The Jacobson Method for Assay of Liver Extracts

In relation to the study of tropical anemias, it was the intention of the authors to follow the method advocated by Jacobson. 1 , 2 , 3 , 4 , 5 This method, which requires the use of the guinea pig in the bioassay of the antianemic principle present in liver extracts, has been employed also by Miller and Rhoads 6 and Mermod 7 in the study of other antianemic substances. While such investigators as Mermod, Miller and Rhoads, Landsberg and Thompson 8 have followed and accept the reliability of the Jacobson method, Goodman, Geiger and Klumpp 9 failed to corroborate the validity of the method.

A total of 40 normal, adult, male guinea pigs (400-700 g), obtained from several local sources, have been used, from which 20 animals were selected according to the standards recommended by Jacobson. All animals remained healthy during the experiment. The reticulocyte count studied during a 10-day period of standardization at 2- or 3-day intervals did not show figures of over 1.2%, except in 2 animals, in which the reticulocyte count was 2%. The animals were fed a mixture of Michigan State rabbit ration and Para grass before and during the experiment. The least possible amount of blood was obtained each time from the ear vessels. The technic employed by C. Mermod (loc. cit.) was followed and a minimum of 1000 red cells were counted in each determination.

One intramuscular injection of 0.5 cc liver extract (prepared from Lilly's 343 and potent in sprue and of which 1 cc was equivalent to 5 g raw liver) was then given to 10 animals (Group I). Another series of 10 pigs (Group II) received 1 cc liver extract.