The relation between dosage and death-time / by A.T. Glenny.

  • Glenny, A. T.
Date:
[1925?]
Catalogue details

Licence: In copyright

Credit: The relation between dosage and death-time / by A.T. Glenny. Source: Wellcome Collection.

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    times would agree more closely with the calculated times, but it must be remembered that so many other factors are involved besides the pathological effect of the pure poison that no simple formula could allow for all variables. Table II. gives corresponding results with 32 guinea-pigs injected with a strong toxin concentrated by the method of Grlenny and Walpole Table II. Observed lethal times in hours, of 32 guinea-pigs of 250 grams iveight injected subcutaneously with different doses of concentrated diphtheria toxin JC 2538. The average lethal times are compared with times calculated according to the -5—^ (T -10) = 12. *00008) K ' formula log Dose. 0'00005. 0-000075. o-oooi. 0-00025. 0-0005. 0-005. 0-05. 0'5. 5-0. r i lived lived 156-0 41-4 25-5 24-0 16-7 17-0 12-5 Observed lethal | 9 9 9 9 120-0 33-0 23-7 23-0 15-5 16-0 10-5 times 1 9 9 134*0 105-0 • • • 23-0 19*5 14-0 11-0 • • • l 99 90-0 86-0 ... 22-2 15-0 13-0 10-0 ... Average lethal times 9 9 lived 116-8 37-2 23-6 20-4 14-8 13-5 11-5 Calculated lethal times 9 9 9 9 133-8 34-2 25-1 16-7 14-3 13-2 12-5 (1915). The M.L.D. of the concentrated toxin was taken to be 000008 c.c.: of 4 guinea-pigs injected with 0-000075 c.c. 1 died i earlier than 5 days, 1 later and 2 survived: of 4 injected with O'OOOl c.c., 1 died at the end of 5 days, 2 earlier and 1 later. If chemically pure toxin could be prepared the constants of the equation connecting dosage with death-time would be the same however the toxin was prepared. But chemically pure toxin has never been prepared: the true toxin molecules probably constitute but a very small fraction of the purest toxin hitherto made. With moderately strong toxin non-specific effects, due to impurities present, may cause some discrepancy between observed and calculated lethal time but i may not greatly affect the value of the constants. The formula for this concentrated toxin JC 2538 was therefore tried with the same constants as those used for the moderately strong toxin previously recorded: (log D - log 0-00008) (T - 10) = 12 gave calculated times in close accord with observed times. Chart 1 shows graphically how a single formula may connect dosage and death-time over a long range from 0 to over 60,000 fatal i doses for two different toxins, one a routine batch of toxin with a ; minimal lethal dose of 0‘002 c.c. and the other a concentrated toxin ! with an M.L.D. of 0-00008 c.c. The points marked on the chart represent the average of the observed lethal times; individual readings differed greatly from the average. The general formula reads:— 12 (log d) (T - 10)= 12 or T = 10+ -r——r
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