| shot-silk phenomenon | The appearance of numerous wavelike, glistening reflexes, like the shimmer of silk, observed sometimes in the retina of a young person. Synonym: shot-silk phenomenon, shot-silk reflex. (05 Mar 2000) |
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| shwartzman phenomenon | A two-stage reaction in which a first encounter with endotoxin produces intravascular fibrin thrombi whose clearance results in reticuloendothelial blockade which prevents the clearance of thrombi caused by a second encounter with endotoxin, resulting in tissue necrosis and/or haemorrhage. In pregnancy gram-negative septicaemia during delivery or abortion may serve as the first or provocative encounter. The phenomenon is non-immunologic and is known to occur only in rabbits and man. (12 Dec 1998) |
| Somogyi phenomenon | A rebound phenomenon of reactive hyperglycaemia following a period of relative hypoglycaemia, which may be subclinical and difficult to detect; the hyperglycaemia induces use of more insulin, thus aggravating the problem. Synonym: posthypoglycaemic hyperglycaemia. (05 Mar 2000) |
| Soret's phenomenon | In a solution kept in a long, upright tube at room temperature, the upper part, being the warmer, is also the more concentrated. (05 Mar 2000) |
| sparing phenomenon | The manner in which a nonessential nutritive component, by its presence in the diet, lowers the dietary requirement for an essential component; thus, nonessential l-cysteine spares essential l-methionine and nonessential l-tyrosine spares essential l-phenylalanine. Synonym: sparing phenomenon. (05 Mar 2000) |
| Splendore-Hoeppli phenomenon | Radiating or annular eosinophilic deposits of host-derived materials, and possibly of parasite antigens, which form around fungi, helminths, or bacterial colonies in tissue. (05 Mar 2000) |
| staircase phenomenon | A phenomenon in cardiac muscle first observed by H.P. Bowditch; if a number of stimuli of the same intensity are sent into the muscle after a quiescent period, the first few contractions of the series show a successive increase in amplitude (strength). Synonym: staircase phenomenon. Origin: Ger. Treppe, staircase (05 Mar 2000) |
| Staub-Traugott phenomenon | The increased rate of removal of loads of glucose given shortly after administration of an initial glucose load. (05 Mar 2000) |
| Negro's phenomenon | A sudden brief halt in usually smooth respiration or other motor activity. Synonym: Negro's phenomenon. (05 Mar 2000) |
| Strassman's phenomenon | In the third stage of labour, failure of placental detachment indicated by transmission of pressure from the fundus uteri to the umbilical vein which becomes engorged; obsolete term. (05 Mar 2000) |
| Strumpell's 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) |
| no reflow phenomenon | Absence of blood flow in a portion of the brain which has been damaged, usually by ischemia. (05 Mar 2000) |
| Danysz phenomenon | Reduction of the neutralizing effect of an antitoxin when toxin is mixed with it in divided portions, rather than adding the same total quantity of toxin in one step. (05 Mar 2000) |
| dawn phenomenon | Abrupt increases in fasting levels of plasma glucose concentrations between 5 and 9 a.m., in the absence of antecedent hypoglycaemia; occurs in diabetic patients receiving insulin therapy. (05 Mar 2000) |
| Debre phenomenon | In measles, the failure of the rash to develop at the site of immune serum injection. (05 Mar 2000) |