FIELDS G-l and G-2 

 Columns 27 and 28 



Symbol R (test compound action on the excised organ isolated ): 



Isolation of the organ coded in Field H-l, by EXCISION . For example, the removal of a 

 turtle heart on which the action of the test compound is to be investigated, by perfusing it 

 with test compound solutions; the fact that this heart is isolated and excised is coded with 

 Symbol R in Field G. 



The preparations described by Symbols P, Q, and R are made because the isolation removes 

 physiological factors from the organism or from the organ, as the case may be, which if present would 

 mask wholly the effect of the test compound or would make extremely difficult the evaluation of the 

 test compound's effect. 



The general definitions of the three symbols, P, 0, and R, are summarized by the following 

 scheme. The symbols represent pretreatment which has as its objective: 



(1) The isolation of the organism (Symbol P) from the influence of one or more of its specific 

 parts (the part being left in situ or excised ), or-- 



(2) The isolation of the organ (Symbols Q and R) from one or more of its specific parts, from 

 material it normally processes, or from the organism of which it is a part. (Symbol Q 

 is used to code the isolation of an organ in situ ; Symbol R is used to code the isolation 

 of an organ by excision . ) 



When coding excised muscle- nerve preparations (see Division 8 of the Specific Directions and 

 Explanations for Field H for a discussion of provisions for this), Symbol R is used in Field G. If the 

 muscle-nerve or gland-nerve preparation is not excised or if the organ-nerve pair is isolated only by 

 the nerve being sectioned, Symbol Q should be used in Field G. The standard heart- lung preparation 

 requires the use of Symbol Q, since the organs are essentially not excised. 



B. Symbol 2 



Any chemical, surgical, or electric shock pret reatment which does NOT have the objective 

 of isolating the organism or the organ is coded by Symbol 2 (in contrast to the pretreatment 

 indicated by Symbols P, Q, and R, as described above). This excludes, however, pretreat- 

 ments by exposures to abnormal chemical or physical environments , Symbols I, 3, 4, etc. 

 Included would be applications of dyes for visual distinctions, surgical exposure merely for 

 observation, and any other special surgical or chemical preparations not adequately des- 

 cribed by one of Symbols P, Q, or R. General anesthesia would also be coded by this 

 symbol, but the CBCC has refrained from designating it, even when it is specifically 

 mentioned by the author, because it is considered a common technical procedure which is 

 assumed to have no significance relative to the outcome of the specific response to the 

 test compound. If, however, the presence of the anesthesia were on some occasion 

 demonstrated to have such significance, it should be indicated without fail by Symbol 2 in 

 Field G. 



C. Chemical pretreatment is not equivalent to treatment with a secondary compound 



Any chemical pretreatment indicated by Symbol 2, P, or Q, is not in any way an interaction 

 with the test compound (as pretreatment with a secondary compound or a test compound 

 would be); it is merely an experimental technique permitting the response to the test 

 compound to be revealed by removing factors that would obscure that response, or a technique 

 for staining or observing an organ or tissue, or for quieting the animal or desensitizing it to 

 pain, etc. 



D. The experimental state of physiological stress excluded from definitions of Symbols 2, P, 

 Q, and R; stress coded by specific symbols 



Any pretreatment, whether chemical or surgical, which has as its objective the production 



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