Enzymatic and bactericidal activity of myeloperoxidase in conditions of halogenative stress

2018 ◽  
Vol 96 (5) ◽  
pp. 580-591 ◽  
Author(s):  
Tatyana V. Vakhrusheva ◽  
Daria V. Grigorieva ◽  
Irina V. Gorudko ◽  
Alexey V. Sokolov ◽  
Valeria A. Kostevich ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bactericidal Activity ◽  
Linear Correlation ◽  
Secondary Products ◽  
Primary Products ◽  
Heme Degradation ◽  
Halogenative Stress ◽  
Negative Linear Correlation ◽  
Reactive Halogen Species ◽  
Halogen Species

Myeloperoxidase (MPO), found mainly in neutrophils, is released in inflammation. MPO produces reactive halogen species (RHS), which are bactericidal agents. However, RHS overproduction, i.e., halogenative stress, can also damage host biomolecules, and MPO itself may be targeted by RHS. Therefore, we examined the susceptibility of MPO to inactivation by its primary products (HOCl, HOBr, HOSCN) and secondary products such as taurine monochloramine (TauCl) and taurine monobromamine (TauBr). MPO was dose-dependently inhibited up to complete inactivity by treatment with HOCl or HOBr. TauBr diminished the activity but did not eliminate it. TauCl had no effect. MPO became inactivated when producing HOCl or HOBr but not HOSCN. Taurine protected MPO against inactivation when MPO was catalyzing oxidation of Cl− to HOCl, whereas taurine failed to prevent inactivation when MPO was working with Br−, either alone or in combination with Cl−. SCN− interfered with HOCl-mediated MPO inhibition. UV–vis spectra showed that heme degradation is involved in HOCl- and HOBr-mediated MPO inactivation. A negative linear correlation between the remaining chlorinating activity of HOCl- or HOBr-modified MPO and Escherichia coli survival upon incubation with MPO/H2O2/Cl− was found. This study elucidated the possibility of MPO downregulation by MPO-derived RHS, which could counteract halogenative stress.

scholarly journals Enzymatic and bactericidal activity of monomeric and dimeric forms of myeloperoxidase

2018 ◽  
Vol 64 (2) ◽  
pp. 175-182
Author(s):  
T.V. Vakhrusheva ◽  
A.V. Sokolov ◽  
V.A. Kostevich ◽  
V.B. Vasilyev ◽  
O.M. Panasenko
Keyword(s):  
Disulfide Bond ◽  
Bactericidal Activity ◽  
Inflammatory Diseases ◽  
Specific Property ◽  
Laboratory Strain ◽  
Bactericidal Effect ◽  
Monomeric Form ◽  
Bacterial Surface ◽  
Halogenative Stress ◽  
Reactive Halogen Species

This study was carried out to compare the enzymatic and bactericidal activity of mature, dimeric myeloperoxidase (MPO) and its monomeric form. Dimeric MPO was isolated from HL-60 cells. Hemi-MPO obtained from dimeric MPO by reductive cleavage of a disulfide bond between protomeric subunits was used as the monomeric form. Both peroxidase and halogenating (chlorinating) activities of MPO were assayed, each of them by two methods. Bactericidal activity of the MPO/Н2О2/Cl- system was tested using the Escherichia coli laboratory strain DH5a. No difference in the enzymatic and bactericidal activity between dimeric MPO and hemi-MPO was found. Both forms of the enzyme also did not differ in the resistance to HOCl, the main product of MPO. HOCl caused a dose-dependent decrease in peroxidase and chlorinating activity, and the pattern of this decrease was identical for dimeric MPO and hemi-MPO. At equal heme concentration, a somewhat higher bactericidal effect was observed for the hemi-MPO/Н2О2/Cl- system compared with the dimeric MPO/Н2О2/Cl- system. However, this is most likely not related to some specific property of hemi-MPO and can be accounted for by the higher probability of contacting between bacterial surface and hemi-MPO molecules due to their two-fold greater number relative to that of dimeric MPO molecules at the same heme concentration. By using Western-blotting with antibodies to MPO, we showed, for the first time, that the dimeric molecule of MPO could be cleaved into two monomeric subunits by HOCl, most probably due to oxidation of the disulfide bond between these subunits. This finding suggests that appearance in blood of MPO corresponding in mass to its monomer may result from the damage of dimeric MPO by reactive halogen species, especially upon their overproduction underlying oxidative/halogenative stress in inflammatory diseases.

Effects of Water Source, Dilution, Storage, and Bacterial and Fecal Loads on the Efficacy of Electrolyzed Oxidizing Water for the Control of Escherichia coli O157:H7

2004 ◽  
Vol 67 (7) ◽  
pp. 1377-1383 ◽  
Author(s):  
S. M. L. STEVENSON ◽  
S. R. COOK ◽  
S. J. BACH ◽  
T. A. McALLISTER
Keyword(s):  
Escherichia Coli ◽  
Bactericidal Activity ◽  
Storage Temperature ◽  
Uv Light ◽  
Tap Water ◽  
Organic Matter Content ◽  
Water Source ◽  
Deionized Water ◽  
Escherichia Coli O157 ◽  
E Coli

To evaluate the potential of using electrolyzed oxidizing (EO) water for controlling Escherichia coli O157:H7 in water for livestock, the effects of water source, electrolyte concentration, dilution, storage conditions, and bacterial or fecal load on the oxidative reduction potential (ORP) and bactericidal activity of EO water were investigated. Anode and combined (7:3 anode:cathode, vol/vol) EO waters reduced the pH and increased the ORP of deionized water, whereas cathode EO water increased pH and lowered ORP. Minimum concentrations (vol/vol) of anode and combined EO waters required to kill 104 CFU/ml planktonic suspensions of E. coli O157:H7 strain H4420 were 0.5 and 2.0%, respectively. Cathode EO water did not inhibit H4420 at concentrations up to 16% (vol/vol). Higher concentrations of anode or combined EO water were required to elevate the ORP of irrigation or chlorinated tap water compared with that of deionized water. Addition of feces to EO water products (0.5% anode or 2.0% combined, vol/vol) significantly reduced (P < 0.001) their ORP values to <700 mV in all water types. A relationship between ORP and bactericidal activity of EO water was observed. The dilute EO waters retained the capacity to eliminate a 104 CFU/ml inoculation of E. coli O157:H7 H4420 for at least 70 h regardless of exposure to UV light or storage temperature (4 versus 24°C). At 95 h and beyond, UV exposure reduced ORP, significantly more so (P < 0.05) in open than in closed containers. Bactericidal activity of EO products (anode or combined) was lost in samples in which ORP value had fallen to ≤848 mV. When stored in the dark, the diluted EO waters retained an ORP of >848 mV and bactericidal efficacy for at least 125 h; with refrigeration (4°C), these conditions were retained for at least 180 h. Results suggest that EO water may be an effective means by which to control E. coli O157:H7 in livestock water with low organic matter content.

Alteration of the phagocytosis and antimicrobial defense of Octodonta nipae (Coleoptera: Chrysomelidae) pupae to Escherichia coli following parasitism by Tetrastichus brontispae (Hymenoptera: Eulophidae)

2018 ◽  
Vol 109 (2) ◽  
pp. 248-256
Author(s):  
E. Meng ◽  
J. Li ◽  
B. Tang ◽  
Y. Hu ◽  
T. Qiao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Immune Response ◽  
Immune Responses ◽  
Mrna Expression ◽  
Bactericidal Activity ◽  
Bacterial Infections ◽  
Expression Level ◽  
Primary Immune Response ◽  
Mrna Expression Level ◽  
E Coli

AbstractAlthough parasites and microbial pathogens are both detrimental to insects, little information is currently available on the mechanism involved in how parasitized hosts balance their immune responses to defend against microbial infections. We addressed this in the present study by comparing the immune response between unparasitized and parasitized pupae of the chrysomelid beetle, Octodonta nipae (Maulik), to Escherichia coli invasion. In an in vivo survival assay, a markedly reduced number of E. coli colony-forming units per microliter was detected in parasitized pupae at 12 and 24 h post-parasitism, together with decreased phagocytosis and enhanced bactericidal activity at 12 h post-parasitism. The effects that parasitism had on the mRNA expression level of selected antimicrobial peptides (AMPs) of O. nipae pupae showed that nearly all transcripts of AMPs examined were highly upregulated during the early and late parasitism stages except defensin 2B, whose mRNA expression level was downregulated at 24 h post-parasitism. Further elucidation on the main maternal fluids responsible for alteration of the primary immune response against E. coli showed that ovarian fluid increased phagocytosis at 48 h post-injection. These results indicated that the enhanced degradation of E. coli in parasitized pupae resulted mainly from the elevated bactericidal activity without observing the increased transcripts of target AMPs. This study contributes to a better understanding of the mechanisms involved in the immune responses of a parasitized host to bacterial infections.

scholarly journals Chemical interactions between ship-originated air pollutants and ocean-emitted halogens

2021 ◽  
Author(s):  
Qinyi Li ◽  
Alba Badia ◽  
Rafael P. Fernandez ◽  
Anoop S. Mahajan ◽  
Ana Isabel López-Noreña ◽  
...  
Keyword(s):  
Air Pollutants ◽  
Atmospheric Composition ◽  
Chemical Transformations ◽  
Chemical Interactions ◽  
China Sea ◽  
Reactive Halogen Species ◽  
The Impact ◽  
Surface Increase ◽  
Halogen Species

<p>Ocean-going ships supply products from one region to another and contribute to the world’s economy. Ship exhaust contains many air pollutants and results in significant changes in marine atmospheric composition. The role of Reactive Halogen Species (RHS) in the troposphere has received increasing recognition and oceans are the largest contributors to their atmospheric burden. However, the impact of shipping emissions on RHS and that of RHS on ship-originated air pollutants have not been studied in detail. Here, an updated WRF-Chem model is utilized to explore the chemical interactions between ship emissions and oceanic RHS over the East Asia seas in summer. The emissions and resulting chemical transformations from shipping activities increase the level of NO and NO<sub>2</sub> at the surface, increase O<sub>3</sub> in the South China Sea, but decrease O<sub>3</sub> in the East China Sea. Such changes in pollutants result in remarkable changes in the levels of RHS as well as in their partitioning. The abundant RHS, in turn, reshape the loadings of air pollutants and those of the oxidants with marked patterns along the ship tracks. We, therefore, suggest that these important chemical interactions of ship-originated emissions with RHS should be considered in the environmental policy assessments of the role of shipping emissions in air quality and climate.</p>

scholarly journals 1D TiO2 Nanostructures Prepared from Seeds Presenting Tailored TiO2 Crystalline Phases and Their Photocatalytic Activity for Escherichia coli in Water

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Julieta Cabrera ◽  
Dwight Acosta ◽  
Alcides López ◽  
Roberto J. Candal ◽  
Claudia Marchi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Photocatalytic Activity ◽  
Bactericidal Activity ◽  
Sol Gel ◽  
Titanium Isopropoxide ◽  
E Coli ◽  
1D Nanostructures ◽  
Sol Gel Synthesis ◽  
Hydrolysis Of ◽  
Tio2 Nanostructures

TiO2 nanotubes were synthesized by alkaline hydrothermal treatment of TiO2 nanoparticles with a controlled proportion of anatase and rutile. Tailoring of TiO2 phases was achieved by adjusting the pH and type of acid used in the hydrolysis of titanium isopropoxide (first step in the sol-gel synthesis). The anatase proportion in the precursor nanoparticles was in the 3–100% range. Tube-like nanostructures were obtained with an anatase percentage of 18 or higher while flake-like shapes were obtained when rutile was dominant in the seed. After annealing at 400°C for 2 h, a fraction of nanotubes was conserved in all the samples but, depending on the anatase/rutile ratio in the starting material, spherical and rod-shaped structures were also observed. The photocatalytic activity of 1D nanostructures was evaluated by measuring the deactivation of E. coli in stirred water in the dark and under UV-A/B irradiation. Results show that in addition to the bactericidal activity of TiO2 under UV-A illumination, under dark conditions, the decrease in bacteria viability is ascribed to mechanical stress due to stirring.

Analysis of the Flagellar Beat Pattern of Male Ectocarpus Siliculosus Gametes (Phaeophyta) in Relation to Chemotactic Stimulation by Female Cells

1981 ◽  
Vol 92 (1) ◽  
pp. 53-66
Author(s):  
ANNETTE GELLER ◽  
DIETER G. MÜLLER
Keyword(s):  
Linear Correlation ◽  
Mode Of Action ◽  
High Speed ◽  
Sex Attractant ◽  
Cell Axis ◽  
Ectocarpus Siliculosus ◽  
Bending Waves ◽  
Flagellar Beat ◽  
Beat Pattern ◽  
Negative Linear Correlation

Heterocontic male Ectocarpus siliculosus gametes respond to the sex-attractant ectocarpen by changing their locomotive behaviour. However, the mode of action of the flagella is not changed by the presence of ectocarpen. High-speed cinemicrography shows that gametes moving close to a coverglass perform planar bending waves with their front flagellum. Straight or slightly curved swimming paths are generated by enhanced upward bends of the front flagellum to compensate for the asymmetrical insertion of both flagella. Narrower curves are connected with increasing downward bends of the front flagellum. There is a negative linear correlation between the average deflexion of the front flagellum (μm) from the cell axis and the radius of track (correlation coefficient 0.94). Additionally, freely swimming gametes exhibit elliptical and rotary wave motions, suggesting a relationship between thigmotaxis and mode of action of the front flagellum. The rigid hind flagellum performs one rapid sideward beat when the gametes swim in narrow curves. This appears to provide a steering function.

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