Some host-tumor relationships with respect to nitrogen.

A number of studies have been reported con cerning the effects of dietary protein on tumor in cidence and growth. These have been recently re viewed by Tannenbaum and Silverstone (11). More information, however, is needed with regard to the effects of the tumor on the nitrogen integri ty of the host animal under the various dietary regimes. Such a study on the nitrogen content of the various tissues of tumor-bearing animals has been introduced by the work of Sherman et cd. (10) who used Walker carcinoma 256. Their data dem onstrate the depleting effects of this tumor. The researches reported here correlate the growth of tumor, carcass, and several tissues of rats fed vari ous levels of dietary protein in an attempt to de velop a more complete picture of the physiological state of the tumor-bearing animal. MATERIALS AND METHODS Male rats of the Wistar strain were kept in individual cages with water available at all times. They were fed the semi-purified diet described by Wase and Allison (18), in which the protein component is casein. Three levels of casein were employed: 0, 9, and 18 per cent. On the lower protein diets the casein was replaced by glucose at an equal weight and caloric value. The tumor used in these experiments was Sarcoma R-l, a very malignant neoplasm developed in these laboratories (6). The original tumor arose spontaneously in the mammary region of an old female rat. During the first few serial trans plants, carcinomatous elements predominated, but it later developed into a fibrosarcoma. It is well vascularized, gives 100 per cent "takes," does not metastasize, and usually kills the * The data presented here are taken from a thesis presented to the Graduate Faculty of Rutgers University in partial fulfil ment of the requirements for the degree of Doctor of Philosophy. 89 host within 3 or 4 weeks. The tumor was transplanted sub-cutaneously in a lateral position by a trocar technic. The tumor-bearing rats were fed ad libitum daily, and control rats of the same body weight were fed the amount eaten by their pairs on the previous day. Each day a control diet was left out to correct the uneaten food for weight loss due to evaporation. The tumor-bearing rats ate approximately the same amount of all three diets. Every other day the rats were weighed, and the tumors were measured with a caliper. Tumor weight …