Search PubMed⌕ Search

Biomedical subjects

F Lutz

Publications and source records attributed to F Lutz.

At least 199 records · Page 11Linked to original sources
PubMed1987

Cytotoxic protein from Pseudomonas aeruginosa: formation of hydrophilic pores in Ehrlich ascites tumor cells and effect on cell viability.

Increased plasma membrane permeability induced by a purified cytotoxic protein from Pseudomonas aeruginosa was studied using mouse Ehrlich ascites tumor cells in incubation medium containing an osmotic stabilizer. In the presence of serum albumin, 40 nM of the cytotoxin was required for cationic imbalance of 2.7 X 10(7) cells per ml at pH 7.4. The rate of passive flux of water-soluble markers with a molecular radius range between 0.3 and 4 nm was used to calculate the size of functional transmembrane pores. Within a short time of intoxication pores of 1 nm in radius were formed. Their stability is inferred from the constant rate of leakage of the most restricted marker during intoxication (60-90 min). The cytotoxin-induced plasma membrane damage led to loss of essential low molecular weight substances and was associated with a decrease of tumor propagation rate in mice. Regression analysis of these functional parameters indicate the reversibility of plasma membrane disorganization up to complete breakdown of the Na+/K+ gradient. The cell can even tolerate partial loss of larger cytosolic compounds under conditions of limited intoxication.

Animals↗
PubMed1987

Schistosoma mansoni: stage-dependent membrane vesiculation and parasite killing induced by a cytotoxin from Pseudomonas aeruginosa.

We have examined the interaction between Schistosoma mansoni and a cytotoxin from Pseudomonas aeruginosa known to affect a variety of cell types through the formation of membrane pores. The killing effect of the cytotoxin on S. mansoni in vitro was strongly dependent on the parasite developmental stage. Skin schistosomula were most sensitive, while 4-week-old or older parasites were less so. In contrast, lung schistosomula were relatively resistant and juvenile mesenteric forms younger than 28 days were almost completely refractory to the action of the toxin. A sharp increase in sensitivity to the toxin was observed between 27 and 28 days of parasite age with a parasite length of about 1.80 mm appearing as the threshold. Thus, the schistosome sensitivity to the cytotoxin changed during parasite development in a way similar to the known sensitivity of the worms to in vitro immune attack. Killing of the parasites by the cytotoxin was preceded by the formation of vesicles which, in the case of adult worms, detached easily from the parasites. Evidence obtained by electron microscopy and by immunofluorescent assays with living worms demonstrated that the outer parasite membrane participated in the formation of the vesicle membrane. Thus, the cytotoxin may be a useful tracer for changes in the properties of the schistosome surface membrane during parasite development.

Animals↗
PubMed1987

The effect of Pseudomonas aeruginosa cytotoxin and toxin A on human polymorphonuclear leukocytes.

After exposure to cytotoxin or toxin A of Pseudomonas aeruginosa, the ultrastructure of resting and phagocytosing human polymorphonuclear leukocytes (PMNL) and of cells of P. aeruginosa strain 1348A was studied by transmission (TEM) and scanning (SEM) electronmicroscopy, and by light microscopy (LM) after histochemical staining of cytoplasmic granules. Cytotoxin caused marked clumping and destruction of PMNL, pyknotic nuclear changes with bleb formation, and release of cytoplasmic granules; phagocytosis was markedly diminished. In contrast, after exposure to toxin A, PMNL phagocytosed actively, but their cytoplasmic pseudopodia were markedly irregular and their nuclei pyknotic. Colloidal-gold-labelled cytotoxin showed an affinity for the cytoplasmic membranes, nuclei and granules of PMNL. Cytotoxin had no apparent effect on cells of P. aeruginosa strain 1348A but there was polar separation of the cytoplasmic membrane in bacteria exposed to toxin A. Cytotoxin and toxin A appear to be important in the pathogenesis of infections caused by P. aeruginosa.

ADP Ribose Transferases↗
PubMed1987

Production of cytotoxin by clinical strains of Pseudomonas aeruginosa.

Presence of cytotoxin was studied in extracts of 57 strains of Pseudomonas aeruginosa (46 bacteremia, 4 environmental, and 7 Fisher immunotype), 10 Pseudomonas species, and 7 nonpseudomonas isolates. Cytotoxin was identified by Western immunoblot in extracts of all P. aeruginosa isolates. None of the Pseudomonas species or nonpseudomonas isolates were shown to produce this protein. No immunologic cross-reactivity was observed between cytotoxin antibody and P. aeruginosa alkaline protease, toxin A, or elastase. In partially purified extracts of two bacteremia strains and PA 158 (parent strain for cytotoxin production), detection of cytotoxin by Western immunoblot was correlated with biological activity, as measured by the cell swelling assay. Cytotoxin appears to be produced by all strains of P. aeruginosa and biological activity can be demonstrated in extracts of the strains tested. This biological activity is neutralized by specific antibody. Because of its known marked cytotoxic effect on most eukaryotic cells, P. aeruginosa cytotoxin might be an important factor in the pathogenesis of P. aeruginosa infections.

Cytotoxins↗
PubMed1987

Margin quality and microleakage of Class II composite resin restorations.

Margin quality and isotope microleakage analyses of Class II restorations placed in extracted human molars were compared using various composite resins and placement techniques. At occlusal margins, the traditional (experimental) composite resin restoration placed by the incremental technique showed less microleakage than did the traditional (commercial) [corrected] composite resin restoration placed by the bulk technique. In each group, the occlusal and proximal adaptations had significantly higher "excellent margin" than did the cervical adaptation. Thus, the marginal adaptation at the cervical aspect of conventional Class II composite resin restorations may present a problem with respect to microleakage.

Calcium Radioisotopes↗
PubMed1986

Interaction of Pseudomonas aeruginosa cytotoxin with plasma membranes from Ehrlich ascites tumor cells.

Biologically active 125I-cytotoxin from Pseudomonas aeruginosa binds to plasma membranes from Ehrlich ascites tumor cells in a saturable manner. The Scatchard plot indicated a single binding site with a capacity of 260 pmoles/mg of membrane protein and a KD of 2 X 10(-8) M. Specific binding was dependent on temperature, pH and ionic strength. Thus constant levels of bound 125I-cytotoxin were attained either within 30 min at 30 degrees C or within 3 h at 4 degrees C. Binding was 30-fold higher at 4 degrees C vs 30 degrees C and 2-6-fold higher at pH 5.3 vs pH 8.3. Binding was not effected by 50 mM sugar or sialic acid. 300 mM sucrose, however, instead of phosphate buffer, reduced binding by 50%. Pretreatment of plasma membranes with trypsin or papain led to a significant decrease in 125I-cytotoxin binding. A pretreatment with phospholipase C or D had no effect, whereas phospholipase A2 induced a decrease by 34%. The collected data suggest that the binding site for 125I-cytotoxin within the plasma membrane from Ehrlich ascites tumor cells is a membrane protein. Correlation of 125I-cytotoxin binding and membrane action of the unlabelled cytotoxin can be observed through (a) increased lowering of the cellular K+ and Na+ gradient by decrease of medium pH, (b) decreased toxicity after substitution of ions by sugar, and (c) increased breakdown of cellular cationic gradient after temperature shift from 4 degrees C to 37 degrees C.

Animals↗