The mode of action of four anthelmintics

Résumé LesAscaris qui se sont «déparalysés» après une incubation prolongée dans 100 ppm de levamisole, ne se contractent pas après injection des anthélminitiques béphenium, méthyridine et pyrantel. Etant donné que la mécamyline et la pempidine bloquent les contractions desAscaris provoquées par le levamisole, il paraît probable que chez les Nématodes ces 4 anthélmintiques sont des stimulateurs des ganglions.     

The mutagenic mode of action of benzimidazole

Summary By using a bacterial mutant strain with a known restricted reversion pattern, it has been shown that benzimidazole induces an unidirectional base change also in vivo. The in vitro demonstrated strict GA transition has thus been confirmed.Acknowledgments. I thank Th. Thurnher for his technical assistance. My thanks go furthermore to Dr Charles Yanofsky (Stanford University, California, USA), who generously supplied hisEscherichia coli strains.     

The activating action of acetylcholine and pilocarpine on the oxidation of luminol

Zusammenfassung Folgende Analogien zwischen der Aktivierung der Chemilumineszenz des Luminols durch Parasympathomimetika und ihrer pharmakologischen Wirkung wurden festgestellt: 1. Synergie zwischen kleinen Dosen von Pilocarpin und Ach; 2. nichtkompetitive Autoinhibition grosser Dosen von Pilocarpin; 3. Inhibition der Wirkung beider Medikamente durch Atropin-sulfat.     

The mode of antifungal action of plant, insect and human defensins

Defensins are small (~5 kDa), basic, cysteine-rich antimicrobial peptides that fulfill an important role in the innate immunity of their host by combating pathogenic invading micro-organisms. Defensins can inhibit the growth or virulence of microorganisms directly or can do so indirectly by enhancing the host's immune system. Because of their wide distribution in nature, defensins are believed to be ancient molecules with a common ancestor that arose more than a billion years ago. This review summarizes current knowledge concerning the mode of antifungal action of plant, insect and human defensins.     

The principal toxin ofDelphinium brownii Rydb., and its mode of action

Summary Examination ofD. brownii, a stock-poison of Western Canada, revealed that the principal toxin was methyllycaconitine: a potent neuromuscular blocking agent which appears to act competitively at nicotinic receptors.We thank the University of Calgary, The National Research Council of Canada, and the Alberta Agriculture Department, for financial assistance.     

The Sushi peptides: structural characterization and mode of action against Gram-negative bacteria

The compositional difference in microbial and human cell membranes allows antimicrobial peptides to preferentially bind microbes. Peptides which specifically target lipopolysaccharide (LPS) and palmitoyl-oleoyl-phosphatidylglycerol (POPG) are efficient antibiotics. From the core LPS-binding region of Factor C, two 34-mer Sushi peptides, S1 and S3, were derived. S1 functions as a monomer, while S3 is active as a dimer. Both S1 and S3 display detergent-like properties in disrupting LPS aggregates, with specificity for POPG resulting from electrostatic and hydrophobic forces between the peptides and the bacterial lipids. During interaction with POPG, the S1 transitioned from a random coil to an α-helix, while S3 resumed a mixture of α-helix and β-sheet structures. The unsaturated nature of POPG confers fluidity and enhances insertion of the peptides into the lipid bilayer, causing maximal disruption of the bacterial membrane. These parameters should be considered in designing and developing new generations of peptide antibiotics with LPS-neutralizing capability. Received 2 October 2007; received after revision 2 November 2007; accepted 4 December 2007 J. L. Ding, B. Ho: Co-senior authors.     

The principal toxin of Delphinium brownii Rydb., and its mode of action.

Examination of D. brownii, a stock-poison of Western Canada, revealed that the principal toxin was methyllycaconitine: a potent neuromuscular blocking agent which appears to act competitively at nicotinic receptors.     

The action of a phenothiazine derivative on enzymes of the pentose phosphate pathway

Résumé La thiopérazine, qui est un derivé de la famille de la phénothiazine, a le pouvour d'inhibition sur l'activité du glucose-6-phosphate déhydrogénase et du 6-phosphogluconate déhydrogénase dans les globules rouges. Ce pouvoir est modifié si on ajoute du TPN dans le système enzymatique. Le degré de cette modification correspond à la dose de TPN employée.

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Supported by the Nebraska Fund for Psychiatric Research.     

Methods of obtaining and mode of action of stage ontogenins

Zusammenfassung Der Verfasser nimmt an, dass durch Konglutination von Spermien mit Embryonen vonTriton cristatus verschiedener Entwicklungsstadien morphogenetische Wirkstoffe entstehen, die je nach Stadium des verwendeten Embryos ganz verschiedene, aber spezifische Wirkungen haben. Es werden die wichtigsten morphogenetischen Prozesse wie Furchung, Morulabildung, Gastrulation und Neurulation selektiv beeinflusst. Diese Wirkstoffe, welche auch in der Normalentwicklung nacheinander entstehen und jedesmal die betreffende Entwicklungsphase einleiten sollen, werden als «Ontogenine» bezeichnet.     

On the mode of action of synthetic antituberculotica

Zusammenfassung Beim Studium des Wirkungsmechanismus der synthetischen Tuberkulostatika INH und PAS wurde festgestellt, dass die inhibierenden Konzentrationen dieser Substanzen eine Steigerung des Verbrauches (evtl. Anhäufung) des Radiophosphors³²P in Zellen der Mykobakterien verursachen. Diese Steigerung des³²P-Verbrauches steht proportionell zur Inhibitionsstufe.     

The mode of action of bacteriocin N5 purified from Clostridium perfringens]

The purified bacteriocin N5 produced by Clostridium perfringens BP6K inhibited simultaneously the syntheses of DNA, RNA and protein in sensitive cells, without DNA degradation. Bacteriocin N5 inhibited the accumulation of leucin and caused the exit of the previously accumulated amino acid. The effects of bacteriocin N5 are very similar to those observed for colicins E1, K, A and I.     

The action of anticholinergic drugs on the oxidation of indole activated by acetylcholine chloride

Zusammenfassung Mittels Fluoreszenzmessung wurde die durch Acetylcholin aktivierte Indoloxydation verfolgt. Es wurde festgestellt, dass alle im Versuch verwendeten anticholinergischen Substanzen diese Reaktion konzentrationsabhängig abschwächen. Ist kein Aktivator vorhanden, verläuft die Indoloxydation äusserst langsam. Es wird angenommen, dass die anticholinergischen Substanzen die aktivierende Wirkung des Acetylcholins aufheben.