ARGINASE 



27 



ARSENIC 



comes nuclear debris and above this 

 cytoplasmic debris. His analysis 

 showed arginase present in the same con- 

 centration in the nuclei as in the cyto- 

 plasm. Blaschko and Jacobson (Bourne, 

 p. 217) remark that this is the first in- 

 stance of the demonstration of an enzyme 

 in the cell nucleus. 

 Arginine Reaction. The method of Serra, 

 J. A., Stain Techn., 1946, 21, 5-18 is 

 detailed by him as follows: Prepare 

 tissue as described under Ninhydrin 

 Reaction. 



"1. Before the reaction the pieces or 

 sections are hardened with 10% for- 

 maldehyde during 12-24 hours, the 

 formalin being afterwards well washed 

 out. (If the fixative contains formalin 

 this step can be omitted.) 



"2. Immerse the pieces for 15 minutes 

 in a mixture consisting of 0.5 ml. of 

 diluted a-naphthol; 0.5 m.l. of N NaOH; 

 and 0.2 ml. of 40% aqueous urea solu- 

 tion. The diluted a-naphthol is pre- 

 pared at the moment of use by diluting 

 a stock solution (1% crystallized a- 

 naphthol in 96% alcohol) 1 : 10 with 40%, 

 alcohol. The watch glass containing 

 the liquids is placed in an ice-bath and 

 the temperature of the reaction fluid 

 inside it must be 0.5°C. 



"3. After 12-15 minutes add 0.2 ml. 

 of a 2% solution of NaOBr. This re- 

 agent is allowed to act for 3 minutes and 

 the solution must be well stirred during 

 this time. The 2% NaOBr must be 

 freshly prepared by pouring 2 g. (or 

 approximately 0.7 ml.) of liquid bro- 

 mine into 100 ml. of 5% NaOH, with 

 agitation and cooling. 



"4. Add another 0.2 ml. of 40% urea 

 solution, stir, and immediately after- 

 ward, 



"5. Add another 0.2 ml. of 2% NaOBr 

 and stir well. The coloration attains 

 its maximum after .3-5 minutes and 

 would last only for a short time if it 

 were not stabilized. To stabilize the 

 coloration: 



"6. Take the pieces out of the reac- 

 tion mixture and immerse in pure 

 glycerin for 2-3 minutes and then trans- 

 fer to fresh glycerin. Repeat the opera- 

 tion another two or three times. The 

 passage through 4 glycerin baths is 

 sufficient to stabilize the coloration 

 for some months, even if the pieces are 

 left at room temperature. (We have 

 not mentioned this improvement in 

 any previous publication.) 



"Besides this procedure, which we 

 may call the normal method, there is 

 also another method which results in 

 stronger colorations .and very satisfac- 

 tory preparations. To accomplish this, 

 after step 6 the pieces are taken off the 



reaction liquid and immersed in NaOBr 

 solution for not more than 3 minutes. 

 Afterwards the coloration is stabilized 

 in glycerin, as in the normal procedure. 

 The pieces are mounted and observed 

 in pure glycerin (See Fig. 1-3). 



"This reaction is specific for guani- 

 dine derivatives in which only one H- 

 atom of one amino group is substituted 

 by a radical of the alkyl or fatty acid 

 type. In proteic compounds it is 

 specific for arginine. As all proteins 

 hitherto analyzed possess arginine in 

 their molecules, the reaction may be 

 used to demonstrate the presence of 

 proteins in general, other compounds 

 with a reactive guanidine group being 

 rare. The test may also be used to 

 characterize the basic proteins." 



Argon, see Atomic Weights. 



Argyrophilic Fibers. Because of their affin- 

 ity for silver. Reticular Fibers are often 

 called argyrophilic. 



Arneth Count of lobes of granular leucocytes 

 as a basis for estimation of their rela- 

 tive age. See Leucocyte Counts. 



Arsenic 1. Use 10% neutral formalin in aq. 

 dest. after test with hydrogen sulphide 

 shows absence of trace of metals. To 

 100 cc. add 2.5 gm. copper sulphate. 

 Fix small pieces of tissue 5 days. Wash 

 24 hrs. in running water. Imbed in 

 paraffin. Direct examination of section 

 after removal of paraffin shows arsenic 

 as well defined green granules of hydro- 

 arsenite of copper (Scheele's green). 

 If neutral acetate of copper is employed 

 in place of the sulphate the green 

 granules are of acetoarsenite of copper 

 (Schweinfurth's green). 



2. Fix pieces of tissue 12-24 hrs. in 

 abs. ale. 50 cc; chloroform, 50 cc; pure 

 hydrochloric acid, 3 cc. saturated by 

 passage of pure hydrogen sulphide. In 

 sections the arsenic ppt. appears as yel- 

 low granules. Double coloration with 

 hematein-eosin is possible. Both tech- 

 niques have been devised by Castel 

 (P., Bull. d'Hist. Appl., 1936, 13, 106- 

 112). He has described the histologic 

 distribution of the arsenic. See, how- 

 ever, paper by Tannenholz, H. and Muir, 

 K. B., Arch. Path., 1933, 15, 789-795 who 

 employed a somewhat similar method 

 and were unable to conclude that the 

 yellow crystals were in fact those of 

 arsenic trisulphide. The}' considered 

 them more probably a sulphur-protein 

 combination. 



Consult the detailed account of Os- 

 borne's method for arsenic given by 

 Heuper, W. C, Occupational Tumors 

 and Allied Diseases. Springfield: 

 Thomas, 1942, 896 pp. (p. 50). This 

 releates particularly to localization of 

 arsenic in the akin. 



