Ligand-Controlled Cobalt-Catalyzed Regio-, Enantio-, and Diastereoselective Oxyheterocyclic Alkene Hydroalkylation.

Metal-hydride-catalyzed alkene hydroalkylation has been developed as an efficient method for C(sp3)-C(sp3) coupling with broad substrate availability and high functional group compatibility. However, auxiliary groups, a conjugated group or a chelation-directing group, are commonly required to attain high regio- and enantioselectivities. Herein, we reported a ligand-controlled cobalt-hydride-catalyzed regio-, enantio-, and diastereoselective oxyheterocyclic alkene hydroalkylation without chelation-directing groups. This reaction enables the hydroalkylation of conjugated and unconjugated oxyheterocyclic alkenes to deliver C2- or C3-alkylated tetrahydrofuran or tetrahydropyran in uniformly good yields and with high regio- and enantioselectivities. In addition, hydroalkylation of C2-substituted 2,5-dihydrofuran resulted in the simultaneous construction of 1,3-distereocenters, providing convenient access to polysubstituted tetrahydrofuran with multiple enantioenriched C(sp3) centers.

TMPRSS4 Drives Angiogenesis in Hepatocellular Carcinoma by Promoting HB-EGF Expression and Proteolytic Cleavage.

BACKGROUND AND AIMS: Heparin-binding epidermal growth factor (HB-EGF), a member of the epidermal growth factor family, plays a pivotal role in the progression of several malignancies, but its role and regulatory mechanisms in hepatocellular carcinoma (HCC) remain obscure. Here, we report that transmembrane protease serine 4 (TMPRSS4) significantly enhanced the expression and proteolytic cleavage of HB-EGF to promote angiogenesis and HCC progression. APPROACH AND RESULTS: A mechanistic analysis revealed that TMPRSS4 not only increased the transcriptional and translational levels of HB-EGF precursor, but also promoted its proteolytic cleavage by enhancing matrix metallopeptidase 9 expression through the EGF receptor/Akt/mammalian target of rapamycin/ hypoxia-inducible factor 1 α signaling pathway. In addition, HB-EGF promoted HCC proliferation and invasion by the EGF receptor/phosphoinositide 3-kinase/Akt signaling pathway. The level of HB-EGF in clinical samples of serum or HCC tissues from patients with HCC was positively correlated with the expression of TMPRSS4 and the microvessel density, and was identified as a prognostic factor for overall survival and recurrence-free survival, which suggests that HB-EGF can serve as a potential therapeutic target for HCC. More importantly, we provide a demonstration that treatment with the HB-EGF inhibitor cross-reacting material 197 alone or in combination with sorafenib can significantly suppress angiogenesis and HCC progression. CONCLUSIONS: HB-EGF can be regulated by TMPRSS4 to promote HCC proliferation, invasion, and angiogenesis, and the combination of the HB-EGF inhibitor cross-reacting material 197 with sorafenib might be used for individualized treatment of HCC.

Effects of hypoxia-inducible factor-1α and hypoxia-inducible factor-2α overexpression on hepatocellular carcinoma survival: A systematic review with meta-analysis.

BACKGROUND AND AIM: The role of hypoxia-inducible factor-1α (HIF-1α) and hypoxia-inducible factor-2α (HIF-2α) has been implicated in the clinical prognosis of hepatocellular carcinoma (HCC), but the results remain controversial. We aim to investigate the association of HIF-1α and HIF-2α overexpression with the prognosis and clinicopathological features of HCC. METHODS: A systematic search was conducted in PubMed, Embase, Scopus, Web of Science, and Cochrane Library until June 20, 2020. Meta-analysis was conducted to generate combined HRs with 95% confidence intervals (CI) for overall survival (OS) and disease-free survival (DFS). Odds ratios (ORs) with 95% CI were also derived by fixed or random effect model. RESULTS: Twenty-two studies involving 3238 patients were included. Combined data suggested that overexpression of HIF-1α in HCC was not only correlated with poorer OS [HR = 1.75 (95% CI: 1.53-2.00)] and DFS [HR = 1.64 (95% CI: 1.34-2.00)] but was also positively associated with vascular invasion [OR = 1.83 (95% CI: 1.36-2.48)], tumor size [OR = 1.36 (95% CI: 1.12-1.66)], and tumor number [1.74 (95% CI: 1.34-2.25)]. In contrast, HIF-2α overexpression was not associated with the prognosis and clinicopathological features of HCC. CONCLUSION: Our data provided compelling evidence of a worse prognosis of HCC in HIF-1α overexpression patients but not HIF-2α overexpression ones.

Correction to: Hepatic metastatic paraganglioma 12 years after retroperitoneal paraganglioma resection: a case report.

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Hepatic metastatic paraganglioma 12 years after retroperitoneal paraganglioma resection: a case report.

BACKGROUND: Paragangliomas, also known as chemodectomas, are rare tumors arise from chemoreceptor tissue, and most commonly locate at the bifurcation of the common carotid, the jugular foramen, aortic arch, and retroperitoneum. Paragangliomas generally are considered to be benign tumors, and rarely produce local or distant metastases. Metastasis to liver is extremely rare. CASE PRESENTATION: We report the case of a 39-year-old woman, who had undergone resection of a retroperitoneal paraganglioma at her local hospital for 12 years. She was referred to our hospital for further evaluation of a hepatic mass, which was misdignosed as hepatocellular carcinoma (HCC) and was treated by transarterial chemoembolization (TACE) in the local hospital 6 years ago. At admission, CT scan revealed a huge hypervascular mass with many feeding arteries, almost the same size as 5 years ago. Ultrasound-guided biopsy of the liver tumor was performed and immunohistochemical examination confirmed the diagnosis of hepatic metastatic paraganglioma. Though liver metastasis failed to achieve complete response or partial response to TACE treatment, it remained stable without progression during the 7-year follow-up. CONCLUSION: Paragangliomas are slow growing tumors and metastasis may develop decades after resection of the primary lesion. Long-term follow-up is necessary, and curative or palliative treatment should be considered to control symptoms, improve life quality, reduce complications and prolong survival.

Precise Regulation on the Bond Dissociation Energy of Exocyclic C-N Bonds in Various N-Heterocycle Electron Donors via Machine Learning.

Heterocycles with saturated N atoms (HetSNs) are widely used electron donors in organic light-emitting diode (OLED) materials. Their relatively low bond dissociation energy (BDE) of exocyclic C-N bonds has been closely related to material intrinsic stability and even device lifetime. Thus, it is imperative to realize fast prediction and precise regulation of those C-N BDEs, which demands a deep understanding of the relationship between the molecular structure and BDE. Herein, via machine learning (ML), we rapidly and accurately predicted C-N BDEs in various HetSNs and found that five-membered HetSNs (5-HetSNs) have much higher BDEs than almost all 6-HetSNs, except emerging boron-N blocks. Thorough analysis disclosed that high aromaticity is the foremost factor accounting for the high BDE of 5-HetSNs, and introducing intramolecular hydrogen-bond or electron-withdrawing moieties could also increase BDE. Importantly, the ML models performed well in various realistic OLED materials, showing great potential in characterizing material intrinsic stability for high-throughput virtual-screening and material design efforts.

Synergistic Intramolecular Non-Covalent Interactions Enable Robust Pure-Blue TADF Emitters.

Stability-issues of organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) require further advancements, especially in pure-blue range of CIEy < 0.20, existing a dilemma between color purity and device lifetime. Though improving bond-dissociation-energy (BDE) can effectively improve material intrinsic stability, strategies to simultaneously improve BDE and photophysical performances are still lacking. Herein, it is disclosed that synergistic intramolecular non-covalent interactions (Intra-NI) can achieve not only the highest C─N BDE among blue TADF materials, but enhanced molecular-rigidity, near-unity photoluminescent quantum yields and short delayed lifetime. Pure-blue TADF-OLEDs based on proof-of-concept TADF material realize high external-quantum-efficiency and record-high LT80@500 cd m-2 of 109 h with CIEy = 0.16. Furthermore, deep-blue TADF-sensitized devices exhibit high LT80@500 cd m-2 of 81 h with CIEy = 0.10. The findings provide new insight into the critical role of Intra-NI in OLED materials and open the way to tackling vexing stability issues for developing robust pure-blue organic emitters and other functional materials.

Longevity gene responsible for robust blue organic materials employing thermally activated delayed fluorescence.

The 3rd-Gen OLED materials employing thermally-activated delayed fluorescence (TADF) combine advantages of first two for high-efficiency and low-cost devices. Though urgently needed, blue TADF emitters have not met stability requirement for applications. It is essential to elucidate the degradation mechanism and identify the tailored descriptor for material stability and device lifetime. Here, via in-material chemistry, we demonstrate chemical degradation of TADF materials involves critical role of bond cleavage at triplet state rather than singlet, and disclose the difference between bond dissociation energy of fragile bonds and first triplet state energy (BDE-ET1) is linearly correlated with logarithm of reported device lifetime for various blue TADF emitters. This significant quantitative correlation strongly reveals the degradation mechanism of TADF materials have general characteristic in essence and BDE-ET1 could be the shared "longevity gene". Our findings provide a critical molecular descriptor for high-throughput-virtual-screening and rational design to unlock the full potential of TADF materials and devices.

Multi-strategy improved salp swarm algorithm and its application in reliability optimization.

To improve the convergence speed and solution precision of the standard Salp Swarm Algorithm (SSA), a hybrid Salp Swarm Algorithm based on Dimension-by-dimension Centroid Opposition-based learning strategy, Random factor and Particle Swarm Optimization's social learning strategy (DCORSSA-PSO) is proposed. Firstly, a dimension-by-dimension centroid opposition-based learning strategy is added in the food source update stage of SSA to increase the population diversity and reduce the inter-dimensional interference. Secondly, in the followers' position update equation of SSA, constant 1 is replaced by a random number between 0 and 1 to increase the randomness of the search and the ability to jump out of local optima. Finally, the social learning strategy of PSO is also added to the followers' position update equation to accelerate the population convergence. The statistical results on ten classical benchmark functions by the Wilcoxon test and Friedman test show that compared with SSA and other well-known optimization algorithms, the proposed DCORSSA-PSO has significantly improved the precision of the solution and the convergence speed, as well as its robustness. The DCORSSA-PSO is applied to system reliability optimization design based on the T-S fault tree. The simulation results show that the failure probability of the designed system under the cost constraint is less than other algorithms, which illustrates that the application of DCORSSA-PSO can effectively improve the design level of reliability optimization.

DFT insights into the Ni-catalyzed regioselective hydrocarboxylation of unsaturated alkenes with CO2.

The nickel-catalyzed hydrocarboxylation of alkenes using carbon dioxide has recently become an appealing method to prepare functionalized carboxylic acids with high efficiency and regioselectivity. Herein, density functional theory (DFT) calculations were conducted on the Ni-catalyzed hydrocarboxylation of aryl-/alkyl-substituted alkenes with CO2. The α- and ß-carboxylation of aromatic and aliphatic olefins originate from distinct catalytic cycles: H-transfer-carboxylation and carboxylation-H-transfer pathways. The typical hydrometallation-carboxylation mechanism is unlikely because water/carbonic acid (H-resource) are inferior hydride donors.

Huaier Granule Combined with Tegafur Gimeracil Oteracil Potassium Promotes Stage IIb Gastric Cancer Prognosis and Induces Gastric Cancer Cell Apoptosis by Regulating Livin.

Gastric cancer is one of the most common malignancies worldwide, with high morbidity and poor survival rate. Its prognosis remains unsatisfactory, with a 5-year survival rate of <30%. Studies have indicated that Huaier granules have good antitumor efficacy and safety in several solid malignant tumors. Recent studies have also found that Huaier polysaccharides can promote apoptosis in numerous tumor cells, although only few studies have focused on the effects of Huaier granules on gastric cancers and the mechanisms underlying their antitumor role. We retrospectively evaluated stage IIb gastric cancer patients at Xiangya Hospital, Central South University, through our outpatient system from January 2013 to December 2015. Fifty-four patients were in the Huaier+Tegafur Gimeracil Oteracil Potassium (TGOP) group and 72 in the TGOP group. Further, we conducted CCK8, colony formation, Annexin V-FITC/PI, Western blot, RT-PCR, and plasmid transfection assays to analyze the mechanism by which Huaier polysaccharides play an antitumor role. We confirmed that Huaier granules combined with Tegafur Gimeracil Oteracil Potassium could promote patient prognosis, with a better disease-free survival rate (51.32 ± 2.23 vs. 44.19 ± 2.26, p = 0.034) and overall survival rate (56.81 ± 1.32 vs. 51.32 ± 1.69, p = 0.020). Moreover, through cell proliferation assays, Western blot, RT-PCR, and detection of Livin expression at the mRNA and protein levels, we found that Huaier polysaccharides could promote gastric cancer cell apoptosis and inhibit gastric cancer cell proliferation in a time- and dose-dependent manner. Finally, we demonstrated that Huaier polysaccharides promote gastric cancer cell apoptosis through the regulation of Livin expression. Overexpression of Livin reversed the gastric cell apoptosis induced by Huaier polysaccharides. Huaier granules combined with Tegafur Gimeracil Oteracil Potassium ameliorated stage IIb gastric cancer prognosis and induced gastric cancer cell apoptosis by regulating Livin.

Somatostatin inhibits insulin release via SSTR2 in hamster clonal beta-cells and pancreatic islets.

Somatostatin (SST) inhibits pancreatic endocrine secretion. It is generally accepted that SSTR2 and SSTR5 mediate the inhibition of glucagon and insulin release, respectively. The present study was performed to test the hypothesis that SSTR2, but not SSTR5, mediates SST-induced inhibition of insulin release in hamster beta-cells. Both hamster clonal beta-cells HIT-T15 and pancreatic islets were used to test this hypothesis. Both SST and a nonpeptide SSTR2 agonist L-779,976 (1-100 nM) inhibited insulin release from HIT-T15 and islets in a concentration-dependent manner. In contrast, nonpeptide agonists for SSTR1, 3, 4 and 5 at the highest concentration studied (1 microM) failed to inhibit insulin release. PRL-2903, a peptide SSTR2 antagonist (0.1-1 muicroM), antagonized SST-induced inhibition of insulin release in a concentration-dependent manner. Taken together, we conclude that, in hamster beta-cells, SST inhibits insulin release via SSTR2 but not SSTR5.

The role of arginine vasopressin in diabetes-associated increase in glucagon secretion.

The purpose of this study was to investigate the role of arginine vasopressin (AVP) on glucagon secretion in both normal and diabetic rats. Diabetes was induced by intravenous administration of 50 mg/kg streptozotocin, 14 days before pancreatic perfusion. Diabetic rats were maintained on insulin replacement therapy until approximately 48 h before the perfusion experiments. Both glucagon and AVP were determined in the effluent of the perfused pancreas using RIA. Both normal and diabetic rats had similar basal glucagon secretion. AVP (3-30 pM) increased glucagon secretion from both normal and diabetic rats in a concentration-dependent manner. However, diabetic subjects were more sensitive to AVP administration than normal subjects with regard to glucagon secretion. By comparison of the areas under the curves, AVP-induced glucagon secretion in diabetic rats was approximately 2-fold that of the normal rats. In addition, immunoreactive AVP was detected in the effluent of the perfused pancreas, and diabetic rats had 70% higher AVP concentrations in the pancreatic effluent than normal rats. We conclude that AVP is secreted from the pancreas and diabetic rats can secrete more AVP from the pancreas than normal rats. Consequently, AVP may have a greater impact on glucagon secretion in diabetic subjects than normal ones. AVP might play an important role in the hypersecretion of glucagon in diabetic subjects.