Two experiments were performed to study the relationship between leukotriene B4 (LTB4) synthesis and placental separation and uterine involution in the cow. In experiment I, the concentration and synthesis of LTB4 by caruncular tissue was lower in cows with retained fetal membranes (RFM cows, n = 11) than in cows that expelled the fetal membranes normally (NFM cows, n = 19). The presence of bacterial cell wall, especially of alpha-hemolytic streptococci and coagulase positive staphylococci enhanced LTB4 synthesis by allantochorion only in NFM cows. In the RFM group, Escherichia coli lipopolysaccharide decreased allantochorionic LTB4 synthesis. With caruncle, only epidermal growth factor increased LTB4 production in NFM cows. In experiment II, the caruncular and endometrial secretion of LTB4 was lower in cows with subuterine involution (SUI cows, n = 5) or cows with SUI and RFM (SUI+RFM cows, n = 4) than in cows with normal uterine involution (NUI cows, n = 8). This decrease was especially noticeable in the previously gravid horn. In the three uterine involution groups, there were no differences in LTB4 synthesis by caruncular tissue taken from the previously gravid horn. However, progesterone and a bacterial suspension of E. coli reduced the synthesis of LTB4. Estradiol had no effect on LTB4 synthesis at the end of the postpartum period. These results suggest that LTB4 may play an important role in both placental separation and uterine involution in cattle and LTB4 synthesis may be modulated by endocrine and bacterial factors.

Two hundred seventy-eight strains of Salmonella typhimurium isolated from 1973 to 1981 from animal sources in New York State were studied for possible virulence determinants and for a serotype-specific plasmid possibly linked with virulence. Of the strains, 98% possessed type-1 fimbriae. All strains possessed flagella and were motile. One hundred twenty-three strains (44%) treated with mitomycin C tested positive for the cholera-Escherichia coli heat labile family of toxins by a kinetics-based ELISA; when treated with mitomycin C and extracted with polymyxin B, 249 (90%) were positive in the kinetics-based ELISA. All strains were negative in the Biken Test. A smooth cell wall was found in 99% of the strains. Sixty-one percent (169) of the strains had a 62-Md plasmid. Seventy-six (27$%) of the strains had detectable plasmids ranging in size from 1 to 124 Md.