| plasma exchange | Removal of plasma and replacement with various fluids, e.g., fresh frozen plasma, plasma protein fractions (ppf), albumin preparations, dextran solutions, saline. Used in treatment of autoimmune diseases, immune complex diseases, diseases of excess plasma factors, and other conditions. (12 Dec 1998) |
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| pulmonary gas exchange | The exchange of oxygen and carbon dioxide between alveolar air and pulmonary capillary blood. (12 Dec 1998) |
| sister chromatid exchange | An aberrant crossing-over event in which there is an exchange of segments between the sister chromatids of a chromosome, either between the sister chromatids of a meiotic tetrad or between the sister chromatids of a duplicated somatic chromosome. It can be induced by ultraviolet and ionizing radiation or by mutagenic agents and is observed by autoradiography. (12 Dec 1998) |
| needle-exchange programs | Organised services for exchange of sterile needles and syringes used for injections as a potential means of reducing the transmission of infectious diseases. (12 Dec 1998) |
| international educational exchange | The exchange of students or professional personnel between countries done under the auspices of an organization for the purpose of further education. (12 Dec 1998) |
| ion exchange | Reversible chemical reaction between a solid, often an ion exchange resin, and a fluid whereby ions may be exchanged from one substance to another. This technique is used in water purification, in research, and in industry. (12 Dec 1998) |
| ion exchange chromatography | <procedure> Separation of molecules by absorption and desorption from charged polymers. An important technique for protein purification. For small molecules the support is usually polystyrene, but for macromolecules, cellulose, acrylamide or agarose supports give less non-specific absorption and denaturation. Typical charged residues are CM carboxymethyl) or DEAE (diethylaminoethyl). (27 Oct 1998) |
| ion exchange resins | <chemistry> High molecular weight, insoluble polymers which contain functional groups that are capable of undergoing exchange reactions (ion exchange) with either cations or anions. See: ion exchange, ion exchanger. (12 Dec 1998) |
| exchange | 1. To part with give, or transfer to another in consideration of something received as an equivalent; usually followed by for before the thing received. "Exchange his sheep for shells, or wool for a sparking pebble or a diamond." (Locke) 2. To part with for a substitute; to lay aside, quit, or resign (something being received in place of the thing with); as, to exchange a palace for cell. "And death for life exchanged foolishly." (Spenser) "To shift his being Is to exchange one misery with another." (Shak) 3. To give and receive reciprocally, as things of the same kind; to barter; to swap; as, to exchange horses with a neighbor; to exchange houses or hats. "Exchange forgiveness with me, noble Hamlet." (Shak) Synonym: To barter, change, commute, interchange, bargain, truck, swap, traffic. Origin: Cf.OF. Eschangier, F. Echanger. See Exchange. 1. The act of giving or taking one thing in return for another which is regarded as an equivalent; as, an exchange of cattle for grain. 2. The act of substituting one thing in the place of another; as, an exchange of grief for joy, or of a scepter for a sword, and the like; also, the act of giving and receiving reciprocally; as, an exchange of civilities or views. 3. The thing given or received in return; especially, a publication exchanged for another. 4. The process of setting accounts or debts between parties residing at a distance from each other, without the intervention of money, by exchanging orders or drafts, called bills of exchange. These may be drawn in one country and payable in another, in which case they are called foreign bills; or they may be drawn and made payable in the same country, in which case they are called inland bills. The term bill of exchange is often abbreviated into exchange; as, to buy or sell exchange. A in London is creditor to B in new York, and C in London owes D in New York a like sum. A in London draws a bill of exchange on B in New York; C in London purchases the bill, by which A receives his debt due from B in New York. C transmits the bill to D in New York, who receives the amount from B. 5. A mutual grant of equal interests, the one in consideration of the other. Estates exchanged must be equal in quantity, as fee simple for fee simple. 6. The place where the merchants, brokers, and bankers of a city meet at certain hours, to transact business. In this sense often contracted to 'Change. Arbitration of exchange. See Arbitration. Bill of exchange. See Bill. Exchange broker. See Broker. Par of exchange, the established value of the coin or standard of value of one country when expressed in the coin or standard of another, as the value of the pound sterling in the currency of France or the United States. The par of exchange rarely varies, and serves as a measure for the rise and fall of exchange that is affected by the demand and supply. Exchange is at par when, for example, a bill in new York, for the payment of one hundred pounds sterling in London, can be purchased for the sum. Exchange is in favor of a place when it can be purchased there at or above par. Telephone exchange, a central office in which the wires of any two telephones or telephone stations may be connected to permit conversation. Synonym: Barter, dealing, trade, traffic, interchange. Origin: OE. Eschange, eschaunge, OF. Eschange, fr. Eschangier, F. Echanger, to exchange; pref. Ex- out + F. Changer. See Change, and cf. Excamb. Source: Websters Dictionary (01 Mar 1998) |
| exchange transfusion | Removal of most of a patient's blood followed by introduction of an equal amount from donors. Synonym: exsanguination transfusion, substitution transfusion, total transfusion. (05 Mar 2000) |
| exchange transfusion, whole blood | Repetitive withdrawal of small amounts of blood and replacement with donor blood until a large proportion of the blood volume has been exchanged. Used in treatment of foetal erythroblastosis, hepatic coma, sickle cell anaemia, disseminated intravascular coagulation, septicaemia, burns, thrombotic thrombopenic purpura, and fulminant malaria. (12 Dec 1998) |
| acrylic resin | A general term applied to a resinous material of the various esters of acrylic acid; used as a denture base material, for other dental restorations, and for trays. (05 Mar 2000) |
| acrylic resin base | A form made of acrylic resin molded to conform to the tissues of the alveolar process and used to support the teeth of a prosthesis. (05 Mar 2000) |
| acrylic resin tooth | A tooth made of acrylic resin. (05 Mar 2000) |
| activated resin | Autopolymerizing resin, any resin that can be polymerised by chemical catalysis rather than by the application of heat; used in dentistry for dental restoration, denture repair, and impression trays. Synonym: activated resin, cold cure resin, cold-curing resin, quick cure resin, self-curing resin. (05 Mar 2000) |