| Hill, Robert | <person> British plant physiologist, *1899. See: Hill reaction. (05 Mar 2000) |
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| hill-sachs deformity | <radiology> Indentation or groove on posterolateral aspect of humeral head, probably due to compression of humeral head on posterior lip of glenoid, suggests repeated or chronic anterior shoulder dislocation, may occur after one episode of dislocation associated with: Bankhart lesion of glenoid (12 Dec 1998) |
| Hill-Sachs lesion | An irregularity seen in the head of the humerus following dislocation of the shoulder; caused by impaction of the head of the humerus against the edge of the glenoid. (05 Mar 2000) |
| Hill's equation | The equation,y(1-y) = [S]n/Kd, where y is the fractional degree of saturation, [S] is the binding ligand concentration, n is the Hill coefficient, and Kd is the dissociation constant for the ligand. The Hill coefficient is a measure of the cooperativity of the protein; the larger the value, the higher the cooperativity. This coefficient cannot be higher than the number of binding sites. For the oxygen binding curve of haemoglobin, an association constant, Ka, is used and the equation becomes y/(1-y) = Ka[S]n. For human blood, n equals 2.5. Compare: Hill plot. (05 Mar 2000) |
| Hill, Sir Leonard Erskine | <person> English physiologist, 1866-1952. See: Hill's sign, Hill's phenomenon. (05 Mar 2000) |
| Hill's phenomenon | <clinical sign> In aortic insufficiency, greater systolic blood pressure in the legs than in the arms; normal arterial systolic pressure in the leg is 10 to 20 mm of Hg above that in the arm, whereas in aortic insufficiency the difference may be 60 to 100 mm of Hg. Synonym: Hill's phenomenon. (05 Mar 2000) |
| Hill's sign | <clinical sign> In aortic insufficiency, greater systolic blood pressure in the legs than in the arms; normal arterial systolic pressure in the leg is 10 to 20 mm of Hg above that in the arm, whereas in aortic insufficiency the difference may be 60 to 100 mm of Hg. Synonym: Hill's phenomenon. (05 Mar 2000) |