| Doppler phenomenon | <radiobiology> Variation in the frequency of a wave (as measured by an observer) due to relative motion between the observer and the source of the wave. (The observed frequency increases if the source is moving towards the observer and vice versa.) The equation can be found in most optics texts and many introductory physics texts. (09 Oct 1997) |
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| Duckworth's phenomenon | Respiratory arrest before cardiac arrest as a result of intracranial disease. (05 Mar 2000) |
| immune adherence phenomenon | A phenomenon manifested by the adherence of antigen-antibody-complement complex to "indicator cells" (microorganisms, platelets, leukocytes, or erythrocytes), the reaction being sensitive and specific for the antigen and antibody in the complex. Synonym: erythrocyte adherence phenomenon, immune adherence phenomenon, red cell adherence phenomenon. (05 Mar 2000) |
| quellung phenomenon | Increase in opacity and visibility of the capsule of capsulated organisms exposed to specific agglutinating anticapsular antibodies. Synonym: Neufeld reaction, quellung phenomenon, quellung reaction, quellung test. Scrotal swelling, the swelling formed after the embryonic genital swellings have fused together, become spherical, and migrated caudally to the base of the penis; just before birth the testis comes to lie within it. Spielmeyer's acute swelling, a form of degeneration of nerve cells in which the cell body and its processes swell and stain palely and diffusely. (05 Mar 2000) |
| on-off phenomenon | A state in the treatment of Parkinson's disease by l-dopa, in which there is a rapid fluctuation of akinetic (off) and choreoathetotic (on) movements. (05 Mar 2000) |
| orbicularis phenomenon | A constriction of both pupils when an effort is made to close eyelids forcibly held apart. A variant of the pupil response to near vision. Synonym: Galassi's pupillary phenomenon, Gifford's reflex, lid-closure reaction, orbicularis phenomenon, orbicularis pupillary reflex, Piltz sign, Westphal's pupillary reflex, Westphal-Piltz phenomenon. (05 Mar 2000) |
| Theobald Smith's phenomenon | A phenomenon observed in guinea pigs that had survived use for diphtheria antitoxin standardization, the animals having been rendered highly susceptible to subsequent inoculation of horse serum. (05 Mar 2000) |
| tibial phenomenon | Dorsal flexion of the great toe, sometimes of the entire foot, in a paralysed limb when the extremity is drawn up against the body, flexing both knee and hip. Synonym: tibial phenomenon. (05 Mar 2000) |
| Ehret's phenomenon | A sudden throb felt by the finger on the brachial artery, as the pressure in the cuff falls during a blood pressure estimation; said to indicate fairly accurately the diastolic pressure. (05 Mar 2000) |
| Ehrlich's phenomenon | The difference between the amount of diphtheria toxin that will exactly neutralise one unit of antitoxin and that which, added to one unit of antitoxin, will leave one lethal dose free is greater than one lethal dose of toxin; i.e., it is necessary to add more than one lethal dose of toxin to a neutral mixture of toxin and antitoxin to make the mixture lethal (the basis of the L+ dose). (05 Mar 2000) |
| toe phenomenon | <clinical sign> Extension of the great toe and abduction of the other toes instead of the normal flexion reflex to plantar stimulation, considered indicative of pyramidal tract involvement ("positive" Babinski). Synonym: Babinski reflex, Babinski's phenomenon, great-toe reflex, paradoxical extensor reflex, toe phenomenon. (05 Mar 2000) |
| tongue phenomenon | <clinical sign> In latent tetany, tapping the tongue causes its depression with a concave dorsum. Synonym: tongue phenomenon. (05 Mar 2000) |
| Tournay's phenomenon | Dilation of the pupil in the abducting eye on extreme lateral gaze. This is present in only a small percentage of the normal popupation and has no known association with disease. Synonym: Tournay sign. (05 Mar 2000) |
| erythrocyte adherence phenomenon | A phenomenon manifested by the adherence of antigen-antibody-complement complex to "indicator cells" (microorganisms, platelets, leukocytes, or erythrocytes), the reaction being sensitive and specific for the antigen and antibody in the complex. Synonym: erythrocyte adherence phenomenon, immune adherence phenomenon, red cell adherence phenomenon. (05 Mar 2000) |
| escape phenomenon | Failure of the pupil in an eye with optic neuritis to maintain constriction as both eyes are alternately stimulated with light. (05 Mar 2000) |