D. R. Meranze

The effect of portacaval shunt on 7,12-dimethylbenz( a ) anthracene-produced mammary carcinoma in the rat

Abstract Portacaval shunt significantly reduces the incidence of DMBA-produced mammary carcinoma in the rat. Tumorogenesis is inhibited whether the shunt is done before or as long as 2 weeks after DMBA administration, indicating that tumor inhibition is related to an effect of the shunt on the metabolism of the host rather than to a direct effect on absorption and metabolism of the carcinogen. The reason for tumor inhibition by the shunt is unknown. Major circulatory, metabolic, and hormonal changes evidently occur after portasystemic bypass; further studies are required to explain the relationship of these changes, individually or collectively, to the significantly decreased incidence of tumor production after portacaval shunting.

The effect of distal small bowel bypass and resection on 7,12-dimethylbenz[a]anthracene-produced mammary carcinoma in the rat☆

Abstract Distal ileal bypass or resection performed prior to the intragastric instillation of DMBA in sesame oil to 50–52-day-old female Holtzman rats significantly reduces tumor production. This effect is not present when animals are bypassed after the administration of carcinogen. Tissue levels of DMBA are low in the groups with lowered incidence of tumor and reflect decreased absorption of this agent. Significantly fewer tumors developed with ileal bypass than with ileal resection. The addition of cholic acid reverses this effect. Both serum cholesterol and weight gain are not affected by these procedures.