| oxygen derived free radicals | An atom or atom group having an unpaired electron on an oxygen atom, typically derived from molecular oxygen. For example, one-electron reduction of O2 produces the superoxide radical, O2-; other examples include the hydroperoxyl radical (HOO-), the hydroxyl radical (HO-), and nitric oxide (NO-). (05 Mar 2000) |
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| oxygen effect | Enhancement of radiosensitivity of cells in a high concentration of oxygen. (05 Mar 2000) |
| oxygen electrode | A sensitive method to detect oxygen consumption, involves a PTFE (Teflon) membrane. (18 Nov 1997) |
| oxygen inhalation therapy | Inhalation of oxygen aimed at restoring toward normal any pathophysiologic alterations of gas exchange in the cardiopulmonary system, as by the use of a respirator, nasal catheter, tent, chamber, or mask. (12 Dec 1998) |
| oxygen isotopes | Stable oxygen atoms that have the same atomic number as the element oxygen, but differ in atomic weight. O-17 and 18 are stable oxygen isotopes. (12 Dec 1998) |
| oxygen poisoning | A body disturbance resulting from breathing high partial pressures of oxygen; characterised by visual and hearing abnormalities, unusual fatigue while breathing, muscular twitching, anxiety, confusion, incoordination, and convulsions; although the mechanism for development of the condition is obscure, a disruption of enzymatic activity is likely, perhaps as a result of free radical formation. Synonym: oxygen poisoning. (05 Mar 2000) |
| oxygen radical | <chemistry> Any oxygen species that carries an unpaired electron (except free oxygen). Examples are the hydroxyl radical and the superoxide anion. These radicals are very powerful oxidizing agents and cause structural damage to proteins and nucleic acids. They mediate the damaging effects of ionising radiation. (18 Nov 1997) |
| oxygen radioisotopes | Unstable isotopes of oxygen that decay or disintegrate emitting radiation. O atoms with atomic weights 13, 14, 15, 19, and 20 are radioactive oxygen isotopes. (12 Dec 1998) |
| oxygen tent | A transparent enclosure, suspended over the bed and enclosing the patient, used to supply a high concentration of oxygen. (05 Mar 2000) |
| oxygen therapy | Treatment in which an increased concentration of oxygen is made available for breathing, through a nasal catheter, tent, chamber, or mask. (05 Mar 2000) |
| oxygen toxicity | A body disturbance resulting from breathing high partial pressures of oxygen; characterised by visual and hearing abnormalities, unusual fatigue while breathing, muscular twitching, anxiety, confusion, incoordination, and convulsions; although the mechanism for development of the condition is obscure, a disruption of enzymatic activity is likely, perhaps as a result of free radical formation. Synonym: oxygen poisoning. (05 Mar 2000) |
| oxygen utilization coefficient | The extraction coefficient for oxygen in any given tissue. (05 Mar 2000) |
| electron transport | The transport of electrons through a number of electron carriers in a set sequence. (09 Oct 1997) |
| electron transport chain | <biochemistry, chemistry> A series of compounds that transfer electrons to an eventual donor with concomitant energy conversion. One of the best studied is in the mitochondrial inner membrane, that takes NADH (from the tricarboxylic acid cycle) or FADH and transfers electrons via ubiquinone, cytochromes and various other compounds, to oxygen. Other electron transport chains are involved in photosynthesis. (18 Nov 1997) |
| electron transport particles | <cell biology> Fragments of mitochondria still capable of transporting electrons. One of the units occurring on the matrical surface of mitochondrial cristae; the head of the particle which measures about 9 nm, attaches to the membrane of the crista by a stalk 5 nm in length; the particle may be concerned with the electron transport system. Synonym: submitochondrial particles. (05 Mar 2000) |