RESUMEN
BACKGROUND: The acute effect of supplemental oxygen during exercise has been shown to differ largely among patients with COPD. It is unknown what factors influence oxygen response. METHODS: In a randomized, single-blind fashion, 124 patients with COPD underwent one 6-min walk test on supplemental oxygen (6MWTO2) and one 6-min walk test on room air after a practice 6-min walk test. Both gases were delivered via standard nasal prongs (2 L/min). For analyses, patients were stratified on the basis of PaO2 values and compared: (1) 34 patients with resting hypoxemia (HYX); (2) 43 patients with exercise-induced hypoxemia (EIH); and (3) 31 patients with normoxemia (NOX). RESULTS: Oxygen supplementation resulted in an increase in the 6-min walk distance in the total cohort (27 ± 42 meters; P < .001) and in the subgroups of HYX (37 ± 40 meters; P < .001) and EIH (28 ± 44 meters; P < .001) but not in the NOX subgroup (15 ± 43 meters; P = .065). Forty-two percent of patients with HYX and 47% of patients with EIH improved their 6-min walk distance to a clinically relevant extent (≥ 30 meters) by using oxygen. These oxygen responders were characterized by significantly lower 6-min walk distance using room air compared with patients without a relevant response (306 ± 106 meters vs 358 ± 113 meters; P < .05). Although oxygen saturation was significantly higher during 6MWTO2 compared with the 6-min walk test on room air in all 3 subgroups, it dropped to < 88% during 6MWTO2 in 73.5% of patients with HYX. CONCLUSIONS: In contrast to patients with NOX, patients with HYX and EIH generally benefit from supplemental oxygen by increasing exercise capacity. However, less than one-half of patients reached the threshold of clinically relevant improvements. These oxygen responders were characterized by significantly lower exercise capacity levels. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT00886639; URL: www.clinicaltrials.gov.
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Terapia por Inhalación de Oxígeno/métodos , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Enfermedad Pulmonar Obstructiva Crónica/terapia , Prueba de Paso , Anciano , Estudios Cruzados , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Índice de Severidad de la Enfermedad , Método Simple Ciego , Resultado del TratamientoRESUMEN
Cells sense the context in which they grow to adapt their phenotype and allow multicellular patterning by mechanisms of autocrine and paracrine signalling. However, patterns also form in cell populations exposed to the same signalling molecules and substratum, which often correlate with specific features of the population context of single cells, such as local cell crowding. Here we reveal a cell-intrinsic molecular mechanism that allows multicellular patterning without requiring specific communication between cells. It acts by sensing the local crowding of a single cell through its ability to spread and activate focal adhesion kinase (FAK, also known as PTK2), resulting in adaptation of genes controlling membrane homeostasis. In cells experiencing low crowding, FAK suppresses transcription of the ABC transporter A1 (ABCA1) by inhibiting FOXO3 and TAL1. Agent-based computational modelling and experimental confirmation identified membrane-based signalling and feedback control as crucial for the emergence of population patterns of ABCA1 expression, which adapts membrane lipid composition to cell crowding and affects multiple signalling activities, including the suppression of ABCA1 expression itself. The simple design of this cell-intrinsic system and its broad impact on the signalling state of mammalian single cells suggests a fundamental role for a tunable membrane lipid composition in collective cell behaviour.
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Adaptación Fisiológica , Comunicación Celular/fisiología , Membrana Celular/química , Fibroblastos/citología , Lípidos/química , Transducción de Señal , Transportador 1 de Casete de Unión a ATP/genética , Transportador 1 de Casete de Unión a ATP/metabolismo , Animales , Recuento de Células , Línea Celular Tumoral , Fibroblastos/química , Fibroblastos/enzimología , Proteína-Tirosina Quinasas de Adhesión Focal/metabolismo , Factores de Transcripción Forkhead/metabolismo , Regulación de la Expresión Génica , Homeostasis , Humanos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones , Modelos Biológicos , TranscriptomaRESUMEN
INTRODUCTION: To date endurance and strength training are established and evidence-based exercise methods in patients with chronic obstructive pulmonary disease (COPD). There is an unmet need for further research in new and complementary exercise modalities. Additional whole body vibration training during pulmonary rehabilitation may be such a new approach that has not yet been investigated in patients with COPD. METHODS: Eighty-two patients (65 ± 9 yrs, FEV(1) pred. 38 ± 11%, female 51%) with COPD in GOLD stage III to IV assessed for a 3-week inpatient multidisciplinary rehabilitation program were on top randomly assigned to one of two intervention groups: (1) 3 × 3 min of bilateral dynamic squat exercises on a side-alternating vibration platform at 24-26 Hz three times per week (WBV) and (2) a control group (CON) with the same amount of exercise time without WBV. RESULTS: Thirty-six patients completed the study in each group. The improvement in 6-min walking distance was significantly higher in the WBV-group when compared to the CON-group (WBV: 64 ± 59 m, CON: 37 ± 52 m with a between-group difference of 27 m [95% CI, 1-53], p = 0.046). The time required for a sit-to-stand test also decreased more markedly in the WBV-group than in the CON-group (WBV: -4.0 ± 4.8 s, CON: -2.0 ± 3.1 s with a between-group difference of -1.9 s [95% CI, -4.0 to 0.1], p = 0.067). Improvements in health-related quality of life were similar in both groups. CONCLUSIONS: WBV training seems to be a promising new exercise modality for patients with COPD and may enhance the effects of a multidisciplinary rehabilitation program.
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Terapia por Ejercicio/métodos , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Enfermedad Pulmonar Obstructiva Crónica/rehabilitación , Pruebas de Función Respiratoria/métodos , Vibración/uso terapéutico , Anciano , Tolerancia al Ejercicio , Femenino , Humanos , Masculino , Modalidades de Fisioterapia , Estudios Prospectivos , Músculos Respiratorios/fisiopatología , Factores de Tiempo , Resultado del Tratamiento , CaminataRESUMEN
Single-cell heterogeneity in cell populations arises from a combination of intrinsic and extrinsic factors. This heterogeneity has been measured for gene transcription, phosphorylation, cell morphology and drug perturbations, and used to explain various aspects of cellular physiology. In all cases, however, the causes of heterogeneity were not studied. Here we analyse, for the first time, the heterogeneous patterns of related cellular activities, namely virus infection, endocytosis and membrane lipid composition in adherent human cells. We reveal correlations with specific cellular states that are defined by the population context of a cell, and we derive probabilistic models that can explain and predict most cellular heterogeneity of these activities, solely on the basis of each cell's population context. We find that accounting for population-determined heterogeneity is essential for interpreting differences between the activity levels of cell populations. Finally, we reveal that synergy between two molecular components, focal adhesion kinase and the sphingolipid GM1, enhances the population-determined pattern of simian virus 40 (SV40) infection. Our findings provide an explanation for the origin of heterogeneity patterns of cellular activities in adherent cell populations.
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Células Clonales/patología , Endocitosis , Virosis/patología , Adhesión Celular , Recuento de Células , Línea Celular Tumoral , Tamaño de la Célula , Células Clonales/virología , Virus del Dengue/fisiología , Quinasa 1 de Adhesión Focal/metabolismo , Gangliósido G(M1)/metabolismo , Humanos , Lípidos de la Membrana/análisis , Lípidos de la Membrana/metabolismo , Virus de la Hepatitis Murina/fisiología , Rotavirus/fisiología , Virus 40 de los Simios/fisiología , Virosis/virologíaRESUMEN
In this article, we define systems biology of virus entry in mammalian cells as the discipline that combines several approaches to comprehensively understand the collective physical behaviour of virus entry routes, and to understand the coordinated operation of the functional modules and molecular machineries that lead to this physical behaviour. Clearly, these are extremely ambitious aims, but recent developments in different life science disciplines slowly allow us to set them as realistic, although very distant, goals. Besides classical approaches to obtain high-resolution information of the molecules, particles and machines involved, we require approaches that can monitor collective behaviour of many molecules, particles and machines simultaneously, in order to reveal design principles of the systems as a whole. Here we will discuss approaches that fall in the latter category, namely time-lapse imaging and single-particle tracking (SPT) combined with computational analysis and modelling, and genome-wide RNA interference approaches to reveal the host components required for virus entry. These techniques should in the future allow us to assign host genes to the systems' functions and characteristics, and allow emergence-driven, in silico assembly of networks that include interactions with increasing hierarchy (molecules-multiprotein complexes-vesicles and organelles), and kinetics and subcellular spatiality, in order to allow realistic simulations of virus entry in real time.
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Virus/patogenicidad , Animales , Antivirales/farmacología , Membrana Celular/virología , Perfilación de la Expresión Génica , Humanos , Modelos Biológicos , Interferencia de ARN , Virus 40 de los Simios/patogenicidad , Virus 40 de los Simios/fisiología , Biología de Sistemas , Virus de la Estomatitis Vesicular Indiana/patogenicidad , Virus de la Estomatitis Vesicular Indiana/fisiología , Virosis/etiología , Virosis/genética , Virosis/fisiopatología , Virosis/virología , Fenómenos Fisiológicos de los Virus , Virus/efectos de los fármacosRESUMEN
Simian Virus 40 (SV40) has been shown to enter host cells by caveolar endocytosis followed by transport via caveosomes to the endoplasmic reticulum (ER). Using a caveolin-1 (cav-1)-deficient cell line (human hepatoma 7) and embryonic fibroblasts from a cav-1 knockout mouse, we found that in the absence of caveolae, but also in wild-type embryonic fibroblasts, the virus exploits an alternative, cav-1-independent pathway. Internalization was rapid (t1/2 = 20 min) and cholesterol and tyrosine kinase dependent but independent of clathrin, dynamin II, and ARF6. The viruses were internalized in small, tight-fitting vesicles and transported to membrane-bounded, pH-neutral organelles similar to caveosomes but devoid of cav-1 and -2. The viruses were next transferred by microtubule-dependent vesicular transport to the ER, a step that was required for infectivity. Our results revealed the existence of a virus-activated endocytic pathway from the plasma membrane to the ER that involves neither clathrin nor caveolae and that can be activated also in the presence of cav-1.