Metabolite profile in milk of lactating rats after treatment with a carcinogen, N-2-fluorenylacetamide.

Metabolites were determined in milk and urine of lactating rats 4 to 5 hr after each of 3 to 6 ip injections of N-2-fluorenylacetamide (2-FAA) at 0.2 mmol/kg of body weight. Milk contained 2-FAA as the major free compound, variable amounts of N-2-fluorenamine (2-FA) and phenols (7- greater than 5- greater than 3-hydroxy-2-FAA) chiefly as glucuronides, and very small amounts of the glucuronide of N-hydroxy-2-FAA. Urine contained large amounts of the phenols and N-hydroxy-2-FAA as free and conjugated compounds, but in contrast to milk, only small amounts of 2-FAA and no 2-FA. Pretreatment of rats with beta-napthoflavone, an inducer of microsomal C- and N-hydroxylations of 2-FAA, increased the amounts of 3- and 5-hydroxy-2-FAA in milk and of 3-hydroxy-2-FAA in urine. However, the total amounts of the compounds excreted in 1 ml of milk or urine, i.e. 0.05 to 0.13% or 0.6% of the dose of 2-FAA, respectively, were similar in the uninduced and induced groups. Protein hydrolysates of milk of 2-FAA-treated rats and of milk interacted with 2-nitrosofluorene (2-NOF) in vitro both contained 2-FA and 9-oxo-2-FA. This suggested formation of 2-NOF in vivo possibly by peroxidative metabolism of N-OH-2-FAA. Since 2-NOF has been reported to form adducts with unsaturated lipids, the effect of treatment of lactating rats with 2-FAA on the fatty acid composition of milk lipids was examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Immune responses in vitro. XIII. MLR detectability of Mlsa-, Mlsb-, Mlsc-, and Mlsd-encoded products.

The Mls locus was originally defined to have four alleles; all controlled products that were detectable in MLR except b, which was described as being null. More recent evidence led other investigators to postulate that the Mls locus is nonpolymorphic, being composed of only the b null allele and a singly expressed allele previously ascribed to be the a and d alleles. Our results indicate that Mlsa and Mlsd control products that are antigenically distinct and, therefore, the products cannot be controlled by the same allele. In addition, the product of Mlsb was easily detectable by Mlsa and Mlsd responding cells and cannot be considered null. Alternative explanations are considered for these conflicting results.