scholarly journals Ozone Sensitivity and Catalase Activity in Pigmented and Non-Pigmented Strains of Serratia Marcescens

2017 ◽  
Vol 11 (1) ◽  
pp. 12-22
Author(s):  
José de Ondarza
Keyword(s):  
Serratia Marcescens ◽  
Stress Responses ◽  
Catalase Activity ◽  
Survival Rates ◽  
Opportunistic Pathogen ◽  
Ozone Exposure ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Ozone Sensitivity ◽  
Gaseous Ozone

Background:Ozone exposure rapidly leads to bacterial death, making ozone an effective disinfectant in food industry and health care arena. However, microbial defenses may moderate this effect and play a role in the effective use of oxidizing agents for disinfection.Serratia marcescensis an opportunistic pathogen, expressing genes differentially during infection of a human host. A better understanding of regulatory systems that control expression ofSerratia’s virulence genes and defenses is therefore valuable.Objective:Here, we investigated the role of pigmentation and catalase inSerratia marcescenson survival to ozone exposure.Method:Pigmented and non-pigmented strains ofSerratia marcescenswere cultured to exponential or stationary phase and exposed to 5 ppm of gaseous ozone for 2.5 – 10 minutes. Survival was calculated via plate counts. Catalase activity was measured photometrically and tolerance to hydrogen peroxide was assayed by disk-diffusion.Results:Exposure ofS. marcescensto 5 ppm gaseous ozone kills > 90% of cells within 10 minutes in a time and concentration-dependent manner. Although pigmentedSerratia(grown at 28°C) survived ozonation better than unpigmentedSerratia(grown at 35°C), non-pigmented mutant strains ofSerratiahad similar ozone survival rates, catalase activity and H2O2tolerance as wild type strains. Rather, ozone survival and catalase activity were elevated in 6 hour cultures compared to 48 hour cultures.Conclusion:Our studies did not bear out a role for prodigiosin in ozone survival. Rather, induction of oxidative stress responses during exponential growth increased both catalase activity and ozone survival in both pigmented and unpigmentedS. marcescens.

scholarly journals Transcriptional Response of Multidrug-Resistant Klebsiella pneumoniae Clinical Isolates to Ciprofloxacin Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Roman Farooq Alvi ◽  
Bilal Aslam ◽  
Muhammad Hidayat Rasool ◽  
Saima Muzammil ◽  
Abu Baker Siddique ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Stress Responses ◽  
Genetic Resistance ◽  
Transcriptional Response ◽  
Multidrug Resistant ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Isolation And Identification ◽  
Concentration Dependent Manner ◽  
High Level

Background. The term “persisters” refers to a small bacterial population that persists during treatment with high antibiotic concentration or dose in the absence of genetic resistance. The present study was designed to investigate the transcriptional response in indigenous Klebsiella pneumoniae under the ciprofloxacin stress. Methods. Isolation and identification of K. pneumoniae were carried out through standard microbiological protocols. The characterization of quinolone resistance was performed by estimating the quinolone susceptibility testing, MIC estimation, and detecting the QRDR and PMQR. Transcriptional response of the isolates to ciprofloxacin was determined using qPCR. Results. Among 34 isolates, 23 (67%) were resistant to ciprofloxacin. Both QRDR (gyrA and gyrB) and PMQR (qnrA, qnrB, and qnrS) were detected in the isolates, and all were found resistant to ciprofloxacin. The mRNA levels of both mutS and euTu under the influence of ciprofloxacin were significantly increased. On ciprofloxacin exposure, the mRNA levels of the DNA damage response element (mutS) were raised in a time-dependent fashion. K. pneumoniae showed high-level resistance to ciprofloxacin in the presence of mutations in QRDR and PMQR genes. Conclusion. The transcriptional response revealed the upregulation of DNA repair and protein folding elements (mutS and euTu) in ciprofloxacin stress and delayed cell division. The ciprofloxacin was found to trigger various stress responses in a time- and concentration-dependent manner.

scholarly journals In the Model Host Caenorhabditis elegans, Sphingosine-1-Phosphate-Mediated Signaling Increases Immunity toward Human Opportunistic Bacteria

2020 ◽  
Vol 21 (21) ◽  
pp. 7813
Author(s):  
Kiho Lee ◽  
Iliana Escobar ◽  
Yeeun Jang ◽  
Wooseong Kim ◽  
Frederick M. Ausubel ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Stress Responses ◽  
Mapk Signaling ◽  
Dependent Manner ◽  
Cellular Functions ◽  
Kinase Gene ◽  
Concentration Dependent Manner ◽  
C Elegans ◽  
Opportunistic Bacteria ◽  
Free Living Nematode

Sphingosine-1-phophate (S1P) is a sphingolipid-derived signaling molecule that controls diverse cellular functions including cell growth, homeostasis, and stress responses. In a variety of metazoans, cytosolic S1P is transported into the extracellular space where it activates S1P receptors in a concentration-dependent manner. In the free-living nematode Caenorhabditis elegans, the spin-2 gene, which encodes a S1P transporter, is activated during Gram-positive or Gram-negative bacterial infection of the intestine. However, the role during infection of spin-2 and three additional genes in the C. elegans genome encoding other putative S1P transporters has not been elucidated. Here, we report an evolutionally conserved function for S1P and a non-canonical role for S1P transporters in the C. elegans immune response to bacterial pathogens. We found that mutations in the sphingosine kinase gene (sphk-1) or in the S1P transporter genes spin-2 or spin-3 decreased nematode survival after infection with Pseudomonas aeruginosa or Enterococcus faecalis. In contrast to spin-2 and spin-3, mutating spin-1 leads to an increase in resistance to P. aeruginosa. Consistent with these results, when wild-type C. elegans were supplemented with extracellular S1P, we found an increase in their lifespan when challenged with P. aeruginosa and E. faecalis. In comparison, spin-2 and spin-3 mutations suppressed the ability of S1P to rescue the worms from pathogen-mediated killing, whereas the spin-1 mutation had no effect on the immune-enhancing activity of S1P. S1P demonstrated no antimicrobial activity toward P. aeruginosa and Escherichia coli and only minimal activity against E. faecalis MMH594 (40 µM). These data suggest that spin-2 and spin-3, on the one hand, and spin-1, on the other hand, transport S1P across cellular membranes in opposite directions. Finally, the immune modulatory effect of S1P was diminished in C. eleganssek-1 and pmk-1 mutants, suggesting that the immunomodulatory effects of S1P are mediated by the p38 MAPK signaling pathway.

scholarly journals Novel Anion Liposome-Encapsulated Antisense Oligonucleotide Restores Susceptibility of Methicillin-Resistant Staphylococcus aureus and Rescues Mice from Lethal Sepsis by Targeting mecA

2009 ◽  
Vol 53 (7) ◽  
pp. 2871-2878 ◽  
Author(s):  
Jingru Meng ◽  
Hui Wang ◽  
Zheng Hou ◽  
Tao Chen ◽  
Jingguo Fu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Survival Rates ◽  
Treated Group ◽  
Antisense Oligodeoxynucleotide ◽  
Control Group ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Lethal Sepsis ◽  
Mueller Hinton Agar ◽  
Novel Strategy

ABSTRACT β-Lactam resistance in methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) is caused by the production of an additional low-affinity penicillin-binding protein 2a, which is encoded by the mecA gene. The disruption of mecA may inhibit mecA expression and thereafter lead to the restoration of MRSA susceptibility to β-lactams. In this study, we developed a novel anionic liposome for encapsulating and delivering the complexes of a specific anti-mecA phosphorothioate oligodeoxynucleotide (PS-ODN833) and polycation polyethylenimine (PEI). The efficiencies of liposome encapsulation of the complexes were around 79.7% ± 2.7%. The liposomes showed sustained release of PS-ODN833 at 37°C but very low levels of release at 4°C and room temperature. The addition of the encapsulated anti-mecA PS-ODN833-PEI complex to cultures of MRSA strains caused 45, 76, 82, and 93% reductions in mecA expression, accompanied by the inhibition of MRSA growth on Mueller-Hinton agar containing oxacillin (6 μg/ml) in a concentration-dependent manner. The encapsulated-PS-ODN833 treatment also reduced the MICs of five of the most commonly used antibiotics for MRSA clinical isolates to values within the sensitivity range and rescued mice from MRSA-caused septic death by downregulating mecA. The survival rates of septic mice increased from 0% for the control group to 53% for the PS-ODN833-treated group. The results were associated with reductions of bacterial titers in the blood of surviving mice. The findings of the present study indicate that an antisense oligodeoxynucleotide targeted to mecA can significantly restore the susceptibility of MRSA to existing β-lactam antibiotics, providing an apparently novel strategy for treating MRSA infections.

scholarly journals A Cationic Porphyrin, ZnPor, Disassembles Pseudomonas aeruginosa Biofilm Matrix, Kills Cells Directly, and Enhances Antibiotic Activity of Tobramycin

Antibiotics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 875
Author(s):  
Neha Patel ◽  
Shawn Swavey ◽  
Jayne Robinson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Infections ◽  
Opportunistic Pathogen ◽  
Uptake System ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Antibiotic Resistant ◽  
The Matrix ◽  
Life Threatening ◽  
Pre Treatment

One of the greatest threats to human health is the rise in antibiotic-resistant bacterial infections. Pseudomonas aeruginosa (PsA) is an “opportunistic” pathogen known to cause life-threatening infections in immunocompromised individuals and is the most common pathogen in adults with cystic fibrosis (CF). We report here a cationic zinc (II) porphyrin, ZnPor, that effectively kills planktonic and biofilm-associated cells of PsA. In standard tests against 16–18 h-old biofilms, concentrations as low as 16 µg/mL resulted in the extensive disruption and detachment of the matrix. The pre-treatment of biofilms for 30 min with ZnPor at minimum inhibitory concentration (MIC) levels (4 µg/mL) substantially enhanced the ability of tobramycin (Tobra) to kill biofilm-associated cells. We demonstrate the rapid uptake and accumulation of ZnPor in planktonic cells even in dedicated heme-uptake system mutants (ΔPhu, ΔHas, and the double mutant). Furthermore, uptake was unaffected by the ionophore carbonyl cyanide m-chlorophenyl hydrazine (CCCP). Cells pre-exposed to ZnPor took up the cell-impermeant dye SYTOXTM Green in a concentration-dependent manner. The accumulation of ZnPor did not result in cell lysis, nor did the cells develop resistance. Taken together, these properties make ZnPor a promising candidate for treating multi-drug-resistant infections, including persistent, antibiotic-resistant biofilms.

scholarly journals Cytotoxicity of Deoxynivalenol after Being Exposed to Gaseous Ozone

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 639 ◽  
Author(s):  
Dongliang Ren ◽  
Enjie Diao ◽  
Hanxue Hou ◽  
Peng Xie ◽  
Ruifeng Mao ◽  
...  
Keyword(s):  
Hela Cells ◽  
Negative Control ◽  
Ozone Exposure ◽  
Dependent Manner ◽  
Order Kinetic ◽  
First Order ◽  
Gaseous Ozone ◽  
Order Kinetic Model ◽  
Ic50 Values ◽  
Dose Dependent

In this study, deoxynivalenol (DON) in aqueous solution was exposed to gaseous ozone for periods ranging from 0 to 20 min. The degradation efficiency and cytotoxicity of DON were investigated after being treated by ozone. The results showed that DON was rapidly degraded from 10.76 ± 0.09 mg/L to 0.22 ± 0.04 mg/L within 15 min (P < 0.05), representing a reduction of 97.95%, and no DON was detected after being exposed to 14.50 mg/L of ozone at a flow rate of 80 mL/min for 20 min. The degradation of DON depended on the ozone exposure time, and followed the first-order kinetic model (R2 = 0.9972). Human hepatic carcinoma (HepG2) and Henrietta Lacks (Hela) cells were used to evaluate the cytotoxicity of DON treated by ozone using the 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. The half-maximal inhibitory concentrations (IC50) values of DON on HepG2 and Hela cells were 2.10 and 1.33 mg/L after 48 h of exposure, respectively, and showed a dose-dependent manner. The cell vitalities of HepG2 and Hela cells on DON were both evidently improved after being exposed to ozone for 15 min, and there were no significant differences between the negative control and that treated at 20 min of ozone exposure. Gaseous ozone can potentially be used as a new method to detoxify DON in agricultural products.

scholarly journals Investigating the Cytotoxicity of Folate-Conjugated Bismuth Oxide Nanoparticles on KB and A549 Cell Lines

2018 ◽  
Vol 8 (4) ◽  
pp. 627-635 ◽  
Author(s):  
Fatemeh Akbarzadeh ◽  
Karim Khoshgard ◽  
Leila Hosseinzadeh ◽  
Elham Arkan ◽  
Davood Rezazadeh
Keyword(s):  
Cell Lines ◽  
A549 Cell ◽  
Bismuth Oxide ◽  
Aminolevulinic Acid ◽  
Survival Rates ◽  
A549 Cells ◽  
Ros Generation ◽  
Dependent Manner ◽  
Concentration Dependent Manner

Purpose: Lately, bismuth-based nanomaterials have been widely utilized in medical researches such as imaging, drug delivery and radio-sensitization. Despite their advantages, bismuth-based compounds have shown toxic effects in humans. There are few studies on cytotoxicity effects of bismuth oxide (Bi2O3) nanoparticles (NPs) in-vitro. In this study, we aimed to investigate cytotoxicity of bare and also folate and 5-aminolevulinic acid (5-ALA)-conjugated Bi2O3 NPs on nasopharyngeal carcinoma (KB) and lung cancer (A549) cell lines. Methods: Bi2O3 NPs were synthesized and conjugated with folate and 5-ALA. KB and A549 cells were cultured and incubated with 10, 20, 50 and 100 μg/ml concentrations of bare and folate-5-ALA-conjugated NPs. The survival rates were obtained after 2 and 24 hours incubation of the cells with NPs using MTT assay. Also, apoptosis and ROS generation induced by the NPs in the treated cells were obtained using Caspases-3 activity assay and flow cytometry analysis, respectively. Results: Bi2O3 NPs were successfully synthesized with average size of 19.2 ± 6.5 nm, then conjugated with 5-ALA and folate. Either naked or folate-conjugated NPs were easily taken up by the cells in a concentration-dependent manner and showed cytotoxic effects. The significant cell death was noted at the concentrations more than 50 μg/ml for both compounds. Conclusion: Results indicated low cytotoxicity of the prepared NPs at lower incubation periods, which is very important for their further applications. However, 24 hours incubation of the cells with both forms of NPs caused more cell killing and the cytotoxicity increased with increasing concentrations of the NPs.

scholarly journals Presynaptic CRF1 Receptors Mediate the Ethanol Enhancement of GABAergic Transmission in the Mouse Central Amygdala

2009 ◽  
Vol 9 ◽  
pp. 68-85 ◽  
Author(s):  
Zhiguo Nie ◽  
Eric P. Zorrilla ◽  
Samuel G. Madamba ◽  
Kenner C. Rice ◽  
Marissa Roberto ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Stress Responses ◽  
Critical Role ◽  
Strong Relationship ◽  
Gaba Release ◽  
Dependent Manner ◽  
Central Amygdala ◽  
Concentration Dependent Manner ◽  
Excessive Alcohol Consumption ◽  
Gabaergic Synaptic Transmission

Corticotropin-releasing factor (CRF) is a 41-amino-acid neuropeptide involved in stress responses initiated from several brain areas, including the amygdala formation. Research shows a strong relationship between stress, brain CRF, and excessive alcohol consumption. Behavioral studies suggest that the central amygdala (CeA) is significantly involved in alcohol reward and dependence. We recently reported that the ethanol augmentation of GABAergic synaptic transmission in rat CeA involves CRF1 receptors, because both CRF and ethanol significantly enhanced the amplitude of evoked GABAergic inhibitory postsynaptic currents (IPSCs) in CeA neurons from wild-type (WT) and CRF2 knockout (KO) mice, but not in neurons of CRF1KO mice. The present study extends these findings using selective CRF receptor ligands, gene KO models, and miniature IPSC (mIPSC) analysis to assess further a presynaptic role for the CRF receptors in mediating ethanol effects in the CeA. In whole-cell patch recordings of pharmacologically isolated GABAAergic IPSCs from slices of mouse CeA, both CRF and ethanol augmented evoked IPSCs in a concentration-dependent manner, with low EC50s. A CRF1(but not CRF2) KO construct and the CRF1-selective nonpeptide antagonist NIH-3 (LWH-63) blocked the augmenting effect of both CRF and ethanol on evoked IPSCs. Furthermore, the new selective CRF1agonist stressin1, but not the CRF2agonist urocortin 3, also increased evoked IPSC amplitudes. Both CRF and ethanol decreased paired-pulse facilitation (PPF) of evoked IPSCs and significantly enhanced the frequency, but not the amplitude, of spontaneous miniature GABAergic mIPSCs in CeA neurons of WT mice, suggesting a presynaptic site of action. The PPF effect of ethanol was abolished in CeA neurons of CRF1KO mice. The CRF1antagonist NIH-3 blocked the CRF- and ethanol-induced enhancement of mIPSC frequency in CeA neurons. These data indicate that presynaptic CRF1receptors play a critical role in permitting or mediating ethanol enhancement of GABAergic synaptic transmission in CeA, via increased vesicular GABA release, and thus may be a rational target for the treatment of alcohol abuse and alcoholism.

The Anti-Atherogenic Properties of Sesamin are Mediated via Improved Macrophage Cholesterol Efflux Through PPARγ1-LXRα and MAPK Signaling

2014 ◽  
Vol 84 (1-2) ◽  
pp. 79-91 ◽  
Author(s):  
Amin F. Majdalawieh ◽  
Hyo-Sung Ro
Keyword(s):  
Cholesterol Efflux ◽  
Transcriptional Activity ◽  
Molecular Mechanisms ◽  
Foam Cell ◽  
Mapk Signaling ◽  
Luciferase Reporter ◽  
Foam Cell Formation ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Macrophage Cholesterol Efflux

Background: Foam cell formation resulting from disrupted macrophage cholesterol efflux, which is triggered by PPARγ1 and LXRα, is a hallmark of atherosclerosis. Sesamin and sesame oil exert anti-atherogenic effects in vivo. However, the exact molecular mechanisms underlying such effects are not fully understood. Aim: This study examines the potential effects of sesamin (0, 25, 50, 75, 100 μM) on PPARγ1 and LXRα expression and transcriptional activity as well as macrophage cholesterol efflux. Methods: PPARγ1 and LXRα expression and transcriptional activity are assessed by luciferase reporter assays. Macrophage cholesterol efflux is evaluated by ApoAI-specific cholesterol efflux assays. Results: The 50 μM, 75 μM, and 100 μM concentrations of sesamin up-regulated the expression of PPARγ1 (p< 0.001, p < 0.001, p < 0.001, respectively) and LXRα (p = 0.002, p < 0.001, p < 0.001, respectively) in a concentration-dependent manner. Moreover, 75 μM and 100 μM concentrations of sesamin led to 5.2-fold (p < 0.001) and 6.0-fold (p<0.001) increases in PPAR transcriptional activity and 3.9-fold (p< 0.001) and 4.2-fold (p < 0.001) increases in LXR transcriptional activity, respectively, in a concentration- and time-dependent manner via MAPK signaling. Consistently, 50 μM, 75 μM, and 100 μM concentrations of sesamin improved macrophage cholesterol efflux by 2.7-fold (p < 0.001), 4.2-fold (p < 0.001), and 4.2-fold (p < 0.001), respectively, via MAPK signaling. Conclusion: Our findings shed light on the molecular mechanism(s) underlying sesamin’s anti-atherogenic effects, which seem to be due, at least in part, to its ability to up-regulate PPARγ1 and LXRα expression and transcriptional activity, improving macrophage cholesterol efflux. We anticipate that sesamin may be used as a therapeutic agent for treating atherosclerosis.

Neutrophil Elastase Potentiates Cathepsin G-lnduced Platelet Activation

1992 ◽  
Vol 68 (05) ◽  
pp. 570-576 ◽  
Author(s):  
Mary A Selak
Keyword(s):  
Neutrophil Elastase ◽  
Cell Activation ◽  
Thromboxane A2 ◽  
Creatine Phosphate ◽  
Dense Granule ◽  
Cathepsin G ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Low Concentrations ◽  
High Concentrations

SummaryWe have previously demonstrated that human neutrophil cathepsin G is a strong platelet agonist that binds to a specific receptor. This work describes the effect of neutrophil elastase on cathepsin G-induced platelet responses. While platelets were not activated by high concentrations of neutrophil elastase by itself, elastase enhanced aggregation, secretion and calcium mobilization induced by low concentrations of cathepsin G. Platelet aggregation and secretion were potentiated in a concentration-dependent manner by neutrophil elastase with maximal responses observable at 200 nM. Enhancement was observed when elastase was preincubated with platelets for time intervals of 10–60 s prior to addition of a low concentration of cathepsin G and required catalytically-active elastase since phenylmethanesulphonyl fluoride-inhibited enzyme failed to potentiate cell activation. Neutrophil elastase potentiation of platelet responses induced by low concentrations of cathepsin G was markedly inhibited by creatine phosphate/creatine phosphokinase and/or indomethacin, indicating that the synergism between elastase and cathepsin G required the participation of ADP and thromboxane A2. On the other hand, platelet responses were not attenuated by the PAF antagonist BN 52021, signifying that PAF-acether did not play a role in elastase potentiation. At higher concentrations porcine pancreatic elastase exhibits similar effects to neutrophil elastase, demonstrating that the effect of elastase was not unique to the neutrophil protease. While neutrophil elastase failed to alter the ability of cathepsin G to hydrolyze a synthetic chromogenic substrate, preincubation of platelets with elastase increased the apparent affinity of cathepsin G binding to platelets. In contrast to their effect on cathepsin G-induced platelet responses, neither neutrophil nor pancreatic elasatse potentiated aggregation or dense granule release initiated by ADP, PAF-acether, arachidonic acid or U46619, a thromboxane A2 mimetic. Moreover, unlike its effect on cathepsin G, neutrophil elastase inhibited thrombin-induced responses. The current observations demonstrate that elastase can potentiate platelet responses mediated by low concentrations of cathepsin G, suggesting that both enzymes may function synergistically to activate platelets under conditions where neutrophil degranulation occurs.

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