Theoretical study on the mechanism of alcohol photooxidation on Nb2O5 surface.

Theoretical modeling of the solid-state photocatalysis is one of the important issues as various useful photocatalysts have been developed to date. In this work, we investigated the mechanism of the alcohol photooxidation on niobium oxide (Nb2O5) which was experimentally developed, using the density functional theory (DFT)/time-dependent (TD)DFT calculations based on the cluster model. The alcohol adsorption and the first hydrogen transfer from hydroxy group to surface occur in the ground state, while the second hydrogen transfer from CH proceeds in the excited states during the photoirradiation of UV or visible light. The spin crossing was identified and the low-lying triplet states were solved for the reaction pathway. The photoabsorption in the visible light region was characterized as the charge transfer transition from O 2p of alcohol to Nb 4d of the Nb2O5 surface. The spin density and the natural population analysis indicated the generation of spin density in the moiety of carbonyl compound and its dissipation to the interface of the surface, which partly explains the electron paramagnetic resonance measurement. It was confirmed that the rate determining step is the desorption of carbonyl compound and water molecule in agreement with the experimental rate equation analysis. The present findings with the theoretical modeling will provide useful information for the further studies of the solid-state photocatalysis.

The structure of the archaeal nuclease RecJ2 implicates its catalytic mechanism and inability to interact with GINS.

Bacterial RecJ exhibits 5'→3' exonuclease activity that is specific to single-stranded DNA (ssDNA); however, archaeal RecJs show 5' or 3' exonuclease activity. The hyperthermophilic archaea Methanocaldococcus jannaschii encodes the 5'-exonuclease MjRecJ1 and the 3'-exonuclease MjRecJ2. In addition to nuclease activity, archaeal RecJ interacts with GINS, a structural subcomplex of the replicative DNA helicase complex. However, MjRecJ1 and MjRecJ2 do not interact with MjGINS. Here, we report the structural basis for the inability of the MjRecJ2 homologous dimer to interact with MjGINS and its efficient 3' hydrolysis polarity for short dinucleotides. Based on the crystal structure of MjRecJ2, we propose that the interaction surface of the MjRecJ2 dimer overlaps the potential interaction surface for MjGINS and blocks the formation of the MjRecJ2-GINS complex. Exposing the interaction surface of the MjRecJ2 dimer restores its interaction with MjGINS. The cocrystal structures of MjRecJ2 with substrate dideoxynucleotides or product dCMP/CMP show that MjRecJ2 has a short substrate binding patch, which is perpendicular to the longer patch of bacterial RecJ. Our results provide new insights into the function and diversification of archaeal RecJ/Cdc45 proteins.

In Situ Electrochemical Atomic Force Microscopy: From Interfaces to Interphases.

The electrochemical interface formed between an electrode and an electrolyte significantly affects the rate and mechanism of the electrode reaction through its structure and properties, which vary across the interface. The scope of the interface has been expanded, along with the development of energy electrochemistry, where a solid-electrolyte interphase may form on the electrode and the active materials change properties near the surface region. Developing a comprehensive understanding of electrochemical interfaces and interphases necessitates three-dimensional spatial resolution characterization. Atomic force microscopy (AFM) offers advantages of imaging and long-range force measurements. Here we assess the capabilities of AFM by comparing the force curves of different regimes and various imaging modes for in situ characterizing of electrochemical interfaces and interphases. Selected examples of progress on work related to the structures and processes of electrode surfaces, electrical double layers, and lithium battery systems are subsequently illustrated. Finally, this review provides perspectives on the future development of electrochemical AFM.

Structure-based design of non-hypertrophic apelin receptor modulator.

Apelin is a key hormone in cardiovascular homeostasis that activates the apelin receptor (APLNR), which is regarded as a promising therapeutic target for cardiovascular disease. However, adverse effects through the ß-arrestin pathway limit its pharmacological use. Here, we report cryoelectron microscopy (cryo-EM) structures of APLNR-Gi1 complexes bound to three agonists with divergent signaling profiles. Combined with functional assays, we have identified "twin hotspots" in APLNR as key determinants for signaling bias, guiding the rational design of two exclusive G-protein-biased agonists WN353 and WN561. Cryo-EM structures of WN353- and WN561-stimulated APLNR-G protein complexes further confirm that the designed ligands adopt the desired poses. Pathophysiological experiments have provided evidence that WN561 demonstrates superior therapeutic effects against cardiac hypertrophy and reduced adverse effects compared with the established APLNR agonists. In summary, our designed APLNR modulator may facilitate the development of next-generation cardiovascular medications.

Fucoidan from Ascophyllum nodosum and Undaria pinnatifida attenuate SARS-CoV-2 infection in vitro and in vivo by suppressing ACE2 and alleviating inflammation.

The global healthcare challenge posed by COVID-19 necessitates the continuous exploration for novel antiviral agents. Fucoidans have demonstrated antiviral activity. However, the underlying structure-activity mechanism responsible for the inhibitory activity of fucoidans from Ascophyllum nodosum (FUCA) and Undaria pinnatifida (FUCU) against SARS-CoV-2 remains unclear. FUCA was characterized as a homopolymer with a backbone structure of repeating (1 â†’ 3) and (1 â†’ 4) linked α-l-fucopyranose residues, whereas FUCU was a heteropolysaccharide composed of Fuc1-3Gal1-6 repeats. Furthermore, FUCA demonstrated significantly higher anti-SARS-CoV-2 activity than FUCU (EC50: 48.66 vs 69.52 µg/mL), suggesting the degree of branching rather than sulfate content affected the antiviral activity. Additionally, FUCA exhibited a dose-dependent inhibitory effect on ACE2, surpassing the inhibitory activity of FUCU. In vitro, both FUCA and FUCU treatments downregulated the expression of pro-inflammatory cytokines (IL-6, IFN-α, IFN-γ, and TNF-α) and anti-inflammatory cytokines (IL-10 and IFN-ß) induced by viral infection. In hamsters, FUCA demonstrated greater effectiveness in attenuating lung and gastrointestinal injury and reducing ACE2 expression, compared to FUCU. Analysis of the 16S rRNA gene sequencing revealed that only FUCU partially alleviated the gut microbiota dysbiosis caused by SARS-CoV-2. Consequently, our study provides a scientific basis for considering fucoidans as poteintial prophylactic food components against SARS-CoV-2.

Conformational transitions and activation of the adhesion receptor CD97.

Adhesion G protein-coupled receptors (aGPCRs) are evolutionarily ancient receptors involved in a variety of physiological and pathophysiological processes. Modulators of aGPCR, particularly antagonists, hold therapeutic promise for diseases like cancer and immune and neurological disorders. Hindered by the inactive state structural information, our understanding of antagonist development and aGPCR activation faces challenges. Here, we report the cryo-electron microscopy structures of human CD97, a prototypical aGPCR that plays crucial roles in immune system, in its inactive apo and G13-bound fully active states. Compared with other family GPCRs, CD97 adopts a compact inactive conformation with a constrained ligand pocket. Activation induces significant conformational changes for both extracellular and intracellular sides, creating larger cavities for Stachel sequence binding and G13 engagement. Integrated with functional and metadynamics analyses, our study provides significant mechanistic insights into the activation and signaling of aGPCRs, paving the way for future drug discovery efforts.

Source term estimation for continuous plume dispersion in Fusion Field Trial-07: Bayesian inference probability adjoint inverse method.

In scenarios involving sudden releases of unidentified gases or concealed pollution emergencies, source control emerges as a critical procedure to safeguard residential air quality. Appropriate inverse source tracking methodology depending on diverse measurement data could be utilized to promptly identify pollutant source parameters. In this study, source term estimation (STE) method, i.e., jointly combining probability adjoint method with the Bayesian inference method, has been proposed. General form of the pollutant inverse transport equation was firstly established. Subsequently, the pollution source information, assumed from single continuous point releases during Fusion Field Trials 2007 under an unsteady wind field, was identified using the Bayesian inference probability adjoint inverse method. Metropolis-Hastings Markov Chain Monte Carlo (MH-MCMC) and Differential Evolution Markov Chain Monte Carlo (DE-MCMC) were then compared as sampling methods for Bayesian inference. Results indicated that the DE-MCMC algorithm has superior convergence and could present higher accuracy of pollutant source information than that of MH-MCMC algorithm, particularly for highly nonlinear and multi-modal distribution systems. Furthermore, the integration of Union standard Adjoint Location Probability (UALP) as prior information into the Bayesian inference probability adjoint inverse method effectively narrowed the sampling range, enhancing both the accuracy and robustness of the proposed approach. Finally, the impact of the covariance matrix on the inverse identification accuracy was explored. Overall, this research has provided insights into the future applicability of this Bayesian inference inversion technique for point source identification.

Comparison of Second-Generation Cryoballoon Ablation and Quantitative Radiofrequency Ablation Guided by Ablation Index for Atrial Fibrillation.

We compared the efficacy and complication rates of quantitative radiofrequency ablation guided by ablation index (RFCA-AI) with those of second-generation cryoballoon ablation (CBA-2). Consecutive patients (n = 230) with symptomatic atrial fibrillation (AF) undergoing a first ablation CBA-2 (92 patients) or RFCA-AI (138 patients) procedure were enrolled in this study. The late recurrence rate in the CBA-2 group was higher than that in the RFCA-AI group (P = .012). Subgroup analysis showed the same result in patients with paroxysmal AF (PAF) (P = .039), but no difference was found in patients with persistent AF (P = .21). The average operation duration in the CBA-2 group (85 [75-99.5] minutes) was shorter than that in the RFCA-AI group (100 [84.5-120] minutes) (P < .0001), but the average exposure time (17.36(13.87-22.49) vs 5.49(4.00-8.24) minutes) in the CBA-2 group and X-ray dose (223.25(149.15-336.95) vs 109.15(80.75-168.7) mGym) were significantly longer than those in RFCA-AI group (P < .0001). Multivariate logistic regression analysis showed that left atrial diameter (LAD), early recurrence, and methods of ablation (cryoballoon ablation) were independent risk factors for late recurrence after AF ablation. Early recurrence of AF and LAD were independent risk factors for predicting late recurrence after AF ablation.

[Effect of Xiaoxuming Decoction on activation of astrocytes in acute cerebral ischemia/reperfusion injury].

This study investigated the effect of Xiaoxuming Decoction(XXMD) on the activation of astrocytes after cerebral ischemia/reperfusion(I/R) injury. The model of cerebral IR injury was established using the middle cerebral artery occlusion method. Fluorocitrate(FC), an inhibitor of astrocyte activation, was applied to inhibit astrocyte activation. Rats were randomly divided into a sham group, a model group, a XXMD group, a XXMD+FC group, and a XXMD+Vehicle group. Neurobehavioral changes at 24 hours after cerebral IR injury, cerebral infarction, histopathological changes observed through HE staining, submicroscopic structure of astrocytes observed through transmission electron microscopy, fluorescence intensity of glial fibrillary acidic protein(GFAP) and thrombospondin 1(TSP1) measured through immunofluorescence, and expression of GFAP and TSP1 in brain tissue measured through Western blot were evaluated in rats from each group. The experimental results showed that neurobehavioral scores and cerebral infarct area significantly increased in the model group. The XXMD group, the XXMD+FC group, and the XXMD+Vehicle group all alleviated neurobehavioral changes in rats. The pathological changes in the brain were evident in the model group, while the XXMD group, the XXMD+FC group, and the XXMD+Vehicle group exhibited milder cerebral IR injury in rats. The submicroscopic structure of astrocytes in the model group showed significant swelling, whereas the XXMD group, the XXMD+FC group, and XXMD+Vehicle group protected the submicroscopic structure of astrocytes. The fluorescence intensity and protein expression of GFAP and TSP1 increased in the model group compared with those in the sham group. However, the XXMD group, the XXMD+FC group, and XXMD+Vehicle group all down-regulated the expression of GFAP and TSP1. The combination of XXMD and FC showed a more pronounced effect. These results indicate that XXMD can improve cerebral IR injury, possibly by inhibiting astrocyte activation and down-regulating the expression of GFAP and TSP1.

Orthosteric and allosteric modulation of human HCAR2 signaling complex.

Hydroxycarboxylic acids are crucial metabolic intermediates involved in various physiological and pathological processes, some of which are recognized by specific hydroxycarboxylic acid receptors (HCARs). HCAR2 is one such receptor, activated by endogenous ß-hydroxybutyrate (3-HB) and butyrate, and is the target for Niacin. Interest in HCAR2 has been driven by its potential as a therapeutic target in cardiovascular and neuroinflammatory diseases. However, the limited understanding of how ligands bind to this receptor has hindered the development of alternative drugs able to avoid the common flushing side-effects associated with Niacin therapy. Here, we present three high-resolution structures of HCAR2-Gi1 complexes bound to four different ligands, one potent synthetic agonist (MK-6892) bound alone, and the two structures bound to the allosteric agonist compound 9n in conjunction with either the endogenous ligand 3-HB or niacin. These structures coupled with our functional and computational analyses further our understanding of ligand recognition, allosteric modulation, and activation of HCAR2 and pave the way for the development of high-efficiency drugs with reduced side-effects.

Synthesis and degradation of the cyclic dinucleotide messenger c-di-AMP in the hyperthermophilic archaeon Pyrococcus yayanosii.

Cyclic di-adenosine monophosphate (c-di-AMP) is a newly identified prokaryotic cyclic dinucleotide second messenger well elucidated in bacteria, while less studied in archaea. Here, we describe the enzymes involved in c-di-AMP metabolism in the hyperthermophilic archaeon Pyrococcus yayanosii. Our results demonstrate that c-di-AMP is synthesized from two molecules of ATP by diadenylate cyclase (DAC) and degraded into pApA and then to AMP by a DHH family phosphodiesterase (PDE). DAC can be activated by a wider variety of ions, using two conserved residues, D188 and E244, to coordinate divalent metal ions, which is different from bacterial CdaA and DisA. PDE possesses a broad substrate spectrum like bacterial DHH family PDEs but shows a stricter base selection between A and G in cyclic dinucleotides hydrolysis. PDE shows differences in substrate binding patches from bacterial counterparts. C-di-AMP was confirmed to exist in Thermococcus kodakarensis cells, and the deletion of the dac or pde gene supports that the synthesis and degradation of c-di-AMP are catalyzed by DAC and PDE, respectively. Our results provide a further understanding of the metabolism of c-di-AMP in archaea.

Mechanistic Studies of Regiocontrolled Bisaddition of Fullerenes Driven by Oriented External Electric Fields.

The challenge of achieving regioselective multifunctionalization on highly symmetric C60 and C70 fullerenes persists as a significant hurdle. In this study, we present a novel approach involving the participation of an oriented external electric field (OEEF) to facilitate the regioselective formation of bisadducts in C60/C70 fullerenes. These products are obtained through consecutive Diels-Alder cycloaddition reactions. We constructed the field strength-barrier relationship and elucidated the OEEF-driven modulation mechanisms quantitatively. Leveraging the interplay between molecular dipoles and electric fields, the diverse reactions at distinct sites exhibit varying degrees of sensitivity to the applied electric fields, thereby leading to a pronounced regioselectivity in the bisaddition process. Our proposition suggests that the angle formed between the bonding direction (referred to as the reaction axis) and the external field can conveniently function as a predictive descriptor for the reactivity of different sites on the fullerene surface when subjected to electric fields.

Boosting reactivity of water-gas shift reaction by synergistic function over CeO2-x/CoO1-x/Co dual interfacial structures.

Dual-interfacial structure within catalysts is capable of mitigating the detrimentally completive adsorption during the catalysis process, but its construction strategy and mechanism understanding remain vastly lacking. Here, a highly active dual-interfaces of CeO2-x/CoO1-x/Co is constructed using the pronounced interfacial interaction from surrounding small CeO2-x islets, which shows high activity in catalyzing the water-gas shift reaction. Kinetic evidence and in-situ characterization results revealed that CeO2-x modulates the oxidized state of Co species and consequently generates the dual active CeO2-x/CoO1-x/Co interface during the WGS reaction. A synergistic redox mechanism comprised of independent contribution from dual functional interfaces, including CeO2-x/CoO1-x and CoO1-x/Co, is authenticated by experimental and theoretical results, where the CeO2-x/CoO1-x interface alleviates the CO poison effect, and the CoO1-x/Co interface promotes the H2 formation. The results may provide guidance for fabricating dual-interfacial structures within catalysts and shed light on the mechanism over multi-component catalyst systems.

Effectiveness of conjunctival bleb scarring by knock-down of heat shock protein 47 in rat model.

AIM: To evaluate the effectiveness of knock-down of heat shock protein 47 (HSP47) on conjunctival bleb scarring in a rat model and its possible mechanism. METHODS: Male Sprague-Dawley rats were used for glaucoma filtration surgery (GFS) and were treated with either phosphate buffered solution, shControl, mitomycin C, or sh-HSP47 using a microsyringe immediately after GFS. The morphology of filtering blebs was observed postoperatively. The levels of HSP47 were analyzed at 2, 5, 8, and 11d after GFS via real-time quantitative polymerase chain reaction (PCR) and Western blot. The silencing effect of HSP47, the expression of collagen I and III, and the potential signaling pathways of HSP47 during scarification were explored 11d post GFS. The protein levels of transforming growth factor-ß1 (TGF-ß1), phospho-Smad2 (pSmad2), phospho-Smad3 (p-Smad3), and phospho-p38 (p-p38) were also analyzed using Western blot. RESULTS: Sh-HSP47 treatment significantly prolonged the functional filtration bleb retention. The levels of HSP47 were increased significantly at 5, 8, and 11d postoperatively compared to the control group (P<0.05, P<0.01, and P<0.001). The levels of HSP47 protein at day 11 postoperatively were significantly down-regulated after HSP47 silencing using sh-HSP47 adenovirus transfection (P<0.01). Expression levels of collagen I and III within the blebs were significantly reduced in the absence of HSP47 (P<0.01). Moreover, the protein levels of TGF-ß1, p-Smad2/3, and p-p38 were dramatically inhibited after treatment with sh-HSP47 (P<0.01). CONCLUSION: The inhibitory effects of HSP47 knock-down on scarring after GFS have the potential to be an efficacious therapeutic option for the treatment of conjunctival bleb scarring.

Unraveling the Mechanism of Very Initial Dendritic Growth Under Lithium Ion Transport Control in Lithium Metal Anodes.

Lithium metal deposition is strongly affected by the intrinsic properties of the solid-electrolyte interphase (SEI) and working electrolyte, but a relevant understanding is far from complete. Here, by employing multiple electrochemical techniques and the design of SEI and electrolyte, we elucidate the electrochemistry of Li deposition under mass transport control. It is discovered that SEIs with a lower Li ion transference number and/or conductivity induce a distinctive current transition even under moderate potentiostatic polarization, which is associated with the control regime transition of Li ion transport from the SEI to the electrolyte. Furthermore, our findings help reveal the creation of a space-charge layer at the electrode/SEI interface due to the involvement of the diffusion process of Li ions through the SEI, which promotes the formation of dendrite embryos that develop and eventually trigger SEI breakage and the control regime transition of Li ion transport. Our insight into the very initial dendritic growth mechanism offers a bridge toward design and control for superior SEIs.

The gut microbiota metabolite butyrate mitigates MPTP/MPP+ -induced Parkinson's disease by inhibiting the JAK2/STAT3 signaling pathway.

Butyrate (BU), a gut microbiota-derived metabolite, has been reported to play a neuroprotective role in Parkinson's disease (PD). However, the specific molecular mechanism of BU has not been fully interpreted. This work aimed to verify the protective effects of BU against MPTP/MPP+ -induced neurotoxicity and explore the mechanisms involved. The results showed that BU protected against MPTP-induced motor dysfunction and decreased tyrosine hydroxylase (TH) and dopamine transporter (DAT) levels. Additionally, BU pretreatment improved PC12 cell viability and reduced MPP+ -induced PC12 cell apoptosis. BU treatment also attenuated MPP+ -stimulated oxidative stress and inflammatory response in PC12 cells. Furthermore, BU inhibited MPTP/MPP+ -induced hyperactivation of the JAK2/STAT3 signaling in mice and PC12 cells. Besides, a JAK2 agonist, Coumermycin A1 (C-A1), substantially reversed BU-mediated inhibition on JAK2/STAT3 phosphorylation in MPP+ -challenged PC12 cells and abated BU-induced repression on MPP+ -triggered apoptosis, oxidative stress, and inflammatory response in PC12 cells. To sum up, BU might exert neuroprotective effects against MPP+ /MPTP-induced neurotoxicity by inactivating the JAK2/STAT3 signaling.

Development and validation of a score predicting mortality for older patients with mitral regurgitation.

OBJECTIVE: To develop and validate a user-friendly risk score for older mitral regurgitation (MR) patients, referred to as the Elder-MR score. METHODS: The China Senile Valvular Heart Disease (China-DVD) Cohort Study functioned as the development cohort, while the China Valvular Heart Disease (China-VHD) Study was employed for external validation. We included patients aged 60 years and above receiving medical treatment for moderate or severe MR (2274 patients in the development cohort and 1929 patients in the validation cohort). Candidate predictors were chosen using Cox's proportional hazards model and stepwise selection with Akaike's information criterion. RESULTS: Eight predictors were identified: age ≥ 75 years, body mass index < 20 kg/m2, NYHA class III/IV, secondary MR, anemia, estimated glomerular filtration rate < 60 mL/min per 1.73 m2, albumin < 35 g/L, and left ventricular ejection fraction < 60%. The model displayed satisfactory performance in predicting one-year mortality in both the development cohort (C-statistic = 0.73, 95% CI: 0.69-0.77, Brier score = 0.06) and the validation cohort (C-statistic = 0.73, 95% CI: 0.68-0.78, Brier score = 0.06). The Elder-MR score ranges from 0 to 15 points. At a one-year follow-up, each point increase in the Elder-MR score represents a 1.27-fold risk of death (HR = 1.27, 95% CI: 1.21-1.34, P < 0.001) in the development cohort and a 1.24-fold risk of death (HR = 1.24, 95% CI: 1.17-1.30, P < 0.001) in the validation cohort. Compared to EuroSCORE II, the Elder-MR score demonstrated superior predictive accuracy for one-year mortality in the validation cohort (C-statistic = 0.71 vs. 0.70, net reclassification improvement = 0.320, P < 0.01; integrated discrimination improvement = 0.029, P < 0.01). CONCLUSIONS: The Elder-MR score may serve as an effective risk stratification tool to assist clinical decision-making in older MR patients.

Effects of ivabradine on ventricular electrophysiological remodeling after myocardial infarction in rats.

Introduction: This study aims to investigate the effects of ivabradine (IVA) on ventricular electrophysiological remodeling after myocardial infarction (MI) in rats. Material and methods: A total of 60 male Sprague-Dawley rats were randomly divided into five groups: an MI group, an IVA group, a metoprolol (MET) group, an IVA + MET group, and a sham group. After a four-week intervention, the ventricular electrophysiological parameters were detected by multichannel electrophysiological polygraph. Then, the morphological characteristics were evaluated using hematoxylin and eosin (H&E) and Masson's staining, and the expression of phosphorylated connexin 43 (p-Cx43) in the left ventricular wall was detected through immunohistochemistry and the Western blot test. Results: The electrophysiological examination revealed that the induction rate and fatality rate of ventricular tachycardia (VT)/ventricular fibrillation (VF) were lower in both the IVA and the MET group, compared with the MI group (6/12, 6/12 vs. 10/11; and 1/12, 1/12 vs. 5/11; all p < 0.05), as well as the IVA + MET group (1/11 vs. 10/11, p < 0.01; and 1/11 vs. 5/11, p < 0.05). The induction rate of VT/VF was lower in the IVA + MET group, compared to the MET group (1/11 vs. 6/12, p < 0.05). H&E and Masson's staining revealed that compared with the MI group, the left ventricular infarction area was lower in the IVA, MET, and IVA + MET groups (p < 0.05, p < 0.05, and p < 0.01, respectively), while collagen volume fraction (CVF) also was lower in the other groups (all p < 0.01). The left ventricular infarction area and CVF both were lower in the IVA + MET group, compared to the MET group (p < 0.05 and p < 0.01, respectively). The immunohistochemistry and Western blot revealed that p-Cx43 expression was higher in the treatment groups, compared with the MI group (all p < 0.01). Conclusions: IVA can reduce the incidence of ventricular arrhythmia after MI in male rats by improving both structural and electrical remodeling, and the combination of IVA and MET is even more effective.