The role of the epithelial cell in asthma

It is done a review of the intervention of the epithelial bronchial cell in the pathophysiology of asthma. The respiratory epithelium acts as a physical barrier that separates the external environment from the pulmonary internal environment. It controls the intercellular and trans -cellular permeability and this way the accessibility of the inhaled pathogens to the antigen presenting cells involved in the immuno -inflammatory response. Epithelial cells connected by tight junctions contribute to the barrier function of the airways. They express a poliovirus receiver - related protein (PRR), toll like receptors (TLRs) and protease- -activated receptors (PARs), which recognize bacterial agents and allergens. Its dysfunction turns them into important sources of inflammatory mediators. The bidirectional interaction between the epithelium and other bronchial wall elements with inhaled particles originates a structure with its own identity, the designated EMTU - Epithelial Mesenchymal Trophic Unit. These observations support a central role for the epithelial cell in chronic inflammation and in the remodelling of the asthmatic process. Infectious diseases and environmental stress can activate different cell receptors and signalling pathways that induce changes in the cell surface modifying their response to future stimulations, namely to other infectious aggressions. The bronchial epithelium has barrier functions with selective permeability; it has metabolic activity producing cytokines and chemokines stimulating the cell's recruitment and activation, increasing the bronchial reactivity and the remodelling of the airways

Exercise and immunoinflammatory responses

O estudo da relação entre o exercício e a resposta inflamatória e imunológica tem motivado um elevado interesse, desde há vários anos. Existe uma estreita comunicação entre o sistema neuroendócrino e as células imunocompetentes através de mensageiros que vão ter uma intervenção importante nessa resposta. O exercício físico determina em geral uma imunossupressão transitória, precedida de um aumento da componente celular e humoral de intensidade e duração variáveis, dependendo da natureza do exercício e da susceptibilidade específica aos mediadores libertados. Os leucócitos totais, particularmente os neutrófilos e células natural killer mantêm-se elevados no período que se segue ao exercício intenso, enquanto os linfócitos tendem rapidamente a atingir contagens semelhantes ou inferiores aos valores pré-exercício. O exercício intenso pode favorecer um desvio do fenótipo linfocitário Th1 para o fenótipo Th2. As imunoglobulinas, particularmente a IgG, tendem a aumentar transitoriamente. As proteínas de fase aguda e as citocinas, principalmente a IL6 e TNFα, terão intervenções particularmente destacadas neste processo. A prática regular de desporto moderado induz um retorno à estabilidade basal da maioria dos parâmetros, bem como a uma protecção acrescida relativamente a agressores microbianos ambientais. Esta observação está limitada pela dificuldade em distinguir uma actividade moderada continuada de um esforço físico intenso cíclico, sendo contudo certo que os benefícios na saúde atribuídos ao exercício físico moderado estão em larga medida relacionados com as modificações que provocam no sistema inflamatório e imunológico

Supergiant Barocaloric Effects in Acetoxy Silicone Rubber over a Wide Temperature Range: Great Potential for Solid-state Cooling

Solid-state cooling based on caloric effects is considered a viable alternative to replace the conventional vapor-compression refrigeration systems. Regarding barocaloric materials, recent results show that elastomers are promising candidates for cooling applications around room-temperature. In the present paper, we report supergiant barocaloric effects observed in acetoxy silicone rubber - a very popular, low-cost and environmentally friendly elastomer. Huge values of adiabatic temperature change and reversible isothermal entropy change were obtained upon moderate applied pressures and relatively low strains. These huge barocaloric changes are associated both to the polymer chains rearrangements induced by confined compression and to the first-order structural transition. The results are comparable to the best barocaloric materials reported so far, opening encouraging prospects for the application of elastomers in near future solid-state cooling devices.Comment: 19 pages, 7 figures, 2 table

Global temperature homogenization can obliterate temporal isolation in migratory animals with potential loss of population structure

Abstract Climate change is expected to increase the spatial autocorrelation of temperature, resulting in greater synchronization of climate variables worldwide. Possibly such ‘homogenization of the world’ leads to elevated risks of extinction and loss of biodiversity. In this study, we develop an empirical example on how increasing synchrony of global temperatures can affect population structure in migratory animals. We studied two subspecies of bar-tailed godwits Limosa lapponica breeding in tundra regions in Siberia: yamalensis in the west and taymyrensis further east and north. These subspecies share pre- and post-breeding stopover areas, thus being partially sympatric, but exhibiting temporal segregation. The latter is believed to facilitate reproductive isolation. Using satellite tracking data, we show that migration timing of both subspecies is correlated with the date of snowmelt in their respective breeding sites (later at the taymyrensis breeding range). Snow-cover satellite images demonstrate that the breeding ranges are on different climate trajectories and become more synchronized over time: between 1997 and 2020, the date of snowmelt advanced on average by 0.5 days/year in the taymyrensis breeding range, while it remained stable in the yamalensis breeding range. Previous findings showed how taymyrensis responded to earlier snowmelt by advancing arrival and clutch initiation. In the predicted absence of such advancements in yamalensis, we expect that the two populations will be synchronized by 2036–2040. Since bar-tailed godwits are social migrants, this raises the possibility of population exchange and prompts the question whether the two subspecies can maintain their geographic and morphological differences and population-specific migratory routines. The proposed scenario may apply to a wide range of (social) migrants as temporal segregation is crucial for promoting and maintaining reproductive isolation in many (partially sympatric) migratory populations. Homogenization of previously isolated populations could be an important consequence of increasing synchronized environments and hence climate change

Global temperature homogenization can obliterate temporal isolation in migratory animals with potential loss of population structure

Abstract Climate change is expected to increase the spatial autocorrelation of temperature, resulting in greater synchronization of climate variables worldwide. Possibly such ‘homogenization of the world’ leads to elevated risks of extinction and loss of biodiversity. In this study, we develop an empirical example on how increasing synchrony of global temperatures can affect population structure in migratory animals. We studied two subspecies of bar-tailed godwits Limosa lapponica breeding in tundra regions in Siberia: yamalensis in the west and taymyrensis further east and north. These subspecies share pre- and post-breeding stopover areas, thus being partially sympatric, but exhibiting temporal segregation. The latter is believed to facilitate reproductive isolation. Using satellite tracking data, we show that migration timing of both subspecies is correlated with the date of snowmelt in their respective breeding sites (later at the taymyrensis breeding range). Snow-cover satellite images demonstrate that the breeding ranges are on different climate trajectories and become more synchronized over time: between 1997 and 2020, the date of snowmelt advanced on average by 0.5 days/year in the taymyrensis breeding range, while it remained stable in the yamalensis breeding range. Previous findings showed how taymyrensis responded to earlier snowmelt by advancing arrival and clutch initiation. In the predicted absence of such advancements in yamalensis, we expect that the two populations will be synchronized by 2036–2040. Since bar-tailed godwits are social migrants, this raises the possibility of population exchange and prompts the question whether the two subspecies can maintain their geographic and morphological differences and population-specific migratory routines. The proposed scenario may apply to a wide range of (social) migrants as temporal segregation is crucial for promoting and maintaining reproductive isolation in many (partially sympatric) migratory populations. Homogenization of previously isolated populations could be an important consequence of increasing synchronized environments and hence climate change