FIELD T-2 

 Columns 58, 59, 60, and 61 



". . . It has been decided not to delete symbols of enzymes which may be later shown to 

 consist of more than one entity. Instead, cross-references will be used to cope with this 

 situation. 



"All possible attempts have been made to include all enzymes known as of July 1953. 

 The following books have been found very helpful: 



1. The Enzymes. Chemistry and Mechanism of Action. Edited by James B. Sumner and 

 Karl Myrback. 



Vol. I, Part 1 (1950) 



Vol. I, Part 2 (1951) 



Vol. II, Part 1 (1951) 



Vol. II, Part 2 (1952). Academic Press, N.Y.C. 



2. Chemistry and Methods of Enzymes. 3rd Edition. By James B. Sumner and 

 G. Fred Somers. Academic Press, N.Y.C. (1953)." 



Since this 1953 revision, so many enzymes have been described that the list presented here 

 may be regarded as obsolete, although, had revision been possible to bring it up-to-date, another 

 five years would doubtless find it in the same state of obsolescence. While this fault is recognized, 

 it is not unique to the enzyme list; the Taxonomy Code of Field T-2 will be found inaccurate and to 

 become more so as time passes for the same reasons of advances in knowledge of organisms' taxonomic 

 relationships. In spite of this, the Enzyme Code is included, just as is the Taxonomy Code, to illus- 

 trate the method whereby the CBCC has assigned symbols, to provide a reference to the CBCC files of 

 coded data, and to serve as basis for a future corrected and expanded list. A recent valuable listing 

 and description of enzymes which should be consulted in revision of this list or in building a new 

 Enzyme Code is ENZYMES by Malcolm Dixon and C. E. Webb, Academic Press, N.Y.C, 1958. 



The Enzyme Code, as used by the CBCC, is in two forms, one arranged as it is here, according 

 to the natural organization (and therefore according to the heirarchy of symbol structure), the second 

 arranged alphabetically by name. While both have been useful, the alphabetical list must be considered 

 a supplemental list because like the alphabetical list of other Field T-2 items prepared for CBCC use, 

 its use leads to incorrect selection of code symbols in coding data, due to not being able to scan all 

 related items listed together and to make the most appropriate selection. 



23. Symbol 8153; extension of the invertebrate body from its encasement or shell 



This condition was added to Field T-2 when coding a large collection of data from molluscacide 

 tests in which one of the typical toxic responses was described merely as the body of the snail being 

 extended from the shell and apparently incapable of withdrawal into the shell. The definite cause for 

 this is not determined and may in some cases be due merely to osmotic phenomena resulting in tissue 

 swelling, though this was not indicated by the description of the response. The phenomenon has been 

 arbitrarily assigned Symbol 8153, associating it with muscular conditions, rather than to code all the 

 data involved as being merely an unspecified systemic toxicity. The term and symbol are candidate 

 for revision with more specific information about the condition. 



24. Symbols of series 82 1-; blood pressure 



The definitions of Symbols 821, 8211, and 8212 indicate their use and limitations. The main- 

 tenance of a blood pressure that is normal for any given individual is the result of a regulated balance 

 of a number of factors. Symbol 821 can be regarded as representing this balance itself and if all that 

 is known about the test compound's effect is the disturbance of the balance, without indication as to 

 whether the pressure is generally increased or decreased, Symbol 821 can be used with Symbol 6 of 

 Field T-l; since such data are improbable and, even if existent, would probably be rejected for coding 

 by the CBCC, Symbol 821 is virtually nothing but the heading for the 821- series. 



Symbols 8211 and 8212 code blood pressure disturbances due only to vasomotor effects 

 (vasopressor and vasodepressor). For an increase (or a decrease) in blood pressure due to any other 

 mechanism or factor, a new symbol or symbols must be added to the Code. For example, none of the 

 following specific states of blood pressure have yet been entered in Field T-2 and assigned a symbol, 



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