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排序方式: 共有122条查询结果,搜索用时 31 毫秒
91.
Rene Buchet Camille Tribes Valentine Rouaix Bastien Doumche Michele Fiore Yuqing Wu David Magne Saida Mebarek 《International journal of molecular sciences》2021,22(6)
(1) Background: Tissue non-specific alkaline phosphatase (TNAP) is suspected to induce atherosclerosis plaque calcification. TNAP, during physiological mineralization, hydrolyzes the mineralization inhibitor inorganic pyrophosphate (PPi). Since atherosclerosis plaques are characterized by the presence of necrotic cells that probably release supraphysiological concentrations of ATP, we explored whether this extracellular adenosine triphosphate (ATP) is hydrolyzed into the mineralization inhibitor PPi or the mineralization stimulator inorganic phosphate (Pi), and whether TNAP is involved. (2) Methods: Murine aortic smooth muscle cell line (MOVAS cells) were transdifferentiated into chondrocyte-like cells in calcifying medium, containing ascorbic acid and β-glycerophosphate. ATP hydrolysis rates were determined in extracellular medium extracted from MOVAS cultures during their transdifferentiation, using 31P-NMR and IR spectroscopy. (3) Results: ATP and PPi hydrolysis by MOVAS cells increased during transdifferentiation. ATP hydrolysis was sequential, yielding adenosine diphosphate (ADP), adenosine monophosphate (AMP), and adenosine without any detectable PPi. The addition of levamisole partially inhibited ATP hydrolysis, indicating that TNAP and other types of ectonucleoside triphoshatediphosphohydrolases contributed to ATP hydrolysis. (4) Conclusions: Our findings suggest that high ATP levels released by cells in proximity to vascular smooth muscle cells (VSMCs) in atherosclerosis plaques generate Pi and not PPi, which may exacerbate plaque calcification. 相似文献
92.
Bastien Tauran Emmanuel Lochin Jrme Lacan Fabrice Arnal Mathieu Gineste Nicolas Kuhn 《International Journal of Satellite Communications and Networking》2020,38(5):407-424
Satellite systems typically use physical and link layer reliability schemes to compensate the significant channel impairments, especially for the link between a satellite and a mobile end‐user. These schemes have been introduced at the price of an increase in the end‐to‐end delay, high jitter, or out‐of‐order packets. This is shown to have a negative impact both on multimedia and best‐effort traffic, decreasing the Quality of Experience (QoE) of users. In this paper, we propose to solve this issue by scheduling data transmission as a function of the channel condition. We first investigate existing scheduling mechanisms and analyze their performance for two kinds of traffic: VoIP and best‐effort. In the case of VoIP traffic, the objective is to lower both latency and jitter, which are the most important metrics to achieve a consistent VoIP service. We select the best candidate among several schedulers and propose a novel algorithm specifically designed to carry VoIP over LEO constellations. We then investigate the performance of the scheduling policies on internet‐browsing traffic carried by TCP, where the goal is now the maximize the users' goodput and select the best candidate in this case. 相似文献
93.
OBJECTIVE: The aim of this work is to assess how adding a driving-related task affects the detection of objects in peripheral vision, under mesopic conditions. BACKGROUND: The main index used to assess the quality of road lighting installations refers to simple detection tasks in foveal vision, which raises methodological and practical questions. METHOD: The experimental design consisted of a three-phase experiment. In the first phase, two groups (control and experimental) performed a peripheral detection task (simple task). Based on these results an individual detection threshold was computed for each participant and eccentricity. A tracking task was performed in Phase 2 for both groups (steering a tracking target along a circuit, on a screen). In the third phase, the control group performed the same task as in Phase 2. The experimental group performed a double task, with a tracking (primary) task and a peripheral detection (secondary) task. RESULTS: The data show an effect of the tracking task and eccentricity on peripheral event detection. The tracking task caused detection performance to decrease from 84.2% to 67.5%, p < .001. CONCLUSION: The small target visibility model used in road lighting may be improved, taking into account the effects of task and eccentricity on target detection. APPLICATION: This study supports improved roadway lighting design by guiding consideration of sign eccentricity and task load. 相似文献
94.
Du ZY Demizieux L Degrace P Gresti J Moindrot B Liu YJ Tian LX Cao JM Clouet P 《Lipids》2004,39(9):849-855
Fish easily accumulate n−3 PUFA of exogenous origin, but the underlying mechanisms are not well established in the whole animal.
This study was undertaken to investigate whether this feature was physiologically associated with mitochondrial and peroxisomal
capacities that differentially affect FA oxidation. For this purpose, peroxisomal FA oxidation was increased by treating rainbow
trout with fenofibrate, which strongly stimulates the peroxisome proliferator-activated receptor-α in rodents. Diets containing
EPA and DHA, with or without fenofibrate added, were administered to male trout for 12 d. After treatment, neither liver hypertrophy
nor accumulation of fat was apparent within the liver and muscle cells. However, fenofibrate treatment decreased the contents
of EPA and DHA in the liver, white muscle, and intraperitoneal fat tissue, which represented (per whole body) at least 280
mg less than in controls. Carnitine-dependent palmitate oxidation rates, expressed per gram of liver, were slightly increased
by fenofibrate when measured from tissue homogenates and were unchanged when calculated from isolated mitochondria, relative
to control fish. The treatment altered neither carnitine palmitoyltransferase I activity rates, expressed per gram of liver,
nor the sensitivity of the enzyme to malonyl-CoA inhibition, but did increase the malonyl-CoA content (+45%). Meanwhile, fenofibrate
increased (by about 30%) the peroxisome-related activities, i.e, catalase, carnitine-independent palmitate oxidation, acyl-CoA
oxidase, and the peroxisomal FA-oxidizing system, relative to the control group. The data strongly suggest that the induction
of peroxisomal activities, some of which being able to oxidize very long chain FA, was responsible for the lower contents
of EPA and DHA in the body lipids of fenofibrate-treated trout. 相似文献
95.
An effective consumer-oriented climate policy requires knowing the GHG reduction potential of sustainable consumption. The aim of this study is to draw lessons from differences in consumption between households with high and low GHG emissions. We evaluate a survey of 14,500 households and use a method that allows measuring changes in price level of consumption. Comparing the 10% of households with the highest GHG emissions per capita with the lowest 10% – controlling for differences in expenditure level and household structure – we find a range 5–17 tons of CO2-equivalent per capita and year. The observed differences stem mainly from heating, electricity use, car use, and travel by aircraft. Consumption patterns with low GHG emissions are characterized by less spending on mobility, but more on leisure and quality oriented consumption (leading to higher prices per unit). Further characteristics are: a higher share of organic food, low meat consumption and fewer detached single family houses. Our findings imply that a significant reduction in GHG emissions would be possible by adopting real-world consumption patterns observable in society. The twin challenge is to shift consumption towards more climate friendly patterns, and to prevent any trend towards high emitting consumption patterns. 相似文献
96.
Luis Vigetti Tatiana Labour Chlo Roumgous Dominique Cannella Bastien Touquet Claudine Mayer Yohann Cout Karine Frnal Isabelle Tardieux Patricia Renesto 《International journal of molecular sciences》2022,23(11)
T. gondii is a eukaryotic parasite that has evolved a stage called tachyzoite which multiplies in host cells by producing two daughter cells internally. These nascent tachyzoites bud off their mother and repeat the division process until the expanding progenies escape to settle and multiply in other host cells. Over these intra- and extra-cellular phases, the tachyzoite maintains an essential apicobasal polarity that emerges through a unique bidirectional budding process of the elongating cells. This process requires the assembly of several molecular complexes that, at the nascent pole, encompass structural and myosin motor elements. To characterize a recently identified basal pole marker named BCC7 with respect to the posterior myosin J and myosin C motors, we used conventional biochemistry as well as advanced proteomic and in silico analysis in conjunction with live and super resolution microscopy of transgenic fluorescent tachyzoites. We document that BCC7 forms a ribbed ring below which myosin C motor entities distribute regularly. In addition, we identified—among 13 BCC7 putative partners—two novel and five known members of the inner membrane complex (IMC) family which ends at the apical side of the ring. Therefore, BCC7 could assist the stabilization of the IMC plaques and contribute to the parasite biomechanical properties. 相似文献
97.
98.
Romain Lardy Alice de Boyer des Roches Jacques Capdeville Renaud Bastien Luc Mounier Isabelle Veissier 《Journal of dairy science》2021,104(2):2164-2184
Maladjusted cubicles for dairy cattle may cause increased skin alterations, lameness, and dirtiness. The International Commission of Agricultural and Biosystems Engineering has produced several recommendations for cubicle design, but a previous study showed that not all of them seem efficient. Here, we aim to refine and complete these recommendations. We collected data on 76 dairy farms (2,404 cows). We modeled the association between combinations of cubicle properties (e.g., type of bedding litter) and dimensions (e.g., cubicle width) relative to cow size, and prevalence of cow skin alterations, lameness, and dirtiness. We used weighted multivariable logistic regression models to predict the presence of skin alteration on the carpus; the neck, shoulder, and back; the flank, side, and udder; and the tarsus or hindquarters. We also evaluated the presence of lameness as well as the dirtiness of the lower hind legs including hocks; the hindquarters, upper hind legs, and flank; the cow rear including tail; and the udder. The risk factors highlighted led us to recommend (1) position cubicles in a way that leaves more than 1 m of clearance from any obstacle in front of the cubicle; (2) if there is an obstacle on the lateral plane (i.e., where the cubicle partition is) in front ahead of the cow, put the obstacle in front of the fore knees; (3) if there is an obstacle in front of the cow on the median plane (e.g., neck or front rail), the position the obstacle between 1.25 and 1.5 of the cow length from the curb and between 1.0 and 1.25 of its height; (4) use curb height between 0.11 and 0.15 of cow height with no sharp edges on the curb; (5) use round or at least has no sharp edges brisket board; (6) use a stone-free soil instead of concrete or use a mattress thicker than 1 cm, with microrelief, and a soft fixing area at the curb, (7) litter with straw (rather than nothing or sawdust) and keep it dry. This risk factor analysis should be followed by experiments in controlled environments to further validate these conclusions and used to update the International Commission of Agricultural and Biosystems Engineering recommendations. 相似文献
99.
N Douziech E Calvo Z Coulombe G Muradia J Bastien RA Aubin A Lajas J Morisset 《Canadian Metallurgical Quarterly》1999,140(2):765-777
Somatostatin (SS-14) and its structural analogue SMS 201-995 (SMS) are recognized as physiological inhibitors of multiple organs and tissue functions through specific membrane receptors (sst1-sst5). The effects of SS-14 and SMS in the growth control of the pancreatic cancer cell lines MIA PaCa-2 and PANC-1 were investigated to identify and clarify the intracellular events involved. In PANC-1 cells, SS-14 and SMS caused inhibition of their basal growth, and that stimulated by epidermal growth factor, with a maximal effect at 0.1-1 microM. To understand the inhibitory mechanisms, we investigated the effects of SS-14 and SMS on phosphotyrosine phosphatase (PTPase) activity and, more specifically, that of tyrosine phosphatase SHP-1 (PTP1C). SS-14 and SMS caused significant increases in total cellular PTPase activity, and particularly SHP-1, with maximal activation within 1 min. Inhibition of membrane tyrosine kinase and p42 MAP kinase activities was also observed, in response to SS-14 and SMS. In MIA PaCa-2 cells, SS-14 and SMS were associated with a positive growth response at 1-10 nM, after 4 days of culture in serum-free medium. Total cellular PTPase activity was slightly increased, but SHP-1 activity could not be detected; its absence in this cell line was confirmed by Western blot. Membrane tyrosine kinase activities were significantly increased by SS-14 and SMS at concentrations needed for maximal growth. p44/p42, which are constitutively active in this cell line, and p38 activities were not affected by somatostatin. In conclusion, somatostatin can exert different effects on human pancreatic cancer cell growth, depending upon the presence or absence of SHP-1. This enzyme can play a key role in the control of cell proliferation, and its cellular presence may determine the therapeutic potential of somatostatin in the control of cancer cell growth. 相似文献
100.
Directed Evolution of a Formate Dehydrogenase for Increased Tolerance to Ionic Liquids Reveals a New Site for Increasing the Stability
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Dr. Alexandre Noiriel Prof. Dr. Loïc J. Blum Dr. Bastien Doumèche 《Chembiochem : a European journal of chemical biology》2014,15(18):2710-2718
The formate dehydrogenase (FDH) from Candida boidinii is a well‐known enzyme in biocatalysis for NADH regeneration. Nevertheless, it has low activity in a water‐miscible ionic liquid (1,3‐dimethylimidazolium dimethyl phosphate, [MMIm][Me2PO4]). In this work, this enzyme was subjected to directed evolution by using error‐prone PCR, and a mutant (N187S/T321S) displaying higher activity was obtained following selection based on the formazan‐based colorimetric assay. The mutation N187S is responsible for improved activity both in aqueous solution and in [MMIm][Me2PO4], through an enhancement of the kcat value by a factor of 5.8. Fluorescence experiments performed in the presence of a quenching agent revealed that the mutant does not unfold in the presence of 50 % (v/v) [MMIm][Me2PO4] whereas the wild‐type enzyme does. Molecular modelling revealed that the mutation is located at the monomer–monomer interface and causes an increase in the pKa of residue E163 from 4.8 to 5.5. Calculation of the pKa of this residue in other microbial FDHs showed that thermostable FDHs have a highly basic glutamate at this position (pKa up to 6.2). We have identified a new site for improving FDH thermostability and tolerance to ionic liquids, and it is linked to the local charge of the enzymes in this class. 相似文献