PROTACTINIUM 



287 



PROTOSIDERIN 



37, 524-548. Inject internal iliac ar- 

 teries of a fresh cadaver with equal 

 parts barium sulphate and water at 200- 

 250 mm. mercury pressure. But be- 

 forehand cut small branch of superior 

 vesical artery to relieve pressure in 

 prostatic vessels. Remove prostate 

 with sufficient surrounding tissue. Cut 

 gland into 5-6 sections each about 1 cm. 

 thick. Dehydrate in ascending alco- 

 hols and clear in oil of wintergreen 

 (methyl salicylate). 



Examination of corpora amylacea by 

 various methods is described by Moore, 

 R. A., Arch. Path., 1936, 22, 24-40. 



Protactinium, see Atomic Weights. 



Protamines, see Saint Hilaires Method 

 discussed under Purines. 



Protargol. This is a light brown protein 

 silver compound containing approxi- 

 mately 8% silver. To demonstrate 

 phagocytosis by the reticulo-endothelial 

 system fine suspensions may be injected 

 intravenously (Askanazy, M., Aschoff 

 Path. Anat., Jena, 1923, 1, 183) but the 

 method is not recommended by Foot 

 (McClung, p. 115). Protargol is also 

 used for staining of paraffin sections 

 (Bank, E. W. and Davenport, H. A., 

 Stain Techn., 1940, 15, 9-14). See 

 Silver Methods, Bodian Method, Pro- 

 tein Silver. 



Protease. An enzyme located in leucocytes 

 which can be demonstrated in small 

 quantities of blood has been described 

 (Cooke, J. v.. Arch. Int. Med., 1932, 

 49, 836-845). Pickford, G. E. and F. 

 Dorris (Science, 1934, 80, 317-319) have 

 reported a micromethod for protease. 

 DeRobertis, E. (Ann. N. Y. Acad. Sci., 

 1949, 50, 317-335) devised micro methods 

 for the analysis of proteolytic activity 

 in thyroid colloid. Sections were in- 

 cubated on plates covered with gelatin, 

 which was subsequently stained. Pro- 

 teolytic activity digested the gelatin, 

 (pausing the film to stain less intensely 

 than neighboring undigested areas. 

 Similar experiments for localizing pro- 

 tease have been carried out using fibrin 

 film as a substrate. 



Protein, see following reactions: Alloxan, 

 Axenfeld, Azo, Indo, Ninhydrin, Nitro, 

 Nitroprusside, Nitrosamino, Romieu, 

 Xanthroproteic. 



Proteolytic enzymes. These include pro- 

 tease and many others. See Click, 

 pp. 302-306. 



Protein Silver for Staining Protozoa — 

 Written by Norman Moskowitz, Dept. 

 of Zoology, University of Pennsylvania, 

 Philadelphia. January 24, 1951 — When 

 commercially prepared silver products 

 suitable for staining Protozoa by the 

 Bodian silver technic apparently be- 

 came unavailable, a substitute for 



Protargol was prepared as follows: 0.9 

 g. of granular gelatin is dissolved by 

 heat in 100 ml. aq. dcst.; to this 0.1 g. 

 of silver nitrate is added at 60° C. ; this 

 solution is poured into Columbia stain- 

 ing dishes (10 ml.) in which one or two 

 drops of M/10 sodium hydroxide have 

 been added. Copper is not used in the 

 impregnating bath. Smears fixed in 

 Hollande's or Schaudinn's fixatives are 

 bleached and impregnated for 36 hours 

 or more at 35°C. Impregnated smears 

 are reduced with a mixture of hydro- 

 quinone and sodium sulfite, and toned 

 with gold chloride. 



1. Fix smears in the recommended 

 fixative. 



2. Wash in 50% ale. to remove fixative. 



3. Harden the smears in 70% ale. in 

 which they may be stored for not 

 more than a few days. 



4. Hydrate smears. 



5. Bleach: Treat preparations in 0.5% 

 potassium permanganate 2 min. 

 Wash in at least two changes of aq. 

 dest., 1 min. each. Treat with 5% 

 oxalic acid 2 min. Wash in three 

 changes aq. dest. 



6. Impregnate smears in protein silver 

 solution for 36 hours at approx- 

 imately 35°C. Results in staining 

 can be varied by omitting the M/10 

 sodium hydroxide or by adding one 

 or two drops of M/10 nitric acid 

 instead of the recommended alkali. 



7. Reduction of silver. Rinse im- 

 pregnated smears in aq. dest. water 

 and treat for 5 minutes in a reducing 

 bath prepared by dissolving 1 g. 

 of hydroquinone and 5 g. of sodium 

 sulfite in 100 ml. aq. dest. 



8. Wash in aq. dest. 1 min. 



9. Toning. Immerse preparations for 

 4 min. in 0.2% (1% may be used) 

 aq. yellow gold chloride. Staining 

 is affected by the duration of the 

 gold toning. 



10. Rinse in aq. dest. 



11. Treat with 2% oxalic acid for 3 

 min. Variation of time in oxalic 

 acid produces staining differences. 



12. Wash 1 min. each in of 3 changes 

 aq. dest. 



13. Treat with 5% sodium thiosulfate 

 for 7-8 min. 



14. Wash in running tap water for ^ hr. 

 or more. 



15. Dehydrate and mount. The im- 

 pregnating medium should not be 

 exposed to intense daylight at any 

 time. 



Proteinase, determinations (Maver, M. E., 

 Mider, G. B., Johnson, J. M. ana 

 Thomp.son, J. W., J. Nat. Cancer Inst., 

 1941, 2, 278). 



Protoslderin, see Lillie, p. 127. 



