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In this paper, a diagnostic procedure for rotor bar faults in induction motors is presented, based on the Hilbert and discrete wavelet transforms. The method is compared with other procedures with the same data, which are based on time-frequency analysis, frequency analysis and time domain. The results show that this method improves the rotor fault detection in transient conditions. Variable speed drive applications are common in industry. However, traditional condition monitoring methods fail in time-varying conditions or with load oscillations. This method is based on the combined use of the Hilbert and discrete wavelet transforms, which compute the energy in a bandwidth corresponding to the maximum fault signature. Theoretical analysis, numerical simulation and experiments are presented, which confirm the enhanced performance of the proposed method with respect to prior solutions, especially in time-varying conditions. The comparison is based on quantitative analysis that helps in choosing the optimal trade-off between performance and (computational) cost.
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Algoritmos , Análisis de Ondículas , Simulación por ComputadorRESUMEN
BACKGROUND: Elevated numbers of circulating fibrocytes are associated with inadequately controlled asthma, poor response to available therapies, and increased risk of adverse outcomes. The lack of reliable and clinically-applicable assays precludes a proper evaluation of blood fibrocyte count as a prognostic biomarker in asthma. This report concerns the use of a multiparameter flow cytometry assay for the enumeration of fibrocytes in the whole blood. METHODS: Consenting fibrocyte donors were 19 patients with asthma well controlled by current treatment, 16 patients with treatment-resistant asthma, 9 patients with transiently uncontrolled asthma and 14 age-matched normal individuals. Blood sampling was performed once in patients with transiently uncontrolled asthma and twice, at an interval of one week, in the other subjects. The assay was performed in 100 µl of whole blood and involved a sequential gating strategy and absolute fibrocyte counting with a single instrument (single-platform assay). RESULTS: The quantification of circulating fibrocytes by this assay was analytically and clinically valid. In individuals with stable clinical conditions, the repeatability of blood fibrocyte counts over one week was good. The intraclass correlation coefficient was 0.939 and 96.88% of the total variability reflected on-average differences among the tested subjects. Stabilized blood samples could be stored at 4 °C for up to 96 h before processing. CONCLUSIONS: The novel assay for the enumeration of fibrocytes in the whole blood is reliable and clinically applicable. GENERAL SIGNIFICANCE: This report demonstrates the validity and reliability of the first optimized assay for the enumeration of circulating fibrocytes in multicenter clinical trials.
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The release of IL-33 increases in the bronchial mucosa of asthmatic patients in relation to disease severity and several studies have demonstrated that IL-33 may enhance airway inflammation in asthma. This study tested the hypothesis that IL-33 may also contribute to the development of irreversible structural changes in asthma by favoring the airway recruitment and profibrotic function of circulating fibrocytes during episodes of allergen-induced asthma exacerbation. The circulating fibrocytes from patients with allergen-exacerbated asthma (PwAA) showed increased expression of the specific IL-33 receptor component ST2L in comparison with the cells from non-asthmatic individuals (NAI). Recombinant IL-33 induced the migration of circulating fibrocytes from PwAA at clinically relevant concentrations and stimulated their proliferation in a concentration-dependent manner between 0.1 and 10 ng/ml, without affecting the constitutive release of type I collagen. The recombinant protein did not induce similar responses in circulating fibrocytes from NAI. This study uncovers an important mechanism through which fibrocytes may accumulate in the airways of allergic asthmatics when their disease is not adequately controlled by current treatment and provides novel information on the function of IL-33 in asthma.
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Alérgenos/inmunología , Asma/inmunología , Asma/patología , Movimiento Celular/inmunología , Proliferación Celular , Interleucinas/metabolismo , Receptores de Superficie Celular/biosíntesis , Movimiento Celular/efectos de los fármacos , Progresión de la Enfermedad , Humanos , Proteína 1 Similar al Receptor de Interleucina-1 , Interleucina-33 , Interleucinas/genética , Interleucinas/farmacología , Proteínas Recombinantes/farmacologíaRESUMEN
The fibrocytes are thought to serve as a source of newly deposited collagens I and III during reparative processes and in certain fibrotic disorders, but their matrix remodelling properties are incompletely understood. We evaluated their ability to produce several extracellular matrix (ECM) components, in comparison with fibroblasts, and to participate in collagen turnover. The collagen gene expression profile of fibrocytes differed from that of fibroblasts because fibrocytes constitutively expressed relatively high levels of the mRNA encoding collagen VI and significantly lower levels of the mRNA encoding collagens I, III and V. The proteoglycan (PG) gene expression profile was also different in fibrocytes and fibroblasts because fibrocytes constitutively expressed the mRNA encoding perlecan and versican at relatively high levels and the mRNA encoding biglycan and decorin at low and very low levels, respectively. Moreover, fibrocytes expressed the mRNA for hyaluronan synthase 2 at higher level than fibroblasts. Significant differences between the two cell populations were also demonstrated by metabolic labelling and analysis of the secreted collagenous proteins, PGs and hyaluronan. Fibrocytes constitutively expressed the scavenger receptors CD163 and CD204 as well as the mannose receptors CD206 and Endo180, and internalized and degraded collagen fragments through an Endo180-mediated mechanism. The results of this study demonstrate that human fibrocytes exhibit ECM remodelling properties previously unexplored, including the ability to participate in collagen turnover. The observed differences in collagen and PG expression profile between fibrocytes and fibroblasts suggest that fibrocytes may predominantly have a matrix-stabilizing function.
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Colágeno/metabolismo , Células del Tejido Conectivo/citología , Matriz Extracelular/metabolismo , Fibroblastos/citología , ARN Mensajero/biosíntesis , Biglicano/genética , Biglicano/metabolismo , Diferenciación Celular , Colágeno/genética , Células del Tejido Conectivo/metabolismo , Decorina/genética , Decorina/metabolismo , Matriz Extracelular/genética , Fibroblastos/metabolismo , Expresión Génica , Perfilación de la Expresión Génica , Glucuronosiltransferasa/genética , Glucuronosiltransferasa/metabolismo , Proteoglicanos de Heparán Sulfato/genética , Proteoglicanos de Heparán Sulfato/metabolismo , Humanos , Hialuronano Sintasas , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Receptor de Manosa , Lectinas de Unión a Manosa/genética , Lectinas de Unión a Manosa/metabolismo , Cultivo Primario de Células , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , ARN Mensajero/análisis , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Receptores Depuradores/genética , Receptores Depuradores/metabolismo , Versicanos/genética , Versicanos/metabolismoRESUMEN
The human peripheral blood contains a multipotent precursor that shows hematopoietic stem cell features and transiently expresses markers of the myeloid lineage. Under permissive conditions, this precursor gives rise to committed progenitors of various lineages, including a mesenchymal progenitor cell known by the name of fibrocyte. The fibrocytes still express some hematopoietic and myeloid antigens together with fibroblast markers. They constitutively release pro-fibrotic and angiogenic factors and can modulate ongoing inflammatory reactions through the release of a number of chemokines. Under appropriate stimulation, fibrocytes produce increased amounts of extracellular matrix components and acquire a contractile phenotype similar to that of activated fibroblasts (myofibroblasts). Fibrocytes synthesizing new collagen or acquiring myofibroblast markers have been detected in pulmonary diseases characterized by an extensive remodeling of the bronchial wall or progressive fibrosis, in the skin of patients affected by nephrogenic systemic fibrosis, in human hypertrophic scars, in proliferative vitreoretinopathies and atherosclerotic lesions. Similar cells also participate in the stromal reaction to tumor development. Prevention of detrimental tissue remodeling in fibrotic diseases may be achieved by inhibiting the accumulation of fibrocytes. In-vitro expanded fibrocytes may be used to improve ineffective tissue repair or may be engineered for the delivery of gene constructs in anti-cancer therapy.
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Antígenos de Diferenciación/metabolismo , Trasplante de Células Madre Mesenquimatosas , Células Madre Mesenquimatosas/metabolismo , Mioblastos del Músculo Liso/metabolismo , Fibrosis Pulmonar/terapia , Remodelación de las Vías Aéreas (Respiratorias) , Animales , Humanos , Células Madre Mesenquimatosas/patología , Mioblastos del Músculo Liso/patología , Fibrosis Pulmonar/patología , Ingeniería de Tejidos , Cicatrización de HeridasRESUMEN
Human fibrocytes are mesenchymal progenitors that exhibit mixed morphological and molecular characteristics of hematopoietic stem cells, monocytes and fibroblasts. They likely represent the obligate intermediate stage of differentiation into mature mesenchymal cells of a bone marrow-derived precursor of the monocyte lineage under permissive conditions. On in vitro stimulation with pro-fibrotic cytokines and growth factors, human fibrocytes produce large quantities of extracellular matrix components and further differentiate into cells identical to the contractile myofibroblasts that emerge at the tissue sites during repair processes and in some fibrotic lesions. Studies in various animal models of wound healing or fibrotic diseases have confirmed the ability of fibrocytes to differentiate into mature mesenchymal cells in vivo and have suggested a causal link between fibrocyte accumulation and ongoing tissue fibrogenesis or vascular remodeling in response to tissue damage or hypoxia. Fibrocytes synthesizing new collagen or acquiring myofibroblast markers have been detected in human hypertrophic scars, in the skin of patients affected by nephrogenic systemic fibrosis, in human atherosclerotic lesions, and in pulmonary diseases characterized by repeated cycles of inflammation and repair, like asthma. The presence of fibrocyte-like cells has been reported in human chronic pancreatitis and chronic cystitis. Similar cells also populate the stroma surrounding human benign tumors. The available data indicate that human fibrocytes serve as a source of mature mesenchymal cells during reparative processes and in fibrotic disorders or stromal reactions predominantly associated with a persistent inflammatory infiltrate or with the selective recruitment of monocytes induced by ischemic changes and tumor development. A deeper understanding of the mechanisms involved in fibrocyte differentiation in these pathological conditions may lead to the development of novel therapies for preventing detrimental tissue or vascular remodeling and metastatic progression of invasive tumors.
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Fibrosis/fisiopatología , Células Madre Mesenquimatosas , Cicatrización de Heridas/fisiología , Animales , Asma/patología , Aterosclerosis , Diferenciación Celular , Humanos , Células Madre Mesenquimatosas/patología , Células Madre Mesenquimatosas/fisiologíaRESUMEN
Myofibroblasts play a key role in wound closure but their origin is poorly understood. To investigate whether fibrocytes contribute to myofibroblast population, we examined the phenotype of fibrocytes and myofibroblasts present in the wounded skin of BALB/c mice. During wound healing, there was a marked increase in the number of cells expressing the myofibroblast marker alpha-smooth muscle actin in the granulation tissue. Between 4 and 7 days post-wounding, more than 50% of these cells also expressed the CD13 antigen. CD13(+)/collagen I+ fibrocytes could be isolated at an early stage of the healing process from digested fragments of wounded tissue by fluorescence-activated cell sorting. Like authentic fibrocytes, these cells were also CD45(+)/CD34(+)/CD14-. Between 4 and 7 days post-injury, 61.4% of the isolated fibrocytes were found to express alpha-smooth muscle actin gene and protein. We repeated similar experiments in female mice that had received a male whole bone marrow transplant after total body irradiation. By in situ hybridization, we identified the Y chromosome in the nuclei of the majority of fibrocytes isolated from the wounded tissue of these animals. Our data indicate that circulating fibrocytes contribute to the myofibroblast population in the wounded skin and that they originate from the bone marrow.