11 results on '"Mohamed Ibrahem Elhawy"'
Search Results
2. Taste Receptor Activation in Tracheal Brush Cells by Denatonium Modulates ENaC Channels via Ca
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Monika I, Hollenhorst, Praveen, Kumar, Maxim, Zimmer, Alaa, Salah, Stephan, Maxeiner, Mohamed Ibrahem, Elhawy, Saskia B, Evers, Veit, Flockerzi, Thomas, Gudermann, Vladimir, Chubanov, Ulrich, Boehm, and Gabriela, Krasteva-Christ more...
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Quaternary Ammonium Compounds ,Mice ,Taste ,Cyclic AMP ,Animals ,Cystic Fibrosis Transmembrane Conductance Regulator ,Epithelial Sodium Channels ,Taste Buds - Abstract
Mucociliary clearance is a primary defence mechanism of the airways consisting of two components, ciliary beating and transepithelial ion transport (I
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- 2022
Catalog
3. The Transcription Factor SpoVG Is of Major Importance for Biofilm Formation of
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Hannah, Benthien, Beate, Fresenborg, Linda, Pätzold, Mohamed Ibrahem, Elhawy, Sylvaine, Huc-Brandt, Christoph, Beisswenger, Gabriela, Krasteva-Christ, Sören L, Becker, Virginie, Molle, Johannes K, Knobloch, and Markus, Bischoff more...
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Mice ,Bacterial Proteins ,Biofilms ,Polysaccharides, Bacterial ,Staphylococcus epidermidis ,Animals ,Iron-Dextran Complex ,Gene Expression Regulation, Bacterial ,Transcription Factors - Published
- 2022
4. Comparison ofin vitroassays to study the effectiveness of antiparasitics againstAcanthamoeba castellanitrophozoites and cysts
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Lorenz Latta, Markus Bischoff, Mohamed Ibrahem Elhawy, Tanja Stachon, Gubesh Gunaratnam, Albrecht F. Kiderlen, Nóra Szentmáry, Lei Shi, Erika Orosz, and Berthold Seitz
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food.ingredient ,medicine.disease_cause ,Fluorescence ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,food ,Parasitic Sensitivity Tests ,Escherichia coli ,medicine ,Agar ,Trophozoites ,030212 general & internal medicine ,Acanthamoeba castellanii ,0303 health sciences ,Miltefosine ,Antiparasitic Agents ,L-Lactate Dehydrogenase ,Staining and Labeling ,General Immunology and Microbiology ,biology ,030306 microbiology ,General Medicine ,biology.organism_classification ,Molecular biology ,In vitro ,Acanthamoeba ,Staining ,chemistry ,Trypan blue ,medicine.drug - Abstract
We aimed to compare LDH release assay, trypan blue and fluorescent stainings, and non-nutrient Escherichia coli plate assay in determining treatment efficacy of antiamoebic agents against Acanthamoeba castellanii trophozoites/cysts, in vitro. 1BU trophozoites/cysts were challenged with 0.02% polyhexamethylene biguanid (PHMB), 0.1% propamidine isethionate (PD), and 0.0065% miltefosine (MF). Efficacies of the drugs were determined by LDH release and trypan blue assays, by Hoechst 33343, calcein-AM, and ethidium homodimer-1 fluorescent dyes, and by a non-nutrient agar E. coli plate assay. All three antiamoebic agents induced a significant LDH release from trophozoites, compared to controls (p < 0.0001). Fluorescent-dye staining in untreated 1BU trophozoites/cysts was negligible, but using antiamoebic agents, there was 59.3%-100% trypan blue, 100% Hoechst 33342, 0%-75.3% calcein-AM, and 100% ethidium homodimer-1 positivity. On E. coli plates, in controls and MF-treated 1BU trophozoites/cysts, new trophozoites appeared within 24 h, encystment occurred after 5 weeks. In PHMB- and PD-treated 1BU throphozoites/cysts, irregularly shaped, smaller trophozoites appeared after 72 h, which failed to form new cysts within 5 weeks. None of the enzymatic- and dye-based viability assays tested here generated survival rates for trophozoites/cysts that were comparable with those yielded with the non-nutrient agar E. coli plate assay, suggesting that the culture-based assay is the best method to study the treatment efficacy of drugs against Acanthamoeba. more...
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- 2019
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5. The Low-Molecular Weight Protein Arginine Phosphatase PtpB Affects Nuclease Production, Cell Wall Integrity, and Uptake Rates of
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Mohamed Ibrahem, Elhawy, Virginie, Molle, Sören L, Becker, and Markus, Bischoff
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Staphylococcus aureus ,Neutrophils ,Virulence Factors ,PtpB ,cell wall integrity ,whole blood phagocytosis assay ,Gene Expression Regulation, Bacterial ,Staphylococcal Infections ,Triton X-100 induced autolysis ,Arginine ,Phosphoric Monoester Hydrolases ,Article ,low-molecular-weight protein arginine phosphatase ,gene transcription ,Molecular Weight ,RNA, Bacterial ,Organophosphorus Compounds ,Bacterial Proteins ,Cell Wall ,Humans ,nuclease ,innate immunity - Abstract
The epidemiological success of Staphylococcus aureus as a versatile pathogen in mammals is largely attributed to its virulence factor repertoire and the sophisticated regulatory network controlling this virulon. Here we demonstrate that the low-molecular-weight protein arginine phosphatase PtpB contributes to this regulatory network by affecting the growth phase-dependent transcription of the virulence factor encoding genes/operons aur, nuc, and psmα, and that of the small regulatory RNA RNAIII. Inactivation of ptpB in S. aureus SA564 also significantly decreased the capacity of the mutant to degrade extracellular DNA, to hydrolyze proteins in the extracellular milieu, and to withstand Triton X-100 induced autolysis. SA564 ΔptpB mutant cells were additionally ingested faster by polymorphonuclear leukocytes in a whole blood phagocytosis assay, suggesting that PtpB contributes by several ways positively to the ability of S. aureus to evade host innate immunity. more...
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- 2021
6. The Phosphoarginine Phosphatase PtpB from
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Mohamed Ibrahem, Elhawy, Sylvaine, Huc-Brandt, Linda, Pätzold, Laila, Gannoun-Zaki, Ahmed Mohamed Mostafa, Abdrabou, Markus, Bischoff, and Virginie, Molle
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Mice ,Staphylococcus aureus ,Organophosphorus Compounds ,Virulence Factors ,Host-Pathogen Interactions ,Animals ,oxidative response ,arginine phosphatase ,Arginine ,Phosphoric Monoester Hydrolases ,Article ,infection - Abstract
Staphylococcus aureus continues to be a public health threat, especially in hospital settings. Studies aimed at deciphering the molecular and cellular mechanisms that underlie pathogenesis, host adaptation, and virulence are required to develop effective treatment strategies. Numerous host-pathogen interactions were found to be dependent on phosphatases-mediated regulation. This study focused on the analysis of the role of the low-molecular weight phosphatase PtpB, in particular, during infection. Deletion of ptpB in S. aureus strain SA564 significantly reduced the capacity of the mutant to withstand intracellular killing by THP-1 macrophages. When injected into normoglycemic C57BL/6 mice, the SA564 ΔptpB mutant displayed markedly reduced bacterial loads in liver and kidney tissues in a murine S. aureus abscess model when compared to the wild type. We also observed that PtpB phosphatase-activity was sensitive to oxidative stress. Our quantitative transcript analyses revealed that PtpB affects the transcription of various genes involved in oxidative stress adaptation and infectivity. Thus, this study disclosed first insights into the physiological role of PtpB during host interaction allowing us to link phosphatase-dependent regulation to oxidative bacterial stress adaptation during infection. more...
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- 2021
7. The Transcription Factor SpoVG Is of Major Importance for Biofilm Formation of Staphylococcus epidermidis under In Vitro Conditions, but Dispensable for In Vivo Biofilm Formation
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Hannah Benthien, Beate Fresenborg, Linda Pätzold, Mohamed Ibrahem Elhawy, Sylvaine Huc-Brandt, Christoph Beisswenger, Gabriela Krasteva-Christ, Sören L. Becker, Virginie Molle, Johannes K. Knobloch, and Markus Bischoff more...
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Inorganic Chemistry ,fungi ,Organic Chemistry ,Staphylococcus epidermidis ,SpoVG ,biofilm formation ,polysaccharide intercellular adhesin ,PIA ,ica ,murine foreign body infection model ,General Medicine ,Physical and Theoretical Chemistry ,Molecular Biology ,Spectroscopy ,Catalysis ,Computer Science Applications - Abstract
Staphylococcus epidermidis is a common cause of device related infections on which pathogens form biofilms (i.e., multilayered cell populations embedded in an extracellular matrix). Here, we report that the transcription factor SpoVG is essential for the capacity of S. epidermidis to form such biofilms on artificial surfaces under in vitro conditions. Inactivation of spoVG in the polysaccharide intercellular adhesin (PIA) producing S. epidermidis strain 1457 yielded a mutant that, unlike its parental strain, failed to produce a clear biofilm in a microtiter plate-based static biofilm assay. A decreased biofilm formation capacity was also observed when 1457 ΔspoVG cells were co-cultured with polyurethane-based peripheral venous catheter fragments under dynamic conditions, while the cis-complemented 1457 ΔspoVG::spoVG derivative formed biofilms comparable to the levels seen with the wild-type. Transcriptional studies demonstrated that the deletion of spoVG significantly altered the expression of the intercellular adhesion (ica) locus by upregulating the transcription of the ica operon repressor icaR and down-regulating the transcription of icaADBC. Electrophoretic mobility shift assays (EMSA) revealed an interaction between SpoVG and the icaA-icaR intergenic region, suggesting SpoVG to promote biofilm formation of S. epidermidis by modulating ica expression. However, when mice were challenged with the 1457 ΔspoVG mutant in a foreign body infection model, only marginal differences in biomasses produced on the infected catheter fragments between the mutant and the parental strain were observed. These findings suggest that SpoVG is critical for the PIA-dependent biofilm formation of S. epidermis under in vitro conditions, but is largely dispensable for biofilm formation of this skin commensal under in vivo conditions. more...
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- 2022
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8. The effect of antiamoebic agents and Ce6‐PDT on acanthamoeba castellani trophozoites and cysts, in vitro
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Lei Shi, Gubesh Gunaratnam, Nóra Szentmáry, Erika Orosz, Tanja Stachon, Markus Bischoff, Berthold Seitz, Albrecht F. Kiderlen, Mohamed Ibrahem Elhawy, and Lorenz Latta
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Ophthalmology ,Acanthamoeba castellani ,General Medicine ,Biology ,In vitro ,Microbiology - Published
- 2019
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9. Comparison of in vitro assays to study the effectiveness of antiparasitics against Acanthamoeba castellanii trophozoites and cysts
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Marukus Bischoff, Tanja Stachon, Mohamed Ibrahem Elhawy, Lorenz Latta, Berthold Seitz, Nóra Szentmáry, Lei Shi, Erika Orosz, and Albrecht F. Kiderlen
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Ophthalmology ,In vitro toxicology ,Acanthamoeba castellanii ,General Medicine ,Biology ,Microbiology - Published
- 2019
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10. The Effect of Anti-Amoebic Agents and Ce6-PDT on Acanthamoeba castellanii Trophozoites and Cysts, In Vitro
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Vithusan Muthukumar, Tanja Stachon, Lei Shi, Mohamed Ibrahem Elhawy, Gubesh Gunaratnam, Lorenz Latta, Albrecht F. Kiderlen, Erika Orosz, Markus Bischoff, Nóra Szentmáry, and Berthold Seitz
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0301 basic medicine ,food.ingredient ,Biomedical Engineering ,Acanthamoeba ,non-nutrient agar E. coli plate ,medicine.disease_cause ,Article ,drugs ,Microbiology ,Agar plate ,03 medical and health sciences ,0302 clinical medicine ,Natamycin ,food ,Escherichia coli ,medicine ,Animals ,Agar ,Amebicides ,Trophozoites ,Acanthamoeba castellanii ,biology ,Chemistry ,trypan blue assay ,Chlorhexidine ,biology.organism_classification ,medicine.disease ,cytotoxicity assay ,Ophthalmology ,030104 developmental biology ,Acanthamoeba keratitis ,030221 ophthalmology & optometry ,Triazenes ,medicine.drug - Abstract
Purpose The purpose of this study was to analyze the concentration-dependent effects of biguanides (polyhexamethylene biguanide [PHMB], chlorhexidine [CH]); diamidines (hexamidine-diisethionate [HD], propamidine-isethionate [PD], dibromopropamidine-diisethionate [DD]); natamycin (NM); miltefosine (MF); povidone iodine (PVPI), and chlorin e6 PDT on Acanthamoeba trophozoites and cysts, in vitro. Methods Strain 1BU was cultured in peptone-yeast extract-glucose medium. Trophozoites or cysts were cultured in PYG medium containing each agent at 100%, 50%, and 25% of maximum concentration for 2 hours. The percentage of dead trophozoites was determined using a non-radioactive cytotoxicity assay and trypan blue staining. Treated cysts were also maintained on non-nutrient agar Escherichia coli (E. coli) plates and observed for 3 weeks. Results All tested drugs displayed significant cytotoxic effects on 1BU cells based on the biochemical and staining-based viability assays tested. On non-nutrient agar E. coli plates, neither trophozoites nor freshly formed cysts were observed after PHMB, PD, NM, and PVPI treatment, respectively, within 3 weeks. However, CH-, HD-, DD-, and MF-treated cysts could excyst, multiply, and encyst again. Conclusions The off-label drugs PHMB, PD, NM, and PVPI are under in vitro conditions more effective against strain 1BU than CH, HD, DD, and MF. Our findings also suggest that the non-nutrient agar E. coli plate assay should be considered as method of choice for the in vitro analysis of the treatment efficacy of anti-amoebic agents. Translational relevance Ophthalmologists may optimize the treatment regime against Acanthamoeba keratitis by pre-testing the in vitro susceptibilities of the Acanthamoeba strain against drugs of interest with the non-nutrient E. coli agar plate assay. more...
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- 2020
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11. PtpA, a secreted tyrosine phosphatase from
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Laila, Gannoun-Zaki, Linda, Pätzold, Sylvaine, Huc-Brandt, Grégory, Baronian, Mohamed Ibrahem, Elhawy, Rosmarie, Gaupp, Marianne, Martin, Anne-Béatrice, Blanc-Potard, François, Letourneur, Markus, Bischoff, and Virginie, Molle more...
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Staphylococcus aureus ,Virulence ,Microfilament Proteins ,Gene Expression ,Staphylococcal Infections ,Microbiology ,Recombinant Proteins ,Mice, Inbred C57BL ,Mice ,RAW 264.7 Cells ,Bacterial Proteins ,Gene Expression Regulation ,Host-Pathogen Interactions ,Animals ,Tyrosine ,Dictyostelium ,Female ,Cloning, Molecular ,Phosphorylation ,Protein Tyrosine Phosphatases ,Protein Binding ,Signal Transduction - Abstract
Secretion of bacterial signaling proteins and adaptation to the host, especially during infection, are processes that are often linked in pathogenic bacteria. The human pathogen Staphylococcus aureus is equipped with a large arsenal of immune-modulating factors, allowing it to either subvert the host immune response or to create permissive niches for its survival. Recently, we showed that one of the low-molecular-weight protein tyrosine phosphatases produced by S. aureus, PtpA, is secreted during growth. Here, we report that deletion of ptpA in S. aureus affects intramacrophage survival and infectivity. We also observed that PtpA is secreted during macrophage infection. Immunoprecipitation assays identified several host proteins as putative intracellular binding partners for PtpA, including coronin-1A, a cytoskeleton-associated protein that is implicated in a variety of cellular processes. Of note, we demonstrated that coronin-1A is phosphorylated on tyrosine residues upon S. aureus infection and that its phosphorylation profile is linked to PtpA expression. Our results confirm that PtpA has a critical role during infection as a bacterial effector protein that counteracts host defenses. more...
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- 2018
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