Palladium-catalysed fragmentary esterification-induced allylic alkylation of allyl carbonates and cyclic vinylogous anhydrides.

An unprecedented palladium-catalysed fragmentary esterification-induced allylic alkylation (FEAA) of cyclic vinylogous anhydrides (CVAs) and allyl carbonates has been disclosed. The protocol features broad sp3-rich scaffold tolerance, rendering highly functionalized 1,6 and 1,7-dicarbonyls in up to high yields and diastereoselectivities. Three-component FEAA is also well tolerant to generate 1,6-dicarbonyls through the addition of extra O/N-nucleophiles. Furthermore, cyclic allyl carbonate-involved FEAA provides an efficient approach for the synthesis of structurally complex medium-sized rings.

Characteristics of the Ocular Surface in Myopic Child Candidates of Orthokeratology Lens Wear.

INTRODUCTION: The purpose of this study was to investigate the characteristics of objective ocular surface parameters using non-invasive objective instruments in children with myopia who are candidates for orthokeratology lens wear. METHODS: Children with myopia who are candidates for orthokeratology lens wear were retrospectively investigated. The subjects were divided into three age groups. The Keratograph 5M and LipiView interferometry were used to assess non-invasive tear meniscus height (TMH), non-invasive tear film break-up time (NIBUT), conjunctival hyperemia redness score (RS), meibomian gland loss (MGL) score, lipid layer thickness (LLT), and blink pattern analysis, including the number of partial blinks (PB) and total blinks (TB), as well as the partial blink rate (PBR). RESULTS: A total of 1119 children with myopia (2070 eyes) aged 7-18 years were selected. The mean TMH, NIBUT, and LLT of the subjects was 0.21 mm, 12.45 s, and 65.28 nm, respectively. The mean RS and upper and lower MGL scores were 0.64, 1.00, and 1.06, respectively. The mean PB, TB, and PBR was 5.13, 6.46, and 0.81, respectively. Age was significantly correlated to all ocular surface parameters (p = 0.00), except for PB. NIBUT and LLT did not differ between male participants and female participants (all p > 0.05). TMH, RS, and upper and lower MGL were significantly higher in male participants than in female participants (all p < 0.01). In addition, NIBUT was positively associated with TMH (r = 0.13, p = 0.00) and LLT (r = 0.28, p = 0.00). Both upper and lower MGL were positively correlated with TMH, PB, and TB (all p = 0.00), whereas upper MGL was negatively correlated with NIBUT and LLT (all p < 0.05). TB was negatively correlated with NIBUT and LLT (all p = 0.00). PB had no relation with TMH, NIBUT, and LLT (all p > 0.05). In addition, PBR was positively correlated with NIBUT and LLT (all p = 0.00) but not with TMH, RS, or MGL (all p > 0.05). Overall, 57.00% had a TMH ≤ 0.2 mm, 43.20% had a NIBUT ≤ 10 s, 48.10% had an LLT ≤ 60 nm, and 88.10% had a PBR > 0.4. CONCLUSIONS: Child orthokeratology candidates have enhanced tear secretion and increased meibomian gland deficiency with aging. In addition, the adult dry eye diagnostic criteria may apply to orthokeratology candidates aged 12-18 years but should be lower for younger candidates. Given the proportion of abnormal risk, it is necessary to assess tear film status and blink pattern by reliable and feasible objective examination before fitting orthokeratology.

PhiReX 2.0: A Programmable and Red Light-Regulated CRISPR-dCas9 System for the Activation of Endogenous Genes in Saccharomyces cerevisiae.

Metabolic engineering approaches do not exclusively require fine-tuning of heterologous genes but oftentimes also modulation or even induction of host gene expression, e.g., in order to rewire metabolic fluxes. Here, we introduce the programmable red light switch PhiReX 2.0, which can rewire metabolic fluxes by targeting endogenous promoter sequences through single-guide RNAs (sgRNAs) and activate gene expression in Saccharomyces cerevisiae upon red light stimulation. The split transcription factor is built from the plant-derived optical dimer PhyB and PIF3, which is fused to a DNA-binding domain based on the catalytically dead Cas9 protein (dCas9) and a transactivation domain. This design combines at least two major advantages: first, the sgRNAs, guiding dCas9 to the promoter of interest, can be exchanged in an efficient and straightforward Golden Gate-based cloning approach, which allows for rational or randomized combination of up to four sgRNAs in a single expression array. Second, target gene expression can be rapidly upregulated by short red light pulses in a light dose-dependent manner and returned to the native expression level by applying far-red light without interfering with the cell culture. Using the native yeast gene CYC1 as an example, we demonstrated that PhiReX 2.0 can upregulate CYC1 gene expression by up to 6-fold in a light intensity-dependent and reversible manner using a single sgRNA.

Enantioselective Synthesis of Ten-Membered Lactones via Palladium-Catalyzed [5 + 5] Annulation.

Ten-membered lactones are the core units of many biologically active natural products but with a great synthetic challenge. Based on the principle of vinylogy, novel types of cyclic vinylogous anhydrides have been designed as five-carbon carbonyl synthons, further applied in [5 + 5] annulation with vinylethylene carbonates under chiral palladium catalysis. This strategy features excellent regioselectivity, mild conditions, and broad substrate scope, affording a range of spiro ten-membered lactones bearing oxindole and pyrrolidinone motif in excellent yield (up to 99%) with moderate to high enantioselectivity (up to 89% ee).

Pd-Catalyzed Tandem [5 + 2] Cycloaddition/Ring Contraction of Phthalide-Derived Alkenes and Vinylethylene Carbonates for the Construction of Benzo-[5,5]-spiroketal Lactones.

An annulation of phthalide-derived activated alkenes is initially disclosed in this work. Specifically, we have developed an unprecedented [5 + 2] cycloaddition/ring-contraction tandem process of activated tetrasubstituted alkenes derived from phthalides or butyrolactone with vinylethylene carbonates under Pd(0) catalysis. Differing from the traditional spirolactonization strategy, this method renders an efficient and mechanistically distinct approach to benzo-[5,5]-spiroketal lactones and [5,5]-spiroketal lactones bearing two vicinal tetrasubstituted centers with high diastereoselectivity.

π-Lewis-Base-Catalyzed Asymmetric Vinylogous Umpolung Reactions of Cyclopentadienones and Tropone.

We disclose that the carbonates of 4-hydroxy-2-cyclopentenones can form π-allylpalladium-based 1,2-carbodipoles, which isomerize to interesting η2 -Pd0 -cyclopentadienone complexes. Compared with the labile parent cyclopentadienone, the HOMO energy of the related η2 -complex was significantly raised via the back-bonding of Pd0 as a π-Lewis base, rendering the uncoordinated C=C bond an electron-richer dienophile in inverse-electron-demand aza-Diels-Alder-type reactions with diverse 1-azadienes. The vinylogous (aza)Morita-Baylis-Hillman or cross Rauhut-Currier addition to (imine)carbonyls or activated alkenes, respectively, was also realized to afford chiral [4+2] or [2+2] cycloadducts, respectively, after trapping the re-generated π-allylpalladium species. New C1 -symmetric ligands from simple chiral sources were developed, exhibiting high stereoselectivity even with racemic substrates via an unusual dynamic kinetic resolution process. Besides, tropone could be similarly activated by a Pd0 complex.

Ligand-Controlled Regiodivergent Asymmetric [5 + 2] and [3 + 2] Annulations of Vinyl Indoloxazolidones Catalyzed by Palladium.

Here, we present palladium-catalyzed regiodivergent asymmetric annulations of vinyl indoloxazolidones, which can act as 1,5-carbodipoles or 1,3-carbodipoles by tuning the chiral ligands and conditions, in the assemblies with sulfamate-derived cyclic imines and even activated alkenes. A diversity of polycyclic products are generally constructed with high regio- and enantioselectivity.

Redox-responsive nanoassembly restrained myeloid-derived suppressor cells recruitment through autophagy-involved lactate dehydrogenase A silencing for enhanced cancer immunochemotherapy.

Myeloid-derived suppressor cells (MDSCs) are the chief accomplices for assisting tumor's survival and suppressing anti-tumor immunity, which can be recruited by tumor-derived cytokines, such as granulocyte-colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF). The plentiful lactate dehydrogenase A (LDHA) in glycolysis is usually accompanied by abundant tumor-derived G-CSF and GM-CSF, further promoting MDSCs recruitment and immunosuppression. Herein, with the aim to achieve powerful anti-tumor immunity, an immunochemotherapy regimen basing on a redox-responsive nanoassembly (R-mPDV/PDV/DOX/siL) is developed, which integrates the combined strategy of restraining cytokines-mediated MDSCs recruitment through LDHA silencing and reinforcing tumor immunogenicity through anthracycline (DOX)-elicited immunogenic cell death (ICD) effects. This redox-responsive nanoassembly is self-assembled by three glutathione (GSH)-responsive polymers, which employ poly(δ-valerolactone) (PVL) as hydrophobic segment and 3, 3'-dithiodipropionic acid (DA) as linkage to connect hydrophilic segment. DOX is encapsulated in the core and LDHA siRNA (siL) is effectively compressed by cationic PAMAM. The cellular internalization and tumor-homing are strengthened by the specific recognition on integrin (αvß3) by c(RGDfk) (RGD) ligand. After escaping from endosomes/lysosomes, R-mPDV/PDV/DOX/siL is disintegrated through GSH-elicited cleavage of DA, realizing burst release of drugs and high-efficient LDHA silencing. The reduced expression of LDHA suppresses the generation of G-CSF and GM-CSF cytokines, restrains MDSCs recruitment and reinforces anti-tumor immunity. Eventually, this therapeutic regimen of DOX and siL on R-mPDV/PDV/DOX/siL nanoassembly achieved powerful anti-tumor efficiency on 4 T1 orthotopic tumor, opening the new horizons for immunochemotherapy.

The anti-angiogenesis role of FBXW7 in diabetic retinopathy by facilitating the ubiquitination degradation of c-Myc to orchestrate the HDAC2.

Diabetic retinopathy (DR) is the most prevalently occurring microvascular complication in diabetic patients that triggers severe visual impairments. The anti-angiogenesis role of FBXW7 has been identified in breast cancer. Therefore, this study intends to decipher the mechanism of FBXW7 in angiogenesis of DR. DR model was induced on mice using high-glucose (HG) and high-fat diet, and retinal microvascular endothelial cells (RMECs) isolated from normal mice were induced with HG, followed by evaluation of FBXW7, Ki67, HIF-1α and VEGF expression by immunofluorescence, immunohistochemistry or Western blot analysis. After gain- and loss-of-function assays in normal and DR mice, angiogenesis was assessed by CD31 fluorescence staining and Western blot analysis. After ectopic expression and silencing experiments in HG-induced RMECs, RMEC proliferation, migration and angiogenesis were, respectively, determined by EdU, Transwell and in vitro angiogenesis assays. The impact of FBXW7 on the ubiquitination of c-Myc was studied by cycloheximide chase assay and proteasome inhibition, and the binding of c-Myc to HDAC2 promoter by dual-luciferase reporter gene experiment. DR mice and HG-induced RMECs possessed down-regulated FBXW7 and up-regulated Ki67, HIF-1α and VEGF. Silencing FBXW7 enhanced angiogenesis in normal mouse retinal tissue, but overexpressing FBXW7 or silencing c-Myc diminished angiogenesis in DR mouse retinal tissue. Overexpressing FBXW7 or silencing c-Myc depressed proliferation, migration and angiogenesis in HG-induced RMECs. FBXW7 induced c-Myc ubiquitination degradation, and c-Myc augmented HDAC2 expression by binding to HDAC2 promoter. Conclusively, our data provided a novel sight of anti-angiogenesis role of FBXW7 in DR by modulating the c-Myc/HDAC2 axis.

Cu(I)-Catalyzed Asymmetric α-Allenylation of Activated Ketimines with 3-Butynoates.

An asymmetric α-regioselective allenylation reaction of activated ketimines with 3-butynoates is disclosed under Cu(I) catalysis, probably via the generation of nucleophilic γ-allenylcopper species in the presence of diisopropylethylamine. A broad range of imines, derived from diverse ketones such as isatins, pyrazolediones, isoquinoline-1,3,4-triones, and even trifluoromethyl alkynyl ketones, can be utilized, generally affording the corresponding α-allenyl amine derivatives in high yields (≤97%) with excellent enantioselectivities (≤99% ee).

Expression profiling of key pathways in rat liver after a one-year feeding trial with transgenic maize MON810.

In a recent one-year feeding study, we observed no adverse effects on tissue level in organs of rats fed with the genetically-modified maize MON810. Here, we assessed RNA expression levels of 86 key genes of the apoptosis-, NF-кB-, DNA-damage response (DDR)-, and unfolded-protein response (UPR) pathways by RT-qPCR in the rat liver. Male and female rats were fed either with 33% MON810 (GMO), isogenic- (ISO), or conventional maize (CONV) and RNAs were quantified from eight rats from each of the six feeding groups. Only Birc2 transcript showed a significant (p ≤ 0.05) consistent difference of ≥1.5-fold between the GMO and ISO groups in both sexes. Unsupervised cluster analysis showed a strong separation of male and female rats, but no clustering of the feeding groups. Individual analysis of the pathways did not show any clustering of the male or female feeding groups either, though transcript levels of UPR pathway-associated genes caused some clustering of the male GMO and CONV feeding group samples. These differences were not seen between the GMO and ISO control or within the female cohort. Our data therefore does not support an adverse effect on rat liver RNA expression through the long-term feeding of MON810 compared to isogenic control maize.

Asymmetric Allylic Alkylation with Deconjugated Carbonyl Compounds: Direct Vinylogous Umpolung Strategy.

An atom-economic and highly efficient vinylogous umpolung strategy is developed for deconjugated carbonyl compounds, which generate electron-deficient π-allylpalladium complexes with Pd(OAc)2 under ligand-free conditions. In cooperation with a chiral-phosphonium-based phase-transfer catalyst, the asymmetric direct oxidative allylic alkylations of 3-substituted oxindoles are furnished under O2 atmosphere. The γ- or even remote ϵ-regioselective alkylation products, with substantial substituents, are delivered with excellent enantioselectivity, and can be further used to access diverse chiral spirocyclic architectures effectively. The Mukaiyama dienol silyl ether can be utilized similarly, indicating that the current active π-allylpalladium species results from tautomerization of the PdII -dienolate intermediate.

Low Molecular Weight Heparin-Coated and Dendrimer-Based Core-Shell Nanoplatform with Enhanced Immune Activation and Multiple Anti-Metastatic Effects for Melanoma Treatment.

High-efficiency treatment for tumor is not easy to achieve owing to the existence of metastasis, which remains the arch-criminal of most tumor deaths. Conventional chemotherapy exhibits insufficient inhibitory efficiency on tumor metastasis and more powerful strategies to conquer metastatic tumors are urgently needed. In this study, a rational chemoimmunotherapy strategy was adopted to treat highly aggressive melanoma based on a newly developed multifunctional nanoplatform. Firstly, immunoadjuvant cytosine-phosphate-guanine oligonucleotides (CpG ODNs) were used to boost the doxorubicin (DOX)-elicited immune responses, which synergistically suppressed tumor growth and metastasis. And the anti-metastatic low molecular weight heparin (LMWH) was also integrated, thus multiple anti-metastatic effects to against tumor metastasis were achieved. Methods: G4 PAMAM was serving as the main support to conjugate DOX by pH-sensitive hydrazone bond (PPD) and the synthesized conjugates were confirmed by 1H-NMR spectra, IR spectra and HRMS. Immunoadjuvant CpG ODNs were loaded by electrostatic adsorption to formulate PPD/CpG. After the coating of anti-metastatic LMWH, the designed LMWH/PPD/CpG was fabricated and characterized. The platelets-related and platelets-unrelated anti-metastatic mechanisms were investigated on B16F10 the immune activation effects, anti-tumor and anti-metastatic efficacy of LMWH/PPD/CpG were evaluated on a B16F10 melanoma xenograft model. Results: DOX elicited tumor-specific immune responses by ICD, and the immunological effects could be further promoted by CpG ODNs, exhibiting enhanced maturation of dendritic cells (DCs) and increased level of cytolytic T lymphocytes (CTLs) in vivo. Owing to the coating of LMWH, the platelets-induced epithelial-mesenchymal-like transition of tumor cells was hindered and the actin cytoskeletal arrangement of tumor cells was affected, thus the migration ability of tumor cells was further inhibited. This multifunctional nanoplatform showed enhanced treatment efficiency on melanoma primary tumor and pulmonary metastasis. Conclusion: The immune activation and multiple anti-metastatic effects of LMWH/PPD/CpG establish a novel therapeutic strategy for melanoma. This anti-metastatic nanoplatform could be broadly applied for the co-delivery of other nucleic acids and chemotherapeutic drugs to treat highly aggressive tumors.

Asymmetric Cascade Assembly of 1,2-Diaza-1,3-dienes and α,ß-Unsaturated Aldehydes via Dienamine Activation.

A cascade vinylogous 1,6-Michael addition/1,4-proton shift/aza-Michael addition/hemiaminal formation sequence of 1,2-diaza-1,3-dienes and ß-substituted 2-butenals has been developed under the influence of dienamine activation of a chiral secondary amine. This method exhibits high regio- and chemoselectivity and provides an efficient and straightforward approach to bicyclic l,8-diazabicyclo[3.3.0]octane skeletons with a tetrasubstituted stereogenic center with fair to excellent enantioselectivity.

Divergent Cyclization Reactions of Morita-Baylis-Hillman Carbonates of 2-Cyclohexenone and Isatylidene Malononitriles.

Zwitterionic dienolates generated from Morita-Baylis-Hillman carbonates of cyclohexen-2-one and a phenolic tertiary amine catalyst underwent divergent cyclization reactions with isatylidene malononitriles. A new [4 + 2] stepwise cyclization process was disclosed to deliver complex bridged spirooxindoles after the initial δ'-regioselective Rauhut-Currier-type reaction with N-methyl electrophiles by the catalysis of ß-isocupreidine, while spirooxindoles incorporating an aromatic chromene motif were generated with N-MOM acceptors in the presence of α-isocupreine through different domino transformations.

Overexpression of porcine lipoprotein-associated phospholipase A2 in swine.

Lipoprotein-associated phospholipase A 2 (Lp-PLA2) is associated with the risk of vascular disease. It circulates in human blood predominantly in association with low-density lipoprotein cholesterol (LDL-C) and hydrolyses oxidized phospholipids into pro-inflammatory products. However, in the mouse circulation, it predominantly binds to high-density lipoprotein cholesterol (HDL-C) and exhibits anti-inflammatory properties. To further investigate the effects of Lp-PLA2 in the circulation, we generated over-expressed Lp-PLA2 transgenic swine. The eukaryotic expression plasmid of porcine Lp-PLA2 which driven by EF1α promoter was constructed and generate transgenic swine via SCNT. The expression and activity of Lp-PLA2 in transgenic swine were evaluated, and the total cholesterol (TC), HDL-C, LDL-C and triglyceride (TG) levels in the fasting and fed states were also assessed. Compared with wild-type swine controls, the transgenic swine exhibited elevated Lp-PLA2 mRNA levels and activities, and the activity did not depend on the feeding state. The TC, HDL-C and LDL-C levels were not significantly increased. There was no change in the TG levels in the fasting state between transgenic and control pigs. However, in the fed state, the TG levels of transgenic swine were slightly increased compared with the control pigs and were significantly elevated compared with the fasting state. In addition, inflammatory gene (interleukin [IL]-6, monocyte chemotactic protein [MCP]-1 and tumor necrosis factor [TNF]-α) mRNA levels in peripheral blood mononuclear cells (PBMCs) were significantly increased. The results demonstrated that Lp-PLA2 is associated with triglycerides which may be helpful for understanding the relationship of this protein with cardiovascular disease.