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Lothman, KA*, et AW Mangel. « Pulse Synchronized Contractions (PSCs) ». Journal of Cardiology and Cardiovascular Medicine 4, no 3 (15 novembre 2019) : 199–200. http://dx.doi.org/10.29328/journal.jccm.1001067.
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Aoki, Hiroyoshi, Hirohide Ohnishi, Kouji Hama, Takako Ishijima, Yukihiro Satoh, Kazunobu Hanatsuka, Akira Ohashi et al. « Autocrine loop between TGF-β1 and IL-1β through Smad3- and ERK-dependent pathways in rat pancreatic stellate cells ». American Journal of Physiology-Cell Physiology 290, no 4 (avril 2006) : C1100—C1108. http://dx.doi.org/10.1152/ajpcell.00465.2005.
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Pancreatic stellate cells (PSCs) are activated during pancreatitis and promote pancreatic fibrosis by producing and secreting ECMs such as collagen and fibronectin. IL-1β has been assumed to participate in pancreatic fibrosis by activating PSCs. Activated PSCs secrete various cytokines that regulate PSC function. In this study, we have examined IL-1β secretion from culture-activated PSCs as well as its regulatory mechanism. RT-PCR and ELISA have demonstrated that PSCs express IL-1β mRNA and secrete IL-1β peptide. Inhibition of TGF-β1 activity secreted from PSCs by TGF-β1-neutralizing antibody attenuated IL-1β secretion from PSCs. Exogenous TGF-β1 increased IL-1β expression and secretion by PSCs in a dose-dependent manner. Adenovirus-mediated expression of dominant-negative (dn)Smad2/3 expression reduced both basal and TGF-β1-stimulated IL-1β expression and secretion by PSCs. Coexpression of Smad3 with dnSmad2/3 restored IL-1β expression and secretion by PSCs, which were attenuated by dnSmad2/3 expression. In contrast, coexpression of Smad2 with dnSmad2/3 did not alter them. Furthermore, inhibition of IL-1β activity secreted from PSCs by IL-1β-neutralizing antibody attenuated TGF-β1 secretion from PSCs. Exogenous IL-1β enhanced TGF-β1 expression and secretion by PSCs. IL-1β activated ERK, and PD-98059, a MEK1 inhibitor, blocked IL-1β enhancement of TGF-β1 expression and secretion by PSCs. We propose that an autocrine loop exists between TGF-β1 and IL-1β in activated PSCs through Smad3- and ERK-dependent pathways.
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Masamune, Atsushi, Kazuhiro Kikuta, Takashi Watanabe, Kennichi Satoh, Morihisa Hirota et Tooru Shimosegawa. « Hypoxia stimulates pancreatic stellate cells to induce fibrosis and angiogenesis in pancreatic cancer ». American Journal of Physiology-Gastrointestinal and Liver Physiology 295, no 4 (octobre 2008) : G709—G717. http://dx.doi.org/10.1152/ajpgi.90356.2008.
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Pancreatic cancer is characterized by excessive desmoplastic reaction and by a hypoxic microenvironment within the solid tumor mass. Chronic pancreatitis is also characterized by fibrosis and hypoxia. Fibroblasts in the area of fibrosis in these pathological settings are now recognized as activated pancreatic stellate cells (PSCs). Recent studies have suggested that a hypoxic environment concomitantly exists not only in pancreatic cancer cells but also in surrounding PSCs. This study aimed to clarify whether hypoxia affected the cell functions in PSCs. Human PSCs were isolated and cultured under normoxia (21% O2) or hypoxia (1% O2). We examined the effects of hypoxia and conditioned media of hypoxia-treated PSCs on cell functions in PSCs and in human umbilical vein endothelial cells. Hypoxia induced migration, type I collagen expression, and vascular endothelial growth factor (VEGF) production in PSCs. Conditioned media of hypoxia-treated PSCs induced migration of PSCs, which was inhibited by anti-VEGF antibody but not by antibody against hepatocyte growth factor. Conditioned media of hypoxia-treated PSCs induced endothelial cell proliferation, migration, and angiogenesis in vitro and in vivo. PSCs expressed several angiogenesis-regulating molecules including VEGF receptors, angiopoietin-1, and Tie-2. In conclusion, hypoxia induced profibrogenic and proangiogenic responses in PSCs. In addition to their established profibrogenic roles, PSCs might play proangiogenic roles during the development of pancreatic fibrosis, where they are subjected to hypoxia.
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Hrabák, P., M. Kalousová, T. Krechler et T. Zima. « Pancreatic stellate cells - rising stars in pancreatic pathologies ». Physiological Research, S4 (30 décembre 2021) : S597—S616. http://dx.doi.org/10.33549//physiolres.934783.
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Pluripotent pancreatic stellate cells (PSCs) receive growing interest in past decades. Two types of PSCs are recognized –vitamin A accumulating quiescent PSCs and activated PSCs- the main producents of extracellular matrix in pancreatic tissue. PSCs plays important role in pathogenesis of pancreatic fibrosis in pancreatic cancer and chronic pancreatitis. PSCs are intensively studied as potential therapeutical target because of their important role in developing desmoplastic stroma in pancreatic cancer. There also exists evidence that PSC are involved in other pathologies like type-2 diabetes mellitus. This article brings brief characteristics of PSCs and recent advances in research of these cells.
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Xu, Lu, Jianjun Zhou, Jingyu Liu, Yong Liu, Lei Wang, Ruiwei Jiang, Zhenyu Diao et al. « Different Angiogenic Potentials of Mesenchymal Stem Cells Derived from Umbilical Artery, Umbilical Vein, and Wharton’s Jelly ». Stem Cells International 2017 (2017) : 1–15. http://dx.doi.org/10.1155/2017/3175748.
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Human mesenchymal stem cells derived from the umbilical cord (UC) are a favorable source for allogeneic cell therapy. Here, we successfully isolated the stem cells derived from three different compartments of the human UC, including perivascular stem cells derived from umbilical arteries (UCA-PSCs), perivascular stem cells derived from umbilical vein (UCV-PSCs), and mesenchymal stem cells derived from Wharton’s jelly (WJ-MSCs). These cells had the similar phenotype and differentiation potential toward adipocytes, osteoblasts, and neuron-like cells. However, UCA-PSCs and UCV-PSCs had more CD146+ cells than WJ-MSCs (P<0.05). Tube formation assay in vitro showed the largest number of tube-like structures and branch points in UCA-PSCs among the three stem cells. Additionally, the total tube length in UCA-PSCs and UCV-PSCs was significantly longer than in WJ-MSCs (P<0.01). Microarray, qRT-PCR, and Western blot analysis showed that UCA-PSCs had the highest expression of the Notch ligand Jagged1 (JAG1), which is crucial for blood vessel maturation. Knockdown of Jagged1 significantly impaired the angiogenesis in UCA-PSCs. In summary, UCA-PSCs are promising cell populations for clinical use in ischemic diseases.
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Plé, Sophie, Viviana Job, Andréa Dessen et Ina Attree. « Cochaperone Interactions in Export of the Type III Needle Component PscF of Pseudomonas aeruginosa ». Journal of Bacteriology 192, no 14 (21 mai 2010) : 3801–8. http://dx.doi.org/10.1128/jb.00117-10.
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ABSTRACT Type III secretion (T3S) systems allow the export and translocation of bacterial effectors into the host cell cytoplasm. Secretion is accomplished by an 80-nm-long needle-like structure composed, in Pseudomonas aeruginosa, of the polymerized form of a 7-kDa protein, PscF. Two proteins, PscG and PscE, stabilize PscF within the bacterial cell before its export and polymerization. In this work we screened the 1,320-Å2 interface between the two chaperones, PscE and PscG, by site-directed mutagenesis and determined hot spot regions that are important for T3S function in vivo and complex formation in vitro. Three amino acids in PscE and five amino acids in PscG, found to be relevant for complex formation, map to the central part of the interacting surface. Stability assays on selected mutants performed both in vitro on purified PscE-PscG complexes and in vivo on P. aeruginosa revealed that PscE is a cochaperone that is essential for the stability of the main chaperone, PscG. Notably, when overexpressed from a bicistronic construct, PscG and PscF compensate for the absence of PscE in cytotoxic P. aeruginosa. These results show that all of the information needed for needle protein stabilization and folding, its presentation to the T3 secreton, and its export is present within the sequence of the PscG chaperone.
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Wang, Hongqiao, Yunfan Wang, Zhipeng Xuan, Tingting Chen, Jingquan Zhang, Xia Hao, Lili Wu, Iordania Constantinou et Dewei Zhao. « Progress in Perovskite Solar Cells towards Commercialization—A Review ». Materials 14, no 21 (1 novembre 2021) : 6569. http://dx.doi.org/10.3390/ma14216569.
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In recent years, perovskite solar cells (PSCs) have experienced rapid development and have presented an excellent commercial prospect as the PSCs are made from raw materials that are readily and cheaply available depending on simple manufacturing techniques. However, the commercial production and utilization of PSCs remain immature, leading to substantial efforts needed to boost the development of scalable fabrication of PSCs, pilot scale tests, and the establishment of industrial production lines. In this way, the PSCs are expected to be successfully popularized from the laboratory to the photovoltaic market. In this review, the history of power conversion efficiency (PCE) for laboratory-scale PSCs is firstly introduced, and then some methods for maintaining high PCE in the upscaling process is displayed. The achievements in the stability and environmental friendliness of PSCs are also summarized because they are also of significance for commercialization. Finally, this review evaluates the commercialization prospects of PSCs from the economic view and provides a short outlook.
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Wang, YanZhi, et Ruixiang Hou. « Fabrication Strategy to Promote Performance of Perovskite Solar Cells ». Journal of Physics : Conference Series 2109, no 1 (1 novembre 2021) : 012007. http://dx.doi.org/10.1088/1742-6596/2109/1/012007.
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Abstract Improvements in process of perovskites, materials of auxiliary layers and encapsulation have significantly enhanced the performance of perovskite solar cells (PSCs). However, unified fabrication of PSCs has not been completely settled till now. Whether it is harmful to the perovskite should be concerned when selecting function layer materials and encapsulation materials of PSCs. Encapsulation is the main way to enhance the stability of PSCs. Besides, to cope with the emerging environment issues, the function layer materials can be modified to adsorb lead, preventing the leakage of lead from PSCs. To integrate the advantages of each part of PSCs, interactions between constituent materials are needed to be studied.
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Tan, Heng Liang, et Andre Choo. « Opportunities for Antibody Discovery Using Human Pluripotent Stem Cells : Conservation of Oncofetal Targets ». International Journal of Molecular Sciences 20, no 22 (15 novembre 2019) : 5752. http://dx.doi.org/10.3390/ijms20225752.
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Pluripotent stem cells (PSCs) comprise both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). The application of pluripotent stem cells is divided into four main areas, namely: (i) regenerative therapy, (ii) the study and understanding of developmental biology, (iii) drug screening and toxicology and (iv) disease modeling. In this review, we describe a new opportunity for PSCs, the discovery of new biomarkers and generating antibodies against these biomarkers. PSCs are good sources of immunogen for raising monoclonal antibodies (mAbs) because of the conservation of oncofetal antigens between PSCs and cancer cells. Hence mAbs generated using PSCs can potentially be applied in two different fields. First, these mAbs can be used in regenerative cell therapy to characterize the PSCs. In addition, the mAbs can be used to separate or eliminate contaminating or residual undifferentiated PSCs from the differentiated cell product. This step is critical as undifferentiated PSCs can form teratomas in vivo. The mAbs generated against PSCs can also be used in the field of oncology. Here, novel targets can be identified and the mAbs developed as targeted therapy to kill the cancer cells. Conversely, as new and novel oncofetal biomarkers are discovered on PSCs, cancer mAbs that are already approved by the FDA can be repurposed for regenerative medicine, thus expediting the route to the clinics.
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A. El-Manstrly, Dahlia. « Cross-cultural validation of switching costs : a four-country assessment ». International Marketing Review 31, no 4 (30 juin 2014) : 413–37. http://dx.doi.org/10.1108/imr-08-2011-0219.
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Purpose – The purpose of this paper is to develop a cross-cultural scale of customers’ perceived switching costs (PSCs). Customers’ PSCs function as a powerful defensive marketing tool that restrains customers from switching. Design/methodology/approach – Four sets of survey data were collected in the UK, Egypt, Germany, and China. An overall response rate of 86 percent was achieved across the four countries. Cross-cultural equivalence of the PSCs scale was assessed using multi-group confirmatory factor analysis. Findings – Tests of configural, metric, and factor variance invariance confirmed that the PSCs scale is appropriate for meaningful cross-cultural comparisons. Research limitations/implications – Data were collected in four countries from the financial service context. Future researchers should test the short-form PSCs (PSCs-S) scale across different cultural and industrial contexts to enhance its generalizability. Practical implications – The cross-cultural PSCs-S scale presented here will enhance international marketing researchers’ ability to test theory containing customers’ PSCs as central variables, and provide managers with a measurement tool that they can use to better segment and manage their customers. Originality/value – This study is one of the first to develop a cross-cultural PSCs scale. Despite the growth of research into customers’ PSCs, research on the topic has been limited by the lack of a cross-cultural measurement instrument. The latter now furnishes the research community with the opportunity to gain a fuller understanding of switching behavior, to establish the scale's generalizability, and to make meaningful comparisons of PSCs across cultures.
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Quinaud, Manuelle, Jacqueline Chabert, Eric Faudry, Emmanuelle Neumann, David Lemaire, Alexandrine Pastor, Sylvie Elsen, Andréa Dessen et Ina Attree. « The PscE-PscF-PscG Complex Controls Type III Secretion Needle Biogenesis in Pseudomonas aeruginosa ». Journal of Biological Chemistry 280, no 43 (22 août 2005) : 36293–300. http://dx.doi.org/10.1074/jbc.m508089200.
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Type III secretion (T3S) systems play key roles in pathogenicity of many Gram-negative bacteria and are employed to inject toxins directly into the cytoplasm of target cells. They are composed of over 20 different proteins that associate into a basal structure that traverses both inner and outer bacterial membranes and a hollow, needle-like structure through which toxins travel. The PscF protein is the main component of the Pseudomonas aeruginosa T3S needle. Here we demonstrate that PscF, when purified on its own, is able to form needle-like fibers of 8 nm in width and >1 μm in length. In addition, we demonstrate for the first time that the T3S needle subunit requires two cytoplasmic partners, PscE and PscG, in P. aeruginosa, which trap PscF in a ternary, 1:1:1 complex, thus blocking it in a monomeric state. Knock-out mutants deficient in PscE and PscG are non-cytotoxic, lack PscF, and are unable to export PscF encoded extrachromosomally. Temperature-scanning circular dichroism measurements show that the PscE-PscF-PscG complex is thermally stable and displays a cooperative unfolding/refolding pattern. Thus, PscE and PscG prevent PscF from polymerizing prematurely in the P. aeruginosa cytoplasm and keep it in a secretion prone conformation, strategies which may be shared by other pathogens that employ the T3S system for infection.
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Hu, Ruiyuan, Yang Li, Zhongbao Que, Shuaibo Zhai, Yifei Feng, Liang Chu et Xing’ao Li. « Low Temperature VOx Hole Transport Layer for Enhancing the Performance of Carbon-Based Perovskite Solar Cells ». Journal of Nanoelectronics and Optoelectronics 16, no 2 (1 février 2021) : 273–80. http://dx.doi.org/10.1166/jno.2021.2952.
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Carbon electrode based perovskite solar cells (PSCs) have attracted more attention owing to low product cost, long term stability and simple fabrication technology. Usually carbon electrode based PSCs are fabricated without hole transport layer, which results in slow development in photovoltaic performance and practical application. In this work, we synthesized p-type semiconductor VOx films via low temperature solution process. And the prepared VOx film was introduced into the carbon electrode based PSCs as hole transport layer, which is highly beneficial to further enhance the power conversion efficiencies. Here, we have demonstrated that solution processed VOx film is suitable to be the hole transport layer for PSCs based on low temperature carbon electrode. With the optimized layers of VOx, carbon electrode based PSCs with VOx exhibit enhanced photovoltaic performance compared with hole transport layer free PSCs. In the meanwhile, carbon electrode based PSCs with VOx hole transport layer have long term stability.
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Aziz, Issa, Kamil Yousif et Naseem Abdel. « Effect of Annealing Temperature on Efficiency of Perovskite Solar Cell ». Journal of Applied Science and Technology Trends 1, no 3 (5 août 2020) : 112–17. http://dx.doi.org/10.38094/jastt1338.
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In this work, a simple method for producing Perovskite solar cells [PSCs] by recycling automobile batteries is used. Trying to get rid of some structures or materials which are harm to the environment (i.e. recycled car batteries) by using lead [Pb] sheets from those battery. Also, by reusing car batteries we will avoid the disposal of toxic battery elements and provide an alternative technique, readily-available Pb source for fabricating PSCs. Perovskite solar cells [PSCs] were prepared by two-step spin coating solution method grown on the FTO glass substrate. The organo-halide PSCs consists of four layers over FTO glass substrate. Lead iodide (PbI2) and methyl-ammonium iodide (CH3NH3I) used to form the structure of the precursor (CH3NH3PbI3) by the above-mentioned coating method. The photovoltaic performance of PSCs was investigated, together with the stability of PSCs, and the effect of annealing temperature of PRK layer on performance of PSCs. Characterization of PSCs achieved by using X-ray diffraction, SEM, and Spectrophotometer techniques. The effect of annealing on the optical properties of MAPbI3 films were studied by measuring spectral transmittance. The energy band gap value of the MAPbI3 film was found to be 1.60 eV.
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Fu, Xuemei, Shouhai Wu, Bo Li, Yang Xu et Jingfeng Liu. « Functions of p53 in pluripotent stem cells ». Protein & ; Cell 11, no 1 (6 novembre 2019) : 71–78. http://dx.doi.org/10.1007/s13238-019-00665-x.
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Abstract Pluripotent stem cells (PSCs) are capable of unlimited self-renewal in culture and differentiation into all functional cell types in the body, and thus hold great promise for regenerative medicine. To achieve their clinical potential, it is critical for PSCs to maintain genomic stability during the extended proliferation. The critical tumor suppressor p53 is required to maintain genomic stability of mammalian cells. In response to DNA damage or oncogenic stress, p53 plays multiple roles in maintaining genomic stability of somatic cells by inducing cell cycle arrest, apoptosis, and senescence to prevent the passage of genetic mutations to the daughter cells. p53 is also required to maintain the genomic stability of PSCs. However, in response to the genotoxic stresses, a primary role of p53 in PSCs is to induce the differentiation of PSCs and inhibit pluripotency, providing mechanisms to maintain the genomic stability of the self-renewing PSCs. In addition, the roles of p53 in cellular metabolism might also contribute to genomic stability of PSCs by limiting oxidative stress. In summary, the elucidation of the roles of p53 in PSCs will be a prerequisite for developing safe PSC-based cell therapy.
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Zhou, Zhen, Xiaodong Sun, Rao Yan, Jinfeng An, Xinjian Zhou, Mingyi Li, Xinsheng Gu, Xincai Hao et Ming Sang. « Resveratrol inhibits high glucose-induced activation and cytokine production of isolated primary pancreatic stellate cells ». Journal of Applied Virology 8, no 3 (8 décembre 2019) : 35–47. http://dx.doi.org/10.21092/jav.v8i3.112.
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Objective: Activation of pancreatic stellate cells (PSCs) is detrimental to pancreas function by promoting pancreatic fibrosis. Resveratrol is a natural and pharmacologically active compound. This study is to investigate the effect of resveratrol on the bilogical behavior of PSCs under high glucose condition.Methods: Isolated primary mouse PSCs were cultured in low glucose ( 5.5 mmol/L glucose, LG group ) medium, high glucose ( 25 mmol/L glucose, HG group ) medium and treated with resveratrol ( 25 μmol/L or 50 μmol/L). Cell proliferation was examined using MTT assay. The expression of α-SMA and collagen I were determined using Western blotting. Alpha-SMA expression was also determined using immunocytochemistry staining. IL-1, IL-6, and TNF-α mRNA levels and secretion levels in media of PSCs were determined using qRT-PCR and ELISA respectively.Results: Cell Proliferation, α-SMA and collagen I expression levels, IL-1, IL-6, and TNF-α mRNA levels and secretion levels of PSCs were increased after high glucose treatment, compared with low glucose treatment. They were significantly decreased in PSCs treated with both high glucose and resveratrol, compared with high glucose treatment.Conclusion: Resveratrol inhibited high glucose induced PSCs proliferation, activation，cytokine expression and secretion in PSCs. Therefore, resveratrol can be potentially used in therapy of diseases such as type 2 diabetes mellitus (T2DM), pancreatitis and pancreatic cancer where PSCs is activated by high glucose.
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Sparmann, Gisela, Änne Glass, Peter Brock, Robert Jaster, Dirk Koczan, Hans-Jürgen Thiesen, Stefan Liebe et Jörg Emmrich. « Inhibition of lymphocyte apoptosis by pancreatic stellate cells : impact of interleukin-15 ». American Journal of Physiology-Gastrointestinal and Liver Physiology 289, no 5 (novembre 2005) : G842—G851. http://dx.doi.org/10.1152/ajpgi.00483.2004.
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There is growing evidence that pancreatic stellate cells (PSCs) produce cytokines and take part in the regulation of inflammatory processes in the pancreas. IL-15 inhibits apoptosis of various cell populations. This study was performed to investigate whether PSCs produce IL-15 and thereby can affect lymphocytes. Primary PSCs were isolated from the rat pancreas using density gradient centrifugation. mRNA expression of IL-15 was demonstrated by RT-PCR, and IL-15 protein was analyzed by immunoblotting. Lymphocytes obtained from rat mesenterial lymph nodes were cocultured with in vitro activated PSCs. Apoptosis has been quantified by the binding of annexin V-FITC with a flow cytometer. Proliferation was monitored using [3H]thymidine incorporation. PSCs express two splice variants of IL-15. The protein was detectable only in cell lysates but not in the cell culture supernatant. Cocultivation of lymphocytes with PSCs and IL-15 inhibited spontaneous lymphocyte apoptosis, and this effect was reduced by an anti-IL-15 antibody. Lymphocytes induced vice versa the proliferation and collagen production of PSCs. The inhibition of spontaneous lymphocyte apoptosis in cocultures with PSCs was at least partially mediated by cell-bound IL-15. This effect and the stimulation of PSCs by lymphocytes may lead to a circulus vitiosus, resulting in the persistence of inflammatory processes and the development of fibrosis during chronic pancreatitis.
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Asaumi, Hiroshi, Shiro Watanabe, Masashi Taguchi, Mitsuo Tashiro et Makoto Otsuki. « Externally applied pressure activates pancreatic stellate cells through the generation of intracellular reactive oxygen species ». American Journal of Physiology-Gastrointestinal and Liver Physiology 293, no 5 (novembre 2007) : G972—G978. http://dx.doi.org/10.1152/ajpgi.00018.2007.
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Local tissue pressure is higher in chronic pancreatitis than in the normal pancreas. We reported recently that pressure application induces synthesis of extracellular matrix (ECM) and cytokines in pancreatic stellate cells (PSCs) and that epigallocatechin gallate (EGCG), a potent antioxidant, inhibits the transformation of PSCs from quiescent to activated phenotype and ethanol-induced synthesis of ECM and cytokines in PSCs. These results suggest that oxidative stress and reactive oxygen species (ROS) are important in PSC activation. The aim of this study was to clarify the effects of ROS on activation and functions of pressure-stimulated PSCs. We used freshly isolated rat PSCs and culture-activated PSCs. Pressure was applied on rat cultured PSCs by adding compressed helium gas into a pressure-loading apparatus. PSCs were cultured with or without antioxidants (EGCG and N-acetyl cysteine) under normal or elevated pressure. Externally applied high pressure (80 mmHg) resulted in a gradual decrease of superoxide dismutase activity in PSCs and increased intracellular ROS generation as early as 30 s, reaching a peak level at 1 h. Antioxidants significantly inhibited ROS generation. Pressure increased the expression levels of α-smooth muscle actin, α1(I)-procollagen, and TGF-β1 in PSCs. EGCG suppressed these alterations, abolished pressure-induced phosphorylation of p38 MAPK, and suppressed pressure-induced PSC transformation to activated phenotype. Our results indicated that ROS is a key player in pressure-induced PSC activation and ECM synthesis. Antioxidants could be potentially effective against the development of pancreatic fibrosis in patients with chronic pancreatitis.
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Aoki, Hiroyoshi, Hirohide Ohnishi, Kouji Hama, Satoshi Shinozaki, Hiroto Kita, Hiroyuki Osawa, Hironori Yamamoto, Kiichi Sato, Kiichi Tamada et Kentaro Sugano. « Cyclooxygenase-2 is required for activated pancreatic stellate cells to respond to proinflammatory cytokines ». American Journal of Physiology-Cell Physiology 292, no 1 (janvier 2007) : C259—C268. http://dx.doi.org/10.1152/ajpcell.00030.2006.
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Cyclooxygenase-2 (COX-2) mediates various inflammatory responses and is expressed in pancreatic tissue from patients with chronic pancreatitis. To examine the role of COX-2 in chronic pancreatitis, we investigated its participation in regulating functions of pancreatic stellate cells (PSCs), using isolated rat PSCs. COX-2 was expressed in culture-activated PSCs but not in freshly isolated quiescent PSCs. TGF-β1, IL-1β, and IL-6 enhanced COX-2 expression in activated PSCs, concomitantly increasing the expression of α-smooth muscle actin (α-SMA), a parameter of PSC activation. The COX-2 inhibitor NS-398 blocked culture activation of freshly isolated quiescent PSCs. NS-398 also inhibited the enhancement of α-SMA expression by TGF-β1, IL-1β, and IL-6 in activated PSCs. These data indicate that COX-2 is required for the initiation and promotion of PSC activation. We further investigated the mechanism by which cytokines enhance COX-2 expression in PSCs. Adenovirus-mediated expression of dominant negative Smad2/3 inhibited the increase in expression of COX-2, α-SMA, and collagen-1 mediated by TGF-β1 in activated PSCs. Moreover, dominant negative Smad2/3 expression attenuated the expression of COX-2 and α-SMA enhanced by IL-1β and IL-6. Anti-TGF-β neutralizing antibody also attenuated the increase in COX-2 and α-SMA expression caused by IL-1β and IL-6. IL-6 as well as IL-1β enhanced TGF-β1 secretion from PSCs. These data indicate that Smad2/3-dependent pathway plays a central role in COX-2 induction by TGF-β1, IL-1β, and IL-6. Furthermore, IL-1β and IL-6 promote PSC activation by enhancing COX-2 expression indirectly through Smad2/3-dependent pathway by increasing TGF-β1 secretion from PSCs.
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Bernad, Raquel, Cian J. Lynch, Rocio G. Urdinguio, Camille Stephan-Otto Attolini, Mario F. Fraga et Manuel Serrano. « Stability of Imprinting and Differentiation Capacity in Naïve Human Cells Induced by Chemical Inhibition of CDK8 and CDK19 ». Cells 10, no 4 (12 avril 2021) : 876. http://dx.doi.org/10.3390/cells10040876.
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Pluripotent stem cells can be stabilized in vitro at different developmental states by the use of specific chemicals and soluble factors. The naïve and primed states are the best characterized pluripotency states. Naïve pluripotent stem cells (PSCs) correspond to the early pre-implantation blastocyst and, in mice, constitute the optimal starting state for subsequent developmental applications. However, the stabilization of human naïve PSCs remains challenging because, after short-term culture, most current methods result in karyotypic abnormalities, aberrant DNA methylation patterns, loss of imprinting and severely compromised developmental potency. We have recently developed a novel method to induce and stabilize naïve human PSCs that consists in the simple addition of a chemical inhibitor for the closely related CDK8 and CDK19 kinases (CDK8/19i). Long-term cultured CDK8/19i-naïve human PSCs preserve their normal karyotype and do not show widespread DNA demethylation. Here, we investigate the long-term stability of allele-specific methylation at imprinted loci and the differentiation potency of CDK8/19i-naïve human PSCs. We report that long-term cultured CDK8/19i-naïve human PSCs retain the imprinting profile of their parental primed cells, and imprints are further retained upon differentiation in the context of teratoma formation. We have also tested the capacity of long-term cultured CDK8/19i-naïve human PSCs to differentiate into primordial germ cell (PGC)-like cells (PGCLCs) and trophoblast stem cells (TSCs), two cell types that are accessible from the naïve state. Interestingly, long-term cultured CDK8/19i-naïve human PSCs differentiated into PGCLCs with a similar efficiency to their primed counterparts. Also, long-term cultured CDK8/19i-naïve human PSCs were able to differentiate into TSCs, a transition that was not possible for primed PSCs. We conclude that inhibition of CDK8/19 stabilizes human PSCs in a functional naïve state that preserves imprinting and potency over long-term culture.
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Lee, Wonho, Jae-Han Kim, Taesu Kim, Seonha Kim, Changyeon Lee, Jin-Seong Kim, Hyungju Ahn, Taek-Soo Kim et Bumjoon J. Kim. « Mechanically robust and high-performance ternary solar cells combining the merits of all-polymer and fullerene blends ». Journal of Materials Chemistry A 6, no 10 (2018) : 4494–503. http://dx.doi.org/10.1039/c7ta11382j.
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Zha, Min, Wei Xu, Qing Zhai, Fengfei Li, Bijun Chen et Zilin Sun. « High Glucose Aggravates the Detrimental Effects of Pancreatic Stellate Cells on Beta-Cell Function ». International Journal of Endocrinology 2014 (2014) : 1–8. http://dx.doi.org/10.1155/2014/165612.
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Background and Aims. We here assess the effects of PSCs onβ-cell function and apoptosisin vivoandin vitro.Materials and Methods.PSCs were transplanted into Wistar and Goto-Kakizaki (GK) rats. Sixteen weeks after transplantation,β-cell function, apoptosis, and islet fibrosis were assessed.In vitrothe effects of PSCs conditioned medium (PSCs-CM) and/or high concentration of glucose on INS-1 cell function was assessed by measuring insulin secretion, INS-1 cell survival, apoptosis, and endoplasmic reticulum stress (ER stress) associated CHOP expression.Results. PSCs transplantation exacerbated the impairedβ-cell function in GK rats, but had no significant effects in Wistar rats.In vitro, PSCs-CM caused impaired INS-1 cell viability and insulin secretion and increased apoptosis, which were more pronounced in the presence of high glucose.Conclusion.Our study demonstrates that PSCs induceβ-cell failurein vitroandin vivo.
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Fueglistaler, S., S. Buss, B. P. Luo, H. Wernli, H. Flentje, C. A. Hostetler, L. R. Poole, K. S. Carslaw et T. Peter. « Detailed modeling of mountain wave PSCs ». Atmospheric Chemistry and Physics Discussions 3, no 1 (13 janvier 2003) : 253–99. http://dx.doi.org/10.5194/acpd-3-253-2003.
Texte intégralRésumé :
Abstract. Polar stratospheric clouds (PSCs) play a key role in polar ozone depletion. In the Arctic, PSCs can occur on the mesoscale due to orographically induced gravity waves. Here we present a detailed study of a mountain wave PSC event on 25–27 January 2000 over Scandinavia. The mountain wave PSCs were intensively observed by in-situ and remote-sensing techniques during the second phase of the SOLVE/THESEO-2000 Arctic campaign. We use these excellent data of PSC observations on 3 successive days to analyze the PSCs and to perform a detailed comparison with modeled clouds. We simulated the 3-dimensional PSC structure on all 3 days with a mesoscale numerical weather prediction (NWP) model and a microphysical box model (using state-of-the-art nucleation rates for ice and nitric acid trihydrate particles). We show that the combined mesoscale/microphysical model is capable to reproduce the PSC measurements within the uncertainty of data interpretation with respect to spatial dimensions, temporal development and microphysical properties, without manipulating temperatures or using other tuning parameters. In contrast, microphysical modeling based upon coarser scale global NWP data, e.g. current ECMWF analysis data, cannot reproduce observations, in particular the occurrence of ice and nitric acid trihydrate clouds. Combined mesoscale/microphysical modeling may be used for detailed a posteriori PSC analysis and for future Arctic campaign flight and mission planning. The fact that remote sensing alone cannot further constrain model results due to uncertainities in the interpretation of measurements, underlines the need for synchronous in-situ PSC observations in campaigns.
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Fueglistaler, S., S. Buss, B. P. Luo, H. Wernli, H. Flentje, C. A. Hostetler, L. R. Poole, K. S. Carslaw et Th Peter. « Detailed modeling of mountain wave PSCs ». Atmospheric Chemistry and Physics 3, no 3 (11 juin 2003) : 697–712. http://dx.doi.org/10.5194/acp-3-697-2003.
Texte intégralRésumé :
Abstract. Polar stratospheric clouds (PSCs) play a key role in polar ozone depletion. In the Arctic, PSCs can occur on the mesoscale due to orographically induced gravity waves. Here we present a detailed study of a mountain wave PSC event on 25-27 January 2000 over Scandinavia. The mountain wave PSCs were intensively observed by in-situ and remote-sensing techniques during the second phase of the SOLVE/THESEO-2000 Arctic campaign. We use these excellent data of PSC observations on 3 successive days to analyze the PSCs and to perform a detailed comparison with modeled clouds. We simulated the 3-dimensional PSC structure on all 3 days with a mesoscale numerical weather prediction (NWP) model and a microphysical box model (using best available nucleation rates for ice and nitric acid trihydrate particles). We show that the combined mesoscale/microphysical model is capable of reproducing the PSC measurements within the uncertainty of data interpretation with respect to spatial dimensions, temporal development and microphysical properties, without manipulating temperatures or using other tuning parameters. In contrast, microphysical modeling based upon coarser scale global NWP data, e.g. current ECMWF analysis data, cannot reproduce observations, in particular the occurrence of ice and nitric acid trihydrate clouds. Combined mesoscale/microphysical modeling may be used for detailed a posteriori PSC analysis and for future Arctic campaign flight and mission planning. The fact that remote sensing alone cannot further constrain model results due to uncertainities in the interpretation of measurements, underlines the need for synchronous in-situ PSC observations in campaigns.
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Herman, M., R. Santer, L. Gonzalez, P. Lecomte et C. Verwaerde. « Observations of PSCs in polarized light ». Geophysical Research Letters 18, no 4 (avril 1991) : 775–78. http://dx.doi.org/10.1029/91gl00770.
Texte intégral
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Achtert, P., M. Karlsson Andersson, F. Khosrawi et J. Gumbel. « Do tropospheric clouds influence Polar Stratospheric cloud occurrence in the Arctic ? » Atmospheric Chemistry and Physics Discussions 11, no 12 (7 décembre 2011) : 32065–84. http://dx.doi.org/10.5194/acpd-11-32065-2011.
Texte intégralRésumé :
Abstract. The type of Polar stratospheric clouds (PSCs) as well as their temporal and spatial extent are important for the occurrence of heterogeneous reactions in the polar stratosphere. The formation of PSCs depends strongly on temperature. However, the mechanisms of the formation of solid PSCs are still poorly understood. Recent satellite studies of Antarctic PSCs have shown that their formation can be associated with deep-tropospheric clouds which have the ability to cool the lower stratosphere radiatively and/or adiabatically. In the present study, lidar measurements aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite were used to investigate whether the formation of Arctic PSCs can be associated with deep-tropospheric clouds as well. Deep-tropospheric cloud systems have a vertical extent of more than 6.5 km with a cloud top height above 7 km altitude. PSCs observed by CALIPSO during the Arctic winter 2007/2008 were classified according to their type (STS, NAT, or ice) and to the kind of underlying tropospheric clouds. Our analysis reveals that 172 out of 211 observed PSCs occurred in connection with tropospheric clouds. 72% of these 172 observed PSCs occured above deep-tropospheric clouds. We also find that the type of PSC seems to be connected to the characteristics of the underlying tropospheric cloud system. During the Arctic winter 2007/2008 PSCs consisting of ice were mainly observed in connection with deep-tropospheric cloud systems while no ice PSC was detected above cirrus. Furthermore, we find no correlation between the occurrence of PSCs and the top temperature of tropospheric clouds. These findings suggest that Arctic PSC formation is connected to adiabatice cooling, i.e. dynamic effects rather than radiative cooling.
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Jakubowska, Monika A., Pawel E. Ferdek, Oleg V. Gerasimenko, Julia V. Gerasimenko et Ole H. Petersen. « Nitric oxide signals are interlinked with calcium signals in normal pancreatic stellate cells upon oxidative stress and inflammation ». Open Biology 6, no 8 (août 2016) : 160149. http://dx.doi.org/10.1098/rsob.160149.
Texte intégralRésumé :
The mammalian diffuse stellate cell system comprises retinoid-storing cells capable of remarkable transformations from a quiescent to an activated myofibroblast-like phenotype. Activated pancreatic stellate cells (PSCs) attract attention owing to the pivotal role they play in development of tissue fibrosis in chronic pancreatitis and pancreatic cancer. However, little is known about the actual role of PSCs in the normal pancreas. These enigmatic cells have recently been shown to respond to physiological stimuli in a manner that is markedly different from their neighbouring pancreatic acinar cells (PACs). Here, we demonstrate the capacity of PSCs to generate nitric oxide (NO), a free radical messenger mediating, for example, inflammation and vasodilatation. We show that production of cytosolic NO in PSCs is unambiguously related to cytosolic Ca 2+ signals. Only stimuli that evoke Ca 2+ signals in the PSCs elicit consequent NO generation. We provide fresh evidence for the striking difference between signalling pathways in PSCs and adjacent PACs, because PSCs, in contrast to PACs, generate substantial Ca 2+ -mediated and NOS-dependent NO signals. We also show that inhibition of NO generation protects both PSCs and PACs from necrosis. Our results highlight the interplay between Ca 2+ and NO signalling pathways in cell–cell communication, and also identify a potential therapeutic target for anti-inflammatory therapies.
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Yan, Bin, Liang Cheng, Zhengdong Jiang, Ke Chen, Cancan Zhou, Liankang Sun, Junyu Cao et al. « Resveratrol Inhibits ROS-Promoted Activation and Glycolysis of Pancreatic Stellate Cells via Suppression of miR-21 ». Oxidative Medicine and Cellular Longevity 2018 (2018) : 1–15. http://dx.doi.org/10.1155/2018/1346958.
Texte intégralRésumé :
Activation of pancreatic stellate cells (PSCs) initiates pancreatic fibrosis in chronic pancreatitis and furnishes a niche that enhances the malignancy of pancreatic cancer cells (PCCs) in pancreatic ductal adenocarcinoma (PDAC). Resveratrol (RSV), a natural polyphenol, exhibits potent antioxidant and anticancer effects. However, whether and how RSV influences the biological properties of activated PSCs and the effects of these changes on tumor remain unknown. In the present study, we found that RSV impeded hydrogen peroxide-driven reactive oxygen species- (ROS-) induced activation, invasion, migration, and glycolysis of PSCs. In addition, miR-21 expression in activated PSCs was downregulated after RSV treatment, whereas the PTEN protein level increased. miR-21 silencing attenuated ROS-induced activation, invasion, migration, and glycolysis of PSCs, whereas the overexpression of miR-21 rescued the responses of PSCs treated with RSV. Moreover, RSV or N-acetyl-L-cysteine (NAC) administration or miR-21 knockdown in PSCs reduced the invasion and migration of PCCs in coculture, and the effects of RSV were partly reversed by miR-21 upregulation. Collectively, RSV inhibits PCC invasion and migration through suppression of ROS/miR-21-mediated activation and glycolysis in PSCs. Therefore, targeting miR-21-mediated glycolysis by RSV in tumor stroma may serve as a new strategy for clinical PDAC prevention or treatment.
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Hamukwaya, Shindume Lomboleni, Huiying Hao, Zengying Zhao, Jingjing Dong, Tingting Zhong, Jie Xing, Liu Hao et Melvin Mununuri Mashingaidze. « A Review of Recent Developments in Preparation Methods for Large-Area Perovskite Solar Cells ». Coatings 12, no 2 (15 février 2022) : 252. http://dx.doi.org/10.3390/coatings12020252.
Texte intégralRésumé :
The recent rapid development in perovskite solar cells (PSCs) has led to significant research interest due to their notable photovoltaic performance, currently exceeding 25% power conversion efficiency for small-area PSCs. The materials used to fabricate PSCs dominate the current photovoltaic market, especially with the rapid increase in efficiency and performance. The present work reviews recent developments in PSCs’ preparation and fabrication methods, the associated advantages and disadvantages, and methods for improving the efficiency of large-area perovskite films for commercial application. The work is structured in three parts. First is a brief overview of large-area PSCs, followed by a discussion of the preparation methods and methods to improve PSC efficiency, quality, and stability. Envisioned future perspectives on the synthesis and commercialization of large-area PSCs are discussed last. Most of the growth in commercial PSC applications is likely to be in building integrated photovoltaics and electric vehicle battery charging solutions. This review concludes that blade coating, slot-die coating, and ink-jet printing carry the highest potential for the scalable manufacture of large-area PSCs with moderate-to-high PCEs. More research and development are key to improving PSC stability and, in the long-term, closing the chasm in lifespan between PSCs and conventional photovoltaic cells.
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Shahiduzzaman, Md, Shoko Fukaya, Ersan Y. Muslih, Liangle Wang, Masahiro Nakano, Md Akhtaruzzaman, Makoto Karakawa, Kohshin Takahashi, Jean-Michel Nunzi et Tetsuya Taima. « Metal Oxide Compact Electron Transport Layer Modification for Efficient and Stable Perovskite Solar Cells ». Materials 13, no 9 (11 mai 2020) : 2207. http://dx.doi.org/10.3390/ma13092207.
Texte intégralRésumé :
Perovskite solar cells (PSCs) have appeared as a promising design for next-generation thin-film photovoltaics because of their cost-efficient fabrication processes and excellent optoelectronic properties. However, PSCs containing a metal oxide compact layer (CL) suffer from poor long-term stability and performance. The quality of the underlying substrate strongly influences the growth of the perovskite layer. In turn, the perovskite film quality directly affects the efficiency and stability of the resultant PSCs. Thus, substrate modification with metal oxide CLs to produce highly efficient and stable PSCs has drawn attention. In this review, metal oxide-based electron transport layers (ETLs) used in PSCs and their systemic modification are reviewed. The roles of ETLs in the design and fabrication of efficient and stable PSCs are also discussed. This review will guide the further development of perovskite films with larger grains, higher crystallinity, and more homogeneous morphology, which correlate to higher stable PSC performance. The challenges and future research directions for PSCs containing compact ETLs are also described with the goal of improving their sustainability to reach new heights of clean energy production.
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Yang, Shaopeng, Tiening Wang, Xiaohui Zhao, Luo Gu, Qiman Yang, Guang Li, Xiaowei Li et Guangsheng Fu. « Semitransparent Polymer Solar Cells Based on Liquid Crystal Reflectors ». International Journal of Photoenergy 2014 (2014) : 1–5. http://dx.doi.org/10.1155/2014/689862.
Texte intégralRésumé :
The effects of liquid crystal (LC) reflectors on semitransparent polymer solar cells (PSCs) were investigated in this paper. By improving the cathode, we manufactured semitransparent PSCs based on the conventional PSCs. We then incorporated the LC reflector into the semitransparent PSCs, which increased the power conversion efficiency (PCE) from 2.11% to 2.71%. Subsequently adjusting the concentration and spinning speed of the active layer material changed its thickness. The maximum light absorption for the active layer was obtained using the optimum thickness, and the PCE eventually reached 3.01%. These results provide a reference for selecting LC reflectors that are suitable for different active layer materials to improve the PCE of semitransparent PSCs.
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Wang, Haoyu, Junjie Yang, Xiaodong Liu, Shuanghong Wu et Xiangru Wang. « Effects of Preheating Treatments on the Performance of Perovskite Solar Cells ». Journal of Physics : Conference Series 2160, no 1 (1 janvier 2022) : 012036. http://dx.doi.org/10.1088/1742-6596/2160/1/012036.
Texte intégralRésumé :
Abstract Perovskite solar cells (PSCs) have fascinated widespread focus for prominent perfomances recently. The processing parameters in spin-coating have great influence on the efficiency of PSCs. Herein, we have researched the influence of different preheating treatments on the perfomance of PSCs. The power conversion efficiency (PCE) has a significant enhancement to 15.89% through preheating the substrate together with precursor solution simultaneously. This work promotes the development of high performance PSCs and their industrialization.
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Xin, Chenguang, Xin Zhou, Fuhua Hou, Yawen Du, Wei Huang, Biao Shi, Changchun Wei et al. « Scalable and efficient perovskite solar cells prepared by grooved roller coating ». Journal of Materials Chemistry A 7, no 4 (2019) : 1870–77. http://dx.doi.org/10.1039/c8ta10092f.
Texte intégralRésumé :
The scalability of perovskite solar cells (PSCs) is another major challenge for PSCs besides high efficiency and stability. The grooved roller coating (GRC) method here enables the scalable and continuous production of PSCs with high utilization ratio of materials.
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Achtert, P., M. Karlsson Andersson, F. Khosrawi et J. Gumbel. « On the linkage between tropospheric and Polar Stratospheric clouds in the Arctic as observed by space–borne lidar ». Atmospheric Chemistry and Physics 12, no 8 (25 avril 2012) : 3791–98. http://dx.doi.org/10.5194/acp-12-3791-2012.
Texte intégralRésumé :
Abstract. The type of Polar stratospheric clouds (PSCs) as well as their temporal and spatial extent are important for the occurrence of heterogeneous reactions in the polar stratosphere. The formation of PSCs depends strongly on temperature. However, the mechanisms of the formation of solid PSCs are still poorly understood. Recent satellite studies of Antarctic PSCs have shown that their formation can be associated with deep-tropospheric clouds which have the ability to cool the lower stratosphere radiatively and/or adiabatically. In the present study, lidar measurements aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite were used to investigate whether the formation of Arctic PSCs can be associated with deep-tropospheric clouds as well. Deep-tropospheric cloud systems have a vertical extent of more than 6.5 km with a cloud top height above 7 km altitude. PSCs observed by CALIPSO during the Arctic winter 2007/2008 were classified according to their type (STS, NAT, or ice) and to the kind of underlying tropospheric clouds. Our analysis reveals that 172 out of 211 observed PSCs occurred in connection with tropospheric clouds. 72% of these 172 observed PSCs occurred above deep-tropospheric clouds. We also find that the type of PSC seems to be connected to the characteristics of the underlying tropospheric cloud system. During the Arctic winter 2007/2008 PSCs consisting of ice were mainly observed in connection with deep-tropospheric cloud systems while no ice PSC was detected above cirrus. Furthermore, we find no correlation between the occurrence of PSCs and the top temperature of tropospheric clouds. Thus, our findings suggest that Arctic PSC formation is connected to adiabatice cooling, i.e. dynamic effects rather than radiative cooling.
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Yu, Xing, Xiaoping Zou, Jin Cheng, Dan Chen, Yujun Yao, Chuangchuang Chang, Baoyu Liu, Junqi Wang, Zixiao Zhou et Guangdong Li. « Investigation on Low-temperature Annealing Process of Solution-processed TiO2 Electron Transport Layer for Flexible Perovskite Solar Cell ». Materials 13, no 5 (25 février 2020) : 1031. http://dx.doi.org/10.3390/ma13051031.
Texte intégralRésumé :
Flexible perovskite solar cells (PSCs) have received increasing attention in wearable and portable devices over the past ten years. The low-temperature process of electron transport layer plays a key role in fabricating flexible PSCs. In this paper, we improve the performance of flexible PSCs by controlling the thermodynamic procedure in the low-temperature annealing process of solution-processed TiO2 layers and modulating the precursor concentration of (6,6)-phenyl c61 butyric acid methyl ester (PC61BM) deposited on fluorine-doped tin oxide (FTO)/TiO2 substrate. The results show that slowing down evaporation rate of residual solvent and adopting PC61BM of appropriate precursor concentration are confirmed to be effective methods to improve the performance of flexible PSCs. We also demonstrate carbon electrode-based flexible PSCs. Our work expands the feasibility of low temperature process for the development of flexible perovskite photodetectors and light-emitting diodes, as well as flexible PSCs.
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Dohme, Lea-Cathrin, David Piggott, Susan Backhouse et Gareth Morgan. « Psychological Skills and Characteristics Facilitative of Youth Athletes’ Development : A Systematic Review ». Sport Psychologist 33, no 4 (1 décembre 2019) : 261–75. http://dx.doi.org/10.1123/tsp.2018-0014.
Texte intégralRésumé :
Research has identified psychological skills and characteristics (PSCs) perceived to facilitate talented youth athletes’ development. However, no systematic categorization or synthesis of these PSCs exists to date. To provide such synthesis, this systematic review aimed to identify PSCs perceived as facilitative of talented youth athletes’ development, group and label synonymous PSCs, and categorize PSCs based on definitions established by Dohme, Backhouse, Piggott, and Morgan (2017). PRISMA systematic-review guidelines were employed and a comprehensive literature search of SPORTDiscus, PsycINFO, PsycARTICLES, and ERIC completed in November 2017. Twenty-five empirical studies published between 2002 and 2017 met the inclusion criteria. Through thematic analysis, 19 PSCs were identified as facilitative of youth athletes’ development—8 were categorized as psychological skills (e.g., goal setting, social-support seeking, and self-talk) and 11 as psychological characteristics (e.g., self-confidence, focus, and motivation). The practical implications of these findings are discussed.
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Caselli, Paola. « Observational Studies of Pre-Stellar Cores and Infrared Dark Clouds ». Proceedings of the International Astronomical Union 7, S280 (juin 2011) : 19–32. http://dx.doi.org/10.1017/s1743921311024835.
Texte intégralRésumé :
AbstractStars like our Sun and planets like our Earth form in dense regions within interstellar molecular clouds, called pre-stellar cores (PSCs). PSCs provide the initial conditions in the process of star and planet formation. In the past 15 years, detailed observations of (low-mass) PSCs in nearby molecular cloud complexes have allowed us to find that they are cold (T < 10K) and quiescent (molecular line widths are close to thermal), with a chemistry profoundly affected by molecular freeze-out onto dust grains. In these conditions, deuterated molecules flourish, becoming the best tools to unveil the PSC physical and chemical structure. Despite their apparent simplicity, PSCs still offer puzzles to solve and they are far from being completely understood. For example, what is happening to the gas and dust in their nuclei (the future stellar cradles) is still a mystery that awaits for ALMA. Other important questions are: how do different environments and external conditions affect the PSC physical/chemical structure? Are PSCs in high-mass star forming regions similar to the well-known low-mass PSCs? Here I review observational and theoretical work on PSCs in nearby molecular cloud complexes and the ongoing search and study of massive PSCs embedded in infrared dark clouds (IRDCs), which host the initial conditions for stellar cluster and high-mass star formation.
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Chinwokwu, Eke Chijioke. « An assessment of the relationship between private security companies and the police in crime prevention in Lagos Metropolis, Nigeria ». International Journal of Police Science & ; Management 20, no 1 (mars 2018) : 80–93. http://dx.doi.org/10.1177/1461355718756413.
Texte intégralRésumé :
This study examined the relationship between private security companies (PSCs) and the police during crime prevention in Lagos Metropolis, Nigeria. The study elicited data from 1500 randomly selected respondents to a self-administered survey. Data were further collected through purposive in-depth interviews. Descriptive statistics was used for data analysis. The results showed that operational collaboration and networking between PSCs and the police during crime-prevention strategies in Lagos Metropolis were imperative for achieving a crime-free society. The study shows that PSCs and the police are in a collaborative relationship that has had a positive impact on the reduction in crime; however, synergy between PSCs and the police is weak. The study further found that areas in which PSCs and the police collaborate include: escort duties, static guards, investigation, crowd control and patrol duties. The study also showed that most of the respondents identified areas of future collaboration and improvement between PSCs and the police, including: training, intelligence sharing, investigation and prosecution. The study findings show that both PSCs and the police see their relationship as cordial and complementary, although sometimes unequal and competitive. The study highlights a need to improve interagency collaboration and networking; strengthen collaboration between PSCs and the police; and pool technical resources to fight crime in Lagos Metropolis in particular, and Nigeria in general.
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Wang, Junqi, Xiaoping Zou, Jialin Zhu, Jin Cheng, Dan Chen, Xiao Bai, Yujun Yao et al. « Effect of Optimization of TiO2 Electron Transport Layer on Performance of Perovskite Solar Cells with Rough FTO Substrates ». Materials 13, no 10 (15 mai 2020) : 2272. http://dx.doi.org/10.3390/ma13102272.
Texte intégralRésumé :
The film quality of the electron transport layer (ETL) plays an important role in improving the performance of perovskite solar cells (PSCs). In order to reduce the effect of rough fluorine-doped SnO2 (FTO)substrate on the film quality of the TiO2 ETL, multiple cycles of spin-coating were employed to realize optimized TiO2 film and improve the performance of PSCs with rough FTO. The results show that TiO2 ETL was optimized most effectively using two spin-coating cycles, obtaining the best performance of PSCs with rough FTO. The carbon electrode-based PSCs were then demonstrated. Our work discusses the feasibility of low-quality rough FTO for the fabrication of PSCs and photodetectors to reduce costs.
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Zhang, Yue, Haiming Zhang, Xiaohui Zhang, Lijuan Wei, Biao Zhang, Yuxuan Sun, Guangyuan Hai et Yujie Li. « Major Impediment to Highly Efficient, Stable and Low-Cost Perovskite Solar Cells ». Metals 8, no 11 (19 novembre 2018) : 964. http://dx.doi.org/10.3390/met8110964.
Texte intégralRésumé :
Organic–inorganic hybrid perovskite solar cells (PSCs) have made immense progress in recent years, owing to outstanding optoelectronic properties of perovskite materials, such as high extinction coefficient, carrier mobility, and low exciton binding energy. Since the first appearance in 2009, the efficiency of PSCs has reached 23.3%. This has made them the most promising rival to silicon-based solar cells. However, there are still several issues to resolve to promote PSCs’ outdoor applications. In this review, three crucial aspects of PSCs, including high efficiency, environmental stability, and low-cost of PSCs, are described in detail. Recent in-depth studies on different aspects are also discussed for better understanding of these issues and possible solutions.
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Nishimura, Ken, Aya Fukuda et Koji Hisatake. « Mechanisms of the Metabolic Shift during Somatic Cell Reprogramming ». International Journal of Molecular Sciences 20, no 9 (7 mai 2019) : 2254. http://dx.doi.org/10.3390/ijms20092254.
Texte intégralRésumé :
Pluripotent stem cells (PSCs), including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), hold a huge promise for regenerative medicine, drug development, and disease modeling. PSCs have unique metabolic features that are akin to those of cancer cells, in which glycolysis predominates to produce energy as well as building blocks for cellular components. Recent studies indicate that the unique metabolism in PSCs is not a mere consequence of their preference for a low oxygen environment, but is an active process for maintaining self-renewal and pluripotency, possibly in preparation for rapid response to the metabolic demands of differentiation. Understanding the regulatory mechanisms of this unique metabolism in PSCs is essential for proper derivation, generation, and maintenance of PSCs. In this review, we discuss the metabolic features of PSCs and describe the current understanding of the mechanisms of the metabolic shift during reprogramming from somatic cells to iPSCs, in which the metabolism switches from oxidative phosphorylation (OxPhos) to glycolysis.
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Mozhejko, L. A. « Role of stellate cells in the morphogenesis of chronic pancreatitis ». Proceedings of the National Academy of Sciences of Belarus, Medical series 15, no 4 (14 janvier 2019) : 455–64. http://dx.doi.org/10.29235/1814-6023-2018-15-4-455-464.
Texte intégralRésumé :
This review presents an analysis of the literature on the role of pancreatic stellate cells (PSCs) in the pathogenesis of fibrosis, a predominant histological feature of chronic alcoholic pancreatitis. It is shown that ethanol and toxic products of its metabolism can affect PSCs directly and indirectly, facilitating their transformation from a quiescent to an activated state. During the pathological process, PSCs interact with parenchymal and immune cells of the pancreas through cytokines and growth factors. In activated PSCs, the proliferative and migratory activity, as well as the synthesis of extracellular matrix (ECM) proteins increases. A continuous activation of PSCs during the disease promotes the maintenance of inflammation, the deposition of excessive amounts of ECM proteins and the development of pancreatic fibrosis.
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Kim, Kwon, Kim, Xu, Seo, Park, Do, Bae et Kang. « Effect of PVP-Capped ZnO Nanoparticles with Enhanced Charge Transport on the Performance of P3HT/PCBM Polymer Solar Cells ». Polymers 11, no 11 (5 novembre 2019) : 1818. http://dx.doi.org/10.3390/polym11111818.
Texte intégralRésumé :
We attempted surface modification in ZnO nanoparticles (NPs) synthesized by the sol–gel process with polyvinyl pyrrolidone (PVP) applied to bulk-heterojunction polymer solar cells (PSCs) as an electron transport layer (ETL). In general, ZnO NPs have trap sites due to oxygen vacancies which capture electrons and degrade the performance of the PSCs. Devices with six different PVP:Zn ratios (0.615 g, 1.230 g, 1.846 g, 2.460 g, 3.075 g, and 3.690 g) were fabricated for surface modification, and the optimized PVP:Zn ratio (2.460 g) was found for PSCs based on P3HT/PCBM. The power conversion efficiency (PCE) of the fabricated PSCs with PVP-capped ZnO exhibited a significant increase of approximately 21% in PCE and excellent air-stability as compared with the uncapped ZnO-based PSCs.
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Li, Chenglin. « Roll-to-Roll Compatible Methods and Outlook for Perovskite Solar Cells ». E3S Web of Conferences 242 (2021) : 01005. http://dx.doi.org/10.1051/e3sconf/202124201005.
Texte intégralRésumé :
Perovskite Solar Cells (PSCs) are regarded as a highly effective low-cost solar energy collector, which is promised to sustain considerable energy supplies for modern society. Roll-to-Roll (R2R) compatible PSCs fabrication method is promised to realized industrialized PSCs production. This paper presents an overview of recent R2R compatible methods for PSC fabrication, which covers five R2R compatible strategies towards industrialized R2R production. To further tackle technical obstacles towards the PSC industrialization, improving perovskite morphology, adopting ambient production conditions and enhancing moisture resistance, as three aspects towards a high-effective, low-cost and highly stable PSCs, are discussed and concluded. This paper also discussed the possibility of hybrid wind-solar energy collector and raises a wind-flutter-PSCs composed conceptional structure.
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Masamune, Atsushi, Takashi Watanabe, Kazuhiro Kikuta, Kennichi Satoh, Atsushi Kanno et Tooru Shimosegawa. « Nuclear expression of interleukin-33 in pancreatic stellate cells ». American Journal of Physiology-Gastrointestinal and Liver Physiology 299, no 4 (octobre 2010) : G821—G832. http://dx.doi.org/10.1152/ajpgi.00178.2010.
Texte intégralRésumé :
Activated pancreatic stellate cells (PSCs) play a pivotal role in pancreatic fibrosis in chronic pancreatitis and pancreatic cancer. Recent studies have suggested a role of IL-33, a newly identified IL-1 family member, in fibrosis. We here examined the expression of IL-33 and the IL-33-mediated regulation of cell functions in PSCs. PSCs were isolated from human and rat pancreas tissues. The expression of IL-33 was examined by Western blotting, PCR, ELISA, and immunostaining. The roles of IL-33 in the regulation of PSC functions were examined by using recombinant IL-33 and small interfering RNA. Activated PSCs expressed IL-33 in the nucleus, and the expression was increased by IL-1β, TNF-α, PDGF-BB, and IFN-γ, but not TGF-β1. Nuclear IL-33 expression was also observed in the pancreatic acinar and ductal cells. IL-1β induced IL-33 expression mainly through the activation of NF-κB and ERK pathways and partially through that of p38 MAP kinase, whereas PDGF-BB induced IL-33 expression mainly through the activation of ERK pathway. PSCs expressed soluble ST2, ST2L, and IL-1RAcP, but the expression level of ST2L was relatively low. Recombinant IL-33 did not stimulate key cell functions of PSCs. Decreased IL-33 expression by small interfering RNA resulted in decreased proliferation in response to PDGF-BB. In conclusion, activated PSCs expressed IL-33 in the nucleus. IL-33 might regulate the PDGF-induced proliferation in PSCs.
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Hu, Zongshan, Yanjie Xu, Jie Li, Zezhang Zhu, Yong Qiu et Zhen Liu. « Bioinformatics Analysis and Experimental Verification Identify Downregulation of COL27A1 in Poor Segmental Congenital Scoliosis ». Computational and Mathematical Methods in Medicine 2022 (9 février 2022) : 1–11. http://dx.doi.org/10.1155/2022/2616827.
Texte intégralRésumé :
Background. Congenital scoliosis (CS) represents the congenital defect disease, and poor segmental congenital scoliosis (PSCS) represents one of its types. Delayed intervention can result in disability and paralysis. In this study, we would identify the core biomarkers for PSCS progression through bioinformatics analysis combined with experimental verification. Methods. This work obtained the GSE11854 expression dataset associated with somite formation in the GEO database, which covers data of 13 samples. Thereafter, we utilized the edgeR of the R package to obtain DEGs in this dataset. Then, GO annotation, KEGG analyses, and DO annotation of DEGs were performed by “clusterProfiler” of the R package. This study performed LASSO regression for screening the optimal predicting factors for somite formation. Through RNA sequencing based on peripheral blood samples from healthy donors and PSCS cases, we obtained the RNA expression patterns and screen out DEGs using the R package DESeq2. The present work analyzed COL27A1 expression in PSCS patients by the RT-PCR assay. Results. A total of 443 genes from the GSE11854 dataset were identified as DEGs, which were involved in BP associated with DNA replication, CC associated with chromosomal region, and MF associated with ATPase activity. These DEGs were primarily enriched in the TGF-β signaling pathway and spinal deformity. Further, LASSO regression suggested that 9 DEGs acted as the signature markers for somite formation. We discovered altogether 162 DEGs in PSCS patients, which were involved in BP associated with cardiac myofibril assembly and MF associated with structural constituent of muscle. However, these 162 DEGs were not significantly correlated with any pathways. Finally, COL27A1 was identified as the only intersected gene between the best predictors for somite formation and PSCS-related DEGs, which was significantly downregulated in PSCS patients. Conclusion. This work sheds novel lights on DEGs related to the PSCS pathogenic mechanism, and COL27A1 is the possible therapeutic target for PSCS. Findings in this work may contribute to developing therapeutic strategies for PSCS.
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Samruan, Worawalan, Nathalie Beaujean et Marielle Afanassieff. « Pluripotent Stem Cells for Transgenesis in the Rabbit : A Utopia ? » Applied Sciences 10, no 24 (11 décembre 2020) : 8861. http://dx.doi.org/10.3390/app10248861.
Texte intégralRésumé :
Pluripotent stem cells (PSCs) possess the following two main properties: self-renewal and pluripotency. Self-renewal is defined as the ability to proliferate in an undifferentiated state and pluripotency as the capacity to differentiate into cells of the three germ layers, i.e., ectoderm, mesoderm, and endoderm. PSCs are derived from early embryos as embryonic stem cells (ESCs) or are produced by reprogramming somatic cells into induced pluripotent stem cells (iPSCs). In mice, PSCs can be stabilized into two states of pluripotency, namely naive and primed. Naive and primed PSCs notably differ by their ability to colonize a host blastocyst to produce germline-competent chimeras; hence, naive PSCs are valuable for transgenesis, whereas primed PSCs are not. Thanks to its physiological and developmental peculiarities similar to those of primates, the rabbit is an interesting animal model for studying human diseases and early embryonic development. Both ESCs and iPSCs have been described in rabbits. They self-renew in the primed state of pluripotency and, therefore, cannot be used for transgenesis. This review presents the available data on the pluripotent state and the chimeric ability of these rabbit PSCs. It also examines the potential barriers that compromise their intended use as producers of germline-competent chimeras and proposes possible alternatives to exploit them for transgenesis.
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Ivanova, Julia S., et Olga G. Lyublinskaya. « Redox Homeostasis and Regulation in Pluripotent Stem Cells : Uniqueness or Versatility ? » International Journal of Molecular Sciences 22, no 20 (11 octobre 2021) : 10946. http://dx.doi.org/10.3390/ijms222010946.
Texte intégralRésumé :
Pluripotent stem cells (PSCs) hold great potential both in studies on developmental biology and clinical practice. Mitochondrial metabolism that encompasses pathways that generate ATP and produce ROS significantly differs between PSCs and somatic cells. Correspondingly, for quite a long time it was believed that the redox homeostasis in PSCs is also highly specific due to the hypoxic niche of their origin—within the pre-implantation blastocyst. However, recent research showed that redox parameters of cultivated PSCs have much in common with that of their differentiated progeny cells. Moreover, it has been proven that, similar to somatic cells, maintaining the physiological ROS level is critical for the regulation of PSC identity, proliferation, differentiation, and de-differentiation. In this review, we aimed to summarize the studies of redox metabolism and signaling in PSCs to compare the redox profiles of pluripotent and differentiated somatic cells. We collected evidence that PSCs possess metabolic plasticity and are able to adapt to both hypoxia and normoxia, that pluripotency is not strictly associated with anaerobic conditions, and that cellular redox homeostasis is similar in PSCs and many other somatic cells under in vitro conditions that may be explained by the high conservatism of the redox regulation system.
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Uchida, Chiaki, Hiroki Mizukami, Yutaro Hara, Takeshi Saito, Satoko Umetsu, Akiko Igawa, Sho Osonoi et al. « Diabetes in Humans Activates Pancreatic Stellate Cells via RAGE in Pancreatic Ductal Adenocarcinoma ». International Journal of Molecular Sciences 22, no 21 (28 octobre 2021) : 11716. http://dx.doi.org/10.3390/ijms222111716.
Texte intégralRésumé :
Pancreatic stellate cells (PSCs) mainly consist of cancer-associating fibroblasts in pancreatic ductal adenocarcinoma (PDAC). The receptor for advanced glycation end products (RAGE) is implicated in the pathophysiology of diabetic complications. Here, we studied the implication of RAGE in PSC activation in PDAC. The activation of cultured mouse PSCs was evaluated by qPCR. The induction of epithelial mesenchymal transition (EMT) in PDAC cell lines was assessed under stimulation with culture supernatant from activated PSCs. A total of 155 surgically resected PDAC subjects (83 nondiabetic, 18 with ≦3-years and 54 with >3-years history of diabetes) were clinicopathologically evaluated. A high-fat diet increased the expression of activated markers in cultured PSCs, which was abrogated by RAGE deletion. Culture supernatant from activated PSCs facilitated EMT of PDAC cells with elevation of TGF−β and IL−6, but not from RAGE−deleted PSCs. Diabetic subjects complicated with metabolic syndrome, divided by cluster analysis, showed higher PSC activation and RAGE expression. In such groups, PDAC cells exhibited an EMT nature. The complication of metabolic syndrome with diabetes significantly worsened disease−free survival of PDAC subjects. Thus, RAGE in PSCs can be viewed as a new promoter and a future therapeutic target of PDAC in diabetic subjects with metabolic syndrome.
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Lee, Brian, Breanna S. Borys, Michael S. Kallos, Carlos A. V. Rodrigues, Teresa P. Silva et Joaquim M. S. Cabral. « Challenges and Solutions for Commercial Scale Manufacturing of Allogeneic Pluripotent Stem Cell Products ». Bioengineering 7, no 2 (28 mars 2020) : 31. http://dx.doi.org/10.3390/bioengineering7020031.
Texte intégralRésumé :
Allogeneic cell therapy products, such as therapeutic cells derived from pluripotent stem cells (PSCs), have amazing potential to treat a wide variety of diseases and vast numbers of patients globally. However, there are various challenges related to the manufacturing of PSCs in large enough quantities to meet commercial needs. This manuscript addresses the challenges for the process development of PSCs production in a bioreactor, and also presents a scalable bioreactor technology that can be a possible solution to remove the bottleneck for the large-scale manufacturing of high-quality therapeutic cells derived from PSCs.
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Navarro, Micaela, Delia A. Soto, Carlos A. Pinzon, Jun Wu et Pablo J. Ross. « Livestock pluripotency is finally captured in vitro ». Reproduction, Fertility and Development 32, no 2 (2020) : 11. http://dx.doi.org/10.1071/rd19272.
Texte intégralRésumé :
Pluripotent stem cells (PSCs) have demonstrated great utility in improving our understanding of mammalian development and continue to revolutionise regenerative medicine. Thanks to the improved understanding of pluripotency in mice and humans, it has recently become feasible to generate stable livestock PSCs. Although it is unlikely that livestock PSCs will be used for similar applications as their murine and human counterparts, new exciting applications that could greatly advance animal agriculture are being developed, including the use of PSCs for complex genome editing, cellular agriculture, gamete generation and invitro breeding schemes.