scholarly journals Modified Virulence of Antibiotic-Induced Burkholderia pseudomallei Filaments

2005 ◽  
Vol 49 (3) ◽  
pp. 1002-1009 ◽  
Author(s):  
Kang Chen ◽  
Guang Wen Sun ◽  
Kim Lee Chua ◽  
Yunn-Hwen Gan
Keyword(s):  
Burkholderia Pseudomallei ◽  
Bacterial Virulence ◽  
In Vitro Assays ◽  
Filamentous Bacteria ◽  
Antibiotic Concentration ◽  
Temporary Reduction ◽  
Monocytic Cells ◽  
Life Threatening ◽  
Sublethal Concentrations

ABSTRACT Melioidosis is a life-threatening bacterial infection caused by Burkholderia pseudomallei. Some antibiotics used to treat melioidosis can induce filamentation in B. pseudomallei. Despite studies on the mechanism of virulence of the bacteria, the properties of B. pseudomallei filaments and their impact on virulence have not been investigated before. To understand the characteristics of antibiotic-induced filaments, we performed in vitro assays to compare several aspects of virulence between normal, nonfilamentous and filamentous B. pseudomallei. Normal, nonfilamentous B. pseudomallei could cause the lysis of monocytic cells, while filaments induced by sublethal concentrations of ceftazidime, ofloxacin, or trimethoprim show decreased lysis of monocytic cells, especially after prolonged antibiotic exposure. The motility of the filamentous bacteria was reduced compared to that of nonfilamentous bacteria. However, the filamentation was reversible when the antibiotics were removed, and the revertant bacteria recovered their motility and ability to lyse monocytic cells. Meanwhile, antibiotic resistance developed in revertant bacteria exposed to ceftazidime at the MIC. Our study highlights the danger of letting antibiotic concentration drop to the MIC or sub-MICs during antibiotic treatment of melioidosis. This could potentially give rise to a temporary reduction of bacterial virulence, only to result in bacteria that are equally virulent but more resistant to antibiotics, should the antibiotics be reduced or removed.

scholarly journals The Burkholderia pseudomallei ΔasdMutant Exhibits Attenuated Intracellular Infectivity and Imparts Protection against Acute Inhalation Melioidosis in Mice

2011 ◽  
Vol 79 (10) ◽  
pp. 4010-4018 ◽  
Author(s):  
Michael H. Norris ◽  
Katie L. Propst ◽  
Yun Kang ◽  
Steven W. Dow ◽  
Herbert P. Schweizer ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Cell Model ◽  
Single Copy ◽  
Wild Type ◽  
Live Attenuated Vaccine ◽  
Content Type ◽  
Life Threatening ◽  
A Cell ◽  
Bioterrorism Agent

ABSTRACTBurkholderia pseudomallei, the cause of serious and life-threatening diseases in humans, is of national biodefense concern because of its potential use as a bioterrorism agent. This microbe is listed as a select agent by the CDC; therefore, development of vaccines is of significant importance. Here, we further investigated the growth characteristics of a recently createdB. pseudomallei1026b Δasdmutantin vitro, in a cell model, and in an animal model of infection. The mutant was typified by an inability to grow in the absence of exogenous diaminopimelate (DAP); upon single-copy complementation with a wild-type copy of theasdgene, growth was restored to wild-type levels. Further characterization of theB. pseudomalleiΔasdmutant revealed a marked decrease in RAW264.7 murine macrophage cytotoxicity compared to the wild type and the complemented Δasdmutant. RAW264.7 cells infected by the Δasdmutant did not exhibit signs of cytopathology or multinucleated giant cell (MNGC) formation, which were observed in wild-typeB. pseudomalleicell infections. The Δasdmutant was found to be avirulent in BALB/c mice, and mice vaccinated with the mutant were protected against acute inhalation melioidosis. Thus, theB. pseudomalleiΔasdmutant may be a promising live attenuated vaccine strain and a biosafe strain for consideration of exclusion from the select agent list.

scholarly journals Severe viral respiratory infections in children with IFIH1 loss-of-function mutations

2017 ◽  
Vol 114 (31) ◽  
pp. 8342-8347 ◽  
Author(s):  
Samira Asgari ◽  
Luregn J. Schlapbach ◽  
Stéphanie Anchisi ◽  
Christian Hammer ◽  
Istvan Bartha ◽  
...  
Keyword(s):  
Respiratory Infections ◽  
In Vitro Assays ◽  
Severe Illness ◽  
Healthy Children ◽  
Loss Of Function ◽  
Life Threatening ◽  
Syncytial Virus ◽  
Viral Respiratory Infections ◽  
Viral Respiratory

Viral respiratory infections are usually mild and self-limiting; still they exceptionally result in life-threatening infections in previously healthy children. To investigate a potential genetic cause, we recruited 120 previously healthy children requiring support in intensive care because of a severe illness caused by a respiratory virus. Using exome and transcriptome sequencing, we identified and characterized three rare loss-of-function variants in IFIH1, which encodes an RIG-I-like receptor involved in the sensing of viral RNA. Functional testing of the variants IFIH1 alleles demonstrated that the resulting proteins are unable to induce IFN-β, are intrinsically less stable than wild-type IFIH1, and lack ATPase activity. In vitro assays showed that IFIH1 effectively restricts replication of human respiratory syncytial virus and rhinoviruses. We conclude that IFIH1 deficiency causes a primary immunodeficiency manifested in extreme susceptibility to common respiratory RNA viruses.

scholarly journals Virulence of the emerging pathogen, Burkholderia pseudomallei, depends upon the O-linked oligosaccharyltransferase, PglL

2020 ◽  
Vol 15 (4) ◽  
pp. 241-257
Author(s):  
Samuel J Willcocks ◽  
Carmen Denman ◽  
Felipe Cia ◽  
Elizabeth McCarthy ◽  
Jon Cuccui ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Galleria Mellonella ◽  
In Vitro Assays ◽  
In Vivo Models ◽  
Bacterial Fitness ◽  
Isogenic Mutants ◽  
Type Strains ◽  
Broad Role

Aim: We sought to characterize the contribution of the O-OTase, PglL, to virulence in two Burkholderia spp. by comparing isogenic mutants in Burkholderia pseudomallei with the related species, Burkholderia thailandensis. Materials & methods: We utilized an array of in vitro assays in addition to Galleria mellonella and murine in vivo models to assess virulence of the mutant and wild-type strains in each Burkholderia species. Results: We found that pglL contributes to biofilm and twitching motility in both species. PglL uniquely affected morphology; cell invasion; intracellular motility; plaque formation and intergenus competition in B. pseudomallei. This mutant was attenuated in the murine model, and extended survival in a vaccine-challenge experiment. Conclusion: Our data support a broad role for pglL in bacterial fitness and virulence, particularly in B. pseudomallei.

scholarly journals Off label, compassionate and irrational use of medicines in Covid-19 pandemic, health consequences and ethical issues

2020 ◽  
Vol 25 (9) ◽  
pp. 3413-3419
Author(s):  
Francisco José Roma Paumgartten ◽  
Ana Cecilia Amado Xavier de Oliveira
Keyword(s):  
Clinical Trials ◽  
Ethical Issues ◽  
Convincing Evidence ◽  
In Vitro Assays ◽  
Off Label ◽  
Viral Respiratory Infection ◽  
Life Threatening ◽  
Antiparasitic Drugs ◽  
Heart Disorders

Abstract When Covid-19 emerged in December last year, there was no vaccine nor was there specific effective treatment for this fast-spreading and life-threatening viral respiratory infection. Clinical trials were planned and are in progress to investigate whether drugs used for influenza, HIV and other viruses, and also anthelmintics (ivermectin, nitazoxanide, niclosamide), and antimalarials (chloroquine, hydroxychloroquine) showing antiviral activity in in vitro assays, are effective and safe for Covid-19. So far there is no convincing evidence that these antiviral and antiparasitic drugs are of any benefit for Covid-19. Notwithsanding the absence of evidence of clinical efficacy, these drugs are widely used outside of clinical trials (off label) for prophylaxis and treatment of this viral infection. The rationale behind the prescription of macrolide antibiotics (azithromycin) for Covid-19 is obscure as well. The widespread prescription and use of drugs of unproven efficacy and safety for Covid-19 is at odds with the rational use of medicines, a cornerstone principle of pharmacotherapy advanced by WHO in 1985. This irrational use of drugs is cause for concern because some of them are associated with serious heart disorders and deaths.

scholarly journals Synthesis and Evaluation of Novel Pyrazole Ethandiamide Compounds as Inhibitors of Human THP-1 Monocytic Cell Neurotoxicity

Cells ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 655
Author(s):  
Jordan A. McKenzie ◽  
Reham F. Barghash ◽  
Azhaar T. Alsaggaf ◽  
Omkar Kulkarni ◽  
Kalun Boudreau ◽  
...  
Keyword(s):  
Cultured Cells ◽  
Neuroprotective Activity ◽  
In Vitro Assays ◽  
Cell Viability Assay ◽  
Monocytic Cell ◽  
Monocytic Cells ◽  
Viability Assay ◽  
Inflammatory Conditions ◽  
New Compounds

Neuroinflammation and microglia-mediated neurotoxicity contribute to the pathogenesis of a broad range of neurodegenerative diseases; therefore, identifying novel compounds that can suppress adverse activation of glia is an important goal. We have previously identified a class of trisubstituted pyrazoles that possess neuroprotective and anti-inflammatory properties. Here, we describe a second generation of pyrazole analogs that were designed to improve their neuroprotective activity toward neurons under inflammatory conditions. Pyrazolyl oxalamide derivatives were designed to explore the effects of steric and electronic factors. Three in vitro assays were performed to evaluate the compounds’ anti-neurotoxic, neuroprotective, and cytotoxic activity using human THP-1, PC-3, and SH-SY5Y cells. Five compounds significantly reduced the neurotoxic secretions from immune-stimulated microglia-like human THP-1 monocytic cells. One of these compounds was also found to protect SH-SY5Y neuronal cells when they were exposed to cytotoxic THP-1 cell supernatants. While one of the analogs was discarded due to its interference with the cell viability assay, most compounds were innocuous to the cultured cells at the concentrations used (1–100 μM). The new compounds reported herein provide a design template for the future development of lead candidates as novel inhibitors of neuroinflammation and neuroprotective drugs.

scholarly journals Monoclonal antibodies opsonise Burkholderia and reduce intracellular actin tail formation in a macrophage infection assay.

2021 ◽  
Author(s):  
A. Taylor ◽  
D. Jenner ◽  
C. Rowland ◽  
T. Laws ◽  
I. Norville ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Burkholderia Pseudomallei ◽  
Bacterial Virulence ◽  
Neglected Tropical Disease ◽  
Intracellular Pathogen ◽  
Murine Macrophage ◽  
Macrophage Infection ◽  
Spread Of Infection ◽  
Selection Of

Melioidosis is a neglected tropical disease caused by the bacterium Burkholderia pseudomallei . The bacterium is intrinsically resistant to various antibiotics and melioidosis is therefore difficult to treat successfully without relapse in infection. B. pseudomallei is an intracellular pathogen, and therefore to eradicate the infection, antimicrobials must be able to access bacteria in an intracellular niche. This study assessed the ability of a panel of monoclonal antibodies to opsonise Burkholderia species and determine the effect that the antibody has on bacterial virulence in vitro . Murine macrophage infection assays demonstrated that monoclonal antibodies to the capsule of B. pseudomallei are opsonising. Furthermore, one of these monoclonal antibodies reduced bacterial actin tail formation in our in vitro assays, indicating antibodies could reduce the intracellular spread of B. thailandensis . The data presented in this paper demonstrates that monoclonal antibodies are opsonising and can decrease bacterial actin tail formation, thus decreasing their intracellular spread. This data has informed selection of an antibody for development of an antibody-antibiotic conjugate for melioidosis. Importance statement Melioidosis is difficult to treat successfully due to the bacterium being resistant to many classes of antibiotics, therefore available therapeutic options are limited. New and improved therapies are urgently required to treat this disease. Here we have investigated the potential of monoclonal antibodies to target this intracellular pathogen. We have demonstrated that monoclonal antibodies can target the bacterium, increase uptake into macrophages and reduce actin tail formation required by the bacterium for spread between cells. Through targeting the bacterium with antibodies we hope to disarm the pathogen, reducing the spread of infection. Ultimately we aim to use an opsonising antibody to deliver antibiotics intracellularly by developing an antibody-antibiotic conjugate therapeutic for melioidosis.

A in Vivo Assay for Standardizing Heparin Preparations

1979 ◽  
Vol 41 (03) ◽  
pp. 576-582
Author(s):  
A R Pomeroy
Keyword(s):  
In Vitro Assays ◽  
British Pharmacopoeia ◽  
In Vitro Method ◽  
Standard Preparation ◽  
Reliable Estimation ◽  
Assay Procedure ◽  
Accuracy And Precision ◽  
Heparin Preparation

SummaryThe limitations of currently used in vitro assays of heparin have demonstrated the need for an in vivo method suitable for routine use.The in vivo method which is described in this paper uses, for each heparin preparation, four groups of five mice which are injected intravenously with heparin according to a “2 and 2 dose assay” procedure. The method is relatively rapid, requiring 3 to 4 hours to test five heparin preparations against a standard preparation of heparin. Levels of accuracy and precision acceptable for the requirements of the British Pharmacopoeia are obtained by combining the results of 3 to 4 assays of a heparin preparation.The similarity of results obtained the in vivo method and the in vitro method of the British Pharmacopoeia for heparin preparations of lung and mucosal origin validates this in vivo method and, conversely, demonstrates that the in vitro method of the British Pharmacopoeia gives a reliable estimation of the in vivo activity of heparin.

Potentially Thrombogenic Materials in Factor IX Concentrates

1975 ◽  
Vol 33 (03) ◽  
pp. 617-631 ◽  
Author(s):  
H. S Kingdon ◽  
R. L Lundblad ◽  
J. J Veltkamp ◽  
D. L Aronson
Keyword(s):  
Human Plasma ◽  
Antithrombin Iii ◽  
Factor Ix ◽  
In Vitro Assays ◽  
Substantial Agreement ◽  
Coefficient Of Correlation

SummaryFactor IX concentrates manufactured from human plasma and intended for therapeutic infusion in man have been suspected for some time of being potentially thrombogenic. In the current studies, assays were carried out in vitro and in vivo for potentially thrombogenic materials. It was possible to rank the various materials tested according to the amount of thrombogenic material detected. For concentrates not containing heparin, there was substantial agreement between the in vivo and in vitro assays, with a coefficient of correlation of 0.77. There was no correlation between the assays for thrombogenicity and the antithrombin III content. We conclude that many presently available concentrates of Factor IX contain substantial amounts of potentially thrombogenic enzymes, and that this fact must be considered in arriving at the decision whether or not to use them therapeutically.

In-silico Studies of Isolated Phytoalkaloid Against Lipoxygenase: Study Based on Possible Correlation

2018 ◽  
Vol 21 (3) ◽  
pp. 215-221
Author(s):  
Haroon Khan ◽  
Muhammad Zafar ◽  
Helena Den-Haan ◽  
Horacio Perez-Sanchez ◽  
Mohammad Amjad Kamal
Keyword(s):  
In Silico ◽  
Docking Studies ◽  
In Vivo Studies ◽  
In Vitro Assays ◽  
Chronic Obstructive ◽  
Lipoxygenase Inhibitors ◽  
Lipoxygenase Inhibition ◽  
In Silico Studies

Aim and Objective: Lipoxygenase (LOX) enzymes play an important role in the pathophysiology of several inflammatory and allergic diseases including bronchial asthma, allergic rhinitis, atopic dermatitis, allergic conjunctivitis, rheumatoid arthritis and chronic obstructive pulmonary disease. Inhibitors of the LOX are believed to be an ideal approach in the treatment of diseases caused by its over-expression. In this regard, several synthetic and natural agents are under investigation worldwide. Alkaloids are the most thoroughly investigated class of natural compounds with outstanding past in clinically useful drugs. In this article, we have discussed various alkaloids of plant origin that have already shown lipoxygenase inhibition in-vitro with possible correlation in in silico studies. Materials and Methods: Molecular docking studies were performed using MOE (Molecular Operating Environment) software. Among the ten reported LOX alkaloids inhibitors, derived from plant, compounds 4, 2, 3 and 1 showed excellent docking scores and receptor sensitivity. Result and Conclusion: These compounds already exhibited in vitro lipoxygenase inhibition and the MOE results strongly correlated with the experimental results. On the basis of these in vitro assays and computer aided results, we suggest that these compounds need further detail in vivo studies and clinical trial for the discovery of new more effective and safe lipoxygenase inhibitors. In conclusion, these results might be useful in the design of new and potential lipoxygenase (LOX) inhibitors.

Repurposing of auranofin against bacterial infections: An In silico and In vitro study

2020 ◽  
Vol 16 ◽  
Author(s):  
Nidhi Sharma ◽  
Arti Singh ◽  
Ruchika Sharma ◽  
Anoop Kumar
Keyword(s):  
Broad Spectrum ◽  
In Silico ◽  
Antibacterial Agent ◽  
Bacterial Infections ◽  
In Vitro Assays ◽  
Infection Model ◽  
Synergistic Activity ◽  
Bacterial Strains ◽  
Molecular Docking Study

Aim: The aim of the study was to find out the role of auranofin as a promising broad spectrum antibacterial agent. Methods: In-vitro assays (Percentage growth retardation, Bacterial growth kinetics, Biofilm formation assay) and In-silico study (Molegro virtual docker (MVD) version 6.0 and Molecular operating environment (MOE) version 2008.10 software). Results: The in vitro assays have shown that auranofin has good antibacterial activity against Gram positive and Gram negative bacterial strains. Further, auranofin has shown synergistic activity in combination with ampicillin against S. aureus and B. subtilis whereas in combination with neomycin has just shown additive effect against E. coli, P. aeruginosa and B. pumilus. In vivo results have revealed that auranofin alone and in combination with standard drugs significantly decreased the bioburden in zebrafish infection model as compared to control. The molecular docking study have shown good interaction of auranofin with penicillin binding protein (2Y2M), topoisomerase (3TTZ), UDP-3-O-[3- hydroxymyristoyl] N-acetylglucosaminedeacetylase (3UHM), cell adhesion protein (4QRK), β-lactamase (5CTN) and arylsulphatase (1HDH) enzyme as that of reference ligand which indicate multimodal mechanism of action of auranofin. Finally, MTT assay has shown non-cytotoxic effect of auranofin. Conclusion: In conclusion, auranofin in combination with existing antibiotics could be developed as a broad spectrum antibacterial agent; however, further studies are required to confirm its safety and efficacy. This study provides possibility of use of auranofin apart from its established therapeutic indication in combination with existing antibiotics to tackle the problem of resistance.

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