Absence de correlation entre serotype et lysotype chezPseudomonas aeruginosa

Zusammenfassung Kaninchen wurden mit den thermostabilen Antigenen einesPseudomonas aeruginosa-Stammes immunisiert. Der Stamm mit den O-Faktoren 4a und 10a nachLanyi gehört einem oft gefundenen Lysotyp an. Das gewonnene Serum agglutiniert einen Teil derPseudomonas aeruginosa-Stämme aus dem Kantonsspital Lausanne bei Verdünnungen von mindestens 1/160 oder mehr, den anderen Teil der Stämme jedoch nicht. Die Lysotypen-Verteilung in beiden serologischen Gruppen zeigt, dass keine Beziehungen zwischen Lysotypie und Serotypie festgestellt werden können, zumindest solange man ein bifaktorielles Serum verwendet.

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Le matériel présenté dans ce travail fait partie de la thèse de E. Sakellarides (Contribution à l'étude dePseudomonas aeruginosa) présentée pour le doctorat en médecine à la Faculté de Médecine de l'Université de Lausanne (1971).     

Lack of correlation between structural features and function of synthetic agents tested for leukocyte chemotaxis

Summary A number of proteins, poly-L-amino acids, oligopeptides and lipids were tested for neutrophil, cosinophil and macrophage chemotactic activity. One myoglobin preparation was active. Based on the negative findings for all other substances, primary structure, secondary structure, degree of hydrophobicity, size and charge of a molecule, could be ruled out as structural features recognized by chemotactically responding phagocytes.I thank Dr J. H. Wissler for suggesting the reported experiments and Dr M. Landy and Prof. E. Sorkin for advice and criticism during preparation of this article. The excellent assistance by Mrs J. Kerschbaumer-Bech and Miss Margrit Bühlmann is gratefully acknowledged. This work was supported by Swiss National Foundation for Scientific Research, grant 3.8750.72, and by Sandoz-Stiftung, Basel.     

Lack of correlation between RNA synthesis and hormonal induction of liver enzymes in carbon tetrachloride treated mice

Résumé Chez des souris traitées par le tétrachlorure de carbone l'induction de quelques enzymes sélectives par la cortisone s'est produite à un moment où la synthèse de l'ARN total était inférieure au niveau observé chez les témoins.     

Immunochemical studies on acetylornithine 5-aminotransferase from Pseudomonas aeruginosa

Summary Mouse antibodies with specificity towards acetylornithine 5-aminotransferase (ACOAT) from Pseudomonas aeruginosa were used to study the structural similarities of serveral isofunctional enzymes from different sources. With the antibody directed against ACOAT, the amounts of enzyme present in cells grown under different conditions were determined. These experiments established that the enzyme is induced by arginine and is subject to repression by carbon sources.Acknowledgment. We wish to thank Prof. J. Lindenmann for helpful discussions.     

Immunochemical studies on acetylornithine 5-aminotransferase from Pseudomonas aeruginosa.

Mouse antibodies with specificity towards acetylornithine 5-aminotransferase (ACOAT) from Pseudomonas aeruginosa were used to study the structural similarities of several isofunctional enzymes from different sources. With the antibody directed against ACOAT, the amounts of enzyme present in cells grown under different conditions were determined. These experiments established that the enzyme is induced by arginine and is subject to repression by carbon sources.     

Immunological studies on the key enzyme of arginine biosynthesis in Pseudomonas aeruginosa

Summary A method to manufacture specific antisera with a minute amount of pure enzyme is presented. The influence of antibodies on activity and inhibition of an allosterically regulated enzyme was studied.Acknowledgments. I wish to thank Prof. Th. Leisinger for helpful discussions. The skilful technical assistance of Miss Ursula Bodmer is acknowledged.     

Immunological studies on the key enzyme of arginine biosynthesis in Pseudomonas aeruginosa.

A method to manufacture specific antisera with a minute amount of prue enzyme is presented. The influence of antibodies on activity and inhibition of an allosterically regulated enzyme was studied.     

Nitrite reduction by NADH, catalyzed by the nitrite reductase of Pseudomonas aeruginosa

Reduction of nitrite by NADH catalyzed by Pseudomonas aeruginosa nitrite reductase is inhibited by a high concentration of nitric oxide NO. Contrary to what is currently admitted, we find that the nitrite reduction proceeds to the nitrogen monoxide N2O stage. EPR spectra show that, during the catalytic cycle, the enzyme forms specific Fe2+-NO heminic complexes.     

Lack of linkage between the Lp and Ld serum systems

Zusammenfassung Mehrere genetisch determinierte Antigenspezifitäten am menschlichen Serum-Lipoprotein, darunter Lp- und Ld-Antigen, sind beschrieben; 9 Familien, in denen beide Antigene segregieren, sind untersucht worden. Es wird gezeigt, dass beide Antigene unabhängig voneinander segregieren, so, dass die Lp-und Ld-Loci nicht eng gekoppelt sein können und demonstriert, dass Loci, die Antigenspezifitäten am selben Serumprotein bestimmen, nicht unbedingt gekoppelt sein müssen.     

Lack of pyrogenic tolerance transmission between brain and periphery in the rabbit

Successive injections of lipopolysaccharide (LPS) either intravenously (i.v.) or intracerebroventricularly (i.c.v.) induced pyrogenic tolerance to LPS in rabbits. Tolerance was shown by a decrease of the magnitude of the fever response to repeated doses of LPS, irrespective of the route of pyrogen administration. A significantly greater and more dramatic decrease of the fever index, however, was observed in rabbits made tolerant to pyrogen given i.v. than when the pyrogen was given i.c.v. Transmission of the pyrogenic tolerance between brain and peripheral tissues, however, has not been ascertained.     

Lack of pyrogenic tolerance transmission between brain and periphery in the rabbit

Summary Successive injections of lipopolysaccharide (LPS) either intravenously (i.v.) or intracerebroventricularly (i.c.v.) induced pyrogenic tolerance to LPS in rabbits. Tolerance was shown by a decrease of the magnitude of the fever response to repeated doses of LPS, irrespective of the route of pyrogen administration. A significantly greater and more dramatic decrease of the fever index, however, was observed in rabbits made tolerant to pyrogen given i.v. than when the pyrogen was given i.c.v. Transmission of the pyrogenic toleraance between brain and peripheral tissues, however, has not been ascertained.     

The opportunistic pathogen Pseudomonas aeruginosa activates the DNA double-strand break signaling and repair pathway in infected cells

Highly hazardous DNA double-strand breaks can be induced in eukaryotic cells by a number of agents including pathogenic bacterial strains. We have investigated the genotoxic potential of Pseudomonas aeruginosa, an opportunistic pathogen causing devastating nosocomial infections in cystic fibrosis or immunocompromised patients. Our data revealed that infection of immune or epithelial cells by P. aeruginosa triggered DNA strand breaks and phosphorylation of histone H2AX (γH2AX), a marker of DNA double-strand breaks. Moreover, it induced formation of discrete nuclear repair foci similar to gamma-irradiation-induced foci, and containing γH2AX and 53BP1, an adaptor protein mediating the DNA-damage response pathway. Gene deletion, mutagenesis, and complementation in P. aeruginosa identified ExoS bacterial toxin as the major factor involved in γH2AX induction. Chemical inhibition of several kinases known to phosphorylate H2AX demonstrated that Ataxia Telangiectasia Mutated (ATM) was the principal kinase in P. aeruginosa-induced H2AX phosphorylation. Finally, infection led to ATM kinase activation by an auto-phosphorylation mechanism. Together, these data show for the first time that infection by P. aeruginosa activates the DNA double-strand break repair machinery of the host cells. This novel information sheds new light on the consequences of P. aeruginosa infection in mammalian cells. As pathogenic Escherichia coli or carcinogenic Helicobacter pylori can alter genome integrity through DNA double-strand breaks, leading to chromosomal instability and eventually cancer, our findings highlight possible new routes for further investigations of P. aeruginosa in cancer biology and they identify ATM as a potential target molecule for drug design.