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immunosuppressive drug

(Encyclopedia)immunosuppressive drug, any of a variety of substances used to prevent production of antibodies. They are commonly used to prevent rejection by a recipient's body of an organ transplanted from a donor...

methotrexate

(Encyclopedia)methotrexate, drug used in halting the growth of actively proliferating tissues. Introduced in the 1950s, it is used in the treatment of leukemia, psoriasis, and non-Hodgkin's lymphoma. By binding to ...

rosin

(Encyclopedia)rosin or colophony, hard, brittle, translucent resin, obtained as a solid residue from crude turpentine. Usually pale yellow or amber, its color may vary from brownish-black to transparent depending o...

Roethke, Theodore

(Encyclopedia)Roethke, Theodore rĕtˈkə [key], 1908–63, American poet, b. Saginaw, Mich., educated at the Univ. of Michigan and Harvard. A poet of the Midwest, Roethke combined a love of the land with his visio...

Crofton, Sir John Wenman

(Encyclopedia)Crofton, Sir John Wenman, 1912–2009, British physician, b. Dublin. He served in the British medical corps during World War II and during 1946–52 was part of a research team studying the effects of...

alanine

(Encyclopedia)CE5 alanine ălˈənēnˌ [key], organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer participates in the biosynthesis of proteins (see stereochemi...

cyanide process

(Encyclopedia)cyanide process or cyanidation, method for extracting gold from its ore. The ore is first finely ground and may be concentrated by flotation; if it contains certain impurities, it may be roasted. It i...

pyrimidine

(Encyclopedia)CE5 Pyrimidines found in deoxyribonucleic acid (DNA) pyrimidine pīrĭmˈĭdēnˌ [key], type of organic base found in certain coenzymes and in the nucleic acids of plant and animal tissue. The th...

ammonium group

(Encyclopedia)ammonium group, in chemistry, a positively charged nitrogen atom joined by single bonds to four other atoms or groups. The simplest ammonium group, NH4+, is formed by protonation of ammonia, NH3, e.g....

hydrogenation

(Encyclopedia)hydrogenation hīdrôjˈənāˌshən, hīˌdrəjənāˈshən [key], chemical reaction of a substance with molecular hydrogen, usually in the presence of a catalyst. A common hydrogenation is the harde...