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The use of molecular fragmentation for fluorometric detection and quantification of nonfluorescent organic and organometallic compounds is described. The measurements are based on the emissive characteristics of many small molecular fragments (OH, CN, CH, etc.). Fragmentation is induced by 100-eV electrons or 193-nm photons. Limits of detection, linearity, reproducibility, and range of applicability of the measurements are discussed. The merits of laser photolysis and electron impact as techniques for generating fluorescent fragments from nonfluorescent analyte molecules are compared.

The attachment of E. histolytica trophozoites from monoxenic TPS-medium to glass surfaces was studied at different temperatures and pH values and in the presence of cytochalasin B, colchicine, and vinblastine. At pH 7.0 and at 36 degrees C optimal adhesion rates of the amebae were observed in the range from 80% to 95%. Marked inhibition of adhesion was noted at higher concentrations of cytochalasin B. The adhesion rate was reduced to 50% by 50 micrograms/ml CB. Higher dosages successively prevented nearly all adhesion. Colchicine was without any effect. Vinblastine had a certain low effect but only at very high dosage. The observations are consistent with the assumption that the adhesion process is at least partially mediated by cytochalasin-sensitive contractile microfilaments, whereas microtubuli are obviously not involved in the cell-substrate adhesion.