| Fischer projection formula | <biochemistry> Of sugars, representations, by projection, of cyclic sugars, or derivatives thereof, in which the carbon chain is depicted vertically. The lowest-numbered asymmetric carbon atom (C-1 in aldoses; C-2 in 2-ketoses, e.g., fructose) is drawn at the top, and the rest of the carbon atoms of the chain are drawn in sequence below the top carbon atom. For each carbon atom, depicted in projection as lying in the plane of the paper, the carbon-to-carbon bond(s), which actually point away from the viewer, are drawn as vertical lines. The left-hand and right-hand bonds of each carbon atom, which actually point toward the viewer, are, in projection, depicted as horizontal lines. The conventions for the Fischer formulas of cyclic sugars are as follows: 1) if the highest-numbered asymmetric carbon atom has its OH (or its replacement) lying to the right, as is the 2-OH of d-glyceraldehyde, the sugar has the d configuration; if the OH is to the left, the sugar has the l configuration. 2) On the anomeric carbon atom (C-1 in the aldoses; C-2 in the 2-ketoses), an OH or substituted OH that lies to the right, with the OH of the highest-numbered asymmetric carbon atom also to the right is defined to be a; if it is to the left, with the OH of the highest-numbered carbon atom still to the right, it is b; the reverse applies if the latter OH is to the left. 3) The orientation of a terminal CH2OH group in the aldoses carries no configurational significance, as it contains no asymmetric carbon atom. (05 Mar 2000) |
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| Fischer's sign | <clinical sign> An obsolete sign: in tuberculosis of the mediastinal or peri-bronchial glands, after bending the patient's head as far back as possible, auscultation over the manubrium sterni will sometimes reveal a continuous loud murmur caused by the pressure of the enlarged glands on the large mediastinal vessels. Synonym: Fischer's symptom. (05 Mar 2000) |
| Fischer's symptom | <clinical sign> An obsolete sign: in tuberculosis of the mediastinal or peri-bronchial glands, after bending the patient's head as far back as possible, auscultation over the manubrium sterni will sometimes reveal a continuous loud murmur caused by the pressure of the enlarged glands on the large mediastinal vessels. Synonym: Fischer's symptom. (05 Mar 2000) |
| Fischer, Emil | <person> German chemist and Nobel laureate, 1852-1919. See: Fischer projection formulas of sugars, Kiliani-Fischer synthesis, Kiliani-Fischer reaction. (05 Mar 2000) |
| Fischer, Louis | <person> U.S. Paediatrician, 1864-1944. See: Fischer's sign, Fischer's symptom. (05 Mar 2000) |
| Kiliani-Fischer synthesis | A synthetic procedure for the extension of the carbon atom chain of aldoses by treatment with cyanide; hydrolysis of the cyanohydrins followed by reduction of the lactone yields the homologous aldose; with this method, d-glucose and d-mannose can be synthesised from d-arabinose. (05 Mar 2000) |
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