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Biomedical subjects

I Lacko

Publications and source records attributed to I Lacko.

At least 19 recordsLinked to original sources
PubMed1994

Quantitative relationships between structure and antimicrobial activity of new "soft" bisquaternary ammonium salts.

New surface-active bisquaternary ammonium salts derived from bis-(2-dimethylaminoethyl) ester of glutaric acid are highly effective against representatives of Gram-positive, Gram-negative bacteria and yeasts. Relationships between structure, lipophilicity and antimicrobial effectiveness were demonstrated by quantitative structure-activity methodology. The non-linear dependence of biological activity on the structure as well as lipophilicity (expressed as critical micelle concentration-CMC) was shown using Kubinyi's bilinear model. The most effective compounds were those with the alkyl chain of 11-12 carbon atoms and with the CMC values around 0.7-1.0 mmol/L. These derivatives possessed higher antimicrobial activity particularly to Gram-negative bacteria.

Anti-Bacterial Agents↗
PubMed1993

Amphiphilic detergents inhibit production of IgG and IgM by human peripheral blood mononuclear cells.

All types (cationic, anionic and non-ionic) amphiphilic detergents significantly inhibited the production of both IgG and IgM by human peripheral blood mononuclear cells after polyclonal activation in vitro. The most potent inhibitors were didodecyldimethylammonium bromide (DDAB) and (1-methyldodecyl)dimethylamine N-oxide (2-ATDNO). They were able to suppress effectively the immunoglobulin production in 10(-3)-10(-8) M concentrations. A medium inhibitory effect was observed with Slovapon, sodium dodecyl sulphate (SDS) and Triton X-100, while Slovanik showed an inhibition only in concentrations higher than 10(-2)%. These results suggest that amphiphilic detergents may be characterized as potential immunotoxic substances with very negative effects on the immunoglobulin production.

Detergents↗
PubMed1992

Potassium leakage from Escherichia coli cells treated by organic ammonium salts.

The effect of the homologous series of 1,1-dialkylpiperidinium bromides on the potassium leakage from Escherichia coli cells has been studied. The minimum concentration for each compound which is able to release maximum of cellular potassium has been determined and correlated with the inhibitory activities of the compounds. The relationship between the structure and the activity enables to consider the K+ leakage as the marker of inhibitory activity of the membrane active antimicrobials.

Cell Membrane Permeability↗
PubMed1992

Enhanced biodegradation of a hard bis-quaternary ammonium salt.

Bacterial strains with a high biodegradation potential were isolated from activated sludge. Their ability to decompose the hard bis-quaternary ammonium salt FB was determined by the method of chemical oxygen demand (COD) in a mineral medium, where the compound FB was the only source of carbon. The COD values were very low after 21 d and in the course of this period they reached zero level twice. The contribution of adsorption to decrease the COD value was small. The maximum COD decrease was accompanied by an increase of cell respiration. It is suggested that FB is effectively decomposed in spite of the fact that according to its structure it is a typical hard detergent.

Bacteria↗
PubMed1991

[Organic ammonium salts. XLI. Preparation, aggregation properties and antimicrobial activity of N-[2-(10-undecenoyloxy)ethyl]-N,N,N-alkyldimethylammonium bromides].

The paper describes the preparation of 7 novel organic ammonium salts of N-[2-(10-undecenoyloxy)ethyl]-N,N,N-alkyl-dimethylammonium bromides, in which the alkyl chain was gradually lengthened from ethyl to tetradecyl, constantly keeping the other groups (10-undecenoyloxyethyl and methyl) bound to the ammonium nitrogen. In the paper the antimicrobial effect of the prepared ammonium salts and the aggregative properties of their aqueous solutions were studied. The aggregative properties are expressed by the values of the critical concentration of the micelles formation, which were determined tensiometrically and conductometrically. The antimicrobial activity expressed by the minimal inhibition concentration in dependence on the prolongation of the alkyl chain was determined by the dilution test on the strains Staphylococcus aureus, Escherichia coli and Candida albicans. As follows from the table, all ammonium salts prepared were active in this respect, the most effective ones possessing 6, 8 and 10 carbon atoms in the alkyl chain. They were more effective than the standard Ajatin to all strains of the microorganisms tested. The antimicrobial effect decreased with the increasing length of the alkyl chain. Also the structure--activity relationship was quantified by the QSAR analysis methods using two procedures: the dependence log ck vs. m was linear and the dependence log (1/MIC) vs. m and log (1/MIC) vs. log ck were nonlinear. The calculated coefficients of regression equations and statistical evaluation of dependences are shown in Table 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Candida albicans↗
PubMed1989

Effect of N,N'-bis(alkyldimethyl)-alpha, omega-alkanediammonium dibromides on bacteria of the genus Clostridium.

Antibacterial effect of 17 ammonium compounds of the type of N,N'-bis(alkyldimethyl)-alpha, omega-alkanediammonium dibromides was tested on anaerobically sporulating bacteria of the genus Clostridium. A sizable antibacterial activity was displayed by five N,N'-bis(alkyldimethyl)-1,6-hexanediammonium dibromides and by four N,N'-bis(decyldimethyl)-alpha, omega-alkanediammonium dibromides. These compounds exhibited activity higher than, or comparable with, that of the reference standards Ajatin and Septonex. The maximum antibacterial activity was found in compounds whose alkyl chain contained 9-12 carbon atoms. Compounds with a lower number of carbon atoms in the chain (less than 8) exhibited a low activity.

Benzalkonium Compounds↗
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↗