Intracellular pathogens alter their host cells' mechanics to promote dissemination through tissues. Conversely, host cells may respond to the presence of pathogens by altering their mechanics to ...limit infection. Here, we monitored epithelial cell monolayers infected with intracellular bacterial pathogens, Listeria monocytogenes or Rickettsia parkeri, over days. Under conditions in which these pathogens trigger innate immune signaling through NF-κB and use actin-based motility to spread non-lytically intercellularly, we found that infected cell domains formed three-dimensional mounds. These mounds resulted from uninfected cells moving toward the infection site, collectively squeezing the softer and less contractile infected cells upward and ejecting them from the monolayer. Bacteria in mounds were less able to spread laterally in the monolayer, limiting the growth of the infection focus, while extruded infected cells underwent cell death. Thus, the coordinated forceful action of uninfected cells actively eliminates large domains of infected cells, consistent with this collective cell response representing an innate immunity-driven process.
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•Epithelial host cells form extruded mounds after infection with L. monocytogenes•3D mounds result from mechanical competition between infected and uninfected cells•Inhibition of cell-matrix and/or cell-cell forces inhibits infection mound formation•Innate immune signals control this mechanical competition that limits pathogen spread
Bastounis et al. show that, during infection with the intracellular bacterial pathogen L. monocytogenes, large infected domains in epithelial cell monolayers extrude to form three-dimensional mounds due to the collective onslaught by their uninfected neighbors. This mechanical competition between uninfected and bacterially infected cells limits pathogen dissemination through the epithelium.
This paper studies the mediating role of cultural values in explaining the total entrepreneurial activity (TEA) and the entrepreneurs’ motivation -differen-tiating opportunity versus necessity ...motives- in countries with different levels of development. Data for 56 countries coming from the Global Entrepreneur-ship Monitor (GEM) and the Schwartz Value Survey (Schwartz, 1994, 2006b) are analysed using structural equations modelling. The results show that only in higher income countries do Autonomy values boost entrepreneurial activ-ity. Additionally, higher entrepreneurship is found in countries where Egalitari-anism predominates, and the effect becomes stronger as income level rises. Furthermore, the Egalitarianism-Hierarchy dimension is also very relevant in explaining the opportunity/necessity ratio.
•Fully coupled fluid–solid simulation of a cell under creeping flows is performed.•The mechanical role of the different cell parts (membrane, nucleus and cytoplasm) in the global deformation of the ...cell is investigated.•The size and mechanical properties of cell nucleus slightly modifies cell deformation.•Different mechanical environments of the cell nucleus are obtained for the different nuclear sizes and mechanical properties, which could be correlated with cell processes such as differentiation, proliferation and death.
Despite the relevant regulatory role that nuclear deformation plays in cell behaviour, a thorough understanding of how fluid flow modulates the deformation of the cell nucleus in non-confined environments is lacking. In this work, we investigated the dynamics of cell deformation under different creeping flows as a general simulation tool for predicting nuclear stresses and strains. Using this solid–fluid modelling interaction framework, we assessed the stress and strain levels that the cell nucleus experiences as a function of different microenvironmental conditions, such as physical constraints, fluid flows, cytosol properties, and nucleus properties and size. Therefore, the simulation methodology proposed here allows the design of deformability-based experiments involving fluid flow, such as real-time deformability cytometry and dynamic cell culture in bioreactors or microfluidic devices.
Different cell migration modes have been identified in 3D environments, e.g., modes incorporating lamellopodia or blebs. Recently, a new type of cellular migration has been investigated: ...lobopodia-based migration, which appears only in three-dimensional matrices under certain conditions. The cell creates a protrusion through which the nucleus slips, dividing the cell into two parts (front and rear) with different hydrostatic pressures. In this work, we elucidate the mechanical conditions that favour this type of migration.
One of the hypotheses about this type of migration is that it depends on the mechanical properties of the extracellular matrix. That is, lobopodia-based migration is dependent on whether the extracellular matrix is linearly elastic or non-linearly elastic.
To determine whether the mechanical properties of the extracellular matrix are crucial in the choice of cell migration mode and which mechanotransduction mechanism the cell might use, we develop a finite element model. From our simulations, we identify two different possible mechanotransduction mechanisms that could regulate the cell to switch from a lobopodial to a lamellipodial migration mode. The first relies on a differential pressure increase inside the cytoplasm while the cell contracts, and the second relies on a change in the fluid flow direction in non-linearly elastic extracellular matrices but not in linearly elastic matrices. The biphasic nature of the cell has been determined to mediate this mechanism and the different behaviours of cells in linearly elastic and non-linearly elastic matrices.
Different cell migration modes have been identified in 3D environments, e.g., modes incorporating lamellopodia or blebs. Recently, a new type of cellular migration has been investigated: ...lobopodia-based migration, which appears only in three-dimensional matrices under certain conditions. The cell creates a protrusion through which the nucleus slips, dividing the cell into two parts (front and rear) with different hydrostatic pressures. In this work, we elucidate the mechanical conditions that favour this type of migration.One of the hypotheses about this type of migration is that it depends on the mechanical properties of the extracellular matrix. That is, lobopodia-based migration is dependent on whether the extracellular matrix is linearly elastic or non-linearly elastic.To determine whether the mechanical properties of the extracellular matrix are crucial in the choice of cell migration mode and which mechanotransduction mechanism the cell might use, we develop a finite element model. From our simulations, we identify two different possible mechanotransduction mechanisms that could regulate the cell to switch from a lobopodial to a lamellipodial migration mode. The first relies on a differential pressure increase inside the cytoplasm while the cell contracts, and the second relies on a change in the fluid flow direction in non-linearly elastic extracellular matrices but not in linearly elastic matrices. The biphasic nature of the cell has been determined to mediate this mechanism and the different behaviours of cells in linearly elastic and non-linearly elastic matrices.
The entrepreneurial function has gained great relevance to explain the development process. From an individual’s cognitive perspective, entrepreneurial intentions are the most relevant elements ...leading to starting up a new venture. Therefore, the main objective of this paper is analysing if different perceptions affect entrepreneurial intentions and examining the possible differences between potential entrepreneurs of two European areas: the Southern countries (Spain, Italy, Greece and Portugal) and the Scandinavian countries (Finland, Sweden and Denmark).The empirical analysis, using logistic regression with Global Entrepreneurship Monitor data, shows that personal, opportunity and socio-cultural perceptions do help explaining entrepreneurial intention. The role of cultural and institutional differences is considered in the conclusions.
Fundamento: El Campylobacter es uno de los principales patógenos entéricos, sin embargo algunos aspectos de su epidemiología no se conocen con precisión. El objetivo de este trabajo es analizar en la ...provincia de Valladolid la tendencia y variación estacional de las gastroenteritis que provoca.
Métodos: Se realizó un análisis de series temporales mediante un modelo aditivo a partir de las declaraciones realizadas al Sistema de Información Microbiológico por los dos principales hospitales de la provincia de Valladolid. Se consideró como caso a los pacientes que presentaron un coprocultivo con un aislamiento de Campylobacter spp. en el período 2000-2004. Se determinaron la tendencia, los coeficientes estacionales de la serie de casos, las tasas de incidencia en función de la edad, el sexo y el año de declaración y las razones de tasas.
Resultados: Se observó una tendencia descendente en la declaración de casos durante el periodo de estudio y se detectó un coeficiente estacional significativo en la cuatrisemana seis (c=12,854, p=0,023). La tasa de incidencia fue mayor en los menores de cinco años y en los hombres, ascendiendo a 1841,9 casos (IC 95: 1797,2-1889,6) y 99,7 casos (IC 95% 96,9-102,4) por 100.000 habitantes-año respectivamente.
Conclusiones: La infección por Campylobacter tiene lugar en mayor medida en la época del final de la primavera, afectando principalmente a los niños. Es necesario profundizar en el conocimiento de la epidemiología de este microorganismo a nivel local con un abordaje multidisciplinar que considere tanto aspectos microbiológicos como epidemiológicos.
Campylobacter is one of the main enteric pathogens, nevertheless many aspects of its epidemiology still are not well known. This study aims to analyze the trend and seasonal pattern in Valladolid.
A ...time series analysis was developed using an additive model. The information sources were the reports to the Microbiological Information System from the main hospitals in Valladolid. Patients who showed a positive coproculture to Campylobacter spp. in the period 2000-2004 were considered cases. Trend, seasonal coefficients, incidence rates by age, sex and year of notification and incidence rate ratios were calculated.
A decreasing trend in reported cases was observed. A significant seasonal coefficient was obtained in the 6th four-week period (c=12,854, p = 0.023). The incidence rate was higher among those under five years of age and among males, rising up to 1841.9 cases (95% CI: 1797.2-1889.6) and 99.7 cases (95% CI: 96.9-102.4) per 100,000 inhabitants-year respectively.
Campylobacter infections occurs to a greater extent in late springtime, affecting mainly children. It is necessary to delve deeper into the knowledge of the epidemiology of this microorganism at the local level with a multidisciplinary approach, taking both microbiological and epidemiological aspects into account.
La función empresarial cobra especial relevancia en la explicación del proceso de desarrollo económico. Desde la perspectiva cognitiva, la intención empresarial es el elemento fundamental que lleva a ...la creación de una empresa. El objetivo fundamental de este artículo es, por tanto, analizar si diferentes percepciones influyen sobre las intenciones empresariales y examinar las posibles diferencias entre los empresarios potenciales de dos áreas europeas: los países del sur (España, Italia, Grecia y Portugal) y los países escandinavos (Finlandia, Suecia y Dinamarca). El análisis empírico, mediante regresión logística con datos del Global Entrepreneurship Monitor, muestra que las percepciones personales, de oportunidad y socio-culturales contribuyen a explicar la intención emprendedora. El papel de las diferencias culturales e institucionales es considerado en las conclusiones.
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