Renal ischaemia-reperfusion injury is promoted by transcription factor NF-kB p65, which inhibits TRPC6 expression by activating miR-150.

AIM: To investigate the mechanism by which NF-κB p65 activates miR-150 to suppress TRPC6 expression and promote renal ischemia-reperfusion injury. METHODS: To assess the transcription of miR-150, NF-B p65, and TRPC6 in HK-2 cells treated with hypoxia reperfusion and rat kidney tissue damaged by ischemia-reperfusion (I/R), qPCR was implemented. The protein production of NF-κB p65 and TRPC6 was assessed by Western blot (WB) analysis. The histological score of rat kidney tissue was assessed using H&E (hematoxylin and eosin) staining. To assess the rate of apoptosis of renal tissue cells following I/R injury, we used the TACS TdT In Situ Apoptosis Detection Kit. To find out the impairment of renal function, blood levels of creatinine (Cr) and blood urea nitrogen (BUN) were tested in rats. Concentrations of inflammatory cytokines, including IL-1ß, IL-10, and TNF-α, were detected in HK-2 cells and rat renal tissue cells utilizing ELISA kits. FITC and CCK-8 were employed to analyze the death rate and cellular proliferation of HK-2 cells. To analyse the mechanism of engagement between NF-κB p65 and the miR-150 promoter, coupled with the detrimental impact of miR-150 on TRPC6, we adopted the dual-luciferase reporter assay. To confirm the activating effect of NF-κB p65 on miR-150,we implemented the ChIP assay. RESULTS: NF-κB p65 expression was significantly upregulated in rat renal tissue following IRI. Applying the dual-luciferase reporter assay, we demonstrated that the specific attachment of NF-B p65 with the miR-150 promoter location is viable, resulting in the promotion of the activity of the promoter. When miR-150 was overexpressed, we observed a notable reduction in cell proliferation. And it notably increased the rate of cellular apoptosis rate and amounts of the proinflammatory cytokines IL-1ß, IL-10, and TNF-α. Employing the dual-luciferase reporter assay, we demonstrated that miR-150 transfection diminished the function of luciferase in the TRPC6-WT group, whereas luciferase activity in the TRPC6-MUT group remained unchanged, indicating that miR-150 is a targeted inhibitor of TRPC6. In the rat renal I/R model, when miR-150 was inhibited or TRPC6 was overexpressed in the rat kidney I/R model, the histological score of rat kidney tissue significantly decreased, so did the quantities of proinflammatory cytokines IL-1ß, IL-10, TNF-α, creatinine (Cr) and blood urea nitrogen (BUN) contents and the rate of cell apoptosis in kidney tissue. CONCLUSION: Activation of miR-150 by NF-κB p65 results in downregulation of TRPC6 expression and promotion of IRI in the kidney.

On the physics of both surface overcharging and charge reversal at heterophase interfaces.

The conventional paradigm for characterizing surface overcharging and charge reversal is based on the so-called Stern layer, in which surface dissociation reaction and specific chemical adsorption are assumed to take place. In this article, a series of Monte Carlo simulations have been applied to obtain useful insights into the underlying physics responsible for these two kinds of anomalous phenomena at the interface of two dielectrics, with special emphasis on the case of divalent counterions that are more relevant in natural and biological environments. At a weakly charged surface, it is found that independent of the type of surface charge distribution and the dielectric response of the solution, the overcharging event is universally driven by the ion size-asymmetric effect. Exceptionally, the overcharging still persists when the surface is highly charged but is only restricted to the case of discrete surface charge in a relatively low dielectric medium. As compared to the adsorption onto the homogeneously smeared charge surface that has the same average affinity for counterions, on the other hand, charge reversal under the action of a dielectric response can be substantially enhanced in the discrete surface charge representation due to strong association of counterions with interfacial groups, and the degree of enhancement depends in a nontrivial way on the reduction of the medium dielectric constant and the steric effects of finite ion size. Rather interestingly, the charge reversal is of high relevance to the overcharging of interfaces because the overwhelming interfacial association forces the coions closer to the surface due to their smaller size than the counterions. Upon the addition of a monovalent salt to the solution, the interfacial association with divalent counterions makes surface overcharging and charge reversal widely unaffected, in contrast to the prevailing notion that screening of surface charge of a homogeneous nature is determined by the competitive effects between size-exclusion effects and energetic contributions. Overall, the present work highlights that the complex interplay between the electrostatic and steric interactions should be coupled to the realistic character of surface charge to establish a faithful description of the overcharging and charge reversal at heterophase interfaces.

Study on a novel core module based on optical fiber bundles for urine dry-chemistry analysis.

A core module with a novel optical structure is presented to analyze urine by the dry-chemistry method in this paper. It consists of a 32-bit microprocessor, optical fiber bundles, a high precision color sensor and a temperature sensor. The optical fiber bundles are adopted to control the spread path of light and reduce the influence of ambient light and the distance between the strip and sensor effectively. And the temperature sensor is applied to detect the environmental temperature to calibrate the measurement results. Therefore, all these can bring a lot of benefits to the core module, such as improving its test accuracy, reducing its volume and cost, and simplifying its assembly. Additionally, some parameters, including the calculation coefficient about reflectivity of each item, semi-quantitative intervals, the number of test items, may be modified by corresponding instructions in order to enhance its applicability. Meanwhile, its outputs can be chosen among the original data, normalized color values, reflectivity, and the semi-quantitative level of each test item by available instructions. Our results show that the module has high measurement accuracy of more than 95%, good stability, reliability, and consistency and can be easily used in various types of urine analyzers.

Examining the Contributions of Image-Charge Forces to Charge Reversal: Discrete Versus Continuum Modeling of Surface Charges.

The effects of both repulsive and attractive image-charge forces on the structure of electric double layers are addressed by Monte Carlo determination, based on a primitive model of electrolytes in contact with two types of identically charged surfaces: one with a homogeneously smeared-out charge density and the other with discrete interfacial groups. It is shown that the behavior of ions is closely related to surface charge distributions. Moreover, charge reversal in the absence of image charges witnesses an initial enhancement and then follows a fast suppression with increasing valence of the interfacial groups. The situation is quite similar to what are observed in the presence of repulsive image charges, which can significantly facilitate counterion condensation by overcoming the electrostatic barrier presented by the low dielectric substrate. With transition to attractive image-charge interactions, however, charge reversal remains widely unaffected in different surface charge representations, which even becomes much weaker when compared to the corresponding cases of both no images and repulsive images, provided that the interfacial groups have adequate valences. The overall scenario is found to be independent of the surface charge density values under study. These findings clearly illustrate the enormous improvement in our quantitative understanding of the electric double layer structure and the associated charge reversal phenomenon at the interface of various substrates.

Self-Assembled Asymmetric Block Copolymer Membranes: Bridging the Gap from Ultra- to Nanofiltration.

The self-assembly of block copolymers is an emerging strategy to produce isoporous ultrafiltration membranes. However, thus far, it has not been possible to bridge the gap from ultra- to nanofiltration and decrease the pore size of self-assembled block copolymer membranes to below 5 nm without post-treatment. It is now reported that the self-assembly of blends of two chemically interacting copolymers can lead to highly porous membranes with pore diameters as small as 1.5 nm. The membrane containing an ultraporous, 60 nm thin separation layer can fully reject solutes with molecular weights of 600 g mol(-1) in aqueous solutions with a water flux that is more than one order of magnitude higher than the permeance of commercial nanofiltration membranes. Simulations of the membrane formation process by dissipative particle dynamics (DPD) were used to explain the dramatic observed pore size reduction combined with an increase in water flux.

Suppression and promotion of charge inversion in the presence of multivalent coions.

We report charge inversion using Monte Carlo calculations for a negatively charged surface in aqueous solutions involving coions of different charges and monovalent counterions. It is shown that a rise in the valence of coions at moderate concentrations can substantially promote charge inversion for the surface charge values of biological relevance, regardless of the representation of surface charges but dependent in a nontrivial way on polarization effects resulting from dielectric discontinuity. These obtained characteristics challenge the traditional belief that the coions are generally considered to suppress charge inversion and expose the important role of coions of higher valence in tailoring the effective interactions of biomolecules with the cell membrane.

Kinetics of laterally nanostructured vesicle formation by self-assembly of miktoarm star terpolymers in aqueous solution.

Dissipative particle dynamics (DPD) simulation was used to study the self-assembly of laterally nanostructured vesicles in aqueous solution from µ-[poly(ethylethylene)]-[poly(ethylene oxide)][poly(perfluoropropylene oxide)] (µ-EOF) star terpolymers. The simulated results show that the laterally nanostructured vesicle forms when the length of the hydrophilic O blocks are relatively short. In the lateral nanostructure, the hexagonally packed domains formed by the hydrophobic F blocks are immersed in a two-dimensional hydrophobic E block matrix. The formation conditions and microstructure of the vesicles in our simulation agree with the reported experimental results from the literature. The complicated formation pathway of laterally nanostructured vesicles follows three stages: (1) combination of spherical and short cylindrical raspberry-like micelles into an intermediate polygonal sheet; (2) the intermediate polygonal sheet grows to form a larger polygonal sheet with a tail; (3) the large polygonal sheet with a tail eventually folds and forms a vesicle.

Looking deeper into the structure of mixed electric double layers near the point of zero charge.

Molecular simulations have been carried out using the Metropolis Monte Carlo approach to investigate the structure of planar electric double layers containing counterion mixture within the framework of the unrestricted primitive model. The results reveal that near the point of zero charge, the rise of monovalent salt drastically elevates the collapse of ions regardless of their polarity. In particular, we fail to observe the formation of a strongly correlated liquid in the first counterion layer due to favorable entropic effects, in contrast to the early data from molecular dynamics simulations [corrected] for a spherical electric double layer [R. Messina, E. González-Tovar, M. Lozada-Cassou, and C. Holm, Europhys. Lett. 60, 383 (2002)]. Moreover, the large size of coions is found to be a pivotal factor in determining the reversal of electrophoretic mobility. On the other hand, the repulsive image charge forces thoroughly annihilate this peculiar reversal of mobility within the investigated scope of concentrations, but exert no effect on the emergence of charge reversal. These findings highlight potential applications of coion's characteristics to control gene delivery and colloidal stability as well as to design viral packing and polyelectrolyte self-assembly.

Study of hierarchical microstructures self-assembled by π-shaped ABC block copolymers in dilute solution using self-consistent field theory.

Microstructures self-assembled by amphiphilic ABC π-shaped block copolymers in dilute solution have been investigated by self-consistent field theory. The effects of architectural parameters and the interaction strength among the three blocks have been studied systematically. Our calculation results show that the distance of the two graft blocks has stronger effect than the length of graft blocks and the position of the first graft point on the phase behavior. The interaction strength among the three blocks is another important factor in controlling the resulting microstructures. Compound-core, multicompartment, and multicore micelles are observed in the case of π-shaped ABC block copolymers with hydrophilic backbone block A and hydrophobic graft blocks B and C. Core-shell-corona, incomplete skin-layered and hamburger micelles are formed when graft block C is hydrophilic and blocks A and B are hydrophobic. The wormlike multicore micelles have drawn our attention. We find that the morphology of wormlike multicore micelle can be controlled by changing the distance of the two graft blocks of the π-shaped block copolymers. In all of the wormlike multicore micelles, the streamline wormlike micelle is more stable than other wormlike micelles from the free energy analysis.

Effect of particle surface selectivity on composite nanostructures in nanoparticle/diblock copolymer mixture dilute solution.

In this study the phase behavior of nanoparticle/diblock copolymer composites in dilute solution has been investigated by the hybrid particle-field (HPF) method. We focus on the influence of particle surface selectivity (i.e. hydrophobic and hydrophilic) on the distribution of nanoparticles in the micelles formed by the diblock copolymers. These two types of particle surface selectivity are simulated systematically. The different competition between the energy from enthalpy and the energy from entropy has been observed in the two kinds of composite systems. Our simulation results show that the particle surface selectivity is a crucial factor for determining the thermodynamic properties in the complex dilute solution, and the morphologies of micelles are controlled by the volume fraction of the nanoparticles. The change of particle distribution in various micelles enriches the composite microstructures that can be formed by nanoparticle and diblock copolymer.

Bump-surface multicompartment micelles from a linear ABC triblock copolymer: a combination study by experiment and computer simulation.

Novel bump-surface multicompartment micelles formed by a linear amphiphilic ABC triblock copolymer via self-assembly in selective solvent were successfully observed both in simulation and experiment. The results revealed that the block A forms the most inner core, and the blocks B and C form the inner and outer layers, respectively, and the bumps were formed by block A and more likely to be born on curving surfaces. Moreover, the micelle shape could be controlled by changing the solvent selectivity of the blocks A and B. Spherical, cylindrical, and discoidal micelles with bumpy surfaces were obtained both in experiment and simulation.