Electroacupuncture Inhibits NLRP3 Activation by Regulating CMPK2 After Spinal Cord Injury.

Objectives: This study aimed to evaluate the expression of cytosine monophosphate kinase 2 (CMPK2) and activation of the NLRP3 inflammasome in rats with spinal cord injury (SCI) and to characterize the effects of electroacupuncture on CMPK2-associated regulation of the NLRP3 inflammasome. Methods: An SCI model was established in Sprague-Dawley (SD) rats. The expression levels of NLRP3 and CMPK2 were measured at different time points following induction of SCI. The rats were randomly divided into a sham group (Sham), a model group (Model), an electroacupuncture group (EA), an adeno-associated virus (AAV) CMPK2 group, and an AAV NC group. Electroacupuncture was performed at jiaji points on both sides of T9 and T11 for 20 min each day for 3 consecutive days. In the AAV CMPK2 and AAV NC groups, the viruses were injected into the T9 spinal cord via a microneedle using a microscope and a stereotactic syringe. The Basso-Beattie-Bresnahan (BBB) score was used to evaluate the motor function of rats in each group. Histopathological changes in spinal cord tissue were detected using H&E staining, and the expression levels of NLRP3, CMPK2, ASC, caspase-1, IL-18, and IL-1ß were quantified using Western blotting (WB), immunofluorescence (IF), and RT-PCR. Results: The expression levels of NLRP3 and CMPK2 in the spinal cords of the model group were significantly increased at day 1 compared with those in the sham group (p < 0.05). The expression levels of NLRP3 and CMPK2 decreased gradually over time and remained low at 14 days post-SCI. We successfully constructed AAV CMPK2 and showed that CMPK2 was significantly knocked down following 2 dilutions. Finally, treatment with EA or AAV CMPK2 resulted in significantly increased BBB scores compared to those in the model group and the AAV NC group (p < 0.05). The histomorphology of the spinal cord in the EA and AAV CMPK2 groups was significantly different than that in the model and AAV NC groups. WB, IF, and PCR analyses showed that the expression levels of CMPK2, NLRP3, ASC, caspase-1, IL-18, and IL-1ß were significantly lower in the EA and AAV CMPK2 groups compared with those in the model and AAV NC groups (p < 0.05). Conclusion: Our study showed that CMPK2 regulated NLRP3 expression in rats with SCI. Activation of NLRP3 is a critical mechanism of inflammasome activation and the inflammatory response following SCI. Electroacupuncture downregulated the expression of CMPK2 and inhibited activation of NLRP3, which could improve motor function in rats with SCI.

Flexible piezoelectric nanogenerators based on ZnO nanorods grown on common paper substrates.

Nanogenerators capable of harvesting energy from environmental mechanical energy are attractive for many applications. In this paper, we present a simple, low-cost approach to convert low-frequency mechanical energy into electric power using piezoelectric ZnO nanorods grown on a common paper substrate. This energy conversion device has ultrahigh flexibility and piezoelectric sensitivity and can produce an output voltage of up to 10 mV and an output current of about 10 nA. It is demonstrated that the device's electric output behavior can be optionally changed between four types of mode simply by controlling the straining rate. Furthermore, it is also shown that the electric output can be enhanced by scaling the size of the device. This energy-harvesting technology provides a simple and cost-effective platform to capture low-frequency mechanical energy, such as body movements, for practical applications.

Theoretical study of cooperativity in biotin.

To give a deeper insight into the widely discussed catalytic mechanism of biotin, four representative model molecules and their aggregates hydrogen bonding (H-bonding) to water molecules were investigated by means of ab initio calculations and compared with molecular dynamics simulations. The roles of the ureido group, the sulfur atom, and the side chain of biotin are examined and discussed, respectively. Some significant H-bonding cooperativities are theoretically demonstrated in the ureido group of biotin. The pi-electron delocalization of the ureido group makes the system a good candidate for the H-bonding cooperativities, which in turn increases the covalent character of the corresponding H-bonds and facilitates the electrophilic substitution of the nitrogen atoms in the ureido group. The sulfur of biotin may participate in the delocalized pi-electron system of the ureido group via special sulfur-nitrogen bonding interactions, which reinforces the H-bonding cooperativities of the ureido group. The side chain of biotin not only reduced the accessibility of 3-NH due to steric hindrance but also enhanced the H-bonding cooperativities of the ureido group by folding over to hydrogen bond to more water molecules. The folded states are a probable way of activating 1-NH by strong cooperative effects. In addition, the H-bonding cooperativities may be a significant reason for the strong and specific binding between biotin and streptavidin.

Tautomerism of uracil and 5-bromouracil in a microcosmic environment with water and metal ions. What roles do metal ions play?

The base tautomerization processes of uracil/5-bromouracil were investigated in a microcosmic environment with both H2O and Na+ (W-M environment). It was found that uracil was more stable in the W-M environment than in the microcosmic environment with only water, which suggested that the metal ions and water work cooperated to maintain the classical nucleic acid bases. However, 5-bromouracil, a chemical mutagen, was found to be less stable than uracil in the W-M environment. Why the 5-bromouracil is easier to tautomerize and therefore induce gene mutation was explained to some extent. Further research revealed that the water molecule would assist the tautomerization in the W-M environment. However, the metal ions in different regions play absolutely opposite roles: in one region, the metal ions can prevent the base from tautomerizing, whereas in another region, the metal ion can assist the tautomerization process. Furthermore, from the viewpoint of ionization of the base, it seems BrU has a stronger tendency to lose the proton at N3, which is an intrinsic consequence of the bromine atom and is not affected by the metal cation.

A theoretical investigation of the interactions between water molecules and ionic liquids.

Quantum chemical calculations have been used to investigate the interaction between water molecules and ionic liquids based on the imidazolium cation with the anions [Cl(-)], [Br(-)], [BF(4)(-)], and [PF(6)(-)]. The predicted geometries and interaction energies implied that the water molecules interact with the Cl(-), Br(-), and BF(4)(-0 anions to form X(-)...W (X = Cl or Br, W = H(2)O), 2X-...2W, BF(4)(-)...W, and W...BF(4)(-)...W complexes. The hydrophobic PF(6)(-) anion could not form a stable complex with the water molecules at the density functional theory (DFT) level. Further studies indicate that the cation could also form a strong interaction with the water molecules. The 1-ethyl-3-methylimidazolium cation (Emim(+)) has been used as a model cation to investigate the interaction between a water molecule and a cation. In addition, the interaction between the ion pairs and the water was studied by using 1-ethyl-3-methylimidazolium chloride (Emim x Cl) as a model ionic liquid. The strengths of the interactions in these categories follow the trend anion-W > cation-W > ion pair-W.

Prediction among different spectroscopic properties for aqueous systems.

Spectroscopic properties obtained by NMR and vibrational spectra both reflect the microscopic environment of solutions, and the local composition (LC) theory can be used to study environmental effects on spectroscopic properties. Based on the LC model, the relationship between NMR and vibrational spectra, including infrared (IR) spectroscopy and Raman, were investigated. For the aqueous systems-water+N, N-dimethylformamide, water+acetone, water+methanol, and water+ethanol, we performed prediction between concentration-dependent peak positions of IR and Raman, as well as between concentration-dependent vibrational properties and 1H NMR chemical shifts. The results showed that reliable prediction could be achieved with the help of the LC model. This suggests that 1H NMR chemical shifts and vibrational spectroscopic properties may tell us the same story about the local environment encountered in solution.

The methyl C-H blueshift in N,N-dimethylformamide-water mixtures probed by two-dimensional Fourier-transform infrared spectroscopy.

Two-dimensional correlation spectroscopy was used to study the composition-dependent spectral variations of the CH-stretching bands of N,N-dimethylformamide (DMF)-water mixtures with X(DMF) ranging from 0.98 to 0.60. By a detailed correlation analysis of the spectral changes of the CH- and OH-stretching bands, it is found that the intensities of the CH and OH bands change in different ways when the water content is increased. It is also found that two different regions of the water content can be distinguished, in which the intensity changes have different signatures. A tentative explanation for how these phenomena might be related to structural changes in the mixture is proposed. The structural change of DMF induced by the water hydrogen bonded on the carbonyl group is supposed to be the possible origin of the methyl C-H blueshift instead of the direct C-H...O interactions before the hydrophobic hydration takes place.

Microenvironment control of methyl rotation induced by proton transfer.

Methyl rotation induced by proton transfer was found for cis-N-methylacetamide (NMA). More interestingly, it was found that the microenvironment could control the methyl rotation. The atom-centered density matrix propagation (ADMP) method, a recently developed ab initio molecular dynamics, was further carried out to depict the trajectories for methyl rotation of NMA. Moreover, trajectories for methyl rotation of NMA complexed with water molecules were also calculated, and water molecules at the two different sites of NMA were found to reverse or cease the rotational direction of the methyl groups of NMA. This finding that microenvironment can not only control rotational direction of methyl groups but can also cease the rotation may be of significant importance for the control of molecular machines.

The chemical nature of the (plus sign in circle)C-H...X- (X=Cl or Br) interaction in imidazolium halide ionic liquids.

The C-H...X (X=Cl or Br) interaction is traditionally characterized as a relatively weak interaction. However, this interaction becomes very strong in the imidazolium-based halide ionic liquids [J. Phys. Chem. 123, 174501 (2005)]. This strong interaction had been attributed to the electrostatic interaction between the imidazolium cation and the halide anion. In this paper, the chemical nature of the (plus sign in circle)C-H...Cl(-) and ( plus sign in circle)C-H...Br(-) interactions is investigated by atoms in molecules (AIM) and natural bond orbital (NBO) analyses. The AIM calculations indicate that in the EmimX complexes, the (plus sign in circle)C-H...Cl(-) and (plus sign in circle)C-H...Br(-) interactions have some covalent character, especially the (plus sign in circle)C-H...Cl(-) interaction. Mulliken, ChelpG charge, and natural bond orbital population analyses for these two kinds of interactions indicate that the charge transfer is important in the interaction of the cation with the anion. In addition, the NBO analysis demonstrated that the stabilization energy is due to an n-->sigma(C-H) (*) orbital interaction. However, in the Emim2X and Emim3X complexes, the calculated results suggested a dominant electrostatic character for the (plus sign in circle)C-H...Cl(-) and (plus sign in circle)C-H...Br(-) interactions.

Structure and conformation properties of 1-alkyl-3-methylimidazolium halide ionic liquids: a density-functional theory study.

The structures and conformational properties of 1-alkyl-3-methylimidazolium halide ionic liquids have been studied with a Becke's 3 Parameter functional method. The interaction mechanisms between the cation and the anion in 1-ethyl-3-methylimidazolium (Emim+) halide and 1-butyl-3-methylimidazolium (Bmim+) halide ionic liquids were investigated using 6-31G*, 6-31++G**, and 6-311++G** basis sets. Forty structures of different ion pairs were optimized and geometrical parameters of them have been discussed in details. Halide ions (Cl- or Br-) have been gradually placed in different regions around imidazolium cation and the interaction energies between the anion and the cation have been calculated. Theoretical results indicate that there are four activity regions in the vicinity of the imidazolium cations, in these regions the imidazolium cations and the halide anions formed stable ion pairs. Imidazolium cations can form hydrogen bond interactions with one, two or three but no more than three nearest halide anions. The halide ions are situated in hydrogen bond positions rather than at random.

Theoretical study of the effect of water in the process of proton transfer of glycinamide.

For the purpose of investigating the tautomerism from glycinamide (G) to glycinamidic acid (G*) induced by proton transfer, we carried out a study of structural interconversion of the two tautomers and the relative stabilizing influences of water during the tautomerization process. Throughout the study, we used density functional theory (DFT) calculations at the B3LYP/6-311++G** level of theory, also considering the correction functions, that is, the effect of basis set superposition error (BSSE). Totally, 42 geometries, including fourteen important transition states, were optimized, and their geometric parameters have also been discussed in detail. Water molecules were gradually put in three different regions in the vicinity of G and its tautomer G*. The calculation results indicate that water in two of these regions can protect G from tautomerizing to G*, while in another region, water can assist in the tautomerism; this reveals that water molecules have stabilization and mutagenicity effects for G simultaneously.

Systematic study of the tautomerism of uracil induced by proton transfer. Exploration of water stabilization and mutagenicity.

To systematically investigate all the possible tautomerisms from uracil (U) and its enol form (U) induced by proton transfer, we describe a study of structural tautomer interconversion in the gas phase, in a continuum solvent, and in a microhydrated environment with 1 or 2 explicit water molecules, using density functional theory (DFT) calculations by means of the B3LYP exchange and correlation functions. A total of 62 geometries including 25 transition states were optimized, and the geometrical parameters have been discussed. Some rules of the configuration variation in tautomerization were summarized. The relative stabilities of all the tautomers were established. When a proton transfers from the di-keto form to the keto-enol form, water molecules in different regions show absolutely opposite effects: some assist, whereas others hinder the tautomerization. However, when a proton transfers from the keto-enol form to the di-enol form, water molecules in different regions show similar effects: the Gibbs free energy always increases and the activation energy always decreases. Additionally, some important factors that obviously affect the activation energy and Gibbs free energy were found and discussed in detail. The reasons that water molecules can assist or prevent the proton transfer were given. Furthermore, on the basis of our calculated results, we explain why it is hard to detect the di-enol form of uracil in general experiments.

All-atom molecular dynamic simulations and relative NMR spectra study of weak C-H...O contacts in amide-water systems.

Amide-water mixtures are studied by all-atom molecular dynamics (MD) simulations and the relative temperature-dependent NMR experiment. The weak C-H...O contacts are found in the amide-water systems theoretically and experimentally. The statistical results of the average numbers of hydrogen bonds indicate that the methyl groups in amide molecules represent different capabilities in forming the weak C-H...O contacts. The statistics also imply that the C-H...O contacts are more obvious in the amide-rich region than those in the water-rich region. The temperature-dependent NMR spectra are also adopted to investigate the weak C-H...O contacts in the amide-water systems. The relative chemical shifts of the methyl groups are in good agreement with the MD simulations.

Mutagenic mechanism of the A-T to G-C transition induced by 5-bromouracil: an ab Initio Study.

The tautomerisms of uracil, 5-bromouracil (BrU), G-U, G-BrU, A-U, and A-BrU have been studied theoretically in an effort to investigate the mutagenicity of BrU. The ab initio calculations have been performed using HF and B3LYP methods with various basis sets. The relative stability of all tautomers was established. The intermolecular interactions between U, BrU, U*, BrU* (asterisks denote enol forms), and water have been studied. It shows that the possibility of tautomerism from BrU to BrU* is much more likely than that from U to U*. Further research indicates that BrU* tends to pair with guanine more easily than U*. The proton transfer process has been investigated by potential energy surface (PES) scan and transition state analysis. The results show that the proton transfer between G-U* and G*-U is monodirectional barrier-free proton transfer (BFPT), which terminates the base mismatch induced by U*. On the other hand, the proton transfer between G-BrU* and G*-BrU is bidirectional BFPT, which makes the base mismatch induced by BrU* sustained. On the basis of all of these calculated results, a new mutagenic mechanism for the A-T to G-C transition induced by 5-bromouracil is described in detail for the first time. It might give a new insight into the origin of the mutagenicity of the 5-Br derivative.

Dynamic Monte Carlo simulation of linear SAW polymer chain near a flat surface.

Investigation of the conformational properties of a SAW polymer chain near an impenetrable, non-interacting flat surface showed that the chain at first contracted and orientated itself to slightly parallel when it pulled close to the surface and at last elongated and reoriented itself to slightly perpendicular to the surface at very small distance from the surface. Simulation showed that most of the disappeared configurations were of large size at moderate distance from the surface while they were of small size at very small distance from the surface; and that the mean-square end-to-end distance was much more prone to be influenced by the surface than the mean-square radius of gyration . The orientational correlation between the direction of the longest principal axis of the moment of inertia and end-to-end vector was also discussed.

Molecular Dynamics Simulations of Biotin in Aqueous Solution.

Molecular dynamics simulations have been used to study the conformational properties and dynamics of biotin in explicit water for the first time. Three simulations, started from different initial conformations, generate similar results, which are characterized in terms of intramolecular distance, radius of gyration, root-mean-square deviation of all atom coordinates, and solvent-accessible surface area. The simulations indicate that biotin in aqueous solution is highly flexible and jumps between extended, semifolded, and folded states. The folded conformations via intramolecular hydrogen bonding are observed. Interestingly, many semifolded biotin molecules involving water-mediated hydrogen bonds between the ureido group and the carboxyl group of the side chain are also observed. The folded and semifolded states of biotin are likely to cause the hydrogen bonding cooperativity, which will activate the 1-NH protons and facilitate the electrophilic substitution of the 1-NH. The flexibility of biotin, the water molecules, and the hydrogen bonding cooperativity may play an essential role in activation of the 1-NH site.