovulum. [Mod. L. ovulum, dim. of L. ovum, egg]

ovulocyclic (ov′u-lo-si′klik, o′vu-)
Denoting any recurrent phenomenon associated with and occurring at a certain time within the ovulatory cycle, as, for example, o. porphyria.

ovulum, pl .ovula (ov′u-lum, o′vu-; -la)
SYN: ovule.

ovum, gen. ovi, pl .ova (o′vum, -vi, -va)
The female sex cell. When fertilized by a spermatozoon, an o. is capable of developing into a new individual of the same species; during maturation, the o., like the spermatozoon, undergoes a halving of its chromosomal complement so that, at its union with the male gamete, the species number of chromosomes (46 in humans) is maintained; yolk contained in the ova of different species varies greatly in amount and distribution, which influences the pattern of the cleavage divisions. [L. egg] alecithal o. an o. in which the yolk is nearly absent, consisting of only a few particles. blighted o. a fertilized o. whose development has ceased at an early stage. centrolecithal o. one in which the yolk is mostly located near the center of the egg, as in arthropods. fertilized o. an o. impregnated by a spermatozoon. isolecithal o. an o. in which the yolk is evenly distributed throughout the cytoplasm. Peters o. an o. with a presumptive fertilization age of about 13 days; for many years, it was one of very few young human embryos recovered in good condition and its study furnished many facts regarding early embryonic changes. telolecithal o. an o. in which there is a large amount of yolk massed at the vegetative pole, as in the eggs of birds and reptiles.

Owen
Sir Richard, English anatomist, 1804–1892. See O. lines, under line, contour lines of O., under line, interglobular space of O..

Owren
Paul A., Norwegian hematologist, *1905. See O. disease.

oxa-
Combining form inserted in names of organic compounds to signify the presence or addition of oxygen atom(s) in a chain or ring (as in ethers), not appended to either (as in ketones and aldehydes). SEE ALSO: hydroxy-, oxo-, oxy-. [English. oxygen]

oxacillin sodium (ok-sa-sil′in)
A semisynthetic penicillin used in the oral therapy of penicillin-resistant staphylococcal infections.

oxalaldehyde (ok-sa-lal′de-hid)
SYN: glyoxal.

oxalate (ok′sa-lat)
A salt of oxalic acid.

oxalemia (ok-sa-le′me-a)
The presence of an abnormally large amount of oxalates in the blood. [oxalate + G. haima, blood]

oxalic acid (ok-sal′ik)
An acid, HOOC–COOH, found in many plants and vegetables, particularly in buckwheat (family Polygoniaceae) and Oxalis (family Oxalidaceae); used as a hemostatic in veterinary medicine, but toxic in elevated levels when ingested by humans; also used in the removal of ink and other stains, and as a general reducing agent; salts of o. are found in renal calculi; accumulates in cases of primary hyperoxaluria.

oxalo (ok′sa-lo)
The monoacyl radical, HOOC–C(O)–.

oxaloacetate transacetase (ok′sa-lo-as′e-tat trans-as′e-tas)
SYN: citrate synthase.

oxaloacetic acid (ok′sa-lo-a-se′tik)
A ketodicarboxylic acid and important intermediate in the tricarboxylic acid cycle; the product formed when l-aspartic acid acts as an amine donor in transamination reactions. SYN: ketosuccinic acid, oxosuccinic acid.

oxalosis (ok-sa-lo′sis)
Widespread deposition of calcium oxalate crystals in the kidneys, bones, arterial media, and myocardium, with increased urinary excretion of oxalate; may be an acquired disorder, as in oxalate poisoning, or represent one aspect of primary hyperoxaluria and o.. [oxalate + -osis, condition]

oxalosuccinic acid (ok′sa-lo-suk-sin′ik)
The product of the dehydrogenation of isocitric acid under the catalytic influence of isocitrate dehydrogenase; an enzyme-bound intermediate of the tricarboxylic acid cycle.

oxalosuccinic carboxylase
SYN: isocitrate dehydrogenase.

oxalourea (ok′sa-lo-u-re′a)
SYN: oxalylurea.

oxaluria (ok-sa-loo′re-a)
SYN: hyperoxaluria. [oxalate + G. ouron, urine]

oxaluric acid (ok-sa-loor′ik)
The ureide of oxalic acid, derived from uric acid or oxalylurea.

oxalyl (ok′sa-lil)
The diacyl radical, –CO–CO– .

oxalylurea (ok′sa-lil-u-re′a)
The cyclic (end-to-end) amide anhydride of oxaluric acid; an oxidation product of uric acid. SYN: oxalourea, parabanic acid.

oxamniquine (oks-am′ni-quin)
A tetrahydroquinoline derivative, similar to hycanthone and lucanthone, effective against Schistosoma mansoni; now largely superseded by the broad-spectrum anthelmintic drug praziquantel.

oxanamide (ok-san′a-mid)
A sedative.

oxandrolone (ok-san′dro-lon)
17β-Hydroxy-17α-methyl-2-oxa-5α-androstan-3-one (C-2 replaced by O in the androstane nucleus); an androgenic anabolic steroid.

oxaphenamide (ok-sa-fen′a-mid)
A choleretic.

oxazepam (ok-sa′ze-pam)
A benzodiazepine chemically and pharmacologically related to chlordiazepoxide and diazepam; an antianxiety agent.

oxazin (ok′sa-zin)
Parent substance of a series of biologic dyes, e.g., gallocyanin, brilliant cresyl blue, cresyl violet acetate.

oxazole (ok′sa-zol)
The fundamental ring system of pyranoses.

oxazolidinediones (ok-sa-zo-lid′in-de-onz)
An obsolescent chemical class of antiepileptic drugs useful in the treatment of absence (petit mal) seizures; examples include trimethadione and paramethadione.

oxazolidinones (oks′a-zo-lid′i-nonz)
A new class of antibacterial antibiotics.

oxeladin (ok-sel′a-din)
An antitussive agent.

oxiconazole (ok′se-ko′na-zol)
Broad-spectrum antifungal agent resembling ketoconazole.

oxidant (ok′si-dant)
The substance that is reduced and that, therefore, oxidizes the other component of an oxidation-reduction system.

oxidase (ok′si-das)
Classically, one of a group of enzymes, now termed oxidoreductases (EC class 1), that bring about oxidation by the addition of oxygen to a metabolite or by the removal of hydrogen or of one or more electrons. O. is now used for those cases in which O2 acts as an acceptor (of H or of electrons); those removing hydrogen are now termed dehydrogenases. For individual oxidases, see the specific names. direct o. originally, an o. catalyzing the transfer of O2 directly to other bodies; now termed oxygenase. indirect o. originally, an o. that acts by reducing a peroxide; now termed peroxidase. terminal o. the last protein in the electron transport, respiratory chain. In mammals this is cytochrome c o..

oxidasis (ok-si-da′sis)
Oxidation by an oxidase.

oxidation (ok-si-da′shun)
1. Combination with oxygen. 2. Increasing the valence of an atom or ion by the loss from it of hydrogen or of one or more electrons thus rendering it more electropositive, as when iron is changed from the ferrous (2+) to the ferric (3+) state. 3. In bacteriology, the aerobic dissimilation of substrates with the production of energy and water; in contrast to fermentation, the transfer of electrons in the o. process is accomplished via the respiratory chain, which utilizes oxygen as the final electron acceptor. alpha-o., α-o. a form of o. of fatty acids in which carbons are removed one at a time in the form of CO2; the α-carbon is first hydroxylated and then converted into a carbonyl; a deficiency of this pathway is associated with Refsum disease. beta-o., β-o. 1. o. of the β-carbon (carbon 3) of a fatty acid, forming the β-keto (β-oxo) acid analog; of importance in fatty acid catabolism; 2. the entire pathway for the catabolism of saturated fatty acids containing an even number of carbon atoms; beta-o. (1) is a part of this pathway; acetyl-CoA is a major product of this pathway. end o. the last o. step in a catabolic pathway. SYN: terminal o.. omega-o., ω-o. o. at the carbon atom farthest removed (ω-carbon) from the carboxyl group (carbon 1); thus, in this pathway, a dicarboxylic acid is formed; an important pathway in the degradation of prostaglandins. terminal o. SYN: end o..

oxidation-reduction
Any chemical oxidation or reduction reaction, which must, in toto, comprise both oxidation and reduction; the basis for calling all oxidative enzymes (formerly oxidases) oxidoreductases. Often shortened to “redox.”

oxidative (ok-si-da′tiv)
Having the power to oxidize; denoting a process involving oxidation.

oxide (ok′sid)
A compound of oxygen with another element or a radical; e.g., mercuric o., HgO. acid o. an acid anhydride; an o. of an electronegative element or radical; it can combine with water to form an acid. basic o. a base anhydride; an o. of an electropositive element or radical; it can combine with water to form a base. indifferent o. SYN: neutral o.. neutral o. an o. that is neither an acid nor a base; e.g., water (hydrogen o., H2O). SYN: indifferent o..

oxidize (ok′si-diz)
To combine or cause an element or radical to combine with oxygen or to lose electrons.

oxidoreductase (ok′si-do-re-duk′tas)
An enzyme (EC class 1) catalyzing an oxidation-reduction reaction. Trivial names for oxidoreductases include dehydrogenase, reductase, oxidase (where O2 is the H acceptor), oxygenase (where O2 is incorporated into the substrate), peroxidase (H2O2 is the acceptor; catalase is an exception), and hydroxylase (coupled oxidation of two donors). SEE ALSO: oxidase.

oxime (ok′sem)
A compound resulting from the action of hydroxylamine, NH2OH, on a ketone or an aldehyde to yield the group &dbond;N–OH attached to the former carbonyl carbon atom. amide oximes SYN: amidoximes.

oximeter (ok-sim′e-ter)
An instrument for determining photoelectrically the oxygen saturation of a sample of blood. cuvette o. an o. that reads the percentage of oxygen saturation of the blood as it passes through a cuvette outside the body.

oximetry (oks-im-a-tree)
Procedure using a device to measure oxygen saturation by fluctations of light absorption in well-vascularized tissue during systole and diastole. The underlying principle is Beer law, or the relationship between the amount of light absorbed by a solute in solution and the concentration of the unknown solute. pulse o. o. performed noninvasively, usually on the finger or ear lobe, in which the small increase in absorption of light during the systolic pulse is used to calculate oxygen saturation.

oxirane (oks′e-ran)
SYN: ethylene oxide.

oxo-
Prefix denoting addition of oxygen; used in place of keto- in systematic nomenclature. SEE ALSO: hydroxy-, oxa-, oxy-.

oxoacetic acid (ok′so-a-se′tik)
SYN: glyoxylic acid.

oxo acid (ok′so)
SYN: keto acid.

3-oxoacid-CoA transferase
An enzyme catalyzing the reversible conversion of acetoacetyl-CoA and succinate into succinyl-CoA and acetoacetate; malonyl-CoA can substitute for succinyl-CoA and a few other 3-oxo acids for the acetoacetate; an important step in order for the ketone bodies to serve as a fuel for extrahepatic tissues. SYN: 3-ketoacid-CoA transferase, acetoacetyl-succinic thiophorase.

3-oxoacyl-ACP reductase (ok′so-as′il)
A part of the fatty acid synthase complex; an enzyme reversibly reacting 3-oxoacyl-ACP (ACP = acyl carrier protein) with NADPH to form d-3-hydroxyacyl-ACP and NADP+. SYN: β-ketoacyl-ACP reductase.

3-oxoacyl-ACP synthase
An enzyme condensing malonyl-ACP (ACP = acyl carrier protein) and acyl-Cys-protein to 3-oxoacyl-ACP + Cys-protein + CO2, and similar reactions, as steps in fatty acid synthesis; Cys-protein is also a part of the fatty acid synthase complex. SYN: acyl-malonyl-ACP synthase, β-ketoacyl-ACP synthase.

2-oxoglutarate dehydrogenase (ok′so-gloo-tar′at)
SYN: α-ketoglutarate dehydrogenase.

2-oxoglutaric acid (oks′-o-gloo-tar-ik)
SYN: α-ketoglutaramic acid.

2-oxo-5-guanidovaleric acid (gwan-e′do-va-ler′ik)
The deaminated derivative of arginine.

oxolamine (ok-sol′a-men)
Used for treatment of bronchopulmonary infections.

oxolinic acid (ok-so-lin′ik)
A quinolone antibacterial agent used in the treatment of urinary tract infections.

oxophenarsine hydrochloride (ok′so-fen-ar′sen)
An antisyphilitic and antitrypanosomal agent.

5-oxoprolinase
An enzyme that catalyzes the ATP-dependent hydrolysis of l-5-oxoproline (ATP + l-5-oxoproline → ADP + orthophosphate + l-glutamate); a deficiency of this enzyme will result in 5-oxoprolinuria.

5-oxoproline (Glp) (oks′o-pro′len)
A keto derivative of proline that is formed nonenzymatically from glutamate, glutamine, and γ-glutamylated peptides; it is also produced by the action of γ-glutamylcyclotransferase; elevated levels of o. are often associated with problems of glutamine or glutathione metabolism. SYN: 5-pyrrolidone-2-carboxylic acid, pyroglutamic acid, pyrrolidone-5-carboxylate.

4-oxoproline reductase
SYN: 4-hydroxyproline oxidase.

5-oxoprolinuria (oks′o-pro′len-ur-e-a)
Elevated levels of 5-oxoproline in the urine.

17-oxosteroids (ok-so-ster′oydz)
SYN: 17-ketosteroids.

oxosuccinic acid (ok′so-suk-sin′ik)
SYN: oxaloacetic acid.

oxotremorine (ok′so-trem′er-en)
An active metabolite of tremorine. Used as a pharmacologic tool for producing a parkinsonian tremor.

oxprenolol hydrochloride (oks-pren′o-lol)
A β-receptor blocking agent with coronary vasodilator activity.

OXT
Abbreviation for oxytocin.

oxtriphylline (oks-tri′fi-lin, oks′tri-fil′in)
A true salt of theophylline; it has mild diuretic, myocardial stimulating vasodilator, and bronchodilator actions, with the same uses as theophylline, but is better absorbed and less irritating. SYN: choline theophyllinate.

oxy-
1. Combining form denoting shrill; sharp, pointed; quick (incorrectly used for ocy-, from G. okys, swift). 2. In chemistry, combining form denoting the presence of oxygen, either added or substituted, in a substance. SEE ALSO: hydroxy-, oxa-, oxo-. [G. oxys, keen]

oxyacoia, oxyakoia (ok′se-a-koy′a)
Increased sensitiveness to sounds, occurring in facial paralysis, especially when the stapedius muscle is paralyzed. [G. oxys, acute, + akoe, hearing]

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