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Biomedical subjects

I Lacko

Publications and source records attributed to I Lacko.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1983

Lecithin: cholesterol acyltransferase in Down's syndrome.

Based on earlier reports indicating that Down's syndrome may represent an atheroma-free human model, two groups of institutionalized subjects were compared with respect to various parameters of their plasma lipid transport system. One group of subjects was comprised of Down's syndrome subjects and the second, a group of mentally retarded individuals. Parameters measured included plasma cholesterol, triglyceride, HDL-cholesterol, apolipoprotein levels (A-I, B, C-III, and E), lecithin:cholesterol acyltransferase (LCAT) activity, body mass and blood pressure. Statistical analyses indicated no significant differences between the two groups except for the lower fractional rate of cholesterol esterification (% cholesterol esterified per hour, p = 0.0049) in the Down's syndrome subjects. Adjustment for the effects of body mass and age revealed no other significant differences between the two groups except for a lower molar rate of esterification (nmol cholesterol esterified X h-1 X ml-1, p less than 0.0063) in the Down's syndrome subjects. Additional differences between the two groups were revealed by partial correlational analyses of LCAT activity with the measured parameters or ratios of these parameters which suggests that the composition and/or metabolism of lipoproteins may differ between these two groups. Whether the lower LCAT activity and the other differences reflected by the correlational analyses contribute to the decreased incidence of atherosclerotic lesions in Down's syndrome remains to be elucidated.

Adolescent↗
PubMed1983

Preparation and antimicrobial activity of some new bisquaternary ammonium salts.

A series of new bisquaternary ammonium dibromides of the type N,N'-bis(decyldimethyl)-alpha, omega-alkanediammonium dibromides and N,N'-bis(4-aryloxybutyldimethyl)-1,6-hexane diammonium dibromides has been prepared and screened for antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans. In the first group of compounds the connecting alkyl chain had 2 to 6, 8, 10 and 12 carbon atoms, in the second one in the 4-aryloxybutyl linkage the aryl was phenyl, p-methylphenyl, p-tert-butylphenyl-p-chlorophenyl-1-naphthyl and 2-naphthyl. The effect on the antimicrobial activity of the length of the hydrocarbon chain linking the two nitrogen atoms and the effect of replacing the long alkyl chain with substituted or unsubstituted 4-aryloxybutyl groups was studied.

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↗
PubMed1980

Interaction of chlorpromazine with the transport system of glucose in human erythrocytes.

The characteristics of inhibition of the glucose uptake in human erythrocytes by chlorpromazine (CPZ) was investigated. It was found that CPZ is a strong inhibitor. The inhibition kinetics indicates that also two molecules of CPZ can bind to the transport system and so from two different CPZ-complexes. The dissociation constants of both the CPZ-complexes and the pH- and temperature-dependence of the inhibition were estimated.

Biological Transport↗