216 research outputs found

    Cycle time reduction in deck roller assembly production unit with value stream mapping analysis

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    Cycle time reduction is of paramount importance in a manufacturing industry as the customer not only emphasizes on the quality of the product but also takes into consideration the timely delivery of the product. The proposed framework and the advanced methodology in this paper are capable of dealing with each stage of the considered manufacturing unit by maximizing the value of the product through reduction of cycle times and minimization of waste. The time required for all the processes in the manufacturing of the deck rollers is identified and are classified into value added (VA) and non-value added (NVA). Finally, the cycle times were reduced by applying the lean tools and principles on some managerial relevances. Also, Arena software was used to simulate the current and future value stream maps and the change in the cycle times, waiting times, machine utilization, etc. was determined.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013.info:eu-repo/semantics/publishedVersio

    Whey protein aerated gels as a new product obtained using ambient temperature magnesium and iron(II) induced gelation

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    The objective of the research was to obtain aerated gels by magnesium and iron(II) ion induced gelation of preheated whey protein isolate dispersions. Preliminary research allowed finding conditions of the pH, protein, and ion concentrations to produce aerated gels capable of holding air bubbles. A novel method applying gelation and aeration process simultaneously was used. Aeration using a laboratory mixer at 2000 r.p.m. produced stronger aerated gels than using a homogenizer at 8000 r.p.m. The gelation process was monitored using an ultrasound viscometer and a constant increase of dynamic viscosity was noted. A different aerated gel microstructure was observed for magnesium and iron(II) induced gels, which probably resulted in differences in the texture and viscosity, as well. The aeration process decreased hardness. In some cases texture parameters correlated with the viscosity measured using an ultrasound viscometer. Aerated whey protein gels could be applied as matrices for food applications or to controlled release of active ingredients

    Expression analysis of somatic embryogenesis-related SERK, LEC1, VP1 and NiR ortologues in rye (Secale cereale L.)

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    The genetic basis of the regeneration process in cultured immature embryos of rye (Secale cereale L.) was analyzed. The experiments were designed to reveal differences between the in vitro culture responses of two inbred lines: L318 (a high regeneration ability) and L9 (a low potential for regeneration). The rye ortologues of plant genes previously recognized as crucial for somatic embryogenesis and morphogenesis in vitro were identified. Using oligonucleotide primers designed to conserved regions of the genes Somatic Embryogenesis Receptor-like Kinase (SERK), Leafy Cotyledon 1 (LEC1), Viviparous 1 (VP1) and NiR (encoding ferredoxin-nitrite reductase), it was possible to amplify specific homologous sequences from rye RNA by RT-PCR. The transcript levels of these genes were then measured during the in vitro culture of zygotic embryos, and the sites of expression localized. The expression profiles of these genes indicate that their function is likely to be correlated with the in vitro response of rye. In line L9, increased expression of the rye SERK ortologue was observed at most stages during the culture of immature embryos. The suppression of ScSERK expression appears to start after the induction of somatic embryogenesis and lasts up to plant regeneration. The rye ortologues of the LEC1 and VP1 genes may function in a complimentary manner and have a negative effect on the production of the embryogenic callus. The expression of the rye NiR ortologue during in vitro culture reveals its importance in the process of plant regeneration

    PPAR? Downregulation by TGF in Fibroblast and Impaired Expression and Function in Systemic Sclerosis: A Novel Mechanism for Progressive Fibrogenesis

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    The nuclear orphan receptor peroxisome proliferator-activated receptor-gamma (PPAR-γ) is expressed in multiple cell types in addition to adipocytes. Upon its activation by natural ligands such as fatty acids and eicosanoids, or by synthetic agonists such as rosiglitazone, PPAR-γ regulates adipogenesis, glucose uptake and inflammatory responses. Recent studies establish a novel role for PPAR-γ signaling as an endogenous mechanism for regulating transforming growth factor-ß (TGF-ß)- dependent fibrogenesis. Here, we sought to characterize PPAR-γ function in the prototypic fibrosing disorder systemic sclerosis (SSc), and delineate the factors governing PPAR-γ expression. We report that PPAR-γ levels were markedly diminished in skin and lung biopsies from patients with SSc, and in fibroblasts explanted from the lesional skin. In normal fibroblasts, treatment with TGF-ß resulted in a time- and dose-dependent down-regulation of PPAR-γ expression. Inhibition occurred at the transcriptional level and was mediated via canonical Smad signal transduction. Genome-wide expression profiling of SSc skin biopsies revealed a marked attenuation of PPAR-γ levels and transcriptional activity in a subset of patients with diffuse cutaneous SSc, which was correlated with the presence of a ''TGF-ß responsive gene signature'' in these biopsies. Together, these results demonstrate that the expression and function of PPAR-γ are impaired in SSc, and reveal the existence of a reciprocal inhibitory cross-talk between TGF-ß activation and PPAR-γ signaling in the context of fibrogenesis. In light of the potent anti-fibrotic effects attributed to PPAR-γ, these observations lead us to propose that excessive TGF-ß activity in SSc accounts for impaired PPAR-γ function, which in turn contributes to unchecked fibroblast activation and progressive fibrosis. © 2010 Wei et al

    The Role of Perfusion Computed Tomography in the Prediction of Cerebral Hyperperfusion Syndrome

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    Hyperperfusion syndrome (HPS) following carotid angioplasty with stenting (CAS) is associated with significant morbidity and mortality. At present, there are no reliable parameters to predict HPS. The aim of this study was to clarify whether perfusion computed tomography (CT) is a feasible and reliable tool in predicting HPS after CAS.We performed a retrospective case-control study of 54 patients (11 HPS patients and 43 non-HPS) with unilateral severe stenosis of the carotid artery who underwent CAS. We compared the prevalence of vascular risk factors and perfusion CT parameters including regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and time to peak (TTP) within seven days prior to CAS. Demographic information, risk factors for atherosclerosis, and perfusion CT parameters were evaluated by multivariable logistic regression analysis. The rCBV index was calculated as [(ipsilateral rCBV - contralateral rCBV)/contralateral rCBV], and indices of rCBF and TTP were similarly calculated. We found that eleven patients had HPS, including five with intracranial hemorrhages (ICHs) of whom three died. After a comparison with non-HPS control subjects, independent predictors of HPS included the severity of ipsilateral carotid artery stenosis, 3-hour mean systolic blood pressure (3 h SBP) after CAS, pre-stenting rCBV index >0.15 and TTP index >0.22.The combination of severe ipsilateral carotid stenosis, 3 h SBP after CAS, rCBV index and TTP index provides a potential screening tool for predicting HPS in patients with unilateral carotid stenosis receiving CAS. In addition, adequate management of post-stenting blood pressure is the most important treatable factor in preventing HPS in these high risk patients

    Towards an anti-fibrotic therapy for scleroderma: targeting myofibroblast differentiation and recruitment

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    BACKGROUND: In response to normal tissue injury, fibroblasts migrate into the wound where they synthesize and remodel new extracellular matrix. The fibroblast responsible for this process is called the myofibroblast, which expresses the highly contractile protein alpha-smooth muscle actin (alpha-SMA). In normal tissue repair, the myofibroblast disappears. Conversely, abnormal myofibroblast persistence is a key feature of fibrotic dieases, including scleroderma (systemic sclerosis, SSc). Myofibroblasts can be derived from differentiation of local resident fibroblasts or by recruitment of microvascular pericytes. CLINICAL PROBLEM ADDRESSED: Controlling myofibroblast differentiation and persistence is crucial for developing anti-fibrotic therapies targeting SSc. BASIC SCIENCE ADVANCES: Insights have been recently generated into how the proteins transforming growth factor beta (TGFbeta), endothelin-1 (ET-1), connective tissue growth factor (CCN2/CTGF) and platelet derived growth factor (PDGF) contribute to myofibroblast differentiation and pericyte recruitment in general and to the persistent myofibroblast phenotype of lesional SSc fibroblast, specifically. RELEVANCE TO CLINICAL CARE: This minireview summarizes recent findings pertinent to the origin of myofibroblasts in SSc and how this knowledge might be used to control the fibrosis in this disease. CONCLUSIONS: TGFbeta, ET-1, CCN2 and PDGF are likely to cooperate in driving tissue repair and fibrogenic responses in fibroblasts. TGFbeta, ET-1 and CCN2 appear to contribute to myofibroblast differentiation; PDGF appears to be involved with pericyte recruitment. Thus, different therapeutic strategies may exist for targeting the multisystem fibrotic disorder SSc

    Rac Inhibition Reverses the Phenotype of Fibrotic Fibroblasts

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    Background: Fibrosis, the excessive deposition of scar tissue by fibroblasts, is one of the largest groups of diseases for which there is no therapy. Fibroblasts from lesional areas of scleroderma patients possess elevated abilities to contract matrix and produce alpha-smooth muscle actin (alpha-SMA), type I collagen and CCN2 (connective tissue growth factor, CTGF). The basis for this phenomenon is poorly understood, and is a necessary prerequisite for developing novel, rational anti-fibrotic strategies.Methods and Findings: Compared to healthy skin fibroblasts, dermal fibroblasts cultured from lesional areas of scleroderma (SSc) patients possess elevated Rac activity. NSC23766, a Rac inhibitor, suppressed the persistent fibrotic phenotype of lesional SSc fibroblasts. NSC23766 caused a decrease in migration on and contraction of matrix, and alpha-SMA, type I collagen and CCN2 mRNA and protein expression. SSc fibroblasts possessed elevated Akt phosphorylation, which was also blocked by NSC23766. Overexpression of rac1 in normal fibroblasts induced matrix contraction and alpha-SMA, type I collagen and CCN2 mRNA and protein expression. Rac1 activity was blocked by PI3kinase/Akt inhibition. Basal fibroblast activity was not affected by NSC23766.Conclusion: Rac inhibition may be considered as a novel treatment for the fibrosis observed in SSc
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