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Biomedical subjects

F Devínsky

Publications and source records attributed to F Devínsky.

At least 55 records · Page 3Linked to original sources
PubMed1989

QSAR study on species differences in microsomal N-oxygenation of N,N-dimethylalkylamines.

The metabolic N-oxygenation of nine long chain N,N-dimethylalkylamines and tri-n-butylamine has been studied using hepatic microsomal homogenates from mice, dogs and guinea-pigs. The relative oxidizability of amines (ROA) was correlated with structure, lipophilicity and nucleophilicity parameters of substrates and corresponding amine oxides formed in this biological reaction. The highest conversion of amines to N-oxides was found with male guinea-pig, followed by dog (male, female) and the lowest amount of amine oxides has been produced with male mice microsomal homogenates. The analyses were carried out by GLC and the results quantified using QSAR methodology. ROA is parabolically dependent upon structure and physicochemical properties of the substrates and products which was proved by the high statistical significance of the regression equations. The biological N-oxygenation of these amines is controlled by lipophilicity, stereochemistry and electronic effects.

Animals↗
PubMed1989

Interaction of amine oxides and quaternary ammonium salts with membrane and membrane-associated processes in E. coli cells: mode of action.

The antimicrobials (1-methyldodecyl)dimethylamine oxide and (1-methyldodecyl)trimethylammonium bromide affect the cytoplasmic membrane of E. coli. The interaction results in release of intracellular material (K+, 260nm-absorbing material), an effect on dehydrogenase enzyme activity and inhibition of respiration. The final effect of both substances is the same; they differ only in their dynamics. The effect of the membrane was correlated with parameters characterizing these surfactants i.e. critical micelle concentration (c.m.c.) minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) over the concentration range of 10(-4) to 10(-1) mmol/dm3 of active substance. The three stage mode of action model can be summarized as follows: 1-polar (coulombic) interactions, 2-polar and hydrophobic interactions, 3-hydrophobic interactions (extraction and solubilization). The polar and hydrophobic interactions (1st and 2nd stage) are discussed also in relation to model membranes.

Cell Membrane↗
PubMed1989

A spin label study of perturbation effects of N-(1-methyldodecyl)-N, N, N-trimethylammonium bromide and N-(1-methyldodecyl)-N, N-dimethylamine oxide on model membranes prepared from Escherichia coli-isolated lipids.

Interaction of bactericidal surfactants N-(1-methyldodecyl)-N, N, N-trimethylammonium bromide (2-ATDBr) and N-(1-methyldodecyl)-N, N-dimethylamine oxide (2-ATDNO) with phospholipid membranes prepared from Escherichia coli -- isolated lipids was studied by ESR spectroscopy using m-doxyl stearic acid (m-DSA, m = 5, 12, 16) and N-cetyl-N, N-dimethyl-N-tempoylammonium bromide spin labels located in different membrane depths. 2-ATDBr was found to be a more potent membrane perturbant than 2-ATDNO both at equal membrane and sample concentrations; this is in compliance with the respective antimicrobial activities of these agents. Using the statistical model of hydrocarbon chains in lipid bilayers, the probabilities of the formation of gauche conformations and the effective energy differences between the trans and gauche conformations were calculated from m-DSA order parameters for two different bilayer regions. Based on these parameters, a molecular model of the location of surfactant molecules in bilayer has been formulated. It has been suggested that at low concentrations the surfactant molecules are located in structural defects between lipid clusters in the bilayer. After filling up these defects, the surfactant molecules penetrate into the clusters between lipid molecules, expand the bilayer laterally and increase the amount of gauche conformations in the hydrocarbon chains in the hydrophobic core of the bilayer.

Cyclic N-Oxides↗
PubMed1988

Inhibitory effect of 1-methyldodecyldimethylamine oxide and N,N-bis(dodecyldimethyl)-1,2-ethanediammonium dibromide on the spores of Bacillus cereus.

1-Methyldodecyldimethylamine oxide (MDDO) and N,N'-bis(dodecyldimethyl)-1,2-ethanediammonium dibromide (BDED) exhibit a significant affinity for the surface of Bacillus cereus spores and adsorb very rapidly to the cells; they have a pronounced inhibitory effect on spore outgrowth. In order to alter the affinity of the spore surface for these inhibitors, the spores were pretreated with sodium dodecyl sulfate (SDS), and with an electronegative (Tween 80) and electropositive (histone) compound. In SDS-pretreated spores the inhibitory effect of MDDO and BDED was abolished to a considerable extent. Whereas the development of intact spores was inhibited already after germination, in SDS-pretreated spores the postgermination development continued but was not completed. In Tween 80-pretreated spores the addition of BDED led only to a retardation of outgrowth and division; BDED added only during the division stage interrupted further development completely. Histone-pretreated spores stopped their development instantaneously after the addition of BDED at any phase of the postgermination development. The possible mechanisms of the interaction of the compounds used with spore surface or rather with the state of its structures are discussed.

Bacillus cereus↗
PubMed1988

The lateral order of dipalmitoylphosphatidylcholine model membranes in the presence of N-alkyl-N,N,N-trimethylammonium ions as studied by Raman spectroscopy.

Effects of N-alkyl-N,N,N-trimethylammonium ions with different alkyl substituents (hexyl, nonyl, dodecyl, and octadecyl) on the lateral packing of lipids in dipalmitoylphosphatidylcholine (DPPC) dispersions in H2O was investigated by Raman spectroscopy in a spectral region of 2800--3100 cm-1 at temperatures between 22--70 degrees C. The lateral order parameter Slat calculated by empirical equation reveals that the addition of the ions decreases the lateral ordering of lipid hydrocarbon chains in the gel phase, while in the liquid crystalline state the lateral ordering is increased. In addition, this observation is supported by decomposition of the spectra into component bands using a computer fitting program. This enabled to follow changes in individual band parameters (position, amplitude, and height) in dependence on temperature and/or additives. The results suggest that N-alkyl-N,N,N-trimethylammonium ions have a condensing effect on DPPC bilayer in the liquid crystalline state, the effect increasing with the increasing length of the alkyl substituent.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1982

Antimicrobial activity of some salts of dialkylthiophosphoric acids.

A total of 18 derivatives of O,O-dialkylthio- and O,O-dialkylthiophosphoric acids were tested for antimicrobial activity using strains of Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Candida albicans. The activity was found to depend on the length of the alkyl substituent and/or the cation size. All derivatives were ineffective with E. coli and C. albicans.

Anti-Bacterial Agents↗
PubMed1981

The effect of quaternary ammonium compounds and amine oxides on spores of Bacillus cereus.

The effect of 1-dodecylpiperidine 1-oxide and N,N'-bis(dodecyldimethyl)-1,2-ethane diammonium dibromide on the spores of Bacillus cereus. particularly their binding to intact spores and spores with reduced cystine bonds, was investigated. The Langmuir type of binding is involved in both cases. Both compounds decreased the thermoresistance of spores. DPNO decreased the fraction of non-germinating spores, the effect of the drug increasing with increasing concentration. This phenomenon was associated with a faster release of dipicolinic acid to the medium. Only microgermination proceeded in the presence of BDED and dipicolinic acid was released only in substantially lower amounts. Both compounds also influenced respiration.

Bacillus cereus↗
PubMed1977

Antimicrobial activity of amine oxides: mode of action and structure-activity correlation.

The effect of N-alkyl derivatives of saturated heterocyclic amine oxides on the growth and metabolism of microorganisms has been studied. 4-Dodecylmorpholine-N-oxide inhibited the differentiation and growth of Bacillus cereus, of different species of filamentous fungi, and of the yeast Saccharomyces cerevisiae. For vegetative cells, the effect of 4-dodecylmorpholine-N-oxide was lethal. Cells of S. cerevisiae, after interaction with 4-dodecylmorpholine-N-oxide, released intracellular K(+) and were unable to oxidize or ferment glucose. The functions of isolated yeast mitochondria were also impaired. 4-Dodecylmorpholine-N-oxide at growth-inhibiting concentrations induced rapid lysis of osmotically stabilized yeast protoplasts, with the rate of lysis a function of temperature and of amine oxide concentration. A study of the relationships between structure, antimicrobial activity, and cytolytic activity was made with a group of structurally different amine oxides involving a series of homologous 4-alkylmorpholine-N-oxides, 1-alkylpiperidine-N-oxides, 1-dodecylpyrrolidine-N-oxide, 1-dodecylperhydroasepine-N-oxide, and N,N-dimethyldodecylamine oxide. Disorganization of the membrane structure after interaction of cells with the tested amine oxides was primarily responsible for the antimicrobial activity of the amine oxides. This activity was found to be dependent on the chain length of the hydrophobic alkyl group and was only moderately influenced by other substituents of the polarized N-oxide group.

Amines↗