scholarly journals Virulent Bacteriophages Can Target O104:H4 Enteroaggregative Escherichia coli in the Mouse Intestine

2012 ◽  
Vol 56 (12) ◽  
pp. 6235-6242 ◽  
Author(s):  
Damien Maura ◽  
Matthieu Galtier ◽  
Chantal Le Bouguénec ◽  
Laurent Debarbieux
Keyword(s):  
Escherichia Coli ◽  
Dependent Manner ◽  
Content Type ◽  
Intestinal Pathogens ◽  
Colonization Model ◽  
Mouse Intestine ◽  
Further Development ◽  
Dose Dependent

ABSTRACTIn vivobacteriophage targeting of enteroaggregativeEscherichia coli(EAEC) was assessed using a mouse intestinal model of colonization with the O104:H4 55989Str strain and a cocktail of three virulent bacteriophages. The colonization model was shown to mimic asymptomatic intestinal carriage found in humans. The addition of the cocktail to drinking water for 24 h strongly decreased ileal and weakly decreased fecal 55989Str concentrations in a dose-dependent manner. These decreases in ileal and fecal bacterial concentrations were only transient, since 55989Str concentrations returned to their original levels 3 days later. These transient decreases were independent of the mouse microbiota, as similar results were obtained with axenic mice. We studied the infectivity of each bacteriophage in the ileal and fecal environments and found that 55989Str bacteria in the mouse ileum were permissive to all three bacteriophages, whereas those in the feces were permissive to only one bacteriophage. Our results provide the first demonstration that bacterial permissivity to infection with virulent bacteriophages is not uniform throughout the gut; this highlights the need for a detailed characterization of the interactions between bacteria and bacteriophagesin vivofor the further development of phage therapy targeting intestinal pathogens found in the gut of asymptomatic human carriers.

scholarly journals Intracellular Free Iron and Its Potential Role in Ultrahigh-Pressure-Induced Inactivation of Escherichia coli

2012 ◽  
Vol 79 (2) ◽  
pp. 722-724 ◽  
Author(s):  
Yuan Yan ◽  
Joy G. Waite-Cusic ◽  
Periannan Kuppusamy ◽  
Ahmed E. Yousef
Keyword(s):  
Escherichia Coli ◽  
Iron Chelator ◽  
Ultrahigh Pressure ◽  
Dependent Manner ◽  
Paramagnetic Resonance ◽  
Free Iron ◽  
Content Type ◽  
E Coli ◽  
Electron Paramagnetic ◽  
Dose Dependent

ABSTRACTIntracellular free iron ofEscherichia coliwas determined by whole-cell electron paramagnetic resonance spectrometry. Ultrahigh pressure (UHP) increased both intracellular free iron and cell lethality in a pressure-dose-dependent manner. The iron chelator 2,2′-dipyridyl protected cells against UHP treatments. A mutation that produced iron overload conditions sensitizedE. colito UHP treatment.

scholarly journals Characterization of RNA damage under oxidative stress in Escherichia coli

2012 ◽  
Vol 393 (3) ◽  
pp. 123-132 ◽  
Author(s):  
Min Liu ◽  
Xin Gong ◽  
Ravi Kumar Alluri ◽  
Jinhua Wu ◽  
Tene’ Sablo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Short Exposure ◽  
Dependent Manner ◽  
Ribosomal Rnas ◽  
Rna Oxidation ◽  
Folded Rna ◽  
Dose Dependent

Abstract We have examined the level of 8-hydroxyguanosine (8-oxo-G), an oxidized form of guanosine, in RNA in Escherichia coli under normal and oxidative stress conditions. The level of 8-oxo-G in RNA rises rapidly and remains high for hours in response to hydrogen peroxide (H2O2) challenge in a dose-dependent manner. H2O2 induced elevation of 8-oxo-G content is much higher in RNA than that of 8-hydroxydeoxyguanosine (8-oxo-dG) in DNA. Under normal conditions, the 8-oxo-G level is low in RNA isolated from the ribosome and it is nearly three times higher in non-ribosomal RNAs. In contrast, 8-oxo-G generated by a short exposure to H2O2 is almost equally distributed in various RNA species, suggesting that although ribosomal RNAs are normally less oxidized, they are not protected against exogenous H2O2. Interestingly, highly folded RNA is not protected from oxidation because 8-oxo-G generated by H2O2 treatment in vitro increases to approximately the same levels in tRNA and rRNA in both native and denatured forms. Lastly, increased RNA oxidation is closely associated with cell death by oxidative stress. Our data suggests that RNA is a primary target for reactive oxygen species and RNA oxidation is part of the paradox that cells have to deal with under oxidative stress.

scholarly journals Cj1386, an Atypical Hemin-Binding Protein, Mediates Hemin Trafficking to KatA in Campylobacter jejuni

2014 ◽  
Vol 197 (5) ◽  
pp. 1002-1011 ◽  
Author(s):  
Annika Flint ◽  
Alain Stintzi
Keyword(s):  
Escherichia Coli ◽  
Campylobacter Jejuni ◽  
Biochemical Properties ◽  
Wild Type ◽  
Visible Spectroscopy ◽  
Content Type ◽  
Increased Sensitivity ◽  
Uv Visible

Catalase enzymes detoxify H2O2by the dismutation of H2O2into O2and H2O through the use of hemin cofactors. While the structure and biochemical properties of catalase enzymes have been well characterized over many decades of research, it remained unclear how catalases acquire hemin. We have previously reported that Cj1386 is essential for ensuring proper hemin content inCampylobacter jejunicatalase (KatA) (A. Flint, Y. Q. Sun, and A. Stintzi, J Bacteriol194:334–345, 2012). In this report, an in-depth molecular characterization of Cj1386 was performed to elucidate the mechanistic details of this association. Coimmunoprecipitation assays revealed that KatA-Cj1386 transiently interactin vivo, and UV-visible spectroscopy demonstrated that purified Cj1386 protein binds hemin. Furthermore, hemin titration experiments determined that hemin binds to Cj1386 in a 1:1 ratio with hexacoordinate hemin binding. Mutagenesis of potential hemin-coordinating residues in Cj1386 showed that tyrosine 57 was essential for hemin coordination when Cj1386 was overexpressed inEscherichia coli. The importance of tyrosine 57 in hemin traffickingin vivowas confirmed by introducing thecj1386Y57Aallele into aC. jejuniΔcj1386mutant background. Thecj1386Y57Amutation resulted in increased sensitivity toward H2O2relative to the wild type, suggesting that KatA was not functional in this strain. In support of this finding, KatA immunoprecipitated from the Δcj1386+cj1386Y57Amutant had significantly reduced hemin content compared to that of thecj1386WTbackground. Overall, these findings indicate that Cj1386 is involved in directly trafficking hemin to KatA and that tyrosine 57 plays a key role in this function.

scholarly journals Impact ofEimeria tenellaCoinfection onCampylobacter jejuniColonization of the Chicken

2018 ◽  
Vol 87 (2) ◽  
Author(s):  
Sarah E. Macdonald ◽  
Pauline M. van Diemen ◽  
Henny Martineau ◽  
Mark P. Stevens ◽  
Fiona M. Tomley ◽  
...  
Keyword(s):  
Well Being ◽  
Dependent Manner ◽  
Secondary Effects ◽  
Negative Effects ◽  
Content Type ◽  
Serovar Typhimurium ◽  
The Impact ◽  
Dose Dependent ◽  
Detrimental Impact

ABSTRACTEimeria tenellacan cause the disease coccidiosis in chickens. The direct and often detrimental impact of this parasite on chicken health, welfare, and productivity is well recognized; however, less is known about the secondary effects that infection may have on other gut pathogens.Campylobacter jejuniis the leading cause of human bacterial foodborne disease in many countries and has been demonstrated to exert negative effects on poultry welfare and production in some broiler lines. Previous studies have shown that concurrentEimeriainfection can influence the colonization and replication of bacteria, such asClostridium perfringensandSalmonella entericaserovar Typhimurium. Through a series ofin vivocoinfection experiments, this study evaluated the impact thatE. tenellainfection had onC. jejunicolonization of chickens, including the influence of variations in parasite dose and sampling time after bacterial challenge. Coinfection withE. tenellaresulted in a significant increase inC. jejunicolonization in the cecum in a parasite dose-dependent manner but a significant decrease inC. jejunicolonization in the spleen and liver of chickens. The results were reproducible at 3 and 10 days after bacterial infection. This work highlights thatE. tenellanot only has a direct impact on the health and well-being of chickens but can have secondary effects on important zoonotic pathogens.

scholarly journals In VivoEvolution of CMY-2 to CMY-33 β-Lactamase in Escherichia coli Sequence Type 131: Characterization of an Acquired Extended-Spectrum AmpC Conferring Resistance to Cefepime

2015 ◽  
Vol 59 (12) ◽  
pp. 7483-7488 ◽  
Author(s):  
João Pires ◽  
Magdalena Taracila ◽  
Christopher R. Bethel ◽  
Yohei Doi ◽  
Sara Kasraian ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bronchoalveolar Lavage Fluid ◽  
Lavage Fluid ◽  
Sequence Type ◽  
Content Type ◽  
E Coli ◽  
Extended Spectrum ◽  
Repetitive Extragenic Palindromic Pcr

ABSTRACTCefepime is frequently prescribed to treat infections caused by AmpC-producing Gram-negative bacteria. CMY-2 is the most common plasmid-mediated AmpC (pAmpC) β-lactamase. Unfortunately, CMY variants conferring enhanced cefepime resistance have been reported. Here, we describe the evolution of CMY-2 to an extended-spectrum AmpC (ESAC) in clonally identicalEscherichia coliisolates obtained from a patient. The CMY-2-producingE. coliisolate (CMY-2-Ec) was isolated from a wound. Thirty days later, one CMY-33-producingE. coliisolate (CMY-33-Ec) was detected in a bronchoalveolar lavage fluid sample. Two weeks before the isolation of CMY-33-Ec, the patient received cefepime. CMY-33-Ecand CMY-2-Ecwere identical by repetitive extragenic palindromic-PCR (rep-PCR), being of hyperepidemic sequence type 131 (ST131) but showing different β-lactam MICs (e.g., cefepime MIC, 16 and ≤0.5 μg/ml for CMY-33-Ecand CMY-2-Ec, respectively). Identical CMY-2-Ecisolates were also found in a rectal swab. CMY-33 differs from CMY-2 by a Leu293-Ala294 deletion. Expressed inE. colistrain DH10B, both CMYs conferred resistance to ceftazidime (≥256 μg/ml), but the cefepime MICs were higher for CMY-33 than CMY-2 (8 versus 0.25 μg/ml, respectively). Thekcat/Kmor inhibitor complex inactivation (kinact)/Kiapp(μM−1s−1) indicated that CMY-33 possesses an extended-spectrum β-lactamase (ESBL)-like spectrum compared to that of CMY-2 (e.g., cefoxitin, 0.2 versus 0.4; ceftazidime, 0.2 versus not measurable; cefepime, 0.2 versus not measurable; and tazobactam, 0.0018 versus 0.0009, respectively). Using molecular modeling, we show that a widened active site (∼4-Å shift) may play a significant role in enhancing cefepime hydrolysis. This is the firstin vivodemonstration of a pAmpC that under cephalosporin treatment expands its substrate spectrum, resembling an ESBL. The prevalence of CMY-2-Ecisolates is rapidly increasing worldwide; therefore, awareness that cefepime treatment may select for resistant isolates is critical.

scholarly journals Characterization of a Mutant Escherichia coli Heat-Labile Toxin, LT(R192G/L211A), as a Safe and Effective Oral Adjuvant

2011 ◽  
Vol 18 (4) ◽  
pp. 546-551 ◽  
Author(s):  
Elizabeth B. Norton ◽  
Louise B. Lawson ◽  
Lucy C. Freytag ◽  
John D. Clements
Keyword(s):  
Escherichia Coli ◽  
Mammalian Cells ◽  
Oral Vaccines ◽  
Content Type ◽  
Intracellular Degradation ◽  
Heat Labile ◽  
Increased Sensitivity

ABSTRACTDespite the fact that the adjuvant properties of the heat-labile enterotoxins ofEscherichia coli(LT) andVibrio cholerae(CT) have been known for more than 20 years, there are no available oral vaccines containing these molecules as adjuvants, primarily because they are both very potent enterotoxins. A number of attempts with various degrees of success have been made to reduce or eliminate the enterotoxicity of LT and CT so they can safely be used as oral adjuvants or immunogens. In this report we characterize the structural, enzymatic, enterotoxic, and adjuvant properties of a novel mutant of LT, designated LT(R192G/L211A), or dmLT. dmLT was not sensitive to trypsin activation, had reduced enzymatic activity for induction of cyclic AMP in Caco-2 cells, and exhibited no enterotoxicity in the patent mouse assay. Importantly, dmLT retained the ability to function as an oral adjuvant for a coadministered antigen (tetanus toxoid) and to elicit anti-LT antibodies.In vitroandin vivodata suggest that the reduced enterotoxicity of this molecule compared to native LT or the single mutant, LT(R192G), is a consequence of increased sensitivity to proteolysis and rapid intracellular degradation in mammalian cells. In conclusion, dmLT is a safe and powerful detoxified enterotoxin with the potential to function as a mucosal adjuvant for coadministered antigens and to elicit anti-LT antibodies without undesirable side effects.

scholarly journals Virulence-Suppressing Effects of Linezolid on Methicillin-Resistant Staphylococcus aureus: Possible Contribution to Early Defervescence

2012 ◽  
Vol 56 (4) ◽  
pp. 1744-1748 ◽  
Author(s):  
Sadako Yoshizawa ◽  
Kazuhiro Tateda ◽  
Tomoo Saga ◽  
Yoshikazu Ishii ◽  
Keizo Yamaguchi
Keyword(s):  
Staphylococcus Aureus ◽  
Inflammatory Cytokines ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Methicillin Resistance ◽  
Positive Culture ◽  
Dependent Manner ◽  
Content Type ◽  
Anti Inflammatory ◽  
Dose Dependent

ABSTRACTIn the present study, immunomodulatory effects of linezolid (LZD) on methicillin-resistanceStaphylococcus aureus(MRSA) infections were evaluated. We have retrospectively reviewed treatment effects of LZD on 52 patients with severe MRSA infections. Sixty-four percent of the febrile patients demonstrated significant defervescence within 3 days, despite the presence of positive culture results. We speculated that this finding might be due to early anti-inflammatory effects of LZD, and to investigate this further we initiatedin vivoexperiments using mice MRSA pneumonia models. Mice were treated with either LZD or vancomycin (VCM) immediately after intranasal administration of MRSA. Bacterial numbers and levels of inflammatory cytokines in the lungs were determined. Although the bacterial burden in the lungs was not apparently different between the two groups, LZD but not VCM treatment significantly reduced induction of inflammatory cytokines in the lungs (P< 0.05). To evaluate whether this anti-inflammatory response was due to suppression of virulence factor expression, filter-sterilized supernatants of MRSA incubated in broth overnight with sub-MICs of LZD were subcutaneously administered to mice. To clarify whether LZD possesses direct host-modulating activity, cytokine responses to the supernatants were examined in mice pretreated with LZD. Interestingly, MRSA solutions prepared in the presence of sub-MICs of LZD revealed significant suppression of interleukin 6 (IL-6) in a dose-dependent manner (P< 0.05), but pretreatment of mice with LZD revealed no changes in cytokines. These findings suggest that sub-MICs of LZD might suppress virulence factors of MRSA, which may be associated with a reduction in endogenous pyrogens. These data may explain at least in part early defervescence observed in LZD-treated individuals.

Effects of prostacyclin and indomethacin on experimental delayed cerebral vasospasm

1983 ◽  
Vol 59 (5) ◽  
pp. 829-834 ◽  
Author(s):  
Toyokazu Fukumori ◽  
Eiichi Tani ◽  
Yukio Maeda ◽  
Atsuhiko Sukenaga
Keyword(s):  
Basilar Artery ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Content Type ◽  
Mean Values ◽  
Delayed Cerebral Vasospasm ◽  
Arterial Blood ◽  
Canine Basilar Artery ◽  
Dose Dependent

✓ Isolated canine basilar artery contracted by prostaglandin E2, hemoglobin, or serum was relaxed in a dose-dependent manner by the addition of 10−8M to 10−6M prostacyclin (PGI2), and was scarcely relaxed by 10−9M PGI2. In other studies, intravenous administration of PGI2 (25 or 75 ng/kg/min), indomethacin (4 mg/kg), or indomethacin (4 mg/kg) plus PGI2 (25 ng/kg/min) failed to reverse angiographic delayed vasospasm produced in vivo in the canine basilar artery by an intracisternal injection of blood. In addition, no significant increase occurred in mean values of regional cerebral blood flow (rCBF) with any treatments, and mean rCBF difference in dogs treated by PGI2 infusion at 25 ng/kg/min was 2.5 ± 1.2 ml/100 gm/min and only significantly increased (p < 0.01). Mean arterial blood pressure was significantly reduced by PGI2 infusion at 25 (p < 0.05) or 75 ng/kg/min (p < 0.005).

Effects of NO-Donors on Thrombus Formation and Microcirculation in Cerebral Vessels of the Rat

1996 ◽  
Vol 76 (01) ◽  
pp. 111-117 ◽  
Author(s):  
Yasuto Sasaki ◽  
Junji Seki ◽  
John C Giddings ◽  
Junichiro Yamamoto
Keyword(s):  
Blood Flow ◽  
Thrombus Formation ◽  
Dependent Manner ◽  
Red Cell ◽  
Cell Velocity ◽  
Red Cell Velocity ◽  
The Mean ◽  
Wall Shear ◽  
Dose Dependent

SummarySodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1), are known to liberate nitric oxide (NO). In this study the effects of SNP and SIN-1 on thrombus formation in rat cerebral arterioles and venules in vivo were assessed using a helium-neon (He-Ne) laser. SNP infused at doses from 10 Μg/kg/h significantly inhibited thrombus formation in a dose dependent manner. This inhibition of thrombus formation was suppressed by methylene blue. SIN-1 at a dose of 100 Μg/kg/h also demonstrated a significant antithrombotic effect. Moreover, treatment with SNP increased vessel diameter in a dose dependent manner and enhanced the mean red cell velocity measured with a fiber-optic laser-Doppler anemometer microscope (FLDAM). Blood flow, calculated from the mean red cell velocity and vessel diameters was increased significantly during infusion. In contrast, mean wall shear rates in the arterioles and venules were not changed by SNP infusion. The results indicated that SNP and SIN-1 possessed potent antithrombotic activities, whilst SNP increased cerebral blood flow without changing wall shear rate. The findings suggest that the NO released by SNP and SIN-1 may be beneficial for the treatment and protection of cerebral infarction

scholarly journals Anti-tumor activity of a novel proteasome inhibitor D395 against multiple myeloma and its lower cardiotoxicity compared with carfilzomib

2021 ◽  
Vol 12 (5) ◽  
Author(s):  
Xuxing Shen ◽  
Chao Wu ◽  
Meng Lei ◽  
Qing Yan ◽  
Haoyang Zhang ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Proteasome Inhibitor ◽  
Osteoclast Differentiation ◽  
Dependent Manner ◽  
Serum Enzyme ◽  
Herg Channels ◽  
Anti Tumor Activity ◽  
Dose Dependent

AbstractCarfilzomib, a second-generation proteasome inhibitor, has significantly improved the survival rate of multiple myeloma (MM) patients, but its clinical application is still restricted by drug resistance and cardiotoxicity. Here, we identified a novel proteasome inhibitor, D395, and assessed its efficacy in treating MM as well as its cardiotoxicity at the preclinical level. The activities of purified and intracellular proteasomes were measured to determine the effect of D395 on the proteasome. CCK-8 and flow cytometry experiments were designed to evaluate the effects of D395 on cell growth and apoptosis. The effects of D395 and carfilzomib on serum enzyme activity, echocardiography features, cardiomyocyte morphology, and hERG channels were also compared. In our study, D395 was highly cytotoxic to MM cell lines and primary MM cells but not normal cells, and it was well tolerated in vivo. Similar to carfilzomib, D395 inhibited osteoclast differentiation in a dose-dependent manner. In particular, D395 exhibited lower cardiotoxicity than carfilzomib in all experiments. In conclusion, D395 is a novel irreversible proteasome inhibitor that has remarkable anti-MM activity and mild cardiotoxicity in vitro and in vivo.

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