Abstract
In connection with studies on the effect of intravenous injection of rats with hemolytic streptococcus extract toxin 1 ∗ (toxic serum extracts of hemolytic streptococci), we discovered that under certain conditions large cytoplasmic bodies appear within the liver cells. On further study, we found that other proteins also caused the development of similar bodies. This preliminary paper deals with the methods used for the production of this lesion and its description and is based on a study of 850 rats.
In Table I are presented: first, the substances that cause the lesion when injected intravenously; second, the percentage of body weight of the substance injected; third, the time elapsing between injection and autopsy. In Table II are presented the substances studied that, under the conditions of these experiments, have not produced inclusions.
The important factors in the production of the lesion are as follows:
Age of Animal. In order to obtain lesions regularly, rats should be at least 7 weeks old. When younger rats are used, the results are often negative.
Amount of Substances Injected. In general, the number and size of the inclusions obtained appear to be directly proportionate to the percentage of body weight of inoculum. To produce numerous and large inclusions, 1 to 3% of the body weight of the substance should be injected.
Earliest Time After Injection of Appearance of the Inclusions. The time of the appearance of the inclusion after injection varies with the material injected. Thus, when streptococcus toxin was injected, the inclusions first appeared at 2 hours after injection but were absent in 30 minutes. (No rats were killed sooner after injection than this.)† With sheep serum (2% of body weight) numerous “early” inclusions were found in 9 of 10 rats within 10 minutes after injection and even in one rat killed immediately.
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