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41.
Regulatory changes occurring early in colorectal cancer development remain poorly investigated. Since the majority of cases develop from polyps in the adenoma-carcinoma transition, a search of early molecular features, such as aberrations in miRNA expression occurring prior to cancer development, would enable identification of potentially causal, rather than consequential, candidates in the progression of polyp to cancer. In the current study, by employing small RNA-seq profiling of colon biopsy samples, we described differentially expressed miRNAs and their isoforms in the adenoma-carcinoma transition. Analysis of healthy-adenoma-carcinoma sequence in an independent validation group enabled us to identify early deregulated miRNAs including hsa-miR-1246 and hsa-miR-215-5p, the expressions of which are, respectively, gradually increasing and decreasing. Loss-of-function experiments revealed that inhibition of hsa-miR-1246 lead to reduced cell viability, colony formation, and migration rate, thereby indicating an oncogenic effect of this miRNA in vitro. Subsequent western blot and luciferase reporter assay provided evidence of hsa-miR-1246 being involved in the regulation of target AXIN2 and CFTR genes’ expression. To conclude, the present study revealed possible involvement of hsa-miR-1246 in early colorectal cancer development and regulation of tumor suppressors AXIN2 and CFTR.  相似文献   
42.
43.
Ethanol is a common cause of both acute and chronic pancreatitis. Studies in other organs suggest that polymorphonuclear neutrophils activated by ethanol may cause tissue injury in a variety of conditions. The aim of this study was to investigate the effects of ethanol on neutrophil extravasation in the feline pancreas. Pancreata were isolated and perfused at different flow rates with varying concentrations of ethanol in either a physiological or neutrophil depleted perfusate. Neutrophil extravasation was assessed by measuring pancreatic tissue myeloperoxidase (MPO) activity. Ethanol at 2.5% (54.25 mmol/liter) was the lowest concentration that still caused significant neutrophil extravasation (3.1+/-0.8 vs 1.9+/-0.2 units, P<0.05) and was accompanied by an increase in vascular resistance of 15%. Reduction of pancreatic perfusion by 15% did not significantly increase neutrophil extravasation. (1.1+/-0.3 vs 1.6+/-0.2 units, NS) Perfusion of the pancreas with neutrophil-depleted blood containing either ethanol or saline, followed by perfusion with an ethanol-free perfusate, showed an increase in neutrophil extravasation in the ethanol group compared to the control group (3.2+/-0.9 vs 1.9+/-0.2 units, P<0.05). In conclusion, ethanol causes neutrophil extravasation in the feline pancreas independent of blood flow changes and occurs despite the absence of direct neutrophil exposure to ethanol.  相似文献   
44.
Around 80% of adults worldwide carry human cytomegaloviris (HCMV). The HCMV gene UL18 is a homolog of HLA class I genes and encodes a protein with high affinity for the NK and T-cell cytotoxicity inhibitor LIR-1. UL18 was deep sequenced from blood, saliva or urine from Indonesian people with HIV (PWH) (n = 28), Australian renal transplant recipients (RTR) (n = 21), healthy adults (n = 7) and neonates (n = 4). 95% of samples contained more than one variant of HCMV UL18, as defined by carriage of nonsynonymous variations. When aligned with immunological markers of the host’s burden of HCMV, the S318N variation associated with high levels of antibody reactive with HCMV lysate in PWH over 12 months on antiretroviral therapy. The A107T variation associated with HCMV antibody levels and inflammatory biomarkers in PWH at early timepoints. Variants D32G, D248N, V250A and E252D aligned with elevated HCMV antibody levels in RTR, while M191K, E196Q and F165L were associated with HCMV-reactive T-cells and proportions of Vδ2 γδ T-cells—populations linked with high burdens of HCMV. We conclude that UL18 is a highly variable gene, where variation may alter the persistent burden of HCMV and/or the host response to that burden.  相似文献   
45.
Starting from gelatinous aluminum chloride hydroxide, the transformation process toward α-Al2O3 was examined using 27Al NMR, both in the liquid and solid states, as a main analytical tool. By increasing the hydrolysis ratio (h, defined as [OH]/[Al3+]) of the starting aqueous precursor up to h = 2.5, the transition temperature to the final product, α-Al2O3, decreased to as low as 500°C. In this case, the structural change from amorphous alumina to α-Al2O3 took place without intermediate transition Al2O3 phases. Examining the process of networking during the transition from aqueous sol–through the state of xerogel–to final anhydrous oxide by nuclear magnetic resonance (NMR) revealed the presence of highly polymeric species mainly ascribed to δ-[Al2O8Al28(OH)56(H2O)24]18+ (δ-Al30). δ-Al30 species were found in the solution phase and became predominant after drying. We conclude that the lower temperature synthesis of α-Al2O3 became possible due to preformation of polymerized AlO6 construction units in the precursor, reducing the energy barrier for the nucleation of the final α-Al2O3 phase.  相似文献   
46.
Topics in Catalysis - The morphology of a thin palladium film deposited on bilayer Al0.35Si0.65O2/Ru(0001), previously proposed as a two-dimensional zeolite model, is investigated using a set of...  相似文献   
47.
Mechanisms of cement hydration   总被引:3,自引:0,他引:3  
The current state of knowledge of cement hydration mechanisms is reviewed, including the origin of the period of slow reaction in alite and cement, the nature of the acceleration period, the role of calcium sulfate in modifying the reaction rate of tricalcium aluminate, the interactions of silicates and aluminates, and the kinetics of the deceleration period. In addition, several remaining controversies or gaps in understanding are identified, such as the nature and influence on kinetics of an early surface hydrate, the mechanistic origin of the beginning of the acceleration period, the manner in which microscopic growth processes lead to the characteristic morphologies of hydration products at larger length scales, and the role played by diffusion in the deceleration period. The review concludes with some perspectives on research needs for the future.  相似文献   
48.
Heat-treated wood is a value-added product but its exposure to various environmental factors leads to discoloration of wood surface due to the photochemical reactions. Discoloration has become an important economic problem for wood industries since product specifications are now more demanding. In addition, stricter environmental legislations necessitate the development of environmentally friendly transparent coatings with minimal use of chemicals which balances aesthetic and protection. In this study, the acrylic polyurethane coating was improved with the addition of natural antioxidant (bark extract) and lignin stabilizer alone or in combination to enhance the resistance of this coating to different weathering factors. An accelerated aging test was conducted with the aim of comparing the acrylic polyurethane coatings containing different additives with the commercially available pigmented solvent borne coating used by industry and organic UV absorbers. The modifications in chemical structure of coatings were characterized by ATR–FT-IR analysis. The color change data showed that the coating containing bark extract was the most effective and performed better than the industrial coating. However, the visual assessment showed that the coating containing bark extract and lignin stabilizer had the best performance. FT-IR analyses suggested that the chain scission reaction took place throughout the weathering but its effect was not significant for any of the coatings.  相似文献   
49.
In this study the rational design, synthesis, and anticancer activity of quinoline‐derived trifluoromethyl alcohols were evaluated. Members of this novel class of trifluoromethyl alcohols were identified as potent growth inhibitors in a zebrafish embryo model. Synthesis of these compounds was carried out with an sp3‐C?H functionalization strategy of methyl quinolines with trifluoromethyl ketones. A zebrafish embryo model was also used to explore the toxicity of ethyl 4,4,4‐trifluoro‐3‐hydroxy‐3‐(quinolin‐2‐ylmethyl)butanoate ( 1 ), 2‐benzyl‐1,1,1‐trifluoro‐3‐(quinolin‐2‐yl)propan‐2‐ol ( 2 ), and trifluoro‐3‐(isoquinolin‐1‐yl)‐2‐(thiophen‐2‐yl)propan‐2‐ol ( 3 ). Compounds 2 and 3 were found to be more toxic than compound 1 ; apoptotic staining assays indicated that compound 3 causes increased cell death. In vitro cell proliferation assays showed that compound 2 , with an LC50 value of 14.14 μm , has more potent anticancer activity than cisplatin. This novel class of inhibitors provides a new direction in the discovery of effective anticancer agents.  相似文献   
50.
This work is aimed to develop a multicomponent evaporation model for droplets of urea‐water solution (UWS) and a thermal decomposition model of urea for automotive exhausts by using the selective catalytic reduction systems. In the multicomponent evaporation model, the influence of urea on the UWS evaporation is taken into account using a nonrandom two‐liquid activity model. The thermal decomposition model is based on a semidetailed kinetic scheme accounting not only for the production of ammonia (NH3) and isocyanic acid but also for the formation of heavier solid by‐products (biuret, cyanuric acid, and ammelide). This kinetics model has been validated against gaseous data as well as solid‐phase concentration profiles obtained by Lundstroem et al. (2009) and Schaber et al. (2004). Both models have been implemented in IFP‐C3D industrial software to simulate UWS droplet evaporation and decomposition as well as the formation of solid by‐products. It has been shown that the presence of the urea solute has a small influence on the water evaporation rate, but its effect on the UWS temperature is significant. In addition, the contributions of hydrolysis and thermolysis to urea decomposition have been assessed. Finally, the impacts of the heating rate as well as gas‐phase chemistry on urea decomposition pathways have been studied in detail. It has been shown that reducing the heating rate of the UWS causes the extent of the polymerization to decrease because of the higher activation energy. © 2011 American Institute of Chemical Engineers AIChE J, 2012  相似文献   
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