Venom Preparations Research Articles

Distribution in the mouse of lethal and sub-lethal doses of cottonmouth moccasin venom labelled with iodine-131.

THOUGH disease and death from the bite of the poisonous snake is considered not unusual, and treatment has become more or less standardized, little is actually known about the site of action of snake venom in vivo. The value of a radioactive tag for studies of this sort is evident, and therefore, an attempt was made to label the whole dried venom of the cottonmouth moccasin(Ancistrodon p. piscivorus) with iodine-131, evaluate its toxicity relative to the original venom preparation, and chart its distribution in the mouse after injection of lethal or sublethal doses.

EFFECTS OF α-METHYL-DL-TRYPTOPHAN ON THE OXIDATION OF TRYPTOPHAN

α-Methyl-DL-tryptophan (AMT) inhibits the oxidation of DL-tryptophan by isotonic suspensions of rat liver, and the oxidation of L-tryptophan, L-tyrosine, DL-phenylalanine, and DL-methionine by cobra venom. The oxidation of L-tryptophan is accompanied by the appearance of a yellow color in the reaction mixtures. AMT also inhibits the formation of kynurenine, detected by its specific absorption at 360 mμ and by diazotization, from L-tryptophan. It protects the kynurenine-forming enzyme system against the inactivation which occurs in the absence of substrate. When injected into the rat, AMT, like tryptophan, causes an adaptive increase in the tryptophan peroxidase–oxidase complex. AMT is not oxidized by the liver and venom preparations used.

EFFECTS OF α-METHYL-DL-TRYPTOPHAN ON THE OXIDATION OF TRYPTOPHAN

α-Methyl-DL-tryptophan (AMT) inhibits the oxidation of DL-tryptophan by isotonic suspensions of rat liver, and the oxidation of L-tryptophan, L-tyrosine, DL-phenylalanine, and DL-methionine by cobra venom. The oxidation of L-tryptophan is accompanied by the appearance of a yellow color in the reaction mixtures. AMT also inhibits the formation of kynurenine, detected by its specific absorption at 360 mμ and by diazotization, from L-tryptophan. It protects the kynurenine-forming enzyme system against the inactivation which occurs in the absence of substrate. When injected into the rat, AMT, like tryptophan, causes an adaptive increase in the tryptophan peroxidase–oxidase complex. AMT is not oxidized by the liver and venom preparations used.

Standardization of Cobra (Naja Flava) Venom Using the Graded Response Method

Summary The relationship between dosage of Naja flava venom and death-time of mice has been examined from experiments using intravenous injection. The observations were found to be well represented by the equation . From this formula, a function of death-time can be constructed that has a linear regression on the logarithm of the dose over a wide range of doses, the function being . The logarithm of the time also is linearly related to the log dose over very nearly the same dose range. For both these response metameters, and over the same range of doses, the variance was found to be almost independent of the mean. Hence the potency of a preparation of venom may be assayed against a standard, using either f(T) or log T as a response metameter, in a parallel line assay of familiar type. The function f(T) has the advantage of giving a linear regression over a slightly greater range of doses, but redetermination of the numerical values of its parameters should precede its use in any other laboratory. At the South African Institute for Medical Research, assays of the (2 + 2) dose design have been found satisfactory; five trial assays reported in this paper used five animals at each of the four doses and gave limits of error of ±20% or less for a probability of 0.95.