| cation | <chemistry> A positively-charged ion. (16 Mar 1998) |
|---|---|
| cation-anion difference | <biochemistry> The difference between the sum of the measured cations and anions in the plasma or serum calculated as follows: (Na + K) -(Cl + HCO3) = < 20 mmol/l. Elevated values may occur in diabetic or lactic acidosis; normal or low values occur in bicarbonate-losing metabolic acidoses. Synonym: cation-anion difference. (05 Mar 2000) |
| cation exchange | The process by which a cation in a liquid phase exchanges with another cation present as the counter-ion of a negatively charged solid polymer (cation exchanger). A cation-exchange reaction in removal of the Na+ of a sodium chloride solution is RSO3-H+ + Na+ → RSO3-Na+ + H+ (R is the polymer, RSO3- is the cation exchanger); if this is combined with the anion-exchange reaction, NaCl is removed from the solution (desalting). Cation exchange may also be used chromatographically, to separate cations, and medicinally, to remove a cation; e.g., H+, from gastric contents, or Na+ and K+ in the intestine. See: anion exchange. (05 Mar 2000) |
| cation exchanger | An insoluble solid (usually a polystyrene or a polysaccharide) that has negatively charged radicals attached to it (e.g., -COO-, -SO3-), which can attract and hold cations that pass by in a moving solution if these are more attracted to the acid groups than the counter ion present. (05 Mar 2000) |
| cation-exchange resin | See: cation exchange, cation exchanger. (05 Mar 2000) |
| cation exchange resins | High molecular weight insoluble polymers which contain functional cationic groups that are capable of undergoing exchange reactions; used in various types of chromatography; also to treat hyperkalaemia. (12 Dec 1998) |
| cation exhange resin | <chemistry> An insoluble resin with fixed anionic groups which is used in chromatography to separate cationic molecules. (16 Mar 1998) |
| acid radical | A radical formed from an acid by loss of one or more hydrogen ions; e.g., SO4-, NO3-. (05 Mar 2000) |
| radical | 1. <chemistry> An atom or or electrically neutral group that has one or more unpaired electrons. 2. <botany> Of leaves, clustered at the base of the stem. (09 Oct 1997) |
| radical cystectomy | Surgery to remove the bladder as well as nearby tissues and organs. (12 Dec 1998) |
| radical, free | In biochemistry, it is a group of atoms bonded together into an entity that is extremely reactive and shortlived. (a free radical is not a political extremist on parole.) (12 Dec 1998) |
| radical hysterectomy | Complete removal of the uterus, upper vagina, and parametrium. (05 Mar 2000) |
| radical mastectomy | <procedure, surgery> The surgical removal of the breast, part of the underlying pectoralmuscle and some or all of the lymph nodes under the armpit. (09 Oct 1997) |
| radical mastectomy, modified | Breast cancer treatment involving removal of the breast, lymph nodes (the glands ) in the armpit and associated skin and subcutaneous tissue. It differs from total radical mastectomy in that the pectoral (chest) muscles are preserved. (12 Dec 1998) |
| radical mastectomy, total | Breast cancer treatment involving removal of the breast, the pectoral (chest) muscles, lymph nodes (the glands ) in the armpit and associated skin and subcutaneous tissue. (12 Dec 1998) |