A naturally occurring epizootic of dermatitis involved all the mice, provisionally designated as DS-Nh, housed under conventional conditions, regardless of age or sex. The disease primarily attacked the lateral aspect of the face, neck and shoulders. The histopathologic features of the dermatitis varied in severity, but all affected regions showed signs of chronic dermatitis, including infiltration of inflammatory cells, parakeratosis and amyloidosis, and contained Gram-positive cocci clusters. Bacteriologically, coagulase-positive Staphylococcus aureus (S. aureus) was recovered in pure culture from the skin lesions. The disease experimentally induced with the S. aureus isolates was indistinguishable from those observed in naturally occurring cases. The results suggested that S. aureus may be casually associated with the disease.
The anti-tumor activity of 7 sphingolipids, 2 ceramides and 5 glycosphingolipids against the syngeneic murine ascitic tumors MH134 and MM102 in C3H mice was examined. Five of these compounds showed anti-tumor activity against the tumors, ceramide type-IV (Cer-IV) having the highest activity without cytotoxic or cytostatic activity. These results indicate that the fatty acid in ceramide and sugar chains binding to it affect the anti-tumor activity in vivo. The anti-tumor activity of Cer-IV depended on the time of treatment. Mice treated with Cer-IV one day after tumor implantation showed the highest rate of survival. The cured mice were resistant to rechallenge with the same tumor (MH134-->MH134, MM102-->MM102) but not with a heterologous tumor (MH134-->X5563, MM102-->X5563), indicating that the effect of Cer-IV may be due to in vivo induction of specific immunity. Studies with various antibodies demonstrated that the anti-tumor effect of Cer-IV was inhibited by all the antibodies tested (L3T4, Lyt-2, and Thy-1,2 T cells, macrophages, and TNF alpha) in the induction phase (before Cer-IV administration) and by the antibodies of L3T4 and TNF alpha in the effector phase (after Cer-IV administration). Therefore, the anti-tumor effect of Cer-IV in this system depended on the host immune response rather than on its direct cytotoxic and/or cytostatic action.
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