OWEN'S BLUE 



249 



OX ID ATION -REDUCTION 

 POTENTIAL 



per, H., Arch. Path., 1942, 36, 647-662 

 nave indeed investigated variations in 

 ovarian fluorescence during cj^clical 

 changes. 



Owen's Blue (British Drug Houses Ltd.), a 

 dis-azo dye similar in composition to 

 Manchester blue. Used best in alco- 

 holic solution (H. G. Cannan, J. Roy. 

 Micr.Soc, 1941,61,88-94). 



Oxalate Solutions, see Anticoagulant Solu- 

 tions. 



Oxazins. Dyes resembling the thiazins but 

 in which sulphur atom is replaced by 

 oxygen. Examples: brilliant cresyl 

 blue, celestin blue B, cresyl violet, gal- 

 lamin blue, gallocyanin, Nile blue sul- 

 phate, resorcin blue. 



Oxidase. Unfortunately, as Lison (p. 263) 

 points out, histologists and biochemists 

 are not always agreed as to terms. The 

 latter include under the designation 

 "o.xidases" all enzymes capable of cata- 

 lysing a reaction of oxidation, for in- 

 stance the phenolases, purinoxidases, 

 succinoxidase, tyrosinase, etc.; whereas 

 what the former describe as "oxidases" 

 are in reality phenolases and thus only a 

 part of the whole group of oxidases. 

 The action of oxidase (or phenolase) in 

 the presence of Oj is the same as a per- 

 o.xidase in the presence of H2O2. But 

 the particular oxidases are more delicate 

 and easily modified in their action by 

 variations in temperature, pH and other 

 factors. The following methods are 

 from Lison, much abbreviated. 



1. M. nadi oxidase reaction (Gratf) 

 = oxidase reaction, modification A (W. 

 H. Schultze) and stabile oxidase reac- 

 tion (V. Gierke). Make 2 solutions : A. 

 Boil 1 gm. anaphthol in 100 cc. aq. dest. 

 Add drop by drop 25% aq. potassium 

 hydroxide until melted a naphthol is 

 dissolved. Cool. Can be kept in dark 

 at least 1 month. B. Obtain good 

 sample dimethyl - p - phenylenediamine 

 furnished in sealed tubes. It blackens 

 quickly when secured in bulk. Graff 

 advised, as more stable, dimethyl-p- 

 phenylenediamine hydrochloride. Make 

 1% solution of either in aq. dest. Boil 

 and cool. Keeps 2-3 weeks in dark. 

 Immediately before using take equal 

 parts A and B, filter and employ filtrate. 

 Place frozen sections of formalin fixed 

 tissues or smears (after fixing for 2 hrs. 

 in formalin vapor or in formol, 10 cc. 

 + 96% alcohol, 40 cc.) in above mixture 

 of A and B in a thin layer at the bottom 

 of a Petri dish. .\gitJite a little to per- 

 mit oxygenation of the fluid. Blue 

 granules quickly appear (1-5 min.). 

 Rinse in water and examine. To make 

 more permanent treat with Lugol's 

 iodine diluted one third, 2-3 min., 

 which makes the blue granules brown. 



Restore blue by washing in aq. dest. 

 -f few drops sat. aq. lithium carbonate. 

 Counterstain with hemalum or .safranin. 

 mount in glycerin. Schmorl advised 

 instead of Lugol's a cone. aq. sol. am- 

 monium molybdate. 



2. G. nadi oxidase reaction (Graff) 

 = labile oxidase reaction (V. Gierke). 



This more difficult method is for fresh 

 tissues. The nadi reagent is prepared 

 without addition of alkali. The re- 

 quired pH depends on the cells investi- 

 gated. For animal tissues Lison recom- 

 mends about 8.2, 8.1 and 7.8 and for 

 plants 3.4-5.9. Directions are given 

 by Grjiff (S., Die Mikromorphologischen 

 Methoden der Fermentforschung, Ab- 

 derhalden's Handb., 1936, 4 (1), 93-142). 



3. Naphthol reaction of Loele. This 

 is not, in the opinion of Lison, strictly 

 speaking a microchemical reaction, but 

 it is as simple. Place small amount 

 a naphthol in a test tube. Add drop by 

 drop 10% aq. potassium hydroxide until 

 naphthol is completely dissolved. Add 

 200 cc. aq. dest. Solution may be used 

 after 24 hrs. It will last about 3 weeks. 

 Frozen sections of formalin fixed tissues 

 treated with this reagent show violet or 

 black granules, which quickly disappear. 



Oxidation-Reduction Potential. Written 

 by Christopher Carruthers, Division 

 of Cancer Research, Washington Uni- 

 versity, St. Louis 10. May 12, 1950. 



This very important measurement is 

 particularly well explained by Seifriz, 

 W., Protoplasm, New York: McGraw- 

 Hill Book Co., 1936, 584 pp. For a 

 comprehensive developmental treat- 

 ment of the subject see Clark, W. M. 

 and coworkers, Hygienic Laboratory 

 Bull., 1928, 151, 1-352. 



Oxidation is the process in which a 

 substance loses electrons, and reduction 

 is the process in which a substance takes 

 on electrons. For example when ferric 

 chloride FeCU gains an electron it is 

 reduced to FeCU, or 



Fe"''"'^ + electron — ► Fe'^ 



Because the ion, Fe"*^, can lose an elec- 

 tron it is a reducing agent or reductant, 

 and since Fe"'"++ can gain an electron it 

 is an oxidizing agent or oxidant. The 

 change is reversible 



Fe-'-^ -t- electron :^ Fe++. 



When an acid mixture of ferrous and 

 ferric chloride is placed in an electrode 

 vessel it will yield a potential— the oxi- 

 dation potential. This potential can 

 be measured by placing a noble metal, 

 such as a bright platinum wire in the 

 solution, and measuring the potential 

 against the normal calomel electrode 

 with a potentiometer. The intensity 

 of the oxidizing or reducing action of a 



