scholarly journals <i>In Vitro</i> Activity of Squaramides and Acyclic Polyamine Derivatives against Trophozoites and Cysts of <i>Acanthamoeba castellanii</i>

2018 ◽  
Vol 06 (08) ◽  
pp. 1-14 ◽  
Author(s):  
M. J. Rosales ◽  
M. Ximenis ◽  
A. Costa ◽  
C. Rotger ◽  
D. Romero ◽  
...  
Keyword(s):  
Acanthamoeba Castellanii ◽  
Polyamine Derivatives

scholarly journals Development of a Fluorescent Tool for Studying Legionella bozemanae Intracellular Infection

2021 ◽  
Vol 9 (2) ◽  
pp. 379
Author(s):  
Breanne M. Head ◽  
Christopher I. Graham ◽  
Teassa MacMartin ◽  
Yoav Keynan ◽  
Ann Karen C. Brassinga
Keyword(s):  
Growth Kinetics ◽  
Legionella Pneumophila ◽  
Fluorescent Protein ◽  
Disease Incidence ◽  
Acanthamoeba Castellanii ◽  
Infection Model ◽  
Intracellular Infection ◽  
Green Fluorescent

Legionnaires’ disease incidence is on the rise, with the majority of cases attributed to the intracellular pathogen, Legionella pneumophila. Nominally a parasite of protozoa, L. pneumophila can also infect alveolar macrophages when bacteria-laden aerosols enter the lungs of immunocompromised individuals. L. pneumophila pathogenesis has been well characterized; however, little is known about the >25 different Legionella spp. that can cause disease in humans. Here, we report for the first time a study demonstrating the intracellular infection of an L. bozemanae clinical isolate using approaches previously established for L. pneumophila investigations. Specifically, we report on the modification and use of a green fluorescent protein (GFP)-expressing plasmid as a tool to monitor the L. bozemanae presence in the Acanthamoeba castellanii protozoan infection model. As comparative controls, L. pneumophila strains were also transformed with the GFP-expressing plasmid. In vitro and in vivo growth kinetics of the Legionella parental and GFP-expressing strains were conducted followed by confocal microscopy. Results suggest that the metabolic burden imposed by GFP expression did not impact cell viability, as growth kinetics were similar between the GFP-expressing Legionella spp. and their parental strains. This study demonstrates that the use of a GFP-expressing plasmid can serve as a viable approach for investigating Legionella non-pneumophila spp. in real time.

Novel Tetrazoles against Acanthamoeba castellanii Belonging to the T4 Genotype

Chemotherapy ◽  
2021 ◽  
Author(s):  
Yassmin Isse Wehelie ◽  
Naveed Ahmed Khan ◽  
Itrat Fatima ◽  
Areeba Anwar ◽  
Kanwal Kanwal ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Silver Nanoparticles ◽  
Reactive Oxygen Species Generation ◽  
Acanthamoeba Castellanii ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Species Determination ◽  
One Pot ◽  
Tetrazole Derivatives

Background: Acanthamoeba castellanii is a pathogenic free-living amoeba responsible for blinding keratitis and fatal granulomatous amoebic encephalitis. However, treatments are not standardized but can involve the use of amidines, biguanides, and azoles. Objectives: The aim of this study was to synthesize a variety of synthetic tetrazole derivatives and test their activities against A. castellanii. Methods: A series of novel tetrazole compounds were synthesized by one-pot method and characterized by NMR and mass spectroscopy. These compounds were subjected to amoebicidal, and cytotoxicity assays against A. castellanii belonging to the T4 genotype and human keratinocyte skin cells respectively. Additionally, reactive oxygen species determination and electron microscopy studies were carried out. Furthermore, two of the seven compounds were conjugated with silver nanoparticles to study their antiamoebic potential. Results: A series of seven tetrazole derivatives were synthesized successfully. The selected tetrazoles showed anti-amoebic activities at 10µM concentration against A. castellanii in vitro. The compounds tested caused increased reactive oxygen species generation in A castellanii, and significant morphological damage to amoebal membranes. Moreover, conjugation of silver nanoparticles enhanced antiamoebic effects of two tetrazoles. Conclusions: The results showed that azole compounds hold promise in the development of new formulations of anti-Acanthamoebic agents.

In vitro activity of 1 H -phenalen-1-one derivatives against Acanthamoeba castellanii Neff and their mechanisms of cell death

2017 ◽  
Vol 183 ◽  
pp. 218-223 ◽  
Author(s):  
Atteneri López-Arencibia ◽  
María Reyes-Batlle ◽  
Mónica Blanco Freijo ◽  
Grant McNaughton-Smith ◽  
Patricia Martín-Rodríguez ◽  
...  
Keyword(s):  
Cell Death ◽  
Acanthamoeba Castellanii ◽  
Vitro Activity ◽  
In Vitro Activity

The effect of polyhydroxyalkanoates in Pseudomonas chlororaphis PA23 biofilm formation, stress endurance, and interaction with the protozoan predator Acanthamoeba castellanii

2021 ◽  
pp. 1-15
Author(s):  
Akrm Ghergab ◽  
Nisha Mohanan ◽  
Grace Saliga ◽  
Ann Karen C. Brassinga ◽  
David Levin ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Acanthamoeba Castellanii ◽  
Pseudomonas Chlororaphis ◽  
Enhanced Sensitivity ◽  
Hostile Environments ◽  
The Impact ◽  
Environmental Fitness ◽  
Root Attachment

Pseudomonas chlororaphis PA23 is a biocontrol agent capable of protecting canola against the fungal pathogen Sclerotinia sclerotiorum. In addition to producing antifungal compounds, this bacterium synthesizes and accumulates polyhydroxyalkanoate (PHA) polymers as carbon and energy storage compounds. Because the role of PHA in PA23 physiology is currently unknown, we investigated the impact of this polymer on stress resistance, adherence to surfaces, and interaction with the protozoan predator Acanthamoeba castellanii. Three PHA biosynthesis mutants were created, PA23phaC1, PA23phaC1ZC2, and PA23phaC1ZC2D, which accumulated reduced PHA. Our phenotypic assays revealed that PA23phaC1ZC2D produced less phenazine (PHZ) compared with the wild type (WT) and the phaC1 and phaC1ZC2 mutants. All three mutants exhibited enhanced sensitivity to UV irradiation, starvation, heat stress, cold stress, and hydrogen peroxide. Moreover, motility, exopolysaccharide production, biofilm formation, and root attachment were increased in strains with reduced PHA levels. Interaction studies with the amoeba A. castellanii revealed that the WT and the phaC1 and phaC1ZC2 mutants were consumed less than the phaC1ZC2D mutant, likely due to decreased PHZ production by the latter. Collectively these findings indicate that PHA accumulation enhances PA23 resistance to a number of stresses in vitro, which could improve the environmental fitness of this bacterium in hostile environments.

Events during eucaryotic rRNA transcription initiation and elongation: conversion from the closed to the open promoter complex requires nucleotide substrates

1988 ◽  
Vol 8 (5) ◽  
pp. 1940-1946
Author(s):  
E Bateman ◽  
M R Paule
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Topological Analysis ◽  
Acanthamoeba Castellanii ◽  
Rna Polymerase I ◽  
Initiation Factor ◽  
Rrna Transcription ◽  
Promoter Complex ◽  
Polymerase I

Chemical footprinting and topological analysis were carried out on the Acanthamoeba castellanii rRNA transcription initiation factor (TIF) and RNA polymerase I complexes with DNA during transcription initiation and elongation. The results show that the binding of TIF and polymerase to the promoter does not alter the supercoiling of the DNA template and the template does not become sensitive to modification by diethylpyrocarbonate, which can identify melted DNA regions. Thus, in contrast to bacterial RNA polymerase, the eucaryotic RNA polymerase I-promoter complex is in a closed configuration preceding addition of nucleotides in vitro. Initiation and 3'-O-methyl CTP-limited translocation by RNA polymerase I results in separation of the polymerase-TIF footprints, leaving the TIF footprint unaltered. In contrast, initiation and translocation result in a significant change in the conformation of the polymerase-DNA complex, culminating in an unwound DNA region of at least 10 base pairs.

scholarly journals In Vitro Growth- and Encystation-Inhibitory Efficacies of Matcha Green Tea and Epigallocatechin Gallate Against Acanthameoba Castellanii

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 763
Author(s):  
Ameliya Dickson ◽  
Elise Cooper ◽  
Lenu B. Fakae ◽  
Bo Wang ◽  
Ka Lung Andrew Chan ◽  
...  
Keyword(s):  
Green Tea ◽  
Colorimetric Assay ◽  
Epigallocatechin Gallate ◽  
Acanthamoeba Castellanii ◽  
Inhibitory Effect ◽  
Response To Treatment ◽  
Ftir Microscopy ◽  
Sulforhodamine B ◽  
Chemical Fingerprinting

We examined the inhibitory effect of matcha green tea (Camellia sinensis) and epigallocatechin gallate (EGCg; the most abundant catechin in tea) on the vegetative growth and encystation of Acanthamoeba castellanii T4 genotype. The sulforhodamine B (SRB) stain-based colorimetric assay and hemocytometer counting were used to determine the reduction in A. castellanii trophozoite proliferation and encystation, in response to treatment with C. sinensis or EGCg. Fourier transform infrared (FTIR) microscopy was used to analyze chemical changes in the trophozoites and cysts due to C. sinensis treatment. Hot brewed and cold brewed matcha inhibited the growth of trophozoites by >40% at a 100 % concentration. EGCg at concentrations of 50 to 500 µM significantly inhibited the trophozoite growth compared to control. Hot brewed matcha (100% concentration) also showed an 87% reduction in the rate of encystation compared to untreated control. Although 500 µM of EGCg increased the rate of encystation by 36.3%, 1000 µM reduced it by 27.7%. Both percentages were not significant compared to control. C. sinensis induced more cytotoxicity to Madin Darby canine kidney cells compared to EGCg. FTIR chemical fingerprinting analysis showed that treatment with brewed matcha significantly increased the levels of glycogen and carbohydrate in trophozoites and cysts.

scholarly journals The Effect of Anti-Amoebic Agents and Ce6-PDT on Acanthamoeba castellanii Trophozoites and Cysts, In Vitro

2020 ◽  
Vol 9 (12) ◽  
pp. 29
Author(s):  
Lei Shi ◽  
Vithusan Muthukumar ◽  
Tanja Stachon ◽  
Lorenz Latta ◽  
Mohamed Ibrahem Elhawy ◽  
...  
Keyword(s):  
Acanthamoeba Castellanii

scholarly journals The Diverse Roles of the Global Transcriptional Regulator PhoP in the Lifecycle of Yersinia pestis

Pathogens ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1039
Author(s):  
Hana S. Fukuto ◽  
Gloria I. Viboud ◽  
Viveka Vadyvaloo
Keyword(s):  
Yersinia Pestis ◽  
Current Knowledge ◽  
Response Regulator ◽  
Expression Profiles ◽  
Critical Role ◽  
Gene Expression Profiles ◽  
Acanthamoeba Castellanii ◽  
Wide Range

Yersinia pestis, the causative agent of plague, has a complex infectious cycle that alternates between mammalian hosts (rodents and humans) and insect vectors (fleas). Consequently, it must adapt to a wide range of host environments to achieve successful propagation. Y. pestis PhoP is a response regulator of the PhoP/PhoQ two-component signal transduction system that plays a critical role in the pathogen’s adaptation to hostile conditions. PhoP is activated in response to various host-associated stress signals detected by the sensor kinase PhoQ and mediates changes in global gene expression profiles that lead to cellular responses. Y. pestis PhoP is required for resistance to antimicrobial peptides, as well as growth under low Mg2+ and other stress conditions, and controls a number of metabolic pathways, including an alternate carbon catabolism. Loss of phoP function in Y. pestis causes severe defects in survival inside mammalian macrophages and neutrophils in vitro, and a mild attenuation in murine plague models in vivo, suggesting its role in pathogenesis. A Y. pestisphoP mutant also exhibits reduced ability to form biofilm and to block fleas in vivo, indicating that the gene is also important for establishing a transmissible infection in this vector. Additionally, phoP promotes the survival of Y. pestis inside the soil-dwelling amoeba Acanthamoeba castellanii, a potential reservoir while the pathogen is quiescent. In this review, we summarize our current knowledge on the mechanisms of PhoP-mediated gene regulation in Y. pestis and examine the significance of the roles played by the PhoP regulon at each stage of the Y. pestis life cycle.

scholarly journals Combined Amoebicidal Effect of Atorvastatin and Commercial Eye Drops against Acanthamoeba castellanii Neff: In Vitro Assay Based on Mixture Design

Pathogens ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 219 ◽  
Author(s):  
Ines Sifaoui ◽  
Eulalia Capote Yanes ◽  
María Reyes-Batlle ◽  
Rubén L. Rodríguez-Expósito ◽  
José E. Piñero ◽  
...  
Keyword(s):  
Acanthamoeba Castellanii ◽  
Acanthamoeba Keratitis ◽  
Eukaryotic Cell ◽  
Resistance Pattern ◽  
Eye Drops ◽  
Current Standard ◽  
Component Mixture ◽  
Vitro Assay ◽  
Mixture System

The establishment of an effective therapeutic agent against Acanthamoeba keratitis (AK), remains until present, an issue to be solved due to the existence of a cyst stage in the life cycle of Acanthamoeba. Moreover, the effectiveness of the current standard therapeutic agents varies depending on the tested Acanthamoeba strains and its resistance pattern. In the present study, two 10-point augmented simplex-centroid designs were used to formulate a three-component mixture system using water, atorvastatin, and Diclofenaco-lepori or Optiben. The amoebicidal effects and in vitro-induced toxicity in a eukaryotic cell line were determined for all experiments. The optimal mixture to inhibit the parasite without inducing toxicity was established in the first plan as 30% Optiben, 63.5% atorvastatin, and 3.1% water. As for the second experimental design, the optimal mixture to inhibit Acanthamoeba with lower toxicity effect was composed of 17.6% Diclofenaco-lepori and 82.4% atorvastatin.

scholarly journals Azole Antifungal Agents To Treat the Human Pathogens Acanthamoeba castellanii and Acanthamoeba polyphaga through Inhibition of Sterol 14α-Demethylase (CYP51)

2015 ◽  
Vol 59 (8) ◽  
pp. 4707-4713 ◽  
Author(s):  
David C. Lamb ◽  
Andrew G. S. Warrilow ◽  
Nicola J. Rolley ◽  
Josie E. Parker ◽  
W. David Nes ◽  
...  
Keyword(s):  
Antifungal Agents ◽  
Acanthamoeba Castellanii ◽  
Therapeutic Agents ◽  
Effective Inhibitor ◽  
Human Pathogens ◽  
Acanthamoeba Polyphaga ◽  
Binding Studies ◽  
Content Type ◽  
Inhibition Concentration

ABSTRACTIn this study, we investigate the amebicidal activities of the pharmaceutical triazole CYP51 inhibitors fluconazole, itraconazole, and voriconazole againstAcanthamoeba castellaniiandAcanthamoeba polyphagaand assess their potential as therapeutic agents againstAcanthamoebainfections in humans. Amebicidal activities of the triazoles were assessed byin vitrominimum inhibition concentration (MIC) determinations using trophozoites ofA. castellaniiandA. polyphaga. In addition, triazole effectiveness was assessed by ligand binding studies and inhibition of CYP51 activity of purifiedA. castellaniiCYP51 (AcCYP51) that was heterologously expressed inEscherichia coli. Itraconazole and voriconazole bound tightly to AcCYP51 (dissociation constant [Kd] of 10 and 13 nM), whereas fluconazole bound weakly (Kdof 2,137 nM). Both itraconazole and voriconazole were confirmed to be strong inhibitors of AcCYP51 activity (50% inhibitory concentrations [IC50] of 0.23 and 0.39 μM), whereas inhibition by fluconazole was weak (IC50, 30 μM). However, itraconazole was 8- to 16-fold less effective (MIC, 16 mg/liter) at inhibitingA. polyphagaandA. castellaniicell proliferation than voriconazole (MIC, 1 to 2 mg/liter), while fluconazole did not inhibitAcanthamoebacell division (MIC, >64 mg/liter)in vitro. Voriconazole was an effective inhibitor of trophozoite proliferation forA. castellaniiandA. polyphaga; therefore, it should be evaluated in trials versus itraconazole for controllingAcanthamoebainfections.

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