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The kynurenine aminotransferase activity of isolated rat kidney mitochondria is enhanced several-fold by membrane disruption or by the addition of 1 mM CaCl2. The addition of CaCl2 can thus be used conveniently to obtain full expression of the mitochondrial enzyme activity. CaCl2 apparently stimulates the activity by facilitating the penetration of the mitochondrial inner membrane by the substrate, alpha-ketoglutarate. Consistent with this view, two inhibitors of dicarboxylate translocation, benzylmalonate and quinolinate, inhibited the activity of the isolated mitochondria but not that of the disrupted mitochondria. Both inhibitions were prevented at higher Ca++ concentrations, suggesting that thes compounds inhibit by complexing Ca++ needed for the translocation of alpha-ketoglutarate. This action of quinolinate may explain its ability to interfere in vivo with the mitochondrial translocation of dicarboxylates as reported by Spydevold et al.

In 101 mice, Lewis lung tumor (25 mg apiece) was implanted subcutaneously in the right hind limb and the mice separated into various groups and protocols to test treatment with immunotherapeutic and chemotherapeutic agents. In those treated intralesionally with BCG, the growth of primary tumor was retarded (P smaller than or equal to .05). Tumor growth in animals treated with systemic BCG and serum from tumor-bearing mice was not different from controls. In 14 of 20 mice treated with chemotherapy (semustine and cyclophosphamide), there was no primary or metastatic growth (P smaller than or equal to .01). The observations show that this sort of systemic immunotherapy had no effect on mouse Lewis lung tumor, that intralesionally there was a retarding effect of BCG (although it did not influence metastases), and that this protocol of chemotherapy was strikingly effective.