CPS1 augments hepatic glucagon response through CaMKII/FOXO1 pathway.

Introduction: Elevated glucagon levels are a characteristic feature of type 2 diabetes. This abnormal increase in glucagon can lead to an accelerated rate of gluconeogenesis. Glucagon also stimulates hepatic metabolism of amino acids, particularly promoting the formation of urea. The specific role of carbamoyl phosphate synthetase 1 (CPS1), a rate-limiting enzyme in the urea cycle, in the development versus the persistence of glucagon-induced hyperglycemia has not been previously established. Methods: The study employed both in vivo and in vitro approaches to assess the impact of CPS1 modulation on glucagon response. CPS1 was knockdown or overexpression to evaluate its influence on hepatic gluconeogenesis. In addition, an in-silico strategy was employed to identify a potential CPS1 inhibitor. Results: Knockdown of CPS1 significantly reduced the glucagon response both in vivo and in vitro. Conversely, overexpression of CPS1 resulted in an overactive hepatic gluconeogenic response. Mechanistically, CPS1 induced the release of calcium ions from the endoplasmic reticulum, which in turn triggered the phosphorylation of CaMKII. The activation of CaMKII then facilitated the dephosphorylation and nuclear translocation of FOXO1, culminating in the enhancement of hepatic gluconeogenesis. Furthermore, cynarin, a natural CPS1 inhibitor derived from the artichoke plant, had the capacity to attenuate the hepatic glucagon response in a CPS1-dependent manner. Discussion: CPS1 played a pivotal role in mediating glucagon-induced hepatic gluconeogenesis. The discovery of cynarin as a natural inhibitor of CPS1 suggested its potential as a therapeutic agent for diabetes treatment.

Capsaicin exerts synergistic pro-apoptotic effects with cisplatin in TSCC through the calpain pathway via TRPV1.

Capsaicin (CAP) exerts significant anti-tumor effects on a variety of tumors, with low intrinsic toxicity. Cisplatin (DDP) is currently the first-line drug for the treatment of oral cancer; however, its clinical efficacy is impeded by chemoresistance and negligible side effects. Whether the combined use of CAP and DDP has a synergistic antitumor effect on tongue squamous cell carcinoma (TSCC) cells and its underlying mechanisms remains unclear. The present study revealed that CAP reduced the activity of TSCC cells in a dose- and time-dependent manner. We also observed changes in the mitochondrial functional structure of TSCC cells, along with the induction of mitochondrial apoptosis. Moreover, when CAP was combined with DDP, a synergistic cytotoxic effect on TSCC cells was observed, which had a significant impact on inducing apoptosis, inhibiting proliferation, and disrupting the mitochondrial membrane potential in TSCC cells compared to the single-drug treatment and control groups. These effects are associated with TRPV1, a high-affinity CAP receptor. The combined use of CAP and DDP can activate the TRPV1 receptor, resulting in intracellular Ca2+ overload and activation of the calpain pathway, ultimately leading to mitochondrial apoptosis. This potential mechanism was validated in TSCC xenograft models. In conclusion, our findings clearly demonstrate that CAP exerts synergistic pro-apoptotic effects with DDP in TSCC through the calpain pathway mediated by TRPV1. Thus, CAP can be considered an effective adjuvant drug for DDP in the treatment of TSCC.

The activation of adenosine monophosphate-activated protein kinase inhibits the migration of tongue squamous cell carcinoma cells by targeting Claudin-1 via epithelial-mesenchymal transition.

BACKGROUND: The role of Claudin-1 in tongue squamous cell carcinoma (TSCC) metastasis needs further clarification, particularly its impact on cell migration. Herein, our study aims to investigate the role of Claudin-1 in TSCC cell migration and its underlying mechanisms. METHODS: 36 TSCC tissue samples underwent immunohistochemical staining for Claudin-1. Western blotting and immunofluorescence analyses were conducted to evaluate Claudin-1 expression and distribution in TSCC cells. Claudin-1 knockdown cell lines were established using short hairpin RNA transfection. Migration effects were assessed through wound healing assays. Furthermore, the expression of EMT-associated molecules was measured via western blotting. RESULTS: Claudin-1 expression decreased as TSCC malignancy increased. Adenosine monophosphate-activated protein kinase (AMPK) activation led to increased Claudin-1 expression and membrane translocation, inhibiting TSCC cell migration and epithelial-mesenchymal transition (EMT). Conversely, Claudin-1 knockdown reversed these inhibitory effects on migration and EMT caused by AMPK activation. CONCLUSIONS: Our results indicated that AMPK activation suppresses TSCC cell migration by targeting Claudin-1 and EMT pathways.

Photoinduced decarboxylative germylation of α-fluoroacrylic acids: access to germylated monofluoroalkenes.

Herein, a novel strategy is presented for the photoinduced decarboxylative and dehydrogenative cross-coupling of a wide range of α-fluoroacrylic acids with hydrogermanes. This methodology provides an efficient and robust approach for producing various germylated monofluoroalkenes with excellent stereoselectivity within a brief photoirradiation period. The feasibility of this reaction has been demonstrated through gram-scale reaction, conversion of germylated monofluoroalkenes, and modification of complex organic molecules.

Real time imaging of cell-permeable nanoreactor with SERS for insight into cellular processes.

Intracellular glucose detection is crucial due to its pivotal role in metabolism and various physiological processes. Precise glucose monitoring holds significance in diabetes management, metabolic studies, and biotechnological applications. In this study, we developed an innovative and expedient cell-permeable nanoreactor for intracellular glucose based on surface-enhanced Raman scattering (SERS). The nanoreactor was designed with gold nanoparticles (AuNPs), which were engineered with glucose oxide (GOx) and a H2O2-responsive Raman reporter 2-mercaptohydroquinone (2-MHQ). The interaction between 2-MHQ and H2O2 generated by glucose and GOx could simultaneously induce the appearance in the peak at 985 cm-1. Our results showed excellent performance in detecting glucose within the concentration range from 0.1 µM to 10 mM, with a low detection limitation of 14.72 nM. In addition, the glucose distribution in single HeLa cells was evaluated by real time SERS mapping. By combining noble metal particles and natural oxidases, the nanoreactor possesses both Raman activity and enzymatic functionality, thus enables sensitive glucose detection and facilitates imaging at a single cell level, which offers an insightful monitoring of cellular processes.

Clinical features, disease progression, and nuclear imaging in ATXN2-related parkinsonism in a longitudinal cohort.

BACKGROUND: Spinocerebellar ataxia 2 (SCA2) with a low range of CAG repeat expansion of ATXN2 gene can present with predominant or isolated parkinsonism that closely resembles Parkinson's disease (PD). This study is aimed at comparing clinical features, disease progression, and nuclear imaging between ATXN2-related parkinsonism (ATXN2-P) and PD. METHODS: Three hundred and seventy-seven clinically diagnosed PD with family history were screened by multiplex ligation-dependent probe amplification, whole-exome sequencing or target sequencing, and dynamic mutation testing of 10 SCA subtypes. The baseline and longitudinal clinical features as well as the dual-tracer positron emission tomography (PET) imaging were compared between ATXN2-P and genetically undefined familial PD (GU-fPD). RESULTS: Fifteen ATXN2-P patients from 7 families and 50 randomly selected GU-fPD patients were evaluated. Significantly less resting tremor and more symmetric signs were observed in ATXN2-P than GU-fPD. No significant difference was found in motor progression and duration from onset to occurrence of fluctuation, dyskinesia, and recurrent falls between the two groups. Cognitive impairment and rapid-eye-movement sleep behavior disorder were more common in ATXN2-P. During follow-up, olfaction was relatively spared, and no obvious progression of cognition dysfunction evaluated by Mini-Mental State Examination scores was found in ATXN2-P. PET results of ATXN2-P demonstrated a symmetric, diffuse, and homogenous dopamine transporter loss of bilateral striatum and a glucose metabolism pattern inconsistent with that in PD. CONCLUSIONS: Symmetric motor signs and unique nuclear imaging might be the clues to distinguish ATXN2-P from GU-fPD.

Spatiotemporal Controlled Formation of Synthetic Nanoreactors in Single Living Cells.

Cellular compartments provide confined environments for spatiotemporal control of biological processes and enzymatic reactions. To mimic such compartmentalization of eukaryotic cells, we report an efficient and general platform to precisely control the formation of artificial nanoreactors in single living cells. We introduce an electroosmotic controlled strategy for the synthesis of ZIF-8 at the nanoscale liquid-liquid interface around the tip of a nanopipet, whereby the formed ZIF-8 nanoparticles are driven into a single living cell by the electroosmotic flow. The porous ZIF-8 nanoparticles, as synthetic nanoreactors, are not only able to harvest fluorescent molecules from peripheral cytoplasm but also perform the subsequent photocatalytic degradation, mimicking compartmentalized chemical reactions in eukaryotic cells. Our strategy provides a useful tool for spatiotemporal controlled synthesis of artificial nanoreactors with on-demand functions in single living cells with versatile applications in chemical biology.

First principles insights into the interaction mechanism of iron doped thermally activated kaolinite with Cd and Pb pollutants in organic solid waste incineration flue gas.

Incineration of organic solid wastes is accompanied by the heavy metal emission through flue gas. As an inexpensive and efficient heavy metal adsorbent, the improvement of kaolinite adsorption performance for heavy metals has drawn widespread interests. In this work, the interaction mechanisms between various kaolinite surfaces and Cd/Pb species are explored through first principles calculations. The results show that the combination of Fe doping and dehydroxylation enhances the activity of kaolinite surfaces, analysis of adsorption configurations reveal that both Cd and Pb species are immobilized through chemisorption on the -H + Fe surface. At the microscopic level, further electronic structure analysis shows that the composite modified kaolinite surface has more electron transfer and more pronounced orbital hybridization and overlap compared to the original kaolinite surface, demonstrating that the modification means of dehydroxylation and Fe doping indeed enhanced the activity of the kaolinite surface, especially the activity of the O atoms in the vicinity of the Fe atom and that the O atoms are more efficiently bonded as ionic connecting Cd/Pb species for the purpose of trapping Cd/Pb species. This study points out the research direction and provides basic theoretical support for the development of new kaolinite adsorbents in the future.

The genetic spectrum of a cohort of patients clinically diagnosed as Parkinson's disease in mainland China.

So far, over 20 causative genes of monogenic Parkinson's disease (PD) have been identified. Some causative genes of non-parkinsonian entities may also manifest with parkinsonism mimicking PD. This study aimed to investigate the genetic characteristics of clinically diagnosed PD with early onset age or family history. A total of 832 patients initially diagnosed with PD were enrolled, of which, 636 were classified into the early-onset group and 196 were classified into the familial late-onset group. The genetic testing included the multiplex ligation-dependent probe amplification and next generation sequencing (target sequencing or whole-exome sequencing). The dynamic variants of spinocerebellar ataxia were tested in probands with family history. In the early-onset group, 30.03% of patients (191/636) harbored pathogenic/likely pathogenic (P/LP) variants in known PD-related genes (CHCHD2, DJ-1, GBA (heterozygous), LRRK2, PINK1, PRKN, PLA2G6, SNCA and VPS35). Variants in PRKN were the most prevalent, accounting for 15.72% of the early-onset patients, followed by GBA (10.22%), and PLA2G6 (1.89%). And 2.52% (16/636) had P/LP variants in causative genes of other diseases (ATXN3, ATXN2, GCH1, TH, MAPT, GBA (homozygous)). In the familial late-onset group, 8.67% of patients (17/196) carried P/LP variants in known PD-related genes (GBA (heterozygous), HTRA2, SNCA) and 2.04% (4/196) had P/LP variants in other genes (ATXN2, PSEN1, DCTN1). Heterozygous GBA variants (7.14%) were the most common genetic cause found in familial late-onset patients. Genetic testing is of vital importance in differential diagnosis especially in early-onset and familial PD. Our findings may also provide some clues to the nomenclature of genetic movement disorders.

Autosomal dominant Parkinson's disease caused by the recently identified LRRK2 N1437D mutation in a Chinese family: Clinical features, imaging findings, and functional impact.

INTRODUCTION: Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic cause of autosomal dominantly inherited Parkinson's disease (PD). Recently, a novel pathogenic variant (N1437D; c.4309A > G; NM_98578) in the LRRK2 gene has been identified in three Chinese families with PD. In this study, we describe a Chinese family with autosomal dominant PD that segregated with the N1437D mutation. A detailed clinical and neuroimaging characterization of the affected family members is reported. We also sought to investigate the functional mechanisms by which the detected mutation could cause PD. METHODS: We characterized the clinical and imaging phenotype of a Chinese pedigree with autosomal dominant PD. We searched for a disease-causing mutation by targeted sequencing and multiple ligation-dependent probe amplification. The functional impact of the mutation was investigated in terms of LRRK2 kinase activity, guanosine triphosphate (GTP) binding, and guanosine triphosphatase (GTPase) activity. RESULTS: The disease was found to co-segregate with the LRRK2 N1437D mutation. Patients in the pedigree exhibited typical parkinsonism (age at onset: 54.0 ± 5.9 years). One affected family member - who had evidence of abnormal tau accumulation in the occipital lobe on tau PET imaging - developed PD dementia at follow-up. The mutation markedly increased LRRK2 kinase activity and promoted GTP binding, without affecting GTPase activity. CONCLUSIONS: This study describes the functional impact of a recently identified LRRK2 mutation, N1437D, that causes autosomal dominant PD in the Chinese population. Further research is necessary to investigate the contribution of this mutation to PD in multiple Asian populations.

A multi-channel responsive AuNP@COF core-shell nanoprobe for simultaneous subcellular profiling of multiple cancer biomarkers.

The abnormal change in the expression profile of multiple cancer biomarkers is closely related to tumor progression and therapeutic effect. Due to their low abundance in living cells and the limitations of existing imaging techniques, simultaneous imaging of multiple cancer biomarkers has remained a significant challenge. Here, we proposed a multi-modal imaging strategy to detect the correlated expression of multiple cancer biomarkers, MUC1, microRNA-21 (miRNA-21) and reactive oxygen (ROS) in living cells, based on a porous covalent organic framework (COF) wrapped gold nanoparticles (AuNPs) core-shell nanoprobe. The nanoprobe is functionalized with Cy5-labeled MUC1 aptamer, a ROS-responsive molecule (2-MHQ), and a miRNA-21-response hairpin DNA tagged by FITC as the reporters for different biomarkers. The target-specific recognition can induce the orthogonal molecular change of these reporters, producing fluorescence and Raman signals for imaging the expression profiles of membrane MUC1 (red fluorescence channel), intracellular miRNA-21 (green fluorescence channel), and intracellular ROS (SERS channel). We further demonstrate the capability of the cooperative expression of these biomarkers, along with the activation of NF-κB pathway. Our research provides a robust platform for imaging multiple cancer biomarkers, with broad potential applications in cancer clinical diagnosis and drug discovery.

Clinical significance of the CD98hc-CD147 complex in ovarian cancer: a bioinformatics analysis.

Ovarian cancer is one of the most common malignant tumours affecting the female reproductive organs. CD147 (BSG) and CD98hc (SLC3A2) are oncogenes that form the CD98hc-CD147 complex, which regulates the proliferation, metastasis, metabolism, and cell cycle of cancer cells. The roles of the CD98hc-CD147 complex in ovarian cancer remain unclear. We analysed the expression and prognostic value of CD147 and CD98hc in ovarian cancer using the TCGA and ICGC databases. The effect of CD147 and CD98hc on the tumour immune response was analysed using the TIMER database. CD98hc was more highly expressed in normal tissues than primary tumour tissues, while CD147 was more highly expressed in primary tumour tissues than normal tissues. CD98hc expression was significantly associated with neutrophil and dendritic cell levels. CD147 and CD98hc were correlated with DNA repair, the cell cycle, and DNA replication. The CD98hc-CD147 complex could serve as a target for ovarian cancer treatment.

What is already known on this subject? CD98hc and CD147 are oncogenes that induce the proliferation and metastasis of cancer cells. The CD98hc-CD147 complex has been identified as a risk factor for cancer patients and causes resistance to cancer treatment.What do the results of this study add? We confirmed the expression levels of CD98hc and CD147 in ovarian cancer tissues and the effects of these oncogenes on the tumour immune response.What are the implications of these findings for clinical practice and/or further research? The CD98hc-CD147 complex may serve as a new target for ovarian cancer therapy.

A comprehensive review of the heavy metal issues regarding commercial vanadium­titanium-based SCR catalyst.

Facing the increasing demand of atmosphere pollutant control, selective catalytic reduction (SCR) technology has been widely applied in various industries for NOx abatement. However, in the condition of complicated flue gas components, the heavy metal issue is a great challenge to the catalyst deactivation and atmospheric pollution control. In this review, with the comprehensive consideration of SCR catalysts in heavy metal-rich flue gas scenarios, the distribution character of heavy metals in SCR system is firstly summarized, then the detailed interaction mechanism between heavy metals and the vanadium­titanium-based catalyst is discussed. Focusing on the mercury oxidation as well as against arsenic/lead poisoning, certain modification strategies are also concluded to develop novel SCR catalysts with multiple functions. Furthermore, the state-of-the-art technologies regarding the regeneration, the valuable metal recovery, and the harmless treatment of the spent SCR catalyst are also reported. This paper provides theoretical guidance for the manufacture of novel SCR catalysts under multiple scenarios, as well as the synergistic control of NOx and heavy metals.

[Study on the Therapeutic Effect of Lenalidomide on Hemophilic Arthropathy].

OBJECTIVE: To explore the effect of lenalidomide on human fibroblast-like synovial cells (HFLS) and the therapeutic efficacy on hemophilic arthropathy in hemophilia A mice model. METHODS: In vitro, to remodel the inflammatory environment of synovial tissue after hemorrhage, ferric citrate and recombinant TNF-α were added into the cell culture medium of HFLS. Cell Counting Kit-8 (CCK-8), Enzyme-linked immunosorbent assay (ELISA), Quantitative Real-time PCR (RT-qPCR) and flow cytometry were employed for detection of the effects of lenalidomide on the proliferation ability, pro-inflammatory cytokines release and apoptosis of HFLS cells. In vivo, hemophilia arthropathy was remodeled in hemophilia A mice by induction of hemarthrosis. A series of doses of lenalidomide (0.1, 0.3 and 1.0 g/kg) was administrated intra-articularly. Tissues of knee joints were collected on the 14th day after administration, and the protective effect of lenalidomide on arthritis in hemophilia A mice were evaluated by RT-qPCR and histological grading. RESULTS: In vitro, compared with the untreated control group, lenalidomide could significantly inhibit the proliferation of HFLS cells (P<0.05), and the effect was the most significant when the concentration was 0.01 µmol/L (P<0.001). Compared with the control group, lenalidomide could significantly inhibit the expression levels of TNF-α, IL-1ß, IL-6 and IFN-γ in HFLS cells (P<0.05). The flow cytometry results showed that lenalidomide could enhance the apoptotis of HFLS cells (P<0.05). The results of RT-qPCR showed that lenalidomide could significantly reduce the mRNA expression levels of TNF-α, IL-1ß, IL-6,MCP-1 and VEGF in the joint tissues (P<0.05). Histological results showed that compared with the injured group, lenalidomide could significantly reduce the pathological sequela after hemarthrosis induction, e.g. synovial thickening and neo-angiogenesis in the synovium. The protection displayed a dose-response pattern roughly. CONCLUSION: In vitro, lenalidomide can inhibit the proliferation of HFLS cells, promote their apoptosis, and inhibit the expression of pro-inflammatory cytokines. In vivo, lenalidomide can significantly decrease the expression of pro-inflammatory cytokines in the joints of mice, and prevent the development of inflammation and neo-angiogenesis. The results provide a theoretical and experimental basis for the clinical application of lenalidomide in the treatment of hemophilic arthropathy.

Performance of the PRISM I, PIM2, PELOD-2 and PRISM IV scoring systems in western China: a multicenter prospective study.

BACKGROUND: The aim of this study was to evaluate the performance of the four scoring tools in predicting mortality in pediatric intensive care units (PICUs) in western China. METHODS: This was a multicenter, prospective, cohort study conducted in six PICUs in western China. The performances of the scoring systems were evaluated based on both discrimination and calibration. Discrimination was assessed by calculating the area under the receiver operating characteristic curve (AUC) for each model. Calibration was measured across defined groups based on mortality risk using the Hosmer-Lemeshow goodness-of-fit test. RESULTS: A total of 2034 patients were included in this study, of whom 127 (6.2%) died. For the entire cohort, AUCs for Pediatric Risk of Mortality Score (PRISM) I, Pediatric Index of Mortality 2 (PIM2), Pediatric Logistic Organ Dysfunction Score-2 (PELOD-2) and PRISM IV were 0.88 [95% confidence interval (CI) 0.85-0.92], 0.84 (95% CI 0.80-0.88), 0.80 (95% CI 0.75-0.85), and 0.91 (95% CI 0.88-0.94), respectively. The Hosmer-Lemeshow goodness-of-fit Chi-square value was 12.71 (P = 0.12) for PRISM I, 4.70 (P = 0.79) for PIM2, 205.98 (P < 0.001) for PELOD-2, and 7.50 (P = 0.48) for PRISM IV [degree of freedom (df) = 8]. The standardized mortality ratios obtained with the PRISM I, PIM2, PELOD-2, and PRISM IV models were 0.87 (95% CI, 0.75-1.01), 0.97 (95% CI, 0.85-1.12), 1.74 (95% CI, 1.58-1.92), and 1.05 (95% CI, 0.92-1.21), respectively. CONCLUSIONS: PRISM IV performed best and can be used as a prediction tool in PICUs in Western China. However, PRISM IV needs to be further validated in NICUs.

Specially Resolved Single Living Cell Perfusion and Targeted Fluorescence Labeling Based on Nanopipettes.

Targeted delivery and labeling of single living cells in heterogeneous cell populations are of great importance to understand the molecular biology and physiological functions of individual cells. However, it remains challenging to perfuse fluorescence markers into single living cells with high spatial and temporal resolution without interfering neighboring cells. Here, we report a single cell perfusion and fluorescence labeling strategy based on nanoscale glass nanopipettes. With the nanoscale tip hole of 100 nm, the use of nanopipettes allows special perfusion and high-resolution fluorescence labeling of different subcellular regions in single cells of interest. The dynamic of various fluorescent probes has been studied to exemplify the feasibility of nanopipette-dependent targeted delivery. According to experimental results, the cytoplasm labeling of Sulfo-Cyanine5 and fluorescein isothiocyanate is mainly based on the Brownian movement due to the dyes themselves and does not have a targeting ability, while the nucleus labeling of 4',6-diamidino-2-phenylindole (DAPI) is originated from the adsorption between DAPI and DNA in the nucleus. From the finite element simulation, the precise manipulation of intracellular delivery is realized by controlling the electro-osmotic flow inside the nanopipettes, and the different delivery modes between nontargeting dyes and nucleus-targeting dyes were compared, showcasing the valuable ability of nanopipette-based method for the analysis of specially defined subcellular regions and the potential applications for single cell surgery, subcellular manipulation, and gene delivery.

[Research progress on antitumor effect and molecular mechanism of capsaicin].

Capsaicin is a lipid-soluble vanillin alkaloid extracted from Capsicum plants in the Solanaceae family, which is the main active ingredient in capsicum, with multiple functions such as anti-inflammation, analgesia, cardiovascular expansion, and gastric mucosa protection. Recently, capsaicin has been confirmed as a potential antitumor compound. It can induce cell cycle arrest, inhibit cancer cell proliferation, metastasis, invasion, and angiogenesis, and promote apoptosis or autophagy in malignancy cell models and animal models of lung cancer, breast cancer, gastric cancer, and liver cancer. Meanwhile, capsaicin shows a synergistic antitumor effect when combined with other antitumor drugs such as sorafenib. Based on the recent literature on the antitumor effect of capsaicin, the present study analyzed the molecular mechanism of capsaicin in resisting tumors by inducing apoptosis and reviewed the effects of capsaicin in inducing tumor cell cycle arrest, inhibiting tumor cell proliferation, metastasis, and angiogenesis, and combating tumors with other drugs, thereby providing a theoretical basis for further research of capsaicin and its rational development and utilization.

C3-Selective Trifluoromethylthiolation and Difluoromethylthiolation of Pyridines and Pyridine Drugs via Dihydropyridine Intermediates.

Herein, we report a method for C3-selective C-H tri- and difluoromethylthiolation of pyridines. The method relies on borane-catalyzed pyridine hydroboration for generation of nucleophilic dihydropyridines; these intermediates react with trifluoromethylthio and difluoromethylthio electrophiles to form functionalized dihydropyridines, which then undergo oxidative aromatization. The method can be used for late-stage functionalization of pyridine drugs for the generation of new drug candidates.

Borane-Catalyzed C3-Alkylation of Pyridines with Imines, Aldehydes, or Ketones as Electrophiles.

Achieving C3-selective pyridine functionalization is a longstanding challenge in organic chemistry. The existing methods, including electrophilic aromatic substitution and C-H activation, often require harsh reaction conditions and excess pyridine and generate multiple regioisomers. Herein, we report a method for borane-catalyzed tandem reactions that result in exclusively C3-selective alkylation of pyridines. These tandem reactions consist of pyridine hydroboration, nucleophilic addition of the resulting dihydropyridine to an imine, an aldehyde, or a ketone, and subsequent oxidative aromatization. Because the pyridine is the limiting reactant and the reaction conditions are mild, this method constitutes a practical tool for late-stage functionalization of structurally complex pharmaceuticals bearing a pyridine moiety.

Mechanism insights into CO oxidation over transition metal modified V2O5/TiO2 catalysts: A theoretical study.

The V2O5/TiO2 based selective catalytic reduction (SCR) catalysts possess not only promising capability on the denitrification of nitrogen oxides (NOx), but also certain effects on the oxidation of carbon monoxide (CO) in the flue gas. Modification of traditional SCR catalysts with certain transition metals can further improve their catalytic oxidation ability of CO. Therefore, it is of great significance to reveal the catalytic oxidation mechanism of CO for developing modified SCR catalysts to achieve the co-removal of CO and NOx. Theoretical calculations based on density functional theory (DFT) were performed to probe the comprehensive reaction mechanism of CO oxidation on M doped V2O5/TiO2 catalysts (M = Mo, Fe, and Co). The whole CO oxidation cycles include three stages, i.e., the first CO oxidation, the re-oxidation of the surface, and the second CO oxidation. The terminal oxygen and the surface oxygen formed by the adsorbed O2 all play vital roles in the whole CO oxidation cycles. The activation barriers of the rate-determining steps for CO oxidation on Fe-V2O5/TiO2 and Co-V2O5/TiO2 are much lower than that of Mo-V2O5/TiO2, which indicates Fe and Co dopants can apparently promote the CO oxidation activities of the modified SCR catalysts. Meanwhile, the electronic structure analysis confirms that Fe and Co dopants can cause electron distribution change with strong oxidation ability at the active oxygen sites.