scholarly journals How Phagocytic Cells Kill Different Bacteria: a Quantitative Analysis Using Dictyostelium discoideum

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tania Jauslin ◽  
Otmane Lamrabet ◽  
Xenia Crespo-Yañez ◽  
Anna Marchetti ◽  
Imen Ayadi ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Dictyostelium Discoideum ◽  
Human Body ◽  
Relative Importance ◽  
Phagocytic Cells ◽  
Bacterial Killing ◽  
Content Type ◽  
Individual Gene ◽  
Genetic Manipulations ◽  
High Degree

ABSTRACT Ingestion and killing of bacteria by phagocytic cells protect the human body against infections. While many mechanisms have been proposed to account for bacterial killing in phagosomes, their relative importance, redundancy, and specificity remain unclear. In this study, we used the Dictyostelium discoideum amoeba as a model phagocyte and quantified the requirement of 11 individual gene products, including nine putative effectors, for the killing of bacteria. This analysis revealed that radically different mechanisms are required to kill Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis. AlyL, a lysozyme-like protein equipped with a distinct bacteriolytic region, plays a specific role in the intracellular killing of K. pneumoniae, with assistance from BpiC and Aoah, two lipopolysaccharide (LPS)-binding proteins. Rapid killing of E. coli and P. aeruginosa requires the presence of BpiC and of the NoxA NADPH oxidase. No single effector tested is essential for rapid killing of S. aureus or B. subtilis. Overall, our observations reveal an unsuspected degree of specificity in the elimination of bacteria in phagosomes. IMPORTANCE Phagocytic cells ingest and kill bacteria, a process essential for the defense of the human body against infections. Many potential killing mechanisms have been identified in phagocytic cells, including free radicals, toxic ions, enzymes, and permeabilizing peptides. Yet fundamental questions remain unanswered: what is the relative importance of these mechanisms, how redundant are they, and are different mechanisms used to kill different species of bacteria? We addressed these questions using Dictyostelium discoideum, a model phagocytic cell amenable to genetic manipulations and quantitative analysis. Our results reveal that vastly different mechanisms are required to kill different species of bacteria. This very high degree of specificity was unexpected and indicates that a lot remains to be discovered about how phagocytic cells eliminate bacteria.

scholarly journals A New Family of Bacteriolytic Proteins in Dictyostelium discoideum

2021 ◽  
Vol 10 ◽  
Author(s):  
Cyril Guilhen ◽  
Wanessa C. Lima ◽  
Estelle Ifrid ◽  
Xenia Crespo-Yañez ◽  
Otmane Lamrabet ◽  
...  
Keyword(s):  
Dictyostelium Discoideum ◽  
Phagocytic Cells ◽  
Bacterial Killing ◽  
Bacteriolytic Activity ◽  
New Family ◽  
Cell Extracts ◽  
New Strategy ◽  
Domain Of Unknown Function ◽  
In Cells

Phagocytic cells ingest and destroy bacteria efficiently and in doing so ensure the defense of the human body against infections. Phagocytic Dictyostelium discoideum amoebae represent a powerful model system to study the intracellular mechanisms ensuring destruction of ingested bacteria in phagosomes. Here, we discovered the presence of a bacteriolytic activity against Klebsiella pneumoniae in cellular extracts from D. discoideum. The bacteriolytic activity was detected only at a very acidic pH mimicking the conditions found in D. discoideum phagosomes. It was also strongly decreased in extracts of kil1 KO cells that were previously described to kill inefficiently internalized bacteria, suggesting that the activity observed in vitro is involved in killing of bacteria in phagosomes. We purified a fraction enriched in bacteriolytic activity where only 16 proteins were detected and focused on four proteins selectively enriched in this fraction. Three of them belong to a poorly characterized family of D. discoideum proteins exhibiting a DUF3430 domain of unknown function and were named BadA (Bacteriolytic D. discoideum A), BadB, and BadC. We overexpressed the BadA protein in cells, and the bacteriolytic activity increased concomitantly in cell extracts. Conversely, depletion of BadA from cell extracts decreased significantly their bacteriolytic activity. Finally, in cells overexpressing BadA, bacterial killing was faster than in parental cells. Together these results identify BadA as a D. discoideum protein required for cellular bactericidal activity. They also define a new strategy to identify and characterize bactericidal proteins in D. discoideum cells.

Quantification of Silica Uptake by Alveolar Macrophages - An Emperical Scanning Electron Microprobe Method

1982 ◽  
Vol 40 ◽  
pp. 332-333
Author(s):  
V. V. Damiano ◽  
R. P. Daniele ◽  
H. T. Tucker ◽  
J. H. Dauber
Keyword(s):  
Quantitative Analysis ◽  
Alveolar Macrophages ◽  
Bulk Sample ◽  
Silica Particles ◽  
Empirical Method ◽  
Phagocytic Cells ◽  
Calibration Standards ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Scanning Electron

An important example of intracellular particles is encountered in silicosis where alveolar macrophages ingest inspired silica particles. The quantitation of the silica uptake by these cells may be a potentially useful method for monitoring silica exposure. Accurate quantitative analysis of ingested silica by phagocytic cells is difficult because the particles are frequently small, irregularly shaped and cannot be visualized within the cells. Semiquantitative methods which make use of particles of known size, shape and composition as calibration standards may be the most direct and simplest approach to undertake. The present paper describes an empirical method in which glass microspheres were used as a model to show how the ratio of the silicon Kα peak X-ray intensity from the microspheres to that of a bulk sample of the same composition correlated to the mass of the microsphere contained within the cell. Irregular shaped silica particles were also analyzed and a calibration curve was generated from these data.

Study on erythrocytes by SEM photogrammetry (SEMP) technique

1990 ◽  
Vol 48 (3) ◽  
pp. 724-725
Author(s):  
Tong Wensheng ◽  
Lu Lianhuang ◽  
Zhang Zhijun
Keyword(s):  
Quantitative Analysis ◽  
Cell Membrane ◽  
Clinical Diagnosis ◽  
Human Body ◽  
Blood Cells ◽  
Three Dimensional ◽  
Normal Person ◽  
Blood Disease ◽  
Computation Technique ◽  
Important Basis

This is a combined study of two diffirent branches, photogrammetry and morphology of blood cells. The three dimensional quantitative analysis of erythrocytes using SEMP technique, electron computation technique and photogrammetry theory has made it possible to push the study of mophology of blood cells from LM, TEM, SEM to a higher stage, that of SEM P. A new path has been broken for deeply study of morphology of blood cells.In medical view, the abnormality of the quality and quantity of erythrocytes is one of the important changes of blood disease. It shows the abnormal blood—making function of the human body. Therefore, the study of the change of shape on erythrocytes is the indispensable and important basis of reference in the clinical diagnosis and research of blood disease.The erythrocytes of one normal person, three PNH Patients and one AA patient were used in this experiment. This research determines the following items: Height;Length of two axes (long and short), ratio; Crevice in depth and width of cell membrane; Circumference of erythrocytes; Isoline map of erythrocytes; Section map of erythrocytes.

scholarly journals Greater fit and a greater gap

2019 ◽  
Vol 26 (4) ◽  
pp. 561-594
Author(s):  
Steven A. Brieger ◽  
Dirk De Clercq ◽  
Jolanda Hessels ◽  
Christian Pfeifer
Keyword(s):  
Life Satisfaction ◽  
Institutional Environment ◽  
Entrepreneurial Activity ◽  
Worker Rights ◽  
Content Type ◽  
Person Environment Fit ◽  
High Power Distance ◽  
High Degree ◽  
The Impact ◽  
Low Uncertainty

Purpose The purpose of this paper is to understand how national institutional environments contribute to differences in life satisfaction between entrepreneurs and employees. Design/methodology/approach Leveraging person–environment fit and institutional theories and using a sample of more than 70,000 entrepreneurs and employees from 43 countries, the study investigates how the impact of entrepreneurial activity on life satisfaction differs in various environmental contexts. An entrepreneur’s life satisfaction arguably should increase when a high degree of compatibility or fit exists between his or her choice to be an entrepreneur and the informal and formal institutional environment. Findings The study finds that differences in life satisfaction between entrepreneurs and employees are larger in countries with high power distance, low uncertainty avoidance, extant entrepreneurship policies, low commercial profit taxes and low worker rights. Originality/value This study sheds new light on how entrepreneurial activity affects life satisfaction, contingent on the informal and formal institutions in a country that support entrepreneurship by its residents.

Evaluation of compression-recovery and thermal characteristics of multilayer bedding textiles

2020 ◽  
Vol 32 (5) ◽  
pp. 631-643
Author(s):  
Sedat Özer ◽  
Yaşar Erayman Yüksel ◽  
Yasemin Korkmaz
Keyword(s):  
Thermal Conductivity ◽  
Sleep Quality ◽  
Thermal Comfort ◽  
Sleep Duration ◽  
Human Body ◽  
Design Methodology ◽  
Thermal Characteristics ◽  
Air Permeability ◽  
Content Type ◽  
Thermal Comfort Properties

PurposeDesign of bedding textiles that contact the human body affects the sleep quality. Bedding textiles contribute to comfort sense during the sleep duration, in addition to ambient and bed microclimate. The purpose of this study is to evaluate the effects of different layer properties on the compression recovery and thermal characteristics of multilayer bedding textiles.Design/methodology/approachIn this study, woven and knitted multilayer bedding textiles were manufactured from fabric, fiber, sponge and interlining, respectively. Different sponge thickness, fiber and interlining weight were used in the layers of samples. Later, the pilling resistance, compression and recovery, air permeability and thermal conductivity of multilayer bedding textiles were investigated.FindingsThe results indicated that samples with the higher layer weight and thickness provide better compression recovery and lower air permeability properties. It was also found that knitted surfaces show the higher air permeability than the woven surfaces depending on the fabric porosity. Layer properties have insignificant effect on the thermal conductivity values.Originality/valueWhile researchers mostly focus on thermal comfort properties of garments, there are limited studies about comfort properties of bedding textiles in the literature. Furthermore, compression recovery properties of bedding textiles have also a great importance in terms of comfort. Originality of this study is that these properties were analyzed together.

scholarly journals Neutrophil Extracellular Traps Exhibit Antibacterial Activity against Burkholderia pseudomallei and Are Influenced by Bacterial and Host Factors

2012 ◽  
Vol 80 (11) ◽  
pp. 3921-3929 ◽  
Author(s):  
Donporn Riyapa ◽  
Surachat Buddhisa ◽  
Sunee Korbsrisate ◽  
Jon Cuccui ◽  
Brendan W. Wren ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Capsular Polysaccharide ◽  
Neutrophil Extracellular Traps ◽  
Polymorphonuclear Neutrophils ◽  
Dependent Manner ◽  
Predisposing Factor ◽  
Bacterial Killing ◽  
Content Type ◽  
Extracellular Traps ◽  
Type Iii Protein Secretion

ABSTRACTBurkholderia pseudomalleiis the causative pathogen of melioidosis, of which a major predisposing factor is diabetes mellitus. Polymorphonuclear neutrophils (PMNs) kill microbes extracellularly by the release of neutrophil extracellular traps (NETs). PMNs play a key role in the control of melioidosis, but the involvement of NETs in killing ofB. pseudomalleiremains obscure. Here, we showed that bactericidal NETs were released from human PMNs in response toB. pseudomalleiin a dose- and time-dependent manner.B. pseudomallei-induced NET formation required NADPH oxidase activation but not phosphatidylinositol-3 kinase, mitogen-activated protein kinases, or Src family kinase signaling pathways.B. pseudomalleimutants defective in the virulence-associated Bsa type III protein secretion system (T3SS) or capsular polysaccharide I (CPS-I) induced elevated levels of NETs. NET induction by such mutants was associated with increased bacterial killing, phagocytosis, and oxidative burst by PMNs. Taken together the data imply that T3SS and the capsule may play a role in evading the induction of NETs. Importantly, PMNs from diabetic subjects released NETs at a lower level than PMNs from healthy subjects. Modulation of NET formation may therefore be associated with the pathogenesis and control of melioidosis.

Technology adoption and company performance

2018 ◽  
Vol 22 (2) ◽  
pp. 143-161
Author(s):  
Yeong-Wha Sawng ◽  
Yongjae Park ◽  
Seok-Hong Jo ◽  
Seung-Lak Park
Keyword(s):  
Performance Index ◽  
Strategic Decision ◽  
Equation Modeling ◽  
Company Performance ◽  
Relative Importance ◽  
Smart Technology ◽  
Content Type ◽  
Internal Process ◽  
Smart Technologies ◽  
Interdisciplinary Study

Purpose The purpose of this paper is to provide useful implications for Korean export companies to adopt the smart technology to improve their performance in the era of industrial convergence with the interdisciplinary study between trade and technology management. Design/methodology/approach This study followed the five-stage procedure and methods. In the first stage, measurement items were developed in four performance factors: leaning and growth, internal process, customer and finance. In the second stage, data were collected by conducting two types of surveys: first, for Korean export companies that have adopted Radio frequency identification (RFID) to test the proposed model and analyze the performance and second, for RFID experts of industry-university R&D cooperation to measure the relative importance of factors and items. In the third stage, the model was verified with structural equation modeling. In the fourth stage, AHP was used to analyze the relative importance of factors and items. In the fifth stage, post-RFID adoption performance in Korean export companies was measured by a formula for the performance index. Through these five-stage procedure and methods, the final performance improvement strategies and practical implications are presented in the conclusion. Findings The framework finds that the total score of RFID post-adoption on company performance proved relatively low, which indicates that the effect of this technology on export companies’ performance is still unsatisfactory. And financial performance proved to be ‘top priority’ area, which requires the most urgent effort for improvement since its importance was higher than learning and growth, internal process and customer performance—but nonetheless its performance index was the lowest. This study finds that strategic decision making is required for adopting smart technology in the perspective of technology convergence to improve the performance of companies among heterogeneous industries. Research limitations/implications Despite the significant results of this study alone, it also has limitations. Therefore, the direction of the future study is as follows: future research should focus on finding specific impact factors enhancing post-adoption of smart technologies including RFID performance by conducting empirical studies that identify the factors affecting post adoption of smart technologies rate directly or indirectly. Originality/value In the current global market environment, not only technological convergence in the same kind of industry but also industrial convergence in the different kinds of industries are essential to manufacturing and service companies including to export companies with perspective of Innovation. This study has the value as an interdisciplinary study to actually measure the performance of a company by industrial convergence through the theme of adoption of smart technology in export companies.

Living in the end times: a short course addressing end of life issues for older people in an English parish church setting

2015 ◽  
Vol 19 (3) ◽  
pp. 140-149 ◽  
Author(s):  
Joanna Collicutt
Keyword(s):  
Older People ◽  
End Of Life ◽  
Group Dynamics ◽  
Death And Dying ◽  
Community Context ◽  
Content Type ◽  
End Of Life Issues ◽  
End Times ◽  
High Level ◽  
High Degree

Purpose – The purpose of this paper is to report a pilot study that evaluated an innovative practice in a faith community context designed to help older people live well at the end of life and prepare for death. Design/methodology/approach – A simple audit of the intervention using a contemporaneous journal kept by the author, and a follow up questionnaire completed by participants. Findings – Rich findings on the process are reported. These indicate a high degree of engagement by participants, the establishment of a high degree of group intimacy and trust, a high level of articulation of wisdom, the emergence of significant anxiety in some isolated cases, and the use made of tea and cake to manage the transition between the existentially demanding nature of the discussions and normal life. The outcome indicated very high levels of appreciation and increased confidence in relation to issues of death and dying. Practical implications – The findings of the pilot have been used to inform training of clergy in the principles of working in this area (e.g. in ways of managing group dynamics and anxiety, pacing, tuning in to archetypes and the natural symbols that people use to talk about death and dying, self-care and supervision of the programme leader/facilitator). Originality/value – The paper adds to knowledge in terms of an in depth description of processes at work in a group of older people working on spiritual and practical issues in relation to death, and offers ideas for supporting older people in this process, some of which are specific to the Christian tradition, and some of which are more widely applicable to people of all faiths and none. It gives a specific worked example of what “spiritual care” in this area might look like.

scholarly journals Improved Protection in a Rabbit Model of Community-Associated Methicillin-Resistant Staphylococcus aureus Necrotizing Pneumonia upon Neutralization of Leukocidins in Addition to Alpha-Hemolysin

2016 ◽  
Vol 60 (10) ◽  
pp. 6333-6340 ◽  
Author(s):  
Binh An Diep ◽  
Vien T. M. Le ◽  
Zehra C. Visram ◽  
Harald Rouha ◽  
Lukas Stulik ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Human Monoclonal Antibody ◽  
Rabbit Model ◽  
Passive Immunization ◽  
Severe Pneumonia ◽  
Phagocytic Cells ◽  
Methicillin Resistant ◽  
Content Type ◽  
Alpha Hemolysin ◽  
Full Protection

ABSTRACTCommunity-associated methicillin-resistantStaphylococcus aureus(CA-MRSA), especially the USA300 pulsotype, is a frequent cause of skin and soft tissue infections and severe pneumonia. Despite appropriate antibiotic treatment, complications are common and pneumonia is associated with high mortality.S. aureusstrains express multiple cytotoxins, including alpha-hemolysin (Hla) and up to five bicomponent leukocidins that specifically target phagocytic cells for lysis. CA-MRSA USA300 strains carry the genes for all six cytotoxins. Species specificity of the leukocidins greatly contributes to the ambiguity regarding their role inS. aureuspathogenesis. We performed a comparative analysis of the leukocidin susceptibility of human, rabbit, and mouse polymorphonuclear leukocytes (PMNs) to assess the translational value of mouse and rabbitS. aureusmodels. We found that mouse PMNs were largely resistant to LukSF-PV, HlgAB, and HlgCB and susceptible only to LukED, whereas rabbit and human PMNs were highly sensitive to all these cytotoxins. In the rabbit pneumonia model with a USA300 CA-MRSA strain, passive immunization with a previously identified human monoclonal antibody (MAb), Hla-F#5, which cross-neutralizes Hla, LukSF-PV, HlgAB, HlgCB, and LukED, provided full protection, whereas an Hla-specific MAb was only partially protective. In the mouse USA300 CA-MRSA pneumonia model, both types of antibodies demonstrated full protection, suggesting that Hla, but not leukocidin(s), is the principal virulence determinant in mice. As the rabbit recapitulates the high susceptibility to leukocidins characteristic of humans, this species represents a valuable model for assessing novel, cytotoxin-targeting anti-S. aureustherapeutic approaches.

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