Experimental researches on specific therapeutics. Lecture III, Chemo-therapeutic studies on trypanosomes / by Paul Ehrlich.
- Paul Ehrlich
- Date:
- 1907
Licence: Public Domain Mark
Credit: Experimental researches on specific therapeutics. Lecture III, Chemo-therapeutic studies on trypanosomes / by Paul Ehrlich. Source: Wellcome Collection.
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![Paul EHhilich 4S] tions there were mentioned almost exclusively experiments carried out at earlier periods of infection. In our cases acetyl-atoxyl will cure mice in nearly 100 per cent. Unfortunately, acetyl- atoxyl is decomposed in other animals, especially in the horse, into acetic acid and aniline, and it cannot, therefore, be nearly as effective as it is in the mouse. Nevertheless, the results obtained in the mouse are so excellent that they must encourage us to energetically pursue the path of these discoveries. I mentioned in my last lecture that it 1s possible to obtain strains of trypanosomes which are resistant to these active sub- stances. Studies, which I have carried out with Dr. Rohl and Dr. Browning, have shown this resistance to be of a very high degree. Thus, atoxyl-fast strains show no sign of being influenced by the highest doses of atoxyl which are applicable to mice. I gave you the explanation for this resistance, viz., that it is the result of a decrease in the avidity of the trypanosomes for these trypan cidal substances. Further, I pointed out that, apart from this resistance, the parasites’ protoplasm, though not their nuclei, had become lhyper-sensitive towards the arsenical preparation. Thus we meet with an important instance of association, in one and the same cell, of resistance and hyper-sensitivity: This asso- ciation, which is of late years proving to be of increasing impor- tance in the question of mammalian immunity, is therefore present even in so simple an organism as that of the protozoon. Although in the mouse atoxyl-resistance usually develops only after a fairly long period, I have occasionally seen it after a fort- night. This observation is very important, because it makes it possible that the negative results observed by Ayres Kopke, Broden, Rodhain, Todd and van Campenhout, in cases of sleeping-sickness which had received a long-continued treatment, may also be due to such a resistance. In the same way as with atoxyl, trypanosomes can also be rendered resistant to para-fuchsin, trypan-red and trypan-blue, and further, it was shown in my Institute by Franke in his work with apes, that it is even possible for trypanosomes to become resistant to those protective substances which are formed after the recovery of the host from a trypanosome infection. A similar discovery has recently been made by Levaditi in the spirochetes of relapsing fever. ‘This is therefore a general law, and it is especially impor- tant, because this change in the trypanosomes, having once become](https://iiif.wellcomecollection.org/image/b3345257x_0005.jp2/full/800%2C/0/default.jpg)
