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PubMed1994

Purification and characterization of two rat liver microsomal carboxylesterases (hydrolase A and B).

The enzymatic hydrolysis of para-nitrophenylacetate by rat liver microsomes is predominantly catalyzed by two esterases: one with high affinity (Km approximately 25 microM) and one with low affinity (Km approximately 400 microM) for the substrate. Two kinetically distinct esterases were similarly detected in liver microsomes from mouse, hamster, guinea pig, rabbit, cat, cynomolgus monkey, and human, but only the high-affinity enzyme was detectable in dog liver microsomes. The tissue distribution of these kinetically distinct esterases was examined in rats. High-affinity (Km 20-35 microM esterase activity toward para-nitrophenylacetate was detected in testis, lung, prostate, and pancreas. The activity in testicular microsomes was comparable to that in liver microsomes. Low-affinity (Km 200-700 microM) esterase activity was detected in kidney, small intestine, lung, spleen, heart, and brain. The activity in kidney microsomes was comparable to that in liver microsomes. The high-affinity esterase in testicular and liver microsomes was highly sensitive to the inhibitory effects of phenylmethylsulfonyl fluoride (PMSF), whereas the low-affinity esterase in kidney and liver microsomes was relatively resistant. These results suggested that rat liver microsomes contain two esterases with high activity toward para-nitrophenylacetate, a PMSF-sensitive esterase with high substrate affinity, and a PMSF-insensitive esterase with low substrate affinity. In support of the hypothesis, we have purified and characterized two esterases, designated hydrolases A and B, which appear be the only abundant enzymes in rat liver microsome that rapidly hydrolyze para-nitrophenylacetate. Hydrolase A hydrolyzed para-nitrophenylacetate with high affinity (Km approximately 25 microM), and was inhibited by extremely low concentrations of PMSF (IC50 approximately 100 nM). In contrast, hydrolase B hydrolyzed para-nitrophenylacetate with low affinity (Km approximately 400 microM) and was inhibited only by relatively high concentrations of PMSF (IC50 approximately 100 microM Paraoxon, the active metabolite of parathion, and cresylbenzodioxaphosphorin oxide, the active metabolite tri-ortho-tolylphosphate, completely inhibited the hydrolysis of pra-nitrophenylacetate by rat liver microsomes and by hydrolases A and B, whereas the sulfhydryl agent, para-chloromercurobenzoate, was not inhibition. These results suggest that hydrolases A and B are both serine esterases. The N-terminal amino acid sequence of hydrolases A and B were similar but distinct (23 the first 30 amino acid residues were identical), indicating that these two esterases are isozymes.(ABSTRACT TRUNCATED AT 400 WORDS)

Amidohydrolases↗
PubMed2005

Chlorine covers on living bacteria: the initial step in antimicrobial action of active chlorine compounds.

OBJECTIVES: Although active chlorine compounds are well-known antimicrobial agents in human medicine, their initial steps of action have not been completely clarified. Using N-chlorotaurine (NCT), an endogenous mild representative, we observed persisting oxidation capacity affixed to bacteria. It was the aim of this study to investigate this 'chlorine cover'. METHODS: Pathogens were incubated in NCT, which was subsequently washed off. The oxidation capacity on the bacterial surface was measured photometrically. RESULTS: Superficial chlorination in the form of covalent N-Cl bonds to Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans could be attached before killing took place. For S. aureus, 3 min incubation with NCT produced a cover of 3.3 x 10(-16) mol Cl(+)/cfu, while the cfu count was reduced by only 26%. The kind of microorganism, coating time, pH, buffer system and, basically, the chlorine compound, influenced the cover strength. The relative cover strength on S. aureus by NCT, chloramine T, sodium dichloro-isocyanurate or N,N-dichlorotaurine was 1:15.7:38.7:0.24. Chlorine covers were surprisingly stable and could be detected for 3 h at 20 degrees C (>8 h at 1 degrees C), even without a reduction of cfu. However, addition of 5% ammonium chloride caused a rapid loss of viability, explained by formation of highly bactericidal NH(2)Cl, an effect that resembles the ignition of a time-bomb. CONCLUSIONS: The chlorine cover can be regarded as the first sign of interaction between chlorinating agent and microorganism, and may explain the non-lethal features of postantibiotic effect and attenuation of bacterial virulence. Furthermore, it may be a decisive step in bacterial inactivation by the myeloperoxidase-hypochlorite system in innate immunity.

Bacteria↗
PubMed1991

[The activity of formaldehyde, glutardialdehyde, peracetic acid, chloramine T (N-chlor-4-toluolsulfonamide), m-cresol, ethanol and benzyldimethyldodecylammonium bromide against bacteria which are found in coagulated blood. (Model studies for chemical disinfection of instruments].

The experiments were performed using frosted glass as carrier with its surface being contaminated with whole blood containing Staphylococcus aureus as test organism. At the time of sampling, a heparin preparation was added to the blood to prevent premature coagulation. After addition of the staphylococci, coagulation was initiated by means of a heparin antagonist. 10, 25, 50, 100, and 150 microliters, respectively, of the blood were homogeneously spread on rectangular test areas of 10 x 20 mm. After the blood had coagulated, each of the test objects was placed in 15 ml of the solution (20 degrees C) containing the active ingredient tested for 60 min. After that, the test objects were removed from the disinfectant and, in order to inactivate any adhering active components, treated with a neutralizing solution of suitable composition. The number of viable germs (colony-forming units) was determined quantitatively. The blood samples were ground together with quartz sand. Aliquots of the diluted suspensions were mixed with molten agar medium. The plates then were incubated at 37 degrees C over a period of 14 days. The relative number of viable germs (N/No) per test object was calculated from the number of colonies. Plotting of the microbicidal effects obtained (log N/No] versus the concentration of the active substance (see Figs. 1-3) yielded curves differing in some characteristics as e.g. curvature, slope of the lower curve section (log N/No). less than -3), concentration range according to the layer thickness of the contamination. To visualize the reduction of the efficacy of the respective disinfectants caused by blood, the concentrations of active components were determined which are necessary to achieve a microbicidal effect of log (N/No) = -4. These concentrations were plotted versus the amounts of blood per test area (Fig. 4). The resulting curve for formaldehyde was slightly U-shaped. With a raising amount of blood, the concentration required slightly decreased in the beginning and increased again from an amount of ca. 100 microliter blood per test area. For all other active substances, the required concentration of these substances increased with the amount of blood used. The curve obtained for ethanol exhibited the lowest slope. The slope of the curves increased in the following order: ethanol, m-cresol, peracetic acid, chloramine T, glutardialdehyde, benzyldimethyldodecylammoniumbromide. The curves for chloramine T and glutardialdehyde nearly paralleled each other.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Inhibition of monoamine oxidase-A activity in rat brain by synthetic hydrazines: structure-activity relationship (SAR).

A series of hydrazine derivatives was synthesized in order to evaluate their monoamine oxidase A (MAO-A) inhibitory effects. MAO-A inhibitory activity of 4-tosyl benzoic acid carbohydrazide was quite potent, similarly to that of the corresponding 4-benzyloxy-benzoic acid carbohydrazide and its N-cyanoethylated derivative. Structural variations of these compounds, such as the replacement of the 4-substitutent, of the aromatic ring on which the carbohydrazide moiety is grafted, as well as cyclization of the hydrazide moiety in five- or six-membered rings caused either significant decline or complete loss of MAO inhibitory properties. The most active compound (4-tosyl benzoic acid carbohydrazide) was also subjected to the forced swim test, an animal model of depression, eliciting a marked reduction in immobility time in rats, without affecting the locomotor activity, implying that it possesses anti-depressant properties due to inhibition of MAO type-A.

Animals↗
PubMed2002

Separation of chiral sulfoxides by liquid chromatography using macrocyclic glycopeptide chiral stationary phases.

A set of 42 chiral compounds containing stereogenic sulfur was prepared. There were 31 chiral sulfoxide compounds, three tosylated sulfilimines and eight sulfinate esters. The separations were done using five different macrocyclic glycopeptide chiral stationary phases (CSPs), namely ristocetin A, teicoplanin, teicoplanin aglycone (TAG), vancomycin and vancomycin aglycone (VAG) and seven eluents, three normal-phase mobile phases, two reversed phases and two polar organic mobile phases. Altogether the macrocyclic glycopeptide CSPs were able to separate the whole set of the 34 sulfoxide enantiomers and tosylated derivatives. Five of the eight sulfinate esters were also separated. The teicoplanin and TAG CSPs were the most effective CSPs able to resolve 35 and 33 of the 42 compounds. The three other CSPs each were able to resolve more than 27 compounds. The normal-phase mode was the most effective followed by the reversed-phase mode with methanol-water mobile phases. Few of these compounds could be separated in the polar organic mode with 100% methanol mobile phases. Acetonitrile was also not a good solvent for the resolution of enantiomers of sulfur-containing compounds, neither in the reversed-phase nor in the polar organic mode. The structure of the chiral molecules was compared to the enantioselectivity factors obtained with the teicoplanin and TAG CSP. It is shown that the polarity, volume and shape of the sulfoxide substituents influence the solute enantioselectivity factor. Changing the oxidation state of the sulfur atom from sulfoxides to sulfinate esters is detrimental to the compound's enantioselectivity. The enantiomeric retention order on the teicoplanin and TAG CSPs was very consistent: the (S)-(+)-sulfoxide enantiomer was always the less retained enantiomer. In contrast, the (R)-(-)-enantiomer was less retained by the ristocetin A, vancomycin and vancomycin aglycone columns, showing the complementarity of these CSPs. The macrocyclic glycopeptide CSPs provided broad selectivity and effective separations of chiral sulfoxides.

Chromatography, Liquid↗
PubMed1998

[Effect on the microbicidal efficacy of formaldehyde, glutardialdehyde, peracetic acid, chloramine T (N-chloro-4-toluenesulfonamide), m-cresol, ethanol and benzyldimethyldodecacylammonium bromide by blood (model experiments for chemical disinfection of instruments)].

In a preceding paper (Zbl. Hyg. 191 [1991] 457-477) we reported on the dependence of the microbicidal efficacy of active agents of the disinfection of instruments on the amount of coagulated blood adhering to the instruments. In the present investigation, we were interested in the dependence of the microbicidal effects on the amount of blood in the solutions of the active agents. Test areas of 2 cm2 were contaminated with 50 and 100 microliters coagulating blood, respectively, containing cells of Staphylococcus aureus as test germ. The solutions of the microbicidal agents were contaminated with heparinized blood up to a concentration of 4% immediately before starting the disinfection and 24 hours before, respectively. After a period of action lasting 1 hour at 20 degrees C, the relative number of test germs capable of multiplying (N/N0) was determined. The concentration of the microbicidal substances reducing the relative number of test germs capable to multiply to 10(-4) served for estimating the dependence of the microbicidal efficacy of the agents on the blood content of the solutions. The experimental results depended on the thickness of the layer of coagulated blood. The dependence of the efficacy of the microbicidal substances on the blood content of the solutions was the higher the thinner the blood layer was. At a thickness of the layer of the coagulated blood of 0.25 mm, a blood content of the solution of 4%, and applying it immediately after adding the blood, the concentration of glutardialdehyde had to be 1.6 times that without blood to reach the same microbicidal efficacy. When applying the solution 24 hours after adding the blood, the concentration of glutardialdehyde had to be 4.2 times that without blood. The quaternary ammonium compound reacted faster with the blood than did glutardialdehyde; the respective factors were 2.6 and 4.5. The concentration factors of chloramine T were 3.3 and 3.8. Under the conditions of the test, peracetic acid exhibited small concentration factors: 1.3 and 1.6. The microbicidal efficacy of ethanol, formaldehyde and m-cresol soap solution was not or only slightly altered by the amount of blood in the solution of the microbicidal agent.

Benzalkonium Compounds↗
PubMed2005

In vitro testing of fungicidal activity of biocides against Aspergillus fumigatus.

The activity of biocides against Aspergillus fumigatus is unknown. In the European guidelines to evaluate the fungicidal activity of a biocide, the critical step concerning the preparation of conidial suspensions is cumbersome and time-consuming. The aims of this study were to evaluate a simplified procedure to prepare conidial suspensions to test a biocide in comparison with the recommended one and to investigate the in vitro activity of seven biocides by the suspension neutralization method against A. fumigatus clinical isolates. The proposed simplified procedure proved reproducible, gave the same results and was quicker than that described in the European guidelines. Benzalkonium chloride (0.25 %), glutaraldehyde (1.6 %), polyvinylpyrrolidone iodine (1 % available iodine) and polyester glycol iodine (0.18 % available iodine) showed biocidal activity in <or=5 min contact time, and chlorine (0.14 % available Cl) and chlorhexidine (0.06 %) after 15 min and 30-60 min, respectively. In contrast, chloramine-T (0.01 %) did not show biocidal activity. In addition, a simplified and reproducible procedure may be used for testing the fungicidal activity of new compounds or combined formulations. In conclusion, the biocides tested, which are commonly used in hospital settings, were shown to display biocidal activity against A. fumigatus and a simplified procedure may be adopted for testing the fungicidal activity of new compounds.

Anti-Infective Agents, Local↗
PubMed2004

Monitoring apoptosis with fluorescent Zn2+-indicators.

Apoptosis, a mechanism of programmed cell death that removes superfluous and harmful cells, is important both during development and in tissue homeostasis. Although Zn2+ is believed to be critical in apoptosis, the precise details of its role have yet to be elucidated. The macrocyclic Zn2+ ligand dansylamidoethylcyclen [L1*(HCl)4*(H2O)2], which is found primarily in a diprotonated form (H2L1), is cell-permeable and forms a strongly fluorescent 1:1 Zn2+ complex when Zn2+ entry into cells is facilitated by the Zn2+ ionophore pyrithione. H2L1 can be used to readily identify HeLa cells undergoing the early stages of etoposide-induced apoptosis because of the increased level of free Zn2+ that occurs at this time. The selectivity of H2L1 for the detection of apoptotic cells was verified by a conventional probe for apoptosis, annexin V-Cy3. Here, we describe methods for detecting apoptotic cells with H2L1 and for comparing detection of apoptosis with H2L1 to detection with annexin V-Cy3 and Zinquin.

Annexin A5↗