Antagonistic Effect of Iodides in Baldness and Toxicity Due To

MAY 23, 1936 NATURE 871

A careful examination, however, of the manner in 0·5 c.c. of calcium iodide, very quickly developed which the velocity constant varies with pressure over dermatitis of the third grade due to the amount of the range 15-800 rom. reveals the existence of a calcium ion administered, and therefore we had to

'segmented' plot of l/t1 , 2 against p 0 • At 475° C. the discontinue the calcium iodide. The animals of the 'period of half change' is almost independent of sixth group (B), which served as controls to the five initial pressure with p 0 > 250 rom. Between c. 250 rom. A groups, received per 08 thallium acetate only in and 40 rom. there is a 'bimolecular' relationship the same quantity as the A groups. However, during between t112 and p 0 , and below c. 40 rom. at least one the experiment the animals of Group B looked very other such 'bimolecular' region. In this respect, ill, and in order to save some animals to the end of therefore, the reaction falls into line with other the experiment we had twice for two days to dis• similar decompositions recently examined•, and can continue the administration of thallium acetate (six be interpreted as involving the superposition of out of ten died). The animals of the seventh group (0), several independent quasi-unimolecular processes. which served as controls, received no chemicals. The energy of activation of the reaction for p 0 > 300 At the end of the experiment, all the animals of mm. is c. 54,000 cal., and at the lowest pressures the first four groups (A) looked healthy, they had (c. 20 rom.) is somewhat lower (c. 50,000 cal.). The increased in weight on the average from 38 gm. to rate at the pressure at which the 'falling-off' is first 135 gm. (two rats of the sodium group and one of manifest is in accordance with the postulation of a the magnesium group died during the experiment) distribution of activation energy among about nine and preserved almost completely their coats; how• squared terms, which appears a more reasonable ever, their hair was softer and lacked the lustre of , value than that previously calculated by Ramsperger•. normal hair. Also the two survivors of Group A 6 Increase in the surface-volume ratio of the reaction which received later on potassium iodide instead of vessel by about eight times at 470° C. lowers the rate calcium iodide, had the same appearance as the by less than 10 per cent, which, allowing for possible animals of the other A groups. errors, is scarcely significant. The existence of The surviving animals of Group B lost their hair appreciably long reaction chains is therefore unlikely. almost completely ; in a few places the lanugo was It has been suggested that isomerisation to acetal• seen, and also the feelers were not affected. These dehyde is the first stage in this decomposition, even animals developed stomatitis, erythema and eczema though no direct evidence for such a mechanism was and at the end of the experiment they looked very obtainable. We have been unable to detect the poor. The most striking effect of thallium acetate presence of acetaldehyde among the reaction products was that all the survivors of this group developed at any stage of the decomposition over the tem• cataracts and other eye defects after 35-50 days of perature range employed. administration of thallium acetate, and the animals Inert gases (argon, nitrogen, helium and others) became entirely blind. This was never observed in retard the decomposition to some extent, but the the rats of the A groups. Also their average weight precise details of this effect require a fuller explana• showed a smaller increase (from 38 gm. to 115 gm.) tion. and was below the weights of the animals which The detailed results will shortly be published received the iodides. elsewhere. The rats of Group 0 increased in weight on the H. w. THOMPSON. average from 36 gm. to 195 gm. and looked entirely M. MEISSNER. normal. Old Chemistry Department, The results of this experiment indicate that lithium Oxford. iodide, potassium iodide, sodium iodide and mag• April 2. nesium iodide prevent to a great extent the falling 1 J. Amer. Chern. Soc., 51, 2706 (1929). out of hair, reduce considerably the toxicity of 1 NATURE, 136, 909 (1935) ; J. Amer. Chem. Soc. , 58, 534 (1936). thallium acetate and prevent the development of • Proc. Roy. Soc., A, 141, 41 (1933) ; A, 146, 327 (1934). 'Chem. Rev., 10, 27 (1932). cataracts and other eye defects brought about by thallium acetate. The best results were obtained with lithium and potassium iodide ; the results with Antagonistic Effect of Iodides in Baldness and sodium and magnesium iodide were a little less Toxicity due to Thallium Acetate satisfactory. Calcium iodide would probably have 2 IN earlier reports1• , we stated that potassium the same biological action as the other iodides used iodide administered subcutaneously prevents the loss in this experiment, but due to its deleterious effect of hair caused by thallium acetate, as well as reduces upon the skin it cannot be used subcutaneously in considerably the toxicity of the latter. such experiments. The object of the present investigation was to find These results are not in accordance with the results out whether other salts of iodine have the same effect of some scientific workers•, who state that potassium as potassium iodide. We used seven groups of rats, iodide does not act as an antidote to thallium (prob• each group consisting of seven rats, except the sixth ably not in acute thallium poisoning) ; in our experi• thallium group which had ten rats. The experiment ment we obtained satisfactory results with potassium continued for 69 days. The first four groups (A) and other iodides as antidotes in chronic thallium were receiving daily per 08 for a period of 32 days poisoning. 0·3 mgm. and for a. further 36 days 0·4 mgm. of 0. v. HYKES. thallium acetate per 100 gm. weight. In addition, Department of General F. A. DIAKOV. the animals of these four groups received daily sub• Biology and Parasitology, cutaneously 0·5 c.c. of lithium iodide, potassium Veterinary College, iodide, sodium iodide and magnesium iodide, re• Brno, Czechoslovakia. spectively (I c.c. of iodide solution contained 20 mgm. April 2. 1 of iodine). The animals of the fifth group (A 6 ), which Hykes and Dlakov, NATURE, 136, 685 (1935). were receiving daily the same quantity of thallium • Hykes and Diakov, PulJlicati(mll biol. Ecole veterin. (Bioi. spisy V. s. zvlrolik.) Brno, 14, 85 (1935). acet-ate p er 08 as the previous four groups and also 'Hesse, "Handb. exper. Phannakol.", ill, Bd. 3, T., 2177 (1934).