FIELD U 

 Columns 65 and 66 



indicative of sensitivity increase or cumulative effects, or (3) diminish with time, which would imply 

 only fatigue or tolerance increase. Finally, note that death or any response that ends in death can 

 not be measured in terms of "duration of action" and in case of such lethal actions, Criteria 13 and 54 

 can not be used nor is there a duration of action value possible in Field U. In addition to death, 

 certain other items of Field T-2 represent self- terminating processes (e. g. , organ destruction) for which 

 the duration of the test compound's effect can not be measured, since that effect is apt to be merely 

 initiatory. 



In a test for a duration of action value, there may be an appreciable interval between the end 

 of administration of the test compound and the beginning of the response. This interval is actually the 

 "time to specific action" and the duration of action value should not include this interval when it is 

 known. When the "time to specific action" is known, Field U may be used to code this value (explained 

 in Division 3A below) and must be used if evaluation is based on it (Criterion 10 or 58 of Field X). 

 However, if duration of action (the first appearance of the response to its end) is the basis of evaluation 

 (Criterion 13 or 54 of Field X), it is that time interval that must be entered in Field U rather than "time 

 to specific action". 



If the response appears (1) prior to the end of the administration of the test compound or (2) 

 simultaneously with the end of administration, or (3) after such a brief period that, relative to the 

 duration period, the interval is insignificant, the duration of action period is considered to begin at 

 the end of administration. If there is known to be an interval between the end of administration and the 

 beginning of the response, yet the length of this interval is not given, the CBCC has considered the 

 duration of action as beginning with the end of administration, though it is preferred to code the actual 

 duration whenever possible as explained in the previous paragraph. 



Duration of action, as defined above, should always be coded in Field U when it is known, 

 even if the criterion for evaluation in Field X is not "duration of action" or, if Field U must be used for 

 coding time to specific action because Field X has been coded with Criterion 10 or 58, and a duration 

 of action value is known, the latter should be included in the written abstract portion of the field. 



When a test compound affects an organism so that the direction of action reverses (Symbol 4 or 

 5 of Field T-l), there would necessarily be two "durations of action", the duration of the increase and 

 the duration of the decrease, although the entire period of the chemical influence, including both the 

 increase and decrease, might conceivably be considered to represent a single "duration of action". 

 When Field T-l is coded with Symbol 4 or 5, evaluation should never be by Criterion 13 or 54 of Field X, 

 since the circumstances would be unusual or improbable when it would be meaningful to evaluate the 

 chemical on the basis of the total period of time over which it has produced a sequence of opposing 

 effects. Consequently, when Symbol 4 or 5 is used in Field T-l, the CBCC has established the rule 

 that Field U should never be coded with either the duration of increase or the duration of decrease of 

 action; both values should be included in the written abstract portion of Field U and the code boxes 

 should be cross-hatched. 



If the test has been performed expressly to determine a duration of action, the time period is 

 apt to be expressed by the author so that the CBCC coder need not be concerned about calculating it; 

 however, lacking an author's statement of a duration of action, but having information in the form of 

 charts, tables, Kymograph records, etc. , which permits deriving the desired time value, the period 

 should be considered to end at the time of the first observation of the organism's return to normal, 

 even if an interval has lapsed between this observation and the previous observation and it is not 

 known exactly when during this interval the organism returned to normal. 



2. Alteration of survival time by the test compound; coding in Field U with Field X Criteria 12 and 57 



The test compound's effect on survival time is defined above in the section on General Use (see 

 specific Use Number 2). When either Criterion 12 or 57 is to be used in Field X, Field U must be coded 

 with a time value representing an increase or decrease in survival time (or with a symbol representing 

 no increase in survival time, Field U Symbols 11 or 91, e. g. ). If the test compound increases survival 

 time, a remedial or ameliorative effect is indicated and Fields T-l and T-2 are coded accordingly 

 (Symbol 1 in Field T-l and Symbol 12 in Field T-2 or Symbol 7 in Field T-l and Symbol 17 53 in Field 

 T-2, according to whether or not the time value is an increase in duration of viability or an increase 

 In time of survival of pathology); even if the test compound produced no change in time, as compared 

 to untreated organisms, Fields T-l and T-2 can be coded with the therapeutic action for which the test 



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