Leukocyte migration inhibition and leukocyte adherence inhibition (LMI- and LAI-assay) in cancer patients by using preparations from human fetuses]

The sensitization of lymphocytes from patients with different tumors was tested against a 3 M KCl-extract of fetal tissue (3.--6. month) by the leukocyte adherence inhibition assay (LAI) and by the leukocyte migration inhibition assay (LMI). Sensitization was compared with the reactivity of controls without any detectable tumor. In the LAI assay the leukocytes of 13/15 patients and 2/12 controls showed an inhibition of the adherence. In the LMI-assay 11/17 tumor-bearing patients and 6/18 controls reacted positive in the presence of the antigen preparation. The two methods demonstrated that patients bearing tumors of different histology are sensitized to fetal antigens.     

Activation of mechanical responses in leukocytes

Different kinds of leukocytes undergo cytoskeleton-dependent mechanical responses associated with their specific physiological functions. We have investigated cellular stiffening of several types of leukocytes using a method which measures the force resisting cellular indentation. We have found that lymphocytes stiffen in response to crosslinking cell surface antigens in a process associated with the much studied capping and patching processes. Further studies of myosin-deficient mutants of the ameba Dictyostelium discoideum suggest that this stiffening process results from a myosin dependent contractile process. Rat basophilic leukemia cells and pancreatic islet cells stiffen when triggered to secrete. The function of these cytoskeleton dependent processes is now unknown, but, at least in the islet cells, may be related to a regulation of the rate of secretion. Primary neutrophils stiffen in response to the chemotactic agent, fMet-Leu-Phe. This stiffening may be responsible for retention of these cells in the pulmonary microcirculation during response to inflammation. These observations pose the challenge of determining the structural basis, mechanism, and physiological function of each of these cellular responses.     

Characterization of the genome of the free-living nematode Panagrellus silusiae: absence of short period interspersion.

The complexity of the DNA of the free-living nematode Panagrellus silusiae has been examined. Reassociation kinetics of pressure-sheared fragments (approximately 290 nucleotides) in 0.18 M Na+ at 60 degrees C showed the presence of foldback, repetitive, and unique DNA sequence elements. The three classes comprise 9.3%, 26.1%, and 61.3% of the total DNA, respectively. The mean length of the foldback duplex DNA after digestion with S1 nuclease is about 185 nucleotides. There are about 1.8 x10(4) inverted repeats per genome. Sequence arrangement was deduced from (1) renaturation kinetic profiles of long and short fragments on hydroxylapatite; (2) the pattern of renaturation of tracer DNA, labeled in vitro with 125I, of various sizes after incubation with excess short fragments; and (3) thermal denaturation behavior of DNA that had been reassociated to various C0t values. It was found that DNA fragments of the repetitive fraction that are, at least, 2000 nucleotides in length are virtually free of unique sequences. Moreover, it is estimated that the repeated segments in this species could extend for 10,000 nucleotide pairs. Thus, Panagrellus DNA lacks the pattern of extensive short period interspersion that is typified by the DNA of Xenopus.     

Sensitivity of Gram-negative microflora to lysozyme]

Sensitivity to lysozyme of the representatives of various species of gramnegative microflora (476 strains) was studied with a new modified procedure, which is more exact and economic as compared to the method of serial dilutions in agar. High resistance of Eltor vibrio cholerae and Pseudomonas to lysozyme was found. Cultures of various sensitivity levels to lysozyme were detected among Aeromonas, enteropathogenic E. coli and NAG-vibrios.