FIELDS W, X, and Y 

 Columns 68; 69 and 

 70; and 71 



Symbol L. If no antagonism appears, use Symbol J or K, according to whether the largest dose admin- 

 istered was the maximum tolerated dose; these negative data, however, must never be coded with 

 Criterion 22, but only with Criterion 62 (or 01 or 02) with Symbol 1 in Field Y. 



17. Criterion 30; weight of the thyroid gland 



Criterion 30 was established for a special coding project the tests of which evaluated each of 

 many compounds on the basis of its ability to increase the weight of the thyroid gland--in other words, 

 for the compound's "anti-thyroid" effect for which the hypertrophy of the gland was a criterion. The defi- 

 nition of the criterion specifies the measure of weight as milligrams of thyroid gland per 100 grams of body 

 weight. A special scale accompanies Criterion 30, built on values representing possible thyroid gland 

 weights (expressed as mg/100 gm of body weight). The ranges of these values represent spans of 

 8 mg/100 gm of body weight; each range, then, is assigned a symbol which is used as the code 

 evaluation in Field Y. As this scale indicates, only compounds that cause more than a four-fold 

 increase in weight are considered highly effective. The criterion does not correlate the intensity of 

 response with the quantity of compound needed to cause that intensity in order to derive the evaluation 

 in Field Y; the Field Y evaluation is only an expression of the intensity of response--the degree of 

 hypertrophy. Thus, with Criterion 30, the test compound's potency is not expressed in Field Y and 

 can be understood only by consulting both Field Y and the dosage fields. 



When Criterion 30 is used, the data must be positive, otherwise Criterion 01 or 02 must be 

 used with Symbol 1 in Field Y and Symbols J or K in Field W, according to whether the compound was 

 known to have been administered at the maximum tolerated dose. When the data are positive and 

 Criterion 30 is used, if only one dose regimen were administered, Field W is coded with Symbol L or 

 M, according to whether the dose were known to be the maximum tolerated. It would probably be a 

 rare drug, tested for this special effect and by this technique, which would be tested repeatedly but 

 at different dosage regimens to determine the minimum dose causing a given intensity of response or 

 the dose causing the maximum response below a toxic level. Nevertheless, if these determinations 

 are made, Symbol N, 0, or P should be used according to their definitions. 



18. Criterion 31; iodine content of the thyroid gland 



Like Criterion 30, Criterion 31 is a special criterion for anti-thyroid studies. In this case, 

 the test compound is evaluated on the basis of its ability to decrease iodine deposit in the thyroid 

 gland. The amount of iodine in the gland, after prolonged treatment with the test compound, is 

 measured in terms of milligrams of iodine per 100 grams of thyroid weight. A special scale accom- 

 panies Criterion 31 whose ranges represent 50% decreases, beginning with a "normal" 40 mg of iodine 

 per 100 gm of thyroid gland. The scale is based on the concept that only compounds that reduce the 

 iodine content to less than 1/8 of that "normal" concentration are to be considered highly effective as 

 anti-thyroid materials. 



Coding in Fields X, Y, and W follows the pattern described for Criterion 30 in Division 17 to 

 which reference should be made. 



19. Criteria 51, 52, and 53; evaluation of potency of the test compound expressed in terms of 

 percentage of organisms affected relative to the quantity of test compound needed to affect 

 that percentage 



Criteria 51, 52, and 53 are used exclusively for evaluating results of tests in which a group of 

 individuals has been administered a given quantity of the test compound or in which several groups 

 have each been administered different quantities of the test compound. The purpose of such tests 

 (sometimes referred to as "population studies") is to determine the percentage of a group of individuals 

 responding to each specific quantity of test compound. In other words, these data are concerned with 

 the variation between individuals of the test organism species and the objective of the test is to 

 determine the minimum quantity of test compound producing a specified response in a given percentage 

 of individuals (e.g., lethal or threshold dose for 50%, 80%, or 100% of the individuals treated) or 

 the reverse, the percentage of individuals giving a specified response to a given quantity of test 

 compound. Under a section of Division 8 designated as Subdivision B, this is described as an 

 expression of potency in terms of dosage vs. percentage of individuals affected at a given intensity 

 of response. The definitions of Criteria 51, 52, and 53 do not bear stipulation of any specific intensity 



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