The standard for the biological assay of strophanthus / by J.H. Burn ; together with a report on the assay by the frog method / by J.W. Trevan.

  • Burn, J. H.
Date:
[1926?]
Catalogue details

Licence: In copyright

Credit: The standard for the biological assay of strophanthus / by J.H. Burn ; together with a report on the assay by the frog method / by J.W. Trevan. Source: Wellcome Collection.

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    lated that the chance of tinctures A and B being actually different is 12'4 to 1. (I am indebted to Dr. Trevan for this calculation.) It is of some interest to point out that while the mean of the figures in Table II. is 3*46, the mean obtained by treating the individual cat values in Table I. as though they had been obtained with one tincture is also 3‘46. On the other hand, the U.S.P. X. demands a minimum ouabain equivalent of 8‘33 Mgm. per C.c. It will be evident that, on any consideration, the figures obtained represent an equivalent substantially less than one-half of this demand. II. The discrepancy between the values obtained for a series of representative tinctures and the U.S.P. figure, at once suggested that a different result was obtained by the cat method than would be obtained by the frog method de¬ manded by the U.S.P. The two tinctures A and B were accordingly sent to Dr. J. W. Trevan, of the Wellcome Physiological Research Laboratories, who agreed to assay them by the frog method. No information was given to Dr. Trevan of the results by the cat method. Dr. Trevan’s Report. Method.—All doses were injected into the dorsal lymph sac of frogs kept at room temperature in bright light. The doses were proportional to the body weight of the frogs in¬ jected, and were all made up to 05 C.c. with 06 per cent, saline before injection. Each group of frogs injected was accompanied by the group injected with the standard ouabain supplied by the United States Department of Agriculture. The twelve hours’ mortality was noted in each group, and the relative potency indicated by the respective mortalities read off from the standard curve (see Fig. 1), which was DOSE Fiff* 1.—Standard curve showing relation between mortality and dose for frogs injected with strophanthus.