As central nodes in cardiomyocyte signaling, nuclear AKT appears to play a cardio-protective role in cardiovascular disease. Here we describe a circular RNA, circ-Amotl1 that is highly expressed in ...neonatal human cardiac tissue, and potentiates AKT-enhanced cardiomyocyte survival. We hypothesize that circ-Amotl1 binds to PDK1 and AKT1, leading to AKT1 phosphorylation and nuclear translocation. In primary cardiomyocytes, epithelial cells, and endothelial cells, we found that forced circ-Amotl1 expression increased the nuclear fraction of pAKT. We further detected increased nuclear pAKT in circ-Amotl1-treated hearts. In vivo, circ-Amotl1 expression was also found to be protective against Doxorubicin (Dox)-induced cardiomyopathy. Putative PDK1- and AKT1-binding sites were then identified
. Blocking oligonucleotides could reverse the effects of exogenous circ-Amotl1. We conclude that circ-Amotl1 physically binds to both PDK1 and AKT1, facilitating the cardio-protective nuclear translocation of pAKT.
Purpose
To investigate the synergistic effect of resveratrol on the bystander effect of TK/GCV suicide gene system in melanoma cells.
Methods
The effect of resveratrol on the growth of B16 cells and ...the synergistic effect of resveratrol with or without GCV were detected by MTT assay and high content screening assay. The effect of resveratrol on GJIC function was detected by flow cytometry combined with fluorescence tracer and fluorescence microscope, and the expression of gap junction protein was detected by western blotting. Synergistic killing effect of resveratrol plus TK/GCV was tested in vivo using transplanted melanoma model.
Results
In vitro, resveratrol can enhanced GJ function and upregulated Cx32 and Cx43 protein expression in B16 cells. Resveratrol synergized with GCV to kill mixed B16 melanoma cells (20% TK
+
cells and 80% TK
−
cells) and to improve apoptosis rate of TK
−
cells (the bystander effect of TK system), and the synergistic action was reversed by the GJ inhibitor AGA. In vivo, when B16 cells were mixed with 30% TK
+
B16 cells, significantly reduced tumor weight and volume were observed after combinational treatment with resveratrol plus GCV as compared with GCV or resveratrol treatment alone.
Conclusions
Resveratrol could synergistically enhance the killing effect of TK/GCV suicide gene system in melanoma B16 cells and transplanted melanoma. It might be a promising adjuvant of TK/GCV therapy.
The bystander effect is an intriguing phenomenon by which adjacent cells become sensitized to drug treatment during gene therapy with herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV). ...This effect is reported to be mediated by gap junctional intercellular communication (GJIC), and therefore, we postulated that upregulation of genes that facilitate GJIC may enhance the HSV-tk/GCV bystander effect. Previous findings have shown Tanshinone IIA (Tan IIA), a chemical substance derived from a Chinese medicine herb, promotes the upregulation of the connexins Cx26 and Cx43 in B16 cells. Because gap junctions are formed by connexins, we hypothesized that Tan IIA might increase GJIC. Our results show that Tan IIA increased GJIC in B16 melanoma cells, leading to more efficient GCV-induced bystander killing in cells stably expressing HSV-tk. Additionally, in vivo experiments demonstrated that tumors in mice with 10% HSV-tk positive B16 cells and 90% wild-type B16 cells became smaller following treatment with the combination of GCV and Tan IIA as compared to GCV or Tan IIA alone. These data demonstrate that Tan IIA can augment the bystander effect of HSV-tk/GCV system through increased gap junction coupling, which adds strength to the promising strategy that develops connexins inducer to potentiate the effects of suicide gene therapy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Melanoma is a global concern and accounts for the major mortality of skin cancers. Herpes simplex virus thymidine kinase gene with ganciclovir (HSV-TK/GCV) is a promising gene therapy for melanoma. ...Despite its low efficiency, it is well known for its bystander effect which is mainly mediated by gap junction. In this study, we found that curcumin reduced B16 melanoma cell viability in both time- and dose-dependent manner. Further study showed that curcumin improved the gap junction intercellular communication (GJIC) function, and upregulated the proteins essential to gap junction, such as connexin 32 and connexin 43, indicating the potential role in enhancing the bystander effect of HSV-TK/GCV. By co-culturing the B16.sup.TK cells, which stably expressed TK gene, with wildtype B16 (B16.sup.WT ) cells, we found that co-treatment of curcumin and GCV synergistically inhibited B16 cell proliferation, but the effect could be eliminated by the gap junction inhibitor AGA. Moreover, curcumin markedly increased apoptosis rate of B16.sup.WT cells, suggesting its effect in enhancing the bystander effect of HSV-TK/GCV. In the in-vivo study, we established the xenografted melanoma model in 14 days by injecting mixture of B16.sup.TK and B16.sup.WT cell in a ratio of 3:7. The result demonstrated that, co-administration of curcumin and GCV significantly inhibited the xenograft growth, as indicated by the smaller size and less weight. The combinational effect was further confirmed as a synergistic effect. In conclusion, the results demonstrated that curcumin could enhance the killing effect and the bystander effect of HSV-TK/GCV in treating melanoma, which might be mediated by improved gap junction. Our data suggested that combination of HSV-TK/GCV with curcumin could be a potential chemosensitization strategy for cancer treatment.
•Pyrolysis of coal with and without the addition of CaO were compared.•Pyrolysis kinetics using 2-DAEM and 3-DAEM were separately developed.•2-DAEM was accurate enough for describing the pyrolysis of ...pure coal.•3-DAEM can capture the main characteristics of coal with CaO additive.•CaO can promote the release of volatiles during coal pyrolysis at lower temperature.
The pyrolysis of coal mixing with CaO can produce uniform mixture of residual char and CaO, which can be further converted into calcium carbide for providing alternative way of ethyne production. Therefore, knowledge on the pyrolysis behavior of coal at the presentation of CaO is important for the industrial production of such mixture of residual char and CaO. By comparing the TG/DTG curves of pure coal and mixture coal (with CaO), it was found that the addition of CaO can promote the release of volatiles especially at lower temperature. The Distributed Activation Energy Model (DAEM) were developed for pure coal and mixture coal separately for analyzing their corresponding pyrolysis kinetics. While 2-DAEM with two-Gaussian functions is accurate enough for describing the pyrolysis of pure coal, 3-DAEM is more suitable for capturing the main pyrolysis characteristics of mixture coal. DAEM results show lower average activation energy for the pyrolysis of mixture coal than that of pure coal, further demonstrating the catalysis effect of CaO on coal pyrolysis.
Computational particle fluid dynamics (CPFD) simulation was performed to study coal pyrolysis in a circulating fluidized bed downer containing binary particles (coal particles and heat carrier ...particles). A suitable drag model, which considers the cluster effect by assuming dynamic equilibrium for particles in and out of the cluster, was incorporated into the CPFD model, which shows acceptable accuracy in describing the hydrodynamics of binary particles in the downer. The predicted mixing index of temperature was also in good agreement with the experiment, indicating that the model can also be used to study heat transfer between binary particles in the downer. The coal pyrolysis kinetics were further incorporated into the model. Simulation results demonstrated that the rapid mixing of coal and heat carrier near the downer inlet was beneficial for the rapid temperature increase of coal particles. The predicted coal pyrolysis behaviors further demonstrated that the gas-solids can flow uniformly with a short residence time and low back-mixing in the downer, which facilitates the rapid pyrolysis of coal. It was concluded that the CPFD modeling can provide reasonable simulation results with respect to hydrodynamics, heat transfer, and chemical reactions in the downer for coal pyrolysis.
A combined Computational Fluid Dynamics and Population Balance Model (CFD-PBM) was developed to study the flow hydrodynamics of the slurry bed. The CFD-PBM applied a modified drag force model by ...considering the reduced drag force between gas and liquid phases at the presence of particle. Results show that the CFD-PBM with the modified drag force model can reasonably predict the flow hydrodynamics compared with the experimental data. It was predicted that the increased particle loading can enhance bubble coalescence to form larger bubbles, which can flow faster and reduce the gas holdup in the slurry bed. In addition, simulation results indicate that the particle flow becomes more non-uniform with much faster upward flow in the center and downward flow near the wall with the increase of superficial velocity. Particle back-mixing can be enhanced at higher superficial gas velocity, which can be beneficial for the reaction system with limited decrease in catalyst particle's reaction activity and unbeneficial for the reaction system with almost fully deactivation of catalyst.
A modified drag force model was developed for describing the gas-liquid interactions by considering the presence of particle. The CFD-PBM with modified drag force model is accurate in predicting hydrodynamics in the slurry bed. Display omitted
•A modified gas-liquid drag force model was proposed at the presence of particle.•The CFD-PBM with modified drag force model is accurate in predicting hydrodynamics.•Increased particle loading can enhance bubble coalescence and reduce gas holdup.•Particle back-mixing can be enhanced at increased superficial gas velocity.
A Computational Particle Fluid Dynamics (CPFD) model, which has the ability of revealing the coupled flow-reaction behaviors on the scales ranging from an individual particle to the whole reactor, ...was developed for studying the gas-solids circulating fluidized bed (CFB) riser reactor handling Geldart A particles. The model was validated against available experimental data with respects to the hydrodynamics (e.g. distributions of solids holdup and solids velocity) and the reaction behaviors (e.g. distribution of ozone concentration for ozone decomposition), and acceptable agreements were achieved between the modeling results and the experimental data. The CPFD model was further extended for analyzing the gas-solids flow hydrodynamics and the cracking reactions in an industrial Fluid Catalytic Cracking (FCC) riser reactor. Modeling results indicate that the volume of gas in the CFB riser will vary due to the presence of interphase chemical reactions (e.g. catalytic cracking reactions in FCC), which can significantly influence the gas-solids flow hydrodynamics. It was demonstrated that the CPFD model can be applied to quantify the relationship between the flow hydrodynamics and the chemical reactions in multiphase flow-reaction systems.
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•A CPFD model was used to reveal flow and reaction behaviors in CFB riser reactor.•Modeling results were in acceptable agreement with experimental data.•The coupled flow-reaction behaviors were demonstrated with the model.
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•A four-zone drag model based on cluster was developed for turbulent fluidized bed•Bottom dense zone and top dilute zone were specified in developing the drag model•The model is ...accurate in simulating turbulent fluidized bed at different conditions•Voids and clusters result in the unique gas-solids flow characteristics in TFB•More small bubbles with a more uniform size distribution exist in TFB than BFB
Gas-solids drag model is crucial for the accurate prediction of gas-solids flow in turbulent fluidized bed (TFB). A four-zone drag model based on cluster was proposed to describe the gas-solids interactions in TFB. The model considers the cluster effect in the bottom dense bubbling zone while regards the particles as discrete ones in the top dilute dispersed zone. The structural parameter model was used to calculate the equivalent cluster diameter in the drag model. Validations against experiments show that the drag model can accurately simulate the gas-solids flow characteristics in TFBs with Geldart A and B particles. Besides, the non-uniform flow structures resulting from gas voids and particle clusters were successfully captured with the model. Compared with the bubbling fluidized bed, more small bubbles with a more uniform size distribution exist in TFB and the variation of operating conditions has little effect on gas voids characteristics in TFB.
In this work, a cluster-based mass transfer and reaction model was proposed according to large number of simulation results by conducting ozone decomposition inside spherical cluster, which is more ...realistic compared with the conventional homogeneous description of mass transfer and chemical reaction process. Then, this model was coupled with three-dimensional Computational Particle Fluid Dynamics (CPFD) approach to simulate the ozone decomposition in pilot-scale gas-solids downer. According to the comparison between simulation results and experiment measurements, it was found that the model sufficiently considering the clustering effects on the hydrodynamics and chemical reaction predicted better ozone concentration distribution than the model based on homogeneous assumption. Meanwhile, the comprehensive model with consideration of cluster could accurately predict the gas-solids flow behaviors and reaction characteristics with different particle properties under different operating conditions. Finally, the effects of operating conditions such as superficial gas velocity and solids circulating flux on the hydrodynamics and reaction characteristics inside downer were fully analyzed on the basis of the accurate model predictions.
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•Existence of cluster plays a key role in mass transfer and reaction in downer.•Heterogeneity index for reaction was obtained under different operating conditions.•Effect of cluster on mass transfer and reaction is considered in simulating downer.•CPFD method with cluster-based model is able to predict ozone decomposition.
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