Influence of subinhibitory concentrations of amikacin and ciprofloxacin on morphology and adherence ability of uropathogenic strains.

The influence of subinhibitory concentrations (1/2, 1/4, 1/8, 1/16 and 1/32 MIC) of amikacin and ciprofloxacin on the morphology and adherence of uropathogenic strains was studied. Intensity of morphological changes was proportional to the concentrations of these antibiotics. Morphological changes were the most prominent after bacterial exposure to sub-MICs of ciprofloxacin. These concentrations, especially 1/2 MIC of ciprofloxacin, induced the formation of filaments of E. coli, K. pneumoniae, K. oxytoca, E. cloacae and A. calcoaceticus biotype anitratus. No morphological changes were observed in P. aeruginosa, S. epidermidis and S. aureus cells after exposure to subinhibitory concentrations of both antibiotics. Sub-MICs of amikacin affected the changes in cell shape only slightly. The exposure of bacterial strains to 1/2 MIC of ciprofloxacin induced increased vacuolation of the cells. We observed shrinkage of the protoplasm and the pleated cell walls in comparison with control cells. The greatest loss of adherence ability occurred at 1/2 MIC of ciprofloxacin after a 1-d incubation.

Virulence factors and in vitro adherence of Enterococcus strains to urinary catheters.

The ability to adhere in vitro to urinary catheters and the presence of enterococcal virulence factors was determined in 30 Enterococcus urinary isolates (12 E. faecalis, 12 E. faecium, 3 E. casseliflavus, 3 E. gallinarum). Silicone, siliconized latex and polyvinyl chloride (PVC) were examined by sonication quantitative culture technique and scanning electron microscope. As compared to E. faecalis and E. faecium, E. casseliflavus and E. gallinarum displayed lower adhesion to all synthetic materials. All the tests performed showed higher adherence of all tested strains to siliconized latex and silicone than to PVC. Biofilmforming ability was observed in 5 E. faecalis but in none of the remaining strains. The gene coding enterococcal surface protein (Esp) was detected in 7 E. faecalis and 6 E. faecium strains. Gelatinase was found in 1 E. faecalis, 2 E. faecium and hemolysins were found in 6 E. faecalis and 1 E. faecium strains. All E. casseliflavus and E. gallinarum strainswere negative for these traits. Hydrophobic type of cell surface (measured by its affinity for n-hexadecane) was shown in a few isolates. Bacterial adherence was not significantly associated with the above pathogenic factors.

Ultrastructural studies on accessory nuclei in developing oocytes of the crustacean, Siphonophanes grubei.

Numerous accessory nuclei (AN) occur within peripheral cytoplasm of Siphonophanes grubei oocytes. They exhibit typical nuclear structure, with double membrane envelope pierced by pore complexes. Although no explicit evidence was shown, indirect arguments exist indicating that AN originate from the oocyte nucleus. Presence of clumps of DNP material within AN suggests that AN might play some role in amplified DNA metabolism. Participation of AN in cellular membrane elaboration is also postulated.

Luteinization in the atresia of maturing ovarian follicles in mouse.

Maturing ovarian follicles undergoing atresia were ultrastructurally analyzed. Using the method of Okrös (1968) the process of luteinization was traced, taking place in the basal layer of cells of granulous membrane and in the cells of inner layer of theca interna during the atresia. In the atresia process, numerous electron dense granules arranged in packets and surrounded by tubular mitochondria are observed in the basal cell layer of granulous membrane. A considerable accumulation of the grains of reaction product and the presence of tubular mitochondria are also found in the cells of theca interna. Such a behaviour of those cells can be associated with an enhanced production of steroid hormones (mainly estrogens) in atretic follicles.

Solute concentration effect on osmotic reflection coefficient.

A theory for the effect of concentration on osmotic reflection coefficient, correct to first order, was developed at the molecular level by considering the effect of solute-solute interactions on solute concentration and the fluid stress tensor within a solvent-filled pore. The solvent was modeled as a continuous fluid and potential energies between solute molecules and the pore wall were assumed to be pairwise additive. Although the theory is more general, calculations are presented only for excluded volume effects (hard-sphere for solute, hard-wall for pore). The relationship between the first-order concentration effect and the infinite dilution value of reflection coefficient appears to be geometry independent. The theory is discussed in light of experimental studies of osmotic flow that have recently appeared in the literature.

Endotoxin-free biologically active component of Escherichia coli.

The proteinaceous component of gram-negative bacteria, which has been termed "protodyne," enhances nonspecific host resistance while eliciting a slight pyrogenic response equivalent to 0.2% that of a typical endotoxin. Since this material still contains small amounts of carbohydrate and lipid, it was imperative to establish that its biological activities are not the result of endotoxin contamination. Evidence that the protective activity of protodyne does not result from endotoxin contamination has now been obtained by an evaluation of the Pronase digestion products of this substance. These digestion products were found to be nonpyrogenic and to contain no measurable amount of 2-keto-3-deoxyoctonate, an essential component of bacterial lipopolysaccharides.