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The effects of three different ganglioside preparations on cholera enterotoxin (CT) and heat-labile Escherichia coli enterotoxin (ECT)-induced steroidogenesis in Y1 and OS, adrenal tumor cells in tissue culture were examined. Only with GM1 ganglioside was any inhibition of the toxins' effects noted. Concentrations of the crude ECT preparation that gave similar morphogenic and steroidogenic effects as CT were inhibited by the same amount or less of GM1 as that required to inhibit the effects of CT. The results of competition experiments also demonstrated that previous incubation of GM1 with one toxin could inhibit the ganglioside's ability to inactivate the other toxin. These findings indicate that at least for Y1 and OS, adrenal tumor cells, GM1 may resemble or be the receptor for both CT and ECT.

The frequency of Legionnaires' disease among 586 cases of pneumonia that occurred in Iowa between fiscal years 1972 and 1977 was studied retrospectively on the basis of paired sera. The frequency of confirmed Legionnaires' disease was 4.1% and of presumptive Legionnaires' disease was 11.4%. Infections with the Legionnaires' disease (LD) bacterium were most frequent in the summer. Of the 22% of pneumonias for which a cause could be defined, Legionnaires' disease was third in frequency behind Mycoplasma pneumoniae and influenza A virus infections. Infections with the LD bacterium occurred in association with pneumonias in most age groups. The youngest patient with LD infection was a 5-year-old boy with pneumonia. The disease occurred 3.2 times more often in males than in females. In males, the frequency of confirmed and presumptive Legionnaires' disease increased steadily to plateau after the fourth decade at about 12% and 28%, respectively. In females the frequency of presumptive Legionnaires' disease was 7% to 16%, relatively evenly distributed over all age groups. Pneumonias associated with LD bacterium infection should be considered in the differential diagnosis of community-acquired pneumonias in most age groups.

The background prevalence of indirect immunofluorescence antibody to Legionella pneumophila in a rural community was determined by testing sera from 517 volunteers. The upper limit of normal antibody titer was found to be 1:64 with L. pneumophila serogroup 1 (Philadelphia 1) used as antigen. High titers (greater than or equal to 1:128) were found in 13.2% of the sera and occurred with similar frequencies in males and females. In individuals 40 years of age and older, however, high titers were 2.7 times as prevalent in males as females.

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