scholarly journals Gamma Interferon Production by Hepatic NK T Cells during Escherichia coli Infection Is Resistant to the Inhibitory Effects of Oxidative Stress

2003 ◽  
Vol 71 (5) ◽  
pp. 2468-2477 ◽  
Author(s):  
Guochi Zhang ◽  
Robert Dru Nichols ◽  
Masaru Taniguchi ◽  
Toshinori Nakayama ◽  
Michael J. Parmely
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Escherichia Coli ◽  
T Cells ◽  
Nk Cells ◽  
Inhibitory Effects ◽  
Gram Negative ◽  
E Coli ◽  
Nk T Cells ◽  
Ifn Γ

ABSTRACT The reductive-oxidative status of tissues regulates the expression of many inflammatory genes that are induced during gram-negative bacterial infections. The cytokine gamma interferon (IFN-γ) is a potent stimulus for host inflammatory gene expression, and oxidative stress has been shown to inhibit its production in mice challenged with Escherichia coli bacteria. The objective of the present study was to characterize the cells that produced IFN-γ in a mouse bacterial peritonitis model and determine the effects of oxidative stress on their activation. The liver contained large numbers of IFN-γ-expressing lymphocytes following challenge with viable E. coli bacteria. The surface phenotypes of IFN-γ-expressing hepatic lymphocytes were those of natural killer (NK) cells (NK1.1+ CD3−), conventional T cells (NK1.1− CD3+), and NK T cells (NK1.1+ CD3+). Treating mice with diethyl maleate to deplete tissue thiols significantly impaired IFN-γ production by NK cells, conventional T cells, and CD1d-restricted NK T cells in response to E. coli challenge. However, IFN-γ expression by a subset of NK T cells, which did not bind α-galactosylceramide-CD1d tetramers, was resistant to the inhibitory effects of tissue oxidative stress. Stress-resistant IFN-γ-expressing cells were also predominantly CD8+ and bore γδ T-cell antigen receptors. The residual IFN-γ response by NK T cells may explain previous reports of hepatic gene expression following gram-negative bacterial challenge in thiol-depleted mice. The finding also demonstrates that innate immune cells differ significantly in their responses to altered tissue redox status.

scholarly journals Cultivation at high osmotic pressure confers ubiquinone 8–independent protection of respiration on Escherichia coli

2019 ◽  
Vol 295 (4) ◽  
pp. 981-993 ◽  
Author(s):  
Laura Tempelhagen ◽  
Anita Ayer ◽  
Doreen E. Culham ◽  
Roland Stocker ◽  
Janet M. Wood
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Escherichia Coli ◽  
Electron Transfer ◽  
Oxygen Uptake ◽  
Osmotic Pressure ◽  
Respiratory Chain ◽  
Membrane Lipid ◽  
E Coli ◽  
Uptake Rates

Ubiquinone 8 (coenzyme Q8 or Q8) mediates electron transfer within the aerobic respiratory chain, mitigates oxidative stress, and contributes to gene expression in Escherichia coli. In addition, Q8 was proposed to confer bacterial osmotolerance by accumulating during growth at high osmotic pressure and altering membrane stability. The osmolyte trehalose and membrane lipid cardiolipin accumulate in E. coli cells cultivated at high osmotic pressure. Here, Q8 deficiency impaired E. coli growth at low osmotic pressure and rendered growth osmotically sensitive. The Q8 deficiency impeded cellular O2 uptake and also inhibited the activities of two proton symporters, the osmosensing transporter ProP and the lactose transporter LacY. Q8 supplementation decreased membrane fluidity in liposomes, but did not affect ProP activity in proteoliposomes, which is respiration-independent. Liposomes and proteoliposomes prepared with E. coli lipids were used for these experiments. Similar oxygen uptake rates were observed for bacteria cultivated at low and high osmotic pressures. In contrast, respiration was dramatically inhibited when bacteria grown at the same low osmotic pressure were shifted to high osmotic pressure. Thus, respiration was restored during prolonged growth of E. coli at high osmotic pressure. Of note, bacteria cultivated at low and high osmotic pressures had similar Q8 concentrations. The protection of respiration was neither diminished by cardiolipin deficiency nor conferred by trehalose overproduction during growth at low osmotic pressure, but rather might be achieved by Q8-independent respiratory chain remodeling. We conclude that osmotolerance is conferred through Q8-independent protection of respiration, not by altering physical properties of the membrane.

scholarly journals Gamma Interferon Prevents the Inhibitory Effects of Oxidative Stress on Host Responses to Escherichia coliInfection

2001 ◽  
Vol 69 (4) ◽  
pp. 2621-2629 ◽  
Author(s):  
Michael J. Parmely ◽  
Fuan Wang ◽  
Douglas Wright
Keyword(s):  
Oxidative Stress ◽  
Bacterial Infections ◽  
Gamma Interferon ◽  
Glutathione Depletion ◽  
Intercellular Adhesion Molecule ◽  
Necrosis Factor Alpha ◽  
Gram Negative ◽  
E Coli ◽  
Redox Imbalance ◽  
Ifn Γ

ABSTRACT Oxidative stress occurs in animals challenged with bacterial endotoxin and can affect the expression of important host inflammatory genes. However, much less is known about the effects of oxidative stress on responses to gram-negative bacteria. The current study compared the effects of redox imbalance on hepatic responses of mice to Escherichia coli bacteria versus purified endotoxic lipopolysaccharide (LPS). Oxidative stress induced by glutathione depletion virtually eliminated hepatic tumor necrosis factor alpha responses to both E. coli and LPS. Inducible NO synthase (iNOS) and intercellular adhesion molecule-1 (ICAM-1) expression was also markedly inhibited by glutathione depletion in LPS-challenged mice, but was unaffected in E. coli-infected animals. Three findings suggested that gamma interferon (IFN-γ) production explained the differences between LPS and bacterial challenge. Glutathione depletion completely inhibited the IFN-γ response to LPS, but only partially inhibited IFN-γ production in infected mice. Exogenous IFN-γ restored iNOS and ICAM-1 responses to LPS in stressed mice. Conversely, IFN-γ-deficient, glutathione-depleted mice showed a marked decrease in iNOS and ICAM-1 expression when challenged with E. coli. These findings indicate that both the nature of the microbial challenge and the production of IFN-γ can be important in determining the effects of redox imbalance during gram-negative bacterial infections.

scholarly journals Oxidative Stress and Antimicrobial Activity of Chromium(III) and Ruthenium(II) Complexes onStaphylococcus aureusandEscherichia coli

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Paulina L. Páez ◽  
Claudia M. Bazán ◽  
María E. Bongiovanni ◽  
Judith Toneatto ◽  
Inés Albesa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Antibacterial Agents ◽  
Antibacterial Activities ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
Diimine Ligands

The prevalence of antibiotic resistance has resulted in the need for new approaches to be developed to combat previously easily treatable infections. The main aim of this work was to establish the potential of the syntheticα-diimine chromium(III) and ruthenium(II) complexes (where theα-diimine ligands are bpy = 2,2-bipyridine, phen = 1,10-phenanthroline, and dppz = dipyrido[3,2-a:2′,3′-c]-phenazine) like [Cr(phen)3]3+, [Cr(phen)2(dppz)]3+, [Ru(phen)3]2+, and [Ru(bpy)3]2+as antibacterial agents by generating oxidative stress. The [Cr(phen)3]3+and [Cr(phen)2(dppz)]3+complexes showed activity against Gram positive and Gram negative bacteria with minimum inhibitory concentrations (MICs) ranging from 0.125 μg/mL to 1 μg/mL, while [Ru(phen)3]2+and [Ru(bpy)3]2+do not exhibit antimicrobial activity against the two bacterial genera studied at the concentration range used. When ciprofloxacin was combined with [Cr(phen)3]3+for the inhibition ofStaphylococcus aureusandEscherichia coli, an important synergistic effect was observed, FIC 0.066 forS. aureusand FIC 0.064 forE. coli. The work described here shows that chromium(III) complexes are bactericidal forS. aureusandE. coli. Our results indicate thatα-diimine chromium(III) complexes may be interesting to open new paths for metallodrug chemotherapy against different bacterial genera since some of these complexes have been found to exhibit remarkable antibacterial activities.

scholarly journals Increasing the Oxidative Stress Response Allows Escherichia coli To Overcome Inhibitory Effects of Condensed Tannins

2003 ◽  
Vol 69 (6) ◽  
pp. 3406-3411 ◽  
Author(s):  
Alexandra H. Smith ◽  
James A. Imlay ◽  
Roderick I. Mackie
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Condensed Tannins ◽  
Resistant Mutant ◽  
Inhibitory Effect ◽  
Oxidative Stress Response ◽  
Inhibitory Effects ◽  
Acacia Mearnsii ◽  
E Coli

ABSTRACT Tannins are plant-derived polyphenols with antimicrobial effects. The mechanism of tannin toxicity towards Escherichia coli was determined by using an extract from Acacia mearnsii (Black wattle) as a source of condensed tannins (proanthocyanidins). E. coli growth was inhibited by tannins only when tannins were exposed to oxygen. Tannins auto-oxidize, and substantial hydrogen peroxide was generated when they were added to aerobic media. The addition of exogenous catalase permitted growth in tannin medium. E. coli mutants that lacked HPI, the major catalase, were especially sensitive to tannins, while oxyR mutants that constitutively overexpress antioxidant enzymes were resistant. A tannin-resistant mutant was isolated in which a promoter-region point mutation increased the level of HPI by 10-fold. Our results indicate that wattle condensed tannins are toxic to E. coli in aerobic medium primarily because they generate H2O2. The oxidative stress response helps E. coli strains to overcome their inhibitory effect.

scholarly journals Contribution of NK, NK T, γδ T, and αβ T Cells to the Gamma Interferon Response Required for Liver Protection against Trypanosoma cruzi

2006 ◽  
Vol 74 (4) ◽  
pp. 2031-2042 ◽  
Author(s):  
Luiz Roberto Sardinha ◽  
Rosa Maria Elias ◽  
Tainá Mosca ◽  
Karina R. B. Bastos ◽  
Cláudio R. F. Marinho ◽  
...  
Keyword(s):  
T Cells ◽  
Trypanosoma Cruzi ◽  
Nk Cells ◽  
Γδ T Cells ◽  
Gamma Interferon ◽  
Cell Populations ◽  
Liver Protection ◽  
Nk T Cells ◽  
Ifn Γ ◽  
Deficient Mice

ABSTRACT In the present work, we show that intracellular Trypanosoma cruzi is rarely found in the livers of acutely infected mice, but inflammation is commonly observed. The presence of numerous intrahepatic amastigotes in infected gamma interferon (IFN-γ)-deficient mice corroborates the notion that the liver is protected by an efficient local immunity. The contribution of different cell populations was suggested by data showing that CD4- and CD8-deficient mice were able to restrain liver parasite growth. Therefore, we have characterized the liver-infiltrating lymphocytes and determined the sources of IFN-γ during acute T. cruzi infection. We observed that natural killer (NK) cells increased by day 7, while T and B cells increased by day 14. Among CD3+ cells, CD4+, CD8+, and CD4− CD8− cell populations were greatly expanded. A large fraction of CD3+ cells were positive for PanNK, a β1 integrin expressed by NK and NK T cells. However, these lymphocytes were not classic NK T cells because they did not express NK1.1 and showed no preferential usage of Vβ8. Otherwise, liver NK T (CD3+ NK1.1+) cells were not increased in acutely infected mice. The majority of PanNK+ CD4+ and PanNK+ CD8+ cells expressed T-cell receptor αβ (TCRαβ), whereas PanNK+ CD4− CD8− cells were positive for TCRγδ. In fact, γδ T cells showed the most remarkable increase (40- to 100-fold) among liver lymphocytes. Most importantly, intracellular analysis revealed high levels of IFN-γ production at day 7 by NK cells and at day 14 by CD4+, CD8+, and CD4− CD8− TCRγδ+ cells. We concluded that NK cells are a precocious source of IFN-γ in the livers of acutely infected mice, and, as the disease progresses, conventional CD4+ and CD8+ T cells and γδ T cells, but not classic NK-T cells, may provide the IFN-γ required for liver protection against T. cruzi.

scholarly journals Carbon starvation-induced lipoprotein Slp directs the synthesis of catalase and expression of OxyR regulator to protect against hydrogen peroxide stress in Escherichia coli

2018 ◽  
Author(s):  
Xiaoxia Li ◽  
Yuanhong Xie ◽  
Junhua Jin ◽  
Hui Liu ◽  
Xiuzhi Gao ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Antioxidant Enzymes ◽  
Mutant Strain ◽  
Carbon Starvation ◽  
E Coli ◽  
Unique Mapping ◽  
Peroxide Stress

AbstractEscherichia coli can induce a group of stress-response proteins, including carbon starvation-induced lipoprotein (Slp), which is an outer membrane lipoprotein expressed in response to stressful environments. In this paper, slp null mutantE. coli were constructed by insertion of the group II intron, and then the growth sensitivity of the slp mutant strain was measured under 0.6% (vol/vol) hydrogen peroxide. The changes in resistance to hydrogen peroxide stress were investigated by detecting antioxidant activity and gene expression in the slp mutant strain. The results showed that deletion of the slp gene increased the sensitivity of E. coli under 0.6% (vol/vol) hydrogen peroxide oxidative stress. Analysis of the unique mapping rates from the transcriptome libraries revealed that four of thirteen remarkably up/down-regulated genes in E. coli were involved in antioxidant enzymes after mutation of the slp gene. Mutation of the slp gene caused a significant increase in catalase activity, which contributed to an increase in glutathione peroxidase activity. The katG gene was activated by the OxyR regulator, which was activated directly by 0.6% (vol/vol) hydrogen peroxide, and HPI encoded by katG was induced against oxidative stress. Therefore, the carbon starvation-induced lipoprotein Slp regulates the expression of antioxidant enzymes and the transcriptional activator OxyR in response to the hydrogen peroxide environment, ensuring that cells are protected from hydrogen peroxide oxidative stress at the level of enzyme activity and gene expression.

Synthesis of Chalcones and Nucleosides Incorporating [1, 3, 4]Oxadiazolenone Core and Evaluation of their Antifungal and Antibacterial Activities

2020 ◽  
Vol 15 (6) ◽  
pp. 665-679
Author(s):  
Alok K. Srivastava ◽  
Lokesh K. Pandey
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Bacillus Subtilis ◽  
Antifungal Activity ◽  
Aspergillus Niger ◽  
Gram Negative ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Good Antibacterial Activity

Background: [1, 3, 4]oxadiazolenone core containing chalcones and nucleosides were synthesized by Claisen-Schmidt condensation of a variety of benzaldehyde derivatives, obtained from oxidation of substituted 5-(3/6 substituted-4-Methylphenyl)-1, 3, 4-oxadiazole-2(3H)-one and various substituted acetophenone. The resultant chalcones were coupled with penta-O-acetylglucopyranose followed by deacetylation to get [1, 3, 4] oxadiazolenone core containing chalcones and nucleosides. Various analytical techniques viz IR, NMR, LC-MS and elemental analysis were used to confirm the structure of the synthesised compounds.The compounds were targeted against Bacillus subtilis, Staphylococcus aureus and Escherichia coli for antibacterial activity and Aspergillus flavus, Aspergillus niger and Fusarium oxysporum for antifungal activity. Methods: A mixture of Acid hydrazides (3.0 mmol) and N, Nʹ- carbonyl diimidazole (3.3 mmol) in 15 mL of dioxane was refluxed to afford substituted [1, 3, 4]-oxadiazole-2(3H)-one. The resulted [1, 3, 4]- oxadiazole-2(3H)-one (1.42 mmol) was oxidized with Chromyl chloride (1.5 mL) in 20 mL of carbon tetra chloride and condensed with acetophenones (1.42 mmol) to get chalcones 4. The equimolar ratio of obtained chalcones 4 and β -D-1,2,3,4,6- penta-O-acetylglucopyranose in presence of iodine was refluxed to get nucleosides 5. The [1, 3, 4] oxadiazolenone core containing chalcones 4 and nucleosides 5 were tested to determined minimum inhibitory concentration (MIC) value with the experimental procedure of Benson using disc-diffusion method. All compounds were tested at concentration of 5 mg/mL, 2.5 mg/mL, 1.25 mg/mL, 0.62 mg/mL, 0.31 mg/mL and 0.15 mg/mL for antifungal activity against three strains of pathogenic fungi Aspergillus flavus (A. flavus), Aspergillus niger (A. niger) and Fusarium oxysporum (F. oxysporum) and for antibacterial activity against Gram-negative bacterium: Escherichia coli (E. coli), and two Gram-positive bacteria: Staphylococcus aureus (S. aureus) and Bacillus subtilis(B. subtilis). Result: The chalcones 4 and nucleosides 5 were screened for antibacterial activity against E. coli, S. aureus and B. subtilis whereas antifungal activity against A. flavus, A. niger and F. oxysporum. Compounds 4a-t showed good antibacterial activity whereas compounds 5a-t containing glucose moiety showed better activity against fungi. The glucose moiety of compounds 5 helps to enter into the cell wall of fungi and control the cell growth. Conclusion: Chalcones 4 and nucleosides 5 incorporating [1, 3, 4] oxadiazolenone core were synthesized and characterized by various spectral techniques and elemental analysis. These compounds were evaluated for their antifungal activity against three fungi; viz. A. flavus, A. niger and F. oxysporum. In addition to this, synthesized compounds were evaluated for their antibacterial activity against gram negative bacteria E. Coli and gram positive bacteria S. aureus, B. subtilis. Compounds 4a-t showed good antibacterial activity whereas 5a-t showed better activity against fungi.

scholarly journals Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Tessa B. Moyer ◽  
Ashleigh L. Purvis ◽  
Andrew J. Wommack ◽  
Leslie M. Hicks
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Antimicrobial Peptides ◽  
Mechanism Of Action ◽  
Gram Negative Bacteria ◽  
Amaranthus Tricolor ◽  
Core Motif ◽  
Gram Negative ◽  
E Coli ◽  
Membrane Lysis

Abstract Background Plant defensins are a broadly distributed family of antimicrobial peptides which have been primarily studied for agriculturally relevant antifungal activity. Recent studies have probed defensins against Gram-negative bacteria revealing evidence for multiple mechanisms of action including membrane lysis and ribosomal inhibition. Herein, a truncated synthetic analog containing the γ-core motif of Amaranthus tricolor DEF2 (Atr-DEF2) reveals Gram-negative antibacterial activity and its mechanism of action is probed via proteomics, outer membrane permeability studies, and iron reduction/chelation assays. Results Atr-DEF2(G39-C54) demonstrated activity against two Gram-negative human bacterial pathogens, Escherichia coli and Klebsiella pneumoniae. Quantitative proteomics revealed changes in the E. coli proteome in response to treatment of sub-lethal concentrations of the truncated defensin, including bacterial outer membrane (OM) and iron acquisition/processing related proteins. Modification of OM charge is a common response of Gram-negative bacteria to membrane lytic antimicrobial peptides (AMPs) to reduce electrostatic interactions, and this mechanism of action was confirmed for Atr-DEF2(G39-C54) via an N-phenylnaphthalen-1-amine uptake assay. Additionally, in vitro assays confirmed the capacity of Atr-DEF2(G39-C54) to reduce Fe3+ and chelate Fe2+ at cell culture relevant concentrations, thus limiting the availability of essential enzymatic cofactors. Conclusions This study highlights the utility of plant defensin γ-core motif synthetic analogs for characterization of novel defensin activity. Proteomic changes in E. coli after treatment with Atr-DEF2(G39-C54) supported the hypothesis that membrane lysis is an important component of γ-core motif mediated antibacterial activity but also emphasized that other properties, such as metal sequestration, may contribute to a multifaceted mechanism of action.

scholarly journals THU0052 RELATIONSHIP BETWEEN INTERFERON-Γ-PRODUCING IMMUNOCOMPETENT CELLS AND DISEASE ACTIVITY IN ADULT-ONSET STILL’S DISEASE

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 238.1-238
Author(s):  
Y. Shimojima ◽  
D. Kishida ◽  
T. Ichikawa ◽  
Y. Sekijima
Keyword(s):  
T Cells ◽  
Disease Activity ◽  
Nk Cells ◽  
Acute Phase ◽  
Serum Ferritin ◽  
Interferon Γ ◽  
Adult Onset Still’S Disease ◽  
Still’S Disease ◽  
Ifn Γ ◽  
Adult Onset Still's Disease

Background:In the acute phase of adult-onset Still’s disease (AOSD), elevated levels of proinflammatory cytokines including interferon-γ (IFN-γ) are shown. Moreover, IFN-γ impacts on activating macrophages which play a crucial role in the pathogenesis of AOSD. Natural killer (NK) cells and T helper cells are in charge of secreting IFN-γ in the innate and adaptive immune systems of disease, respectively. However, the features of their IFN-γ-producing variation depending on disease activity are still uncertain in AOSD.Objectives:We investigated characteristics of IFN-γ-producing CD4+T cells and NK cells in patients with AOSD.Methods:Twenty-four patients in the acute phase of AOSD (active AOSD), 8 of them after treatment (remission), and 12 healthy controls (HC) were recruited in this study. Peripheral blood mononuclear cells and serum samples were provided from them for the experimental analysis. Flow cytometry was used for analyzing CD4+T cells, CD4+regulatory T cells (Tregs), NK cells, and their intracellular IFN-γ expression levels as well as suppression assay of Tregs. The serum concentration of interleukin-18 (IL-18) was measured using commercially available ELISA kit. Relationship between the analyzed data and clinical findings related to disease activity were statistically evaluated.Results:IFN-γ expression in CD4+T cells was significantly higher in active AOSD than in HC (p < 0.05). Tregs also significantly indicated higher expression of IFN-γ in active AOSD than in HC (p < 0.0001); and moreover, Tregs were significantly impaired in their suppression ability (p < 0.05). In both CD4+T cells and Tregs, expression of IFN-γ was significantly correlated with serum ferritin levels in active AOSD (p < 0.05). IFN-γ expression in CD4+T cells was significantly higher in patients with splenomegaly than those without that (p < 0.05). The proportion of NK cells was significantly lower in active AOSD than in HC (p < 0.005), whereas IFN-γ expression in NK cells was significantly higher in active AOSD than in HC (p < 0.0005). The number of NK cells and IFN-γ-expressing NK cells had inverse relationship with serum ferritin levels in active AOSD (p < 0.05 and p < 0.005, respectively). Increased number of NK cells and their decreased expression of IFN-γ were significantly demonstrated in remission (p < 0.05). In the analyses of NK cell subsets, lower expression of IFN-γ in CD56brightNK cells and higher that in CD56dimNK cells were significantly indicated in active AOSD than HC (p < 0.05). In remission, IFN-γ expression was significantly decreased in CD56dimNK cells (p < 0.05) despite no significant recovery of that in CD56brightNK cells (p = 0.311). Meanwhile, increased expression of IFN-γ in CD56brightNK cells was demonstrated in only patients who were treated with biologics. Although serum levels of IL-18 were significantly higher in active AOSD than in remission and HC; however, they had no significant correlations with any analyzed data.Conclusion:CD4+T cells and NK cells promote IFN-γ expression in the acute phase of AOSD. Meanwhile, increased expression of IFN-γ in CD4+T cells and decreased number of NK cells were correlated with serum ferritin levels, suggesting that they are indicators of disease activity. Furthermore, high disease activity may impact on the alteration of IFN-γ-producing balance in two distinct population of NK cells, and the plasticity of Tregs leading to defect in suppression ability.Disclosure of Interests:None declared

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