scholarly journals Imaging the Antistaphylococcal Activity of CATH-2: Mechanism of Attack and Regulation of Inflammatory Response

mSphere ◽  
2017 ◽  
Vol 2 (6) ◽  
Author(s):  
Viktoria A. F. Schneider ◽  
Maarten Coorens ◽  
Johanna L. M. Tjeerdsma-van Bokhoven ◽  
George Posthuma ◽  
Albert van Dijk ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Immune Activation ◽  
Live Imaging ◽  
Mechanisms Of Action ◽  
Bacterial Membrane ◽  
Methicillin Resistant ◽  
Content Type ◽  
Naturally Occurring ◽  
Novel Approach ◽  
Near Future

ABSTRACT Due to the high use of antibiotics in both human and veterinary settings, many bacteria have become resistant to those antibiotics that we so heavily rely on. Methicillin-resistant S. aureus (MRSA) is one of these difficult-to-treat resistant pathogens for which novel antimicrobial therapies will be required in the near future. One novel approach could be the utilization of naturally occurring antimicrobial peptides, such as chicken CATH-2, which have been show to act against a wide variety of bacteria. However, before these peptides can be used clinically, more knowledge of their functions and mechanisms of action is required. In this study, we used live imaging and electron microscopy to visualize in detail how CATH-2 kills S. aureus, and we investigated how CATH-2 affects immune activation by S. aureus. Together, these results give a better understanding of how CATH-2 kills S. aureus and what the potential immunological consequences of this killing can be. Chicken cathelicidin-2 (CATH-2) is a broad-spectrum antimicrobial host defense peptide (HDP) that may serve as a paradigm for the development of new antimicrobial agents. While previous studies have elucidated the mechanism by which CATH-2 kills Escherichia coli, its mode of action against Gram-positive bacteria remains to be determined. In this study, we explored the underlying antibacterial mechanism of CATH-2 against a methicillin-resistant strain of Staphylococcus aureus and the effect of CATH-2-mediated S. aureus killing on immune activation. Visualization of the antimicrobial activity of CATH-2 against S. aureus with live-imaging confocal microscopy demonstrated that CATH-2 directly binds the bacteria, which is followed by membrane permeabilization and cell shrinkage. Transmission electron microscopy (TEM) studies further showed that CATH-2 initiated pronounced morphological changes of the membrane (mesosome formation) and ribosomal structures (clustering) in a dose-dependent manner. Immunolabeling of these sections demonstrated that CATH-2 binds and passes the bacterial membrane at subminimal bactericidal concentrations (sub-MBCs). Furthermore, competition assays and isothermal titration calorimetry (ITC) analysis provided evidence that CATH-2 directly interacts with lipoteichoic acid and cardiolipin. Finally, stimulation of macrophages with S. aureus and CATH-2 showed that CATH-2 not only kills S. aureus but also has the potential to limit S. aureus-induced inflammation at or above the MBC. Taken together, it is concluded that at sub-MBCs, CATH-2 perturbs the bacterial membrane and subsequently enters the cell and binds intracellular S. aureus components, while at or above the MBC, CATH-2 causes disruption of membrane integrity and inhibits S. aureus-induced macrophage activation. IMPORTANCE Due to the high use of antibiotics in both human and veterinary settings, many bacteria have become resistant to those antibiotics that we so heavily rely on. Methicillin-resistant S. aureus (MRSA) is one of these difficult-to-treat resistant pathogens for which novel antimicrobial therapies will be required in the near future. One novel approach could be the utilization of naturally occurring antimicrobial peptides, such as chicken CATH-2, which have been show to act against a wide variety of bacteria. However, before these peptides can be used clinically, more knowledge of their functions and mechanisms of action is required. In this study, we used live imaging and electron microscopy to visualize in detail how CATH-2 kills S. aureus, and we investigated how CATH-2 affects immune activation by S. aureus. Together, these results give a better understanding of how CATH-2 kills S. aureus and what the potential immunological consequences of this killing can be.

scholarly journals The Killing Mechanism of Teixobactin against Methicillin-Resistant Staphylococcus aureus: an Untargeted Metabolomics Study

mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Maytham Hussein ◽  
John A. Karas ◽  
Elena K. Schneider-Futschik ◽  
Fan Chen ◽  
James Swarbrick ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Membrane Lipids ◽  
Cell Envelope ◽  
Teichoic Acid ◽  
Bacterial Membrane ◽  
Gram Positive ◽  
Methicillin Resistant ◽  
Content Type ◽  
Metabolomics Study

ABSTRACT Antibiotics have served humankind through their use in modern medicine as effective treatments for otherwise fatal bacterial infections. Teixobactin is a first member of newly discovered natural antibiotics that was recently identified from a hitherto-unculturable soil bacterium, Eleftheria terrae, and recognized as a potent antibacterial agent against various Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci. The most distinctive characteristic of teixobactin as an effective antibiotic is that teixobactin resistance could not be evolved in a laboratory setting. It is purported that teixobactin’s “resistance-resistant” mechanism of action includes binding to the essential bacterial cell wall synthesis building blocks lipid II and lipid III. In the present study, metabolomics was used to investigate the potential metabolic pathways involved in the mechanisms of antibacterial activity of the synthetic teixobactin analogue Leu10-teixobactin against a MRSA strain, S. aureus ATCC 700699. The metabolomes of S. aureus ATCC 700699 cells 1, 3, and 6 h following treatment with Leu10-teixobactin (0.5 μg/ml, i.e., 0.5× MIC) were compared to those of the untreated controls. Leu10-teixobactin significantly perturbed bacterial membrane lipids (glycerophospholipids and fatty acids), peptidoglycan (lipid I and II) metabolism, and cell wall teichoic acid (lipid III) biosynthesis as early as after 1 h of treatment, reflecting an initial activity on the cell envelope. Concordant with its time-dependent antibacterial killing action, Leu10-teixobactin caused more perturbations in the levels of key intermediates in pathways of amino-sugar and nucleotide-sugar metabolism and their downstream peptidoglycan and teichoic acid biosynthesis at 3 and 6 h. Significant perturbations in arginine metabolism and the interrelated tricarboxylic acid cycle, histidine metabolism, pantothenate, and coenzyme A biosynthesis were also observed at 3 and 6 h. To conclude, this is the first study to provide novel metabolomics mechanistic information, which lends support to the development of teixobactin as an antibacterial drug for the treatment of multidrug-resistant Gram-positive infections. IMPORTANCE Antimicrobial resistance is one of the greatest threats to the global health system. It is imperative that new anti-infective therapeutics be developed against problematic “superbugs.” The cyclic depsipeptide teixobactin holds much promise as a new class of antibiotics for highly resistant Gram-positive pathogens (e.g., methicillin-resistant Staphylococcus aureus [MRSA]). Understanding its molecular mechanism(s) of action could lead to the design of new compounds with a broader activity spectrum. Here, we describe the first metabolomics study to investigate the killing mechanism(s) of teixobactin against MRSA. Our findings revealed that teixobactin significantly disorganized the bacterial cell envelope, as reflected by a profound perturbation in the bacterial membrane lipids and cell wall biosynthesis (peptidoglycan and teichoic acid). Importantly, teixobactin significantly suppressed the main intermediate d-alanyl-d-lactate involved in the mechanism of vancomycin resistance in S. aureus. These novel results help explain the unique mechanism of action of teixobactin and its lack of cross-resistance with vancomycin.

“Something feels different..” delivering skills from dialectical behaviour therapy in a recovery college

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Toni King ◽  
Joanna Dawson ◽  
Francess SmilleyAnderson ◽  
Richard Taylor
Keyword(s):  
Design Methodology ◽  
Mechanisms Of Action ◽  
Behaviour Therapy ◽  
Effect Change ◽  
Dialectical Behaviour Therapy ◽  
Content Type ◽  
Novel Approach ◽  
Similar Content

Purpose This paper aims to explore why a course with similar content feels different when delivered in a Recovery College as compared to an NHS therapy. Design/methodology/approach It is offered as a case study based on reflections from several perspectives. Findings This novel approach emphasises predictable factors such as the educational and recovery focussed environment. It also contributes further to thinking around how relationships are differently navigated and developed in Recovery Colleges compared to NHS settings. Originality/value The reflections are offered to act as a stimulus to promote wider conversations about how Recovery Colleges effect change, with an emphasis on comparing how relationships and power are influenced for those involved. This paper considers this in relation to the Mechanisms of Action identified in Toney et al., 2018 paper.

scholarly journals Cryo-Electron Microscopy Structure of Seneca Valley Virus Procapsid

2017 ◽  
Vol 92 (6) ◽  
Author(s):  
Mike Strauss ◽  
Nadishka Jayawardena ◽  
Eileen Sun ◽  
Richard A. Easingwood ◽  
Laura N. Burga ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Virus Infections ◽  
Content Type ◽  
Agricultural Industry ◽  
Lung Cancers ◽  
Cryo Electron Microscopy ◽  
Naturally Occurring ◽  
Interesting Possibility ◽  
Seneca Valley Virus

ABSTRACTSeneca Valley virus (SVV), like some other members of thePicornaviridae, forms naturally occurring empty capsids, known as procapsids. Procapsids have the same antigenicity as full virions, so they present an interesting possibility for the formation of stable virus-like particles. Interestingly, although SVV is a livestock pathogen, it has also been found to preferentially infect tumor cells and is being explored for use as a therapeutic agent in the treatment of small-cell lung cancers. Here we used cryo-electron microscopy to investigate the procapsid structure and describe the transition of capsid protein VP0 to the cleaved forms of VP4 and VP2. We show that the SVV receptor binds the procapsid, as evidence of its native antigenicity. In comparing the procapsid structure to that of the full virion, we also show that a cage of RNA serves to stabilize the inside surface of the virus, thereby making it more acid stable.IMPORTANCEViruses are extensively studied to help us understand infection and disease. One of the by-products of some virus infections are the naturally occurring empty virus capsids (containing no genome), termed procapsids, whose function remains unclear. Here we investigate the structure and formation of the procapsids of Seneca Valley virus, to better understand how they form, what causes them to form, how they behave, and how we can make use of them. One potential benefit of this work is the modification of the procapsid to develop it for targetedin vivodelivery of therapeutics or to make a stable vaccine against SVV, which could be of great interest to the agricultural industry.

scholarly journals Old Drugs To Treat Resistant Bugs: Methicillin-Resistant Staphylococcus aureus Isolates withmecCAre Susceptible to a Combination of Penicillin and Clavulanic Acid

2015 ◽  
Vol 59 (12) ◽  
pp. 7396-7404 ◽  
Author(s):  
Xiaoliang Ba ◽  
Ewan M. Harrison ◽  
Andrew L. Lovering ◽  
Nicholas Gleadall ◽  
Ruth Zadoks ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Clavulanic Acid ◽  
Methicillin Resistant ◽  
Content Type ◽  
Novel Approach ◽  
Novel Variant ◽  
Resistance To Penicillin ◽  
Mrsa Strains

ABSTRACTβ-Lactam resistance in methicillin-resistantStaphylococcus aureus(MRSA) is mediated by the expression of an alternative penicillin-binding protein 2a (PBP2a) (encoded bymecA) with a low affinity for β-lactam antibiotics. Recently, a novel variant ofmecA, known asmecC, was identified in MRSA isolates from both humans and animals. In this study, we demonstrate thatmecC-encoded PBP2c does not mediate resistance to penicillin. Rather, broad-spectrum β-lactam resistance in MRSA strains carryingmecC(mecC-MRSA strains) is mediated by a combination of both PBP2c and the distinct β-lactamase encoded by theblaZgene of strain LGA251 (blaZLGA251), which is part ofmecC-encoding staphylococcal cassette chromosomemec(SCCmec) type XI. We further demonstrate thatmecC-MRSA strains are susceptible to the combination of penicillin and the β-lactam inhibitor clavulanic acidin vitroand that the same combination is effectivein vivofor the treatment of experimentalmecC-MRSA infection in wax moth larvae. Thus, we demonstrate how the distinct biological differences betweenmecA- andmecC-encoded PBP2a and PBP2c have the potential to be exploited as a novel approach for the treatment ofmecC-MRSA infections.

A cell-based smoothed point interpolation method (CS-PIM) for 2D thermoelastic problems

2017 ◽  
Vol 27 (6) ◽  
pp. 1249-1265 ◽  
Author(s):  
Yijun Liu ◽  
Guiyong Zhang ◽  
Huan Lu ◽  
Zhi Zong
Keyword(s):  
Thermal Stresses ◽  
Interpolation Method ◽  
Content Type ◽  
Novel Approach ◽  
Convergence Results ◽  
Point Interpolation Method ◽  
Point Interpolation ◽  
Thermoelastic Problems ◽  
Gradient Smoothing ◽  
Practical Implications

Purpose Due to the strong reliance on element quality, there exist some inherent shortcomings of the traditional finite element method (FEM). The model of FEM behaves overly stiff, and the solutions of automated generated linear elements are generally of poor accuracy about especially gradient results. The proposed cell-based smoothed point interpolation method (CS-PIM) aims to improve the results accuracy of the thermoelastic problems via properly softening the overly-stiff stiffness. Design/methodology/approach This novel approach is based on the newly developed G space and weakened weak (w2) formulation, and of which shape functions are created using the point interpolation method and the cell-based gradient smoothing operation is conducted based on the linear triangular background cells. Findings Owing to the property of softened stiffness, the present method can generally achieve better accuracy and higher convergence results (especially for the temperature gradient and thermal stress solutions) than the FEM does by using the simplest linear triangular background cells, which has been examined by extensive numerical studies. Practical implications The CS-PIM is capable of producing more accurate results of temperature gradients as well as thermal stresses with the automated generated and unstructured background cells, which make it a better candidate for solving practical thermoelastic problems. Originality/value It is the first time that the novel CS-PIM was further developed for solving thermoelastic problems, which shows its tremendous potential for practical implications.

A new rat model of chronic cerebral hypoperfusion associated with arteriovenous malformations

2002 ◽  
Vol 97 (5) ◽  
pp. 1198-1202 ◽  
Author(s):  
Jian Hai ◽  
Meixiu Ding ◽  
Zhilin Guo ◽  
Bingyu Wang
Keyword(s):  
Electron Microscopy ◽  
Animal Model ◽  
Arteriovenous Malformations ◽  
Perfusion Pressure ◽  
Chronic Cerebral Hypoperfusion ◽  
Cerebral Hypoperfusion ◽  
Model Group ◽  
Content Type ◽  
The Right ◽  
Fine Print

Object. A new experimental model of chronic cerebral hypoperfusion was developed to study the effects of systemic arterial shunting and obstruction of the primary vessel that drains intracranial venous blood on cerebral perfusion pressure (CPP), as well as cerebral pathological changes during restoration of normal perfusion pressure. Methods. Twenty-four Sprague—Dawley rats were randomly assigned to either a sham-operated group, an arteriovenous fistula (AVF) group, or a model group (eight rats each). The animal model was readied by creating a fistula through an end-to-side anastomosis between the right distal external jugular vein (EJV) and the ispilateral common carotid artery (CCA), followed by ligation of the left vein draining the transverse sinus and bilateral external carotid arteries. Systemic mean arterial pressure (MAP), draining vein pressure (DVP), and CPP were monitored and compared among the three groups preoperatively, immediately postoperatively, and again 90 days later. Following occlusion of the fistula after a 90-day interval, blood—brain barrier (BBB) disruption and water content in the right cortical tissues of the middle cerebral artery territory were confirmed and also quantified with transmission electron microscopy. Formation of a fistula resulted in significant decreases in MAP and CPP, and a significant increase in DVP in the AVF and model groups. Ninety days later, there were still significant increases in DVP and decreases in CPP in the model group compared with the other groups (p < 0.05). Damage to the BBB and brain edema were noted in animals in the model group during restoration of normal perfusion pressure by occlusion of the fistula. Electron microscopy studies revealed cerebral vasogenic edema and/or hemorrhage in various amounts, which correlated with absent astrocytic foot processes surrounding some cerebral capillaries. Conclusions. The results demonstrated that an end-to-side anastomosis between the distal EJV and CCA can induce a decrease in CPP, whereas a further chronic state of cerebral hypoperfusion may be caused by venous outflow restriction, which is associated with perfusion pressure breakthrough. This animal model conforms to the basic hemodynamic characteristics of human cerebral arteriovenous malformations.

Transdural herniation of the thoracic spinal cord: untethering via a posterolateral transpedicular approach

2004 ◽  
Vol 1 (2) ◽  
pp. 223-227 ◽  
Author(s):  
Ryder Gwinn ◽  
Fraser Henderson
Keyword(s):  
Spinal Cord ◽  
Posterior Approach ◽  
Thoracic Spinal Cord ◽  
Dural Repair ◽  
Content Type ◽  
Transpedicular Approach ◽  
Thoracic Spinal ◽  
Novel Approach ◽  
Spinal Cord Herniation ◽  
Thoracic Cord

✓ Anterior spinal cord herniation is a well-documented condition in which the thoracic cord becomes tethered within a defect in the anterior dura mater. Typical procedures have involved a posterior approach with direct manipulation of the thoracic cord to expose and blindly release its point of tethering. The authors report three cases in which a novel approach for the treatment of anterior thoracic cord herniation was performed, cord manipulation and traction are minimized, and direct dural repair of the defect is performed.

Bankarization in the first European cities with an equal number of Muslim and Christian inhabitants

2017 ◽  
Vol 10 (4) ◽  
pp. 554-580
Author(s):  
Miguel Ángel Pérez-Castro ◽  
Miguel Ángel Montero-Alonso ◽  
Akram Abderrahman-Azaar
Keyword(s):  
North Coast ◽  
Content Type ◽  
European Cities ◽  
The North ◽  
Financial Depth ◽  
Financial Framework ◽  
European Banks ◽  
The Mean ◽  
Different Cultures ◽  
Near Future

Purpose This paper aims to analyze the situation of the financial system in the Spanish-governed cities of Melilla and Ceuta, Christian and Muslim cities located on the north coast of Africa, and compared it with the mean bankarization level in the rest of Spain in 2000-2015. Design/methodology/approach Although different calculation methods have been proposed, most authors agree that the bankarization level of a country or a territory reflects the development of the society as a whole and has a positive correlation with economic growth. The indicators of financial depth proposed by these researchers are not only the ratio between variables such as loans, deposits, etc., but also the ratios of these variables to the population and the gross domestic product (GDP) of the country or territory. Findings The results obtained revealed that there are differences between these two North African Spanish cities. Furthermore, the financing gap between the mean bankarization levels of these cities and those of mainland Spain was found to be even larger than most of the other economic indicators (GDP per capita and the unemployment rate). Practical implications The authors are convinced that the manuscript is a contribution of great interest for serving pilot experience in cities wishing to offer a development of traditional banking and Islamic banking. The paper should be of interest to readers in the areas of finance systems and commercial banks where two different cultures coexist. Originality/value This is the first research study on the financial framework of European cities whose populations have an approximately equal percentage of Christians and Muslims. The data reflected the existence of savings and loan methods parallel to conventional banking. The conclusion was that in the near future, it would be advisable for European banks to take into account the cultural customs and religious practices of potential Muslim clients.

scholarly journals In VitroActivities of Daptomycin-, Vancomycin-, and Teicoplanin-Loaded Polymethylmethacrylate against Methicillin-Susceptible, Methicillin-Resistant, and Vancomycin-Intermediate Strains of Staphylococcus aureus

2011 ◽  
Vol 55 (12) ◽  
pp. 5480-5484 ◽  
Author(s):  
Yuhan Chang ◽  
Wen-Chien Chen ◽  
Pang-Hsin Hsieh ◽  
Dave W. Chen ◽  
Mel S. Lee ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
High Performance ◽  
Low Dose ◽  
Antibacterial Activities ◽  
High Dose ◽  
Bone Cements ◽  
Antibacterial Effects ◽  
Methicillin Resistant ◽  
Content Type

ABSTRACTThe objective of this study was to evaluate the antibacterial effects of polymethylmethacrylate (PMMA) bone cements loaded with daptomycin, vancomycin, and teicoplanin against methicillin-susceptibleStaphylococcus aureus(MSSA), methicillin-resistantStaphylococcus aureus(MRSA), and vancomycin-intermediateStaphylococcus aureus(VISA) strains. Standardized cement specimens made from 40 g PMMA loaded with 1 g (low-dose), 4 g (middle-dose) or 8 g (high-dose) antibiotics were tested for elution characteristics and antibacterial activities. The patterns of release of antibiotics from the cement specimens were evaluated usingin vitrobroth elution assay with high-performance liquid chromatography. The activities of broth elution fluid against differentStaphylococcus aureusstrains (MSSA, MRSA, and VISA) were then determined. The antibacterial activities of all the tested antibiotics were maintained after being mixed with PMMA. The cements loaded with higher dosages of antibiotics showed longer elution periods. Regardless of the antibiotic loading dose, the teicoplanin-loaded cements showed better elution efficacy and provided longer inhibitory periods against MSSA, MRSA, and VISA than cements loaded with the same dose of vancomycin or daptomycin. Regarding the choice of antibiotics for cement loading in the treatment ofStaphylococcus aureusinfection, teicoplanin was superior in terms of antibacterial effects.

Chiasmatic optic glioma treated with chemotherapy

1985 ◽  
Vol 63 (6) ◽  
pp. 862-866 ◽  
Author(s):  
Jeffrey G. Rosenstock ◽  
Roger J. Packer ◽  
Larissa Bilaniuk ◽  
Derek A. Bruce ◽  
Jerri-Lynne Radcliffe ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Young Children ◽  
Progressive Disease ◽  
Actinomycin D ◽  
Initial Therapy ◽  
Optic Glioma ◽  
Newly Diagnosed ◽  
Content Type ◽  
Novel Approach ◽  
Clinical Stabilization

✓ Chiasmatic optic glioma is a rare tumor with an erratic natural history, usually seen in young children. A prior study from this institution demonstrated that these lesions were frequently lethal, despite initial clinical stabilization following radiation therapy, and that visual, intellectual, and late endocrinological disabilities were prevalent. A novel approach was developed in 1977, when an initial clinical response to vincristine was recorded in a child with a recurrent optic glioma. Since then, all children with recurrent optic glioma and all children aged 6 years old and under with newly diagnosed optic glioma have been offered a program of initial therapy with vincristine and actinomycin D for six cycles over 18 months. The four children with recurrent tumor who were treated with that regimen remain clinically stable 13 to 115 months after chemotherapy. Twelve children (eight under 24 months old) with newly diagnosed optic glioma have been treated with this program, and three are still on therapy. Four developed progression while on therapy, and five remain stable from 1 to 60 months posttherapy. The four children who developed progressive disease have been treated with radiation therapy and remain stable. Six of the 12 children showed shrinkage of their tumor on computerized tomography while receiving chemotherapy. This program may serve as an alternative to initial radiation therapy in young children.

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