Publications by authors named "Kai Guo"

476 Publications

Artificial intelligence and machine learning in design of mechanical materials.

Mater Horiz 2021 Apr 7;8(4):1153-1172. Epub 2021 Jan 7.

Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave. 1-290, Cambridge, Massachusetts 02139, USA.

Artificial intelligence, especially machine learning (ML) and deep learning (DL) algorithms, is becoming an important tool in the fields of materials and mechanical engineering, attributed to its power to predict materials properties, design de novo materials and discover new mechanisms beyond intuitions. As the structural complexity of novel materials soars, the material design problem to optimize mechanical behaviors can involve massive design spaces that are intractable for conventional methods. Addressing this challenge, ML models trained from large material datasets that relate structure, properties and function at multiple hierarchical levels have offered new avenues for fast exploration of the design spaces. The performance of a ML-based materials design approach relies on the collection or generation of a large dataset that is properly preprocessed using the domain knowledge of materials science underlying chemical and physical concepts, and a suitable selection of the applied ML model. Recent breakthroughs in ML techniques have created vast opportunities for not only overcoming long-standing mechanics problems but also for developing unprecedented materials design strategies. In this review, we first present a brief introduction of state-of-the-art ML models, algorithms and structures. Then, we discuss the importance of data collection, generation and preprocessing. The applications in mechanical property prediction, materials design and computational methods using ML-based approaches are summarized, followed by perspectives on opportunities and open challenges in this emerging and exciting field.
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http://dx.doi.org/10.1039/d0mh01451fDOI Listing
April 2021

LncRNA-MIAT promotes thyroid cancer progression and function as ceRNA to target EZH2 by sponging miR-150-5p.

Cell Death Dis 2021 Nov 22;12(12):1097. Epub 2021 Nov 22.

Department of Head and Neck Surgery, Shanghai Jiao Tong University School of Medicine Affiliated Renji Hospital, 200001, Shanghai, China.

While long noncoding RNAs (lncRNAs) have been reported to play an important role in human cancer types, they remain poorly understood in papillary thyroid carcinoma (PTC). The aim of this study was to use genome-wide expression profiling to identify lncRNAs acting as competing endogenous RNAs (ceRNAs) in PTC. We constructed a ceRNA network based on our lncRNA microarray data and validated the correlation between myocardial infarction-associated transcript lncRNA (MIAT), miRNA-150-5p, and EZH2 in vitro and in vivo. We found 15 lncRNAs, 28 miRNAs, and hundreds of mRNAs involved in this ceRNA network. Splendid positive correlations were found between the MIAT and EZH2 expression in types of cancer in TCGA data. Besides, significant differences in MIAT/EZH2 expression were found among various clinicopathological features. Gain- and loss-of-function experiments revealed that MIAT inhibited cell proliferation and migration in vitro. Moreover, EZH2 was identified as a direct downstream target of miR-150-5p in PTC cells. Restoration of EZH2 expression partially abolished the biological effects of miR-150-5p. Furthermore, overexpression of MIAT was inversely correlated with miR-150-5p expression. Knockdown of MIAT produced significant behavioral alter maybe partly due to the function of the MIAT-150-5p-EZH2 network. Our findings suggest MIAT may inhibit EZH2 expression and promote PTC cell invasion via the miR-150/EZH2 pathway. Therefore, MIAT may serve as a valuable prognostic biomarker and therapeutic target for PTC.
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http://dx.doi.org/10.1038/s41419-021-04386-0DOI Listing
November 2021

Electrochemical C-N bond activation for deaminative reductive coupling of Katritzky salts.

Nat Commun 2021 Nov 19;12(1):6745. Epub 2021 Nov 19.

Jiangsu Key Laboratory of Advanced Organic Materials, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China.

Electrosynthesis has received great attention among researchers in both academia and industry as an ideal technique to promote single electron reduction without the use of expensive catalysts. In this work, we report the electrochemical reduction of Katritzky salts to alkyl radicals by sacrificing the easily accessible metal anode. This catalyst and electrolyte free platform has broad applicability to single electron transfer chemistry, including fluoroalkenylation, alkynylation and thiolation. The deaminative functionalization is facilitated by the rapid molecular diffusion across microfluidic channels, demonstrating the practicality that outpaces the conventional electrochemistry setups.
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http://dx.doi.org/10.1038/s41467-021-27060-7DOI Listing
November 2021

Emodin-Conjugated PEGylation of FeO Nanoparticles for FI/MRI Dual-Modal Imaging and Therapy in Pancreatic Cancer.

Int J Nanomedicine 2021 6;16:7463-7478. Epub 2021 Nov 6.

Department of Radiology, Jiangsu Province Hospital of Chinese Medicine, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu Province, 210029, People's Republic of China.

Background: Pancreatic cancer (PC) remains a difficult tumor to diagnose and treat. It is often diagnosed as advanced by reason of the anatomical structure of the deep retroperitoneal layer of the pancreas, lack of typical symptoms and effective screening methods to detect this malignancy, resulting in a low survival rate. Emodin (EMO) is an economical natural product with effective treatment and few side effects of cancer treatment. Magnetic nanoparticles (MNPs) can achieve multiplexed imaging and targeted therapy by loading a wide range of functional materials such as fluorescent dyes and therapeutic agents.

Purpose: The purpose of this study was to design and evaluate a multifunctional theranostic nanoplatform for PC diagnosis and treatment.

Methods: In this study, we successfully developed EMO-loaded, Cy7-functionalized, PEG-coated FeO (FeO-PEG-Cy7-EMO). Characteristics including morphology, hydrodynamic size, zeta potentials, stability, and magnetic properties of FeO-PEG-Cy7-EMO were evaluated. Fluorescence imaging (FI)/magnetic resonance imaging (MRI) and therapeutic treatment were examined in vitro and in vivo.

Results: FeO-PEG-Cy7-EMO nanoparticles had a core size of 9.9 ± 1.2 nm, which showed long-time stability and FI/MRI properties. Bio-transmission electron microscopy (bio-TEM) results showed that FeO-PEG-Cy7-EMO nanoparticles were endocytosed into BxPC-3 cells, while few were observed in hTERT-HPNE cells. Prussian blue staining also confirmed that BxPC-3 cells have a stronger phagocytic ability as compared to hTERT-HPNE cells. Additionally, FeO-PEG-Cy7-EMO had a stronger inhibition effect on BxPC-3 cells than FeO-PEG and EMO. The hemolysis experiment proved that FeO-PEG-Cy7-EMO can be used in vivo experiments. In vivo analysis demonstrated that FeO-PEG-Cy7-EMO enabled FI/MRI dual-modal imaging and targeted therapy in pancreatic tumor xenografted mice.

Conclusion: FeO-PEG-Cy7-EMO may serve as a potential theranostic nanoplatform for PC.
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http://dx.doi.org/10.2147/IJN.S335588DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8579871PMC
November 2021

Fully Reduced HMGB1-Containing Peptide-Based Polyurethane Scaffold with Minimal Functional Unit of Skin (MFUS) Enhances Large and Deep Wounded Skin Healing.

Macromol Biosci 2021 Nov 16:e2100403. Epub 2021 Nov 16.

Department of Neurosurgery and Plastic and Reconstructive Surgery, Shengjing Hospital of China Medical University, 36 Sanhao Street, Shenyang, 110004, China.

A novel peptide-based polymer is developed by lysine-diisocyanate (LDI), glycerol (Gly), and fully reduced HMGB1 (frHMGB1). This frHMGB1-LDI-Gly polymer either forms sponge-like foam (scaffold) or a hydrogel or a film under different reaction conditions. It degrades into nontoxic lysine, glycerol, and frHMGB1. The hydrogel glues tissues together and the glued tissues have strong mechanical properties. The film and scaffold provide the suitable environment for enhancing cell proliferation by releasing frHMGB1. The scaffold carries 1 mm diameter of full-thickness rat skin-island as a minimal functional unit of skin (MFUS) to treat large full thickness skin wounds, and the hydrogel glues the MFUS and scaffold with skin edges together (MFUS+Scaffold group). The scaffold treated wounds (Scaffold group) heal much faster than the wounds either treated with MFUS (MFUS group) or without treatment (Wound group). The MFUS+Scaffold treated wound regenerates more functional full-thickness skin with more hair follicles and sweat glands, higher CD146 and α-smooth muscle actin levels, more blood vessels and collagen productions, and less scar tissues when compared to the other three groups. The results demonstrate that the combination of frHMGB1-LDI-Gly polymer with MFUS provides a new tissue engineering approach for large full-thickness skin wound healing.
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http://dx.doi.org/10.1002/mabi.202100403DOI Listing
November 2021

The Electrical and Thermal Transport Properties of La-Doped SrTiO with ScO Composite.

Materials (Basel) 2021 Oct 21;14(21). Epub 2021 Oct 21.

School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China.

Donor-doped strontium titanate (SrTiO) is one of the most promising n-type oxide thermoelectric materials. Routine doping of La at Sr site can change the charge scattering mechanism, and meanwhile can significantly increase the power factor in the temperature range of 423-773 K. In addition, the introduction of Sc partially substitutes Sr, thus further increasing the electron concentration and optimizing the electrical transport properties. Moreover, the excess Sc in the form of ScO composite suppresses multifrequency phonon transport, leading to low thermal conductivity of = 3.78 W·m·K at 773 K for sample SrLaScTiO with the highest doping content. Thus, the thermoelectric performance of SrTiO can be significantly enhanced by synergistic optimization of electrical transport and thermal transport properties via cation doping and composite engineering.
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http://dx.doi.org/10.3390/ma14216279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8585205PMC
October 2021

An extremely promiscuous terpenoid synthase from the Lamiaceae plant var. catalyzes the formation of sester-/di-/sesqui-/mono-terpenoids.

Plant Commun 2021 Sep 12;2(5):100233. Epub 2021 Aug 12.

State Key Laboratory of Phytochemistry and Plant Resources in West China and Yunnan Key Laboratory of Natural Medicinal Chemistry, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, P. R. China.

Terpenoids are the largest class of natural products with complex structures and extensive bioactivities; their scaffolds are generated by diverse terpenoid synthases (TPSs) from a limited number of isoprenoid diphosphate precursors. Promiscuous TPSs play important roles in the evolution of terpenoid chemodiversity, but they remain largely unappreciated. Here, an extremely promiscuous terpenoid synthase (CcTPS1) of the TPS-b subfamily was cloned and functionally characterized from a leaf-specific transcriptome of the Lamiaceae plant var. . CcTPS1 is the first sester-/di-/sesqui-/mono-TPS identified from the plant kingdom, accepting C/C/C/C diphosphate substrates to generate a panel of sester-/di-/sesqui-/mono-terpenoids. Engineered expressing produced three previously unreported terpenoids (two sesterterpenoids and a diterpenoid) with rare cyclohexane-containing skeletons, along with four sesquiterpenoids and one monoterpenoid. Their structures were elucidated by extensive nuclear magnetic resonance spectroscopy. transiently expressing also produced the diterpenoid and sesquiterpenoids, demonstrating the enzyme's promiscuity . Its highly leaf-specific expression pattern combined with detectable terpenoid products in leaves of . var. and expressing suggested that CcTPS1 was mainly responsible for diterpenoid and sesquiterpenoid biosynthesis in plants. expression and the terpenoid products could be induced by methyl jasmonate, suggesting their possible role in plant-environment interaction. CcTPS1 was localized to the cytosol and may differ from mono-TPSs in subcellular compartmentalization and substrate tolerance. These findings will greatly aid our understanding of plant TPS evolution and terpenoid chemodiversity; they also highlight the enormous potential of transcriptome mining and heterologous expression for the exploration of unique enzymes and natural products hidden in plants.
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http://dx.doi.org/10.1016/j.xplc.2021.100233DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8554039PMC
September 2021

Evaluation of HRCT for the Differential Diagnosis of Pneumonia-Like Consolidation Pattern of Pulmonary MALT Lymphoma from Lobar Pneumonia.

Cancer Manag Res 2021 12;13:7813-7821. Epub 2021 Oct 12.

Department of Radiology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People's Republic of China.

Purpose: To assess the performance of high-resolution computed tomography (HRCT) in discriminating the consolidation pattern of pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma from lobar pneumonia.

Patients And Methods: This retrospective study comprised 26 patients with pathologically confirmed consolidation pattern of pulmonary MALT lymphoma (12 men and 14 women; mean age, 59.4±12.1 years) and 36 patients with lobar pneumonia confirmed by body fluids or respiratory secretion culture (16 men and 20 women; mean age, 41.8±26.3 years). Two radiologists independently evaluated the CT images. The effectiveness of these variables in distinguishing lobar pneumonia from MALT lymphoma was analyzed using logistic regression analysis.

Results: The average age of lobar pneumonia patients was younger than that of MALT lymphoma patients (=0.002). The respiratory symptom was more common in lobar pneumonia than MALT lymphoma (=0.002). Signs of bronchiectasis within the consolidation and bulging of interlobar fissure occurred significantly more often in MALT lymphoma than pneumonia (69.2% vs 11.1%, <0.0001; 46.2% vs 19.4%, =0.024). We used the predictors with <0.05 (age, respiratory symptoms, bronchiectasis, and bulging of interlobar fissure) to construct a logistic regression model. The area under curve (AUC), negative predictive value (NPV), positive predictive value (PPV), sensitivity, specificity, and accuracy were 0.891, 84.21%, 83.33%, 88.89%, 76.92%, and 83.87% for discriminating lobar pneumonia from MALT lymphoma.

Conclusion: Middle-aged, presence of mild clinical symptoms, bronchiectasis and bulging of the interlobar fissure on chest CT images are potential markers to distinguish pulmonary MALT lymphoma from lobar pneumonia.
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http://dx.doi.org/10.2147/CMAR.S327846DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8520482PMC
October 2021

Total Synthesis of (+)-Cyclobutastellettolide B.

J Am Chem Soc 2021 Nov 20;143(43):18287-18293. Epub 2021 Oct 20.

State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.

A convenient enantioselective total synthesis of (+)-cyclobutastellettolide B via a strategy that involves a diastereoselective Johnson-Claisen rearrangement, a regioselective cyclopropoxytrimethylsilane ring-opening reaction, and a Norrish-Yang cyclization is described. The results of computational and experimental studies indicate that the regio- and stereoselectivity of the Norrish-Yang reaction are controlled by the C-H bond dissociation energy and restricted rotation of the C13-C14 bond.
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http://dx.doi.org/10.1021/jacs.1c08880DOI Listing
November 2021

Dynamic impact of virome on colitis and colorectal cancer: Immunity, inflammation, prevention and treatment.

Semin Cancer Biol 2021 Oct 14. Epub 2021 Oct 14.

Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA. Electronic address:

The gut microbiome includes a series of microorganism genomes, such as bacteriome, virome, mycobiome, etc. The gut microbiota is critically involved in intestine immunity and diseases, including inflammatory bowel disease (IBD) and colorectal cancer (CRC); however, the underlying mechanism remains incompletely understood. Clarifying the relationship between microbiota and inflammation may profoundly improve our understanding of etiology, disease progression, patient management, and the development of prevention and treatment. In this review, we discuss the latest studies of the influence of enteric viruses (i.e., commensal viruses, pathogenic viruses, and bacteriophages) in the initiation, progression, and complication of colitis and colorectal cancer, and their potential for novel preventative approaches and therapeutic application. We explore the interplay between gut viruses and host immune systems for its effects on the severity of inflammatory diseases and cancer, including both direct and indirect interactions between enteric viruses with other microbes and microbial products. Furthermore, the underlying mechanisms of the virome's roles in gut inflammatory response have been explained to infer potential therapeutic targets with examples in specific clinical trials. Given that very limited literature has thus far discussed these various topics with the gut virome, we believe these extensive analyses may provide insight into the understanding of the molecular pathogenesis of IBD and CRC, which could help add the design of improved therapies for these important human diseases.
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http://dx.doi.org/10.1016/j.semcancer.2021.10.004DOI Listing
October 2021

Associations between vitamin D levels and glucose metabolism markers among pregnant women and their infants in Puerto Rico.

Nutr Hosp 2021 Oct 14. Epub 2021 Oct 14.

Center for Clinical Research and Health Promotion. Medical Sciences Campus. University of Puerto Rico.

Objectives: low vitamin D during pregnancy is common and could adversely affect health outcomes. This study evaluated vitamin D status during pregnancy and early in life, and its association with glucose metabolism.

Methods: maternal serum 25(OH)D, glucose, and insulin levels were measured longitudinally during pregnancy in Hispanic women with overweight/obesity (n = 31) and their infants at birth and 4 months.

Results: insulin and HOMA-IR levels were higher among women with vitamin D below adequate levels compared to those with adequate levels in pregnancy (p < 0.05). Late in pregnancy, as vitamin D increased by one unit (ng/mL), insulin decreased by 0.44 units and HOMA-IR by 0.09 units. Maternal vitamin D late in pregnancy was correlated with infant vitamin D levels at birth (r = 0.89; p < 0.01) and 4 months (r = 0.9; p = 0.04), and with glucose (r = 0.79; p = 0.03) and insulin (r = 0.83; p = 0.04) at 4 months.

Conclusion: maternal vitamin D status was associated with maternal and infant glucose metabolism in this sample.
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http://dx.doi.org/10.20960/nh.03600DOI Listing
October 2021

An Efficient Closed Form Solution to the Absolute Orientation Problem for Camera with Unknown Focal Length.

Sensors (Basel) 2021 Sep 28;21(19). Epub 2021 Sep 28.

Northwest Institute of Nuclear Technology, Xi'an 710024, China.

In this paper we propose an efficient closed form solution to the absolute orientation problem for cameras with an unknown focal length, from two 2D-3D point correspondences and the camera position. The problem can be decomposed into two simple sub-problems and can be solved with angle constraints. A polynomial equation of one variable is solved to determine the focal length, and then a geometric approach is used to determine the absolute orientation. The geometric derivations are easy to understand and significantly improve performance. Rewriting the camera model with the known camera position leads to a simpler and more efficient closed form solution, and this gives a single solution, without the multi-solution phenomena of perspective-three-point (P3P) solvers. Experimental results demonstrated that our proposed method has a better performance in terms of numerical stability, noise sensitivity, and computational speed, with synthetic data and real images.
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http://dx.doi.org/10.3390/s21196480DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8512203PMC
September 2021

Second harmonic generation enhancement and directional emission from topological corner state based on the quantum spin Hall effect.

Opt Express 2021 Aug;29(17):26841-26850

Topological corner state has attracted much research interests since it does not obey the conventional bulk-edge correspondence and enables tightly confined light within small volumes. In this work, we demonstrate an enhanced second harmonic generation (SHG) from a topological corner state and its directional emission. To this end, we design an all-dielectric topological photonic crystal based on optical quantum spin Hall effect. In this framework, pseudospin states of photons, topological phase, and topological corner state are subsequently constructed by engineering the structures. It is shown that a high Q-factor of 3.66×10 can be obtained at the corner state, showing strong confinement of light at the corner. Consequently, SHG is significantly boosted and manifests directional out-of-plane emission. More importantly, the enhanced SHG has robustness against a broad class of defects. These demonstrated properties offer practical advantages for integrated optical circuits.
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http://dx.doi.org/10.1364/OE.432660DOI Listing
August 2021

Polarization-insensitive ultra-short waveguide taper.

Opt Lett 2021 Oct;46(19):5027-5030

Waveguide taper, a key component in the photonic integrated circuit (PIC), enables on-chip mode conversion, but large-footprint tapers are detrimental to the PIC, which desires compact and efficient devices. Polarization sensitivity also limits the tapers in the applications involving orthogonal modes. In this work, we design an efficient polarization-insensitive ultra-short MMI-based waveguide taper, through the mode spreading principle and the self-image principle. The proposed taper is 26.3 µm long, one order of magnitude shorter than the standard linear taper. We fabricate the taper, and experimentally demonstrate that it exhibits a high transmission efficiency of ∼70 and a wide 1 dB bandwidth of >54, for both TE and TM polarizations.
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http://dx.doi.org/10.1364/OL.436223DOI Listing
October 2021

Secoiridoids and triterpenoids from the traditional Tibetan medicine Gentiana veitchiorum and their immunosuppressive activity.

Phytochemistry 2021 Dec 27;192:112961. Epub 2021 Sep 27.

State Key Laboratory of Southwestern Chinese Medicine Resources, And Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, PR China; State Key Laboratory of Phytochemistry and Plant Resources in West China, And Yunnan Key Laboratory of Natural Medicinal Chemistry, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, PR China. Electronic address:

Two undescribed secoiridoids (dehydroxyl-swerimilegenin H and 9-oxo-swerimuslactone A) with eight known ones, and two undescribed triterpenoids [28-O-(3,4-dihydroxyl-benzyl)-lupeol and 17-hydroperoxide-28-norurs-12-en-3-one] with seven known ones, were isolated from the aerial parts of Gentiana veitchiorum, a traditional Tibetan medicine. The structures of these compounds were elucidated by detailed spectroscopic analyses (including 1D and 2D NMR, HRMS, IR, and specific rotation) and comparison with structurally related known compounds. The isolates were selected to evaluate for their immunosuppressive activity via inhibiting the proliferation of T cells and cytokine IFN-γ production in T cells. Among them, 28-O-(3,4-dihydroxyl-benzyl)-lupeol exhibited significant effect by inhibiting the proliferation of T cells (IC, 20.08 μM) and T cell IFN-γ production (IC, 7.29 μM).
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http://dx.doi.org/10.1016/j.phytochem.2021.112961DOI Listing
December 2021

Single-Nucleotide Polymorphism LncRNA AC008392.1/rs7248320 in CARD8 is Associated with Kawasaki Disease Susceptibility in the Han Chinese Population.

J Inflamm Res 2021 21;14:4809-4816. Epub 2021 Sep 21.

Department of Transfusion Medicine, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, People's Republic of China.

Background: Kawasaki disease (KD) is a multisystem vasculitis in infants and young children and involved in the NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome activation. Genetic factors may increase the risk of KD. To assess the association between rs7248320 in long noncoding RNA (lncRNA) AC008392.1 located in the upstream region of CARD8 and the risk of KD, a case-control study was conducted in the Han Chinese population.

Methods: This study genotyped the polymorphism rs7248320 in the lncRNA AC008392.1 gene using the TaqMan real-time polymerase chain reaction assay. The genetic contribution of rs7248320 was evaluated using odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression analysis. The association between rs7248320 and KD susceptibility was analyzed by performing a hospital-based case-control study including 559 KD patients and 1055 non-KD controls.

Results: In this study, a significant relationship between rs7248320 and KD risk was observed in the genotype/allele frequency distribution. The rs7248320 polymorphism was associated with a significantly decreased risk of KD after adjustment for age and sex (AG vs AA: adjusted OR = 0.80, 95% CI: 0.64-0.99, = 0.0421; GG vs AA: adjusted OR = 0.71, 95% CI: 0.51-1.00, = 0.0492; AG/GG vs AA: adjusted OR = 0.78, 95% CI: 0.63-0.96, = 0.0186). Moreover, the rs7248320 G allele also exhibited a decreased risk for KD (adjusted OR = 0.83, 95% CI: 0.72-0.97, = 0.0193) compared with the A allele. In the stratification analysis, compared to the rs7248320 AA genotype, AG/GG genotypes were more protective for males (OR = 0.71, 95% CI: 0.55-0.93, = 0.0122).

Conclusion: This study suggests for the first time that the lncRNA AC008392.1 rs7248320 polymorphism may be involved in KD susceptibility in the Han Chinese population.
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http://dx.doi.org/10.2147/JIR.S331727DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8464376PMC
September 2021

A Cryptic Plant Terpene Cyclase Producing Unconventional 18- and 14-Membered Macrocyclic C and C Terpenoids with Immunosuppressive Activity.

Angew Chem Int Ed Engl 2021 11 28;60(48):25468-25476. Epub 2021 Oct 28.

State Key Laboratory of Southwestern Chinese Medicine Resources, and, Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, 611137, P. R. China.

A versatile terpene synthase (LcTPS2) producing unconventional macrocyclic terpenoids was characterized from Leucosceptrum canum. Engineered Escherichia coli and Nicotiana benthamiana expressing LcTPS2 produced six 18-/14-membered sesterterpenoids including five new ones and two 14-membered diterpenoids. These products represent the first macrocyclic sesterterpenoids from plants and the largest sesterterpenoid ring system identified to date. Two variants F516A and F516G producing approximately 3.3- and 2.5-fold, respectively, more sesterterpenoids than the wild-type enzyme were engineered. Both 18- and 14-membered ring sesterterpenoids displayed significant inhibitory activity on the IL-2 and IFN-γ production of T cells probably via inhibition of the MAPK pathway. The findings will contribute to the development of efficient biocatalysts to create bioactive macrocyclic sesterterpenoids, and also herald a new potential in the well-trodden territory of plant terpenoid biosynthesis.
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http://dx.doi.org/10.1002/anie.202110842DOI Listing
November 2021

First report of bean common mosaic virus infecting heavenly bamboo (Nandina domestica) in China.

Plant Dis 2021 Sep 21. Epub 2021 Sep 21.

Zhejiang A and F University, 12627, College of Forestry and Biotechnology, Hangzhou, Zhejiang, China;

Heavenly bamboo (Nandina domestica) is an evergreen ornamental plant with worldwide distribution. In May 2018, seven out of twenty N. domestica plants showing virus-like symptoms, such as yellow mosaic and curling, were observed in Lin'an, Zhejiang province. To determine the causal agent, a small RNA library was constructed using the Small RNA v1.5 Sample Prep Kit (Illumina, San Diego, USA) with total RNA extracted from leaves of a symptomatic plant. The library was sequenced by the Solexa platform at BGI Genomics (Shenzhen, China). A total number of 21,071,675 high-quality reads of 17-28 nucleotides (nt) in length remained after trimming adapter sequences and quality control. Reads were assembled using Velvet 0.7.31 and Oases 0.2.07 with the k-mer value of 17 (Schulz et al. 2012). BlastN and BlastX search against the GenBank viral nonredundant sequence databases revealed fifty-six contigs homologous to bean common mosaic virus (BCMV; genus Potyvirus; family Potyviridae). No contig homologous to the genomic sequence of other plant-infecting viruses was identified. These contigs were further assembled into a 9,315-nt fragment by SeqMan Pro 7.1.0 in Lasergene package (DNASTAR, Madison, WI), which covered 92.68% of the genome of BCMV strain CT (BCMV-CT; GenBank accession no. KM076650). The genome of this BCMV isolate (BCMV-NTZ1) was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) using primers designed based on assembled contigs with the Phusion® High-Fidelity DNA Polymerase (New England Biolabs, Beijing, China) and the FirstChoice® RLM-RACE Kit (Invitrogen, Carlsbad, USA), respectively. Amplicons were cloned and Sanger sequenced with three independent clones per amplicon. The genome is 10,052 nt in length excluding the poly-A tail (Genbank accession no. MZ670770) and shared the highest nt sequence identities with BCMV-CT (88.46%). The putative polyprotein shared 93.36% amino acid (aa) sequence identity with that of BCMV-CT. BCMV-NTZ1 also clustered with BCMV-CT in phylogenetic trees based on BCMV full genomes and aa sequences of coat protein. Five-leaf-stage seedlings of Nicotiana tabacum, N. benthamiana, Glycine max (Linn.) Merr., and Capsicum frutescens were mechanically inoculated with sap of BCMV-infected N. domestica leaves at fifteen plants per species. Seedlings of G. max developed virus-like (mosaic and leaf deformity) symptoms (7/15) at 15 days post-inoculation, while other plants remained symptomless throughout the experiment. Subsequent RT-PCR on all the plants using primers 27F1/14Rter and sequencing confirmed the presence and absence of BCMV-NTZ1 in all symptomatic G. max seedlings and other asymptomatic indicator plants, respectively. Subsequent RT-PCR survey further confirmed the association of BCMV with symptomatic heavenly bamboo samples but not asymptomatic plants (7/20). To the best of our knowledge, this is the first report of BCMV naturally infecting heavenly bamboo in China. N. domestica is susceptible to many viruses, e.g., cucumber mosaic virus, plantago asiatica mosaic virus, nandina stem pitting virus, apple stem grooving virus, and alternanthera mosaic virus (Barnett et al. 1973; Ahmed et al. 1983; Hughes et al. 2002, 2005; Tang et al. 2010; Wei et al. 2015). Our results indicate that N. domestica can also serve as an overwinter reservoir for BCMV and special attention should be paid to the damage it may cause.
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http://dx.doi.org/10.1094/PDIS-07-21-1591-PDNDOI Listing
September 2021

Clinical and Molecular Characterizations of Papillary Thyroid Cancer in Children and Young Adults: A Multicenter Retrospective Study.

Thyroid 2021 Nov;31(11):1693-1706

Department of Head and Neck Surgery, Shanghai Jiao Tong University School of Medicine Affiliated Renji Hospital, Shanghai, China.

Papillary thyroid carcinoma (PTC) is a rare malignancy in children and young adults (CAYA). It often presents with aggressive disease patterns and advanced stages, which are clinically distinct from those in adult patients. In this study, we sought to characterize and better understand the clinical variants of PTC in CAYA and explore the underlying mechanisms. CAYA patients (age ≤18 years) diagnosed with PTC between June 2006 and June 2018 were retrospectively recruited from five hospitals. Demographic information, pathological data, and follow-up status were recorded. Tumor samples obtained from 20 children (mean age 15.15 years) and 10 adults (mean age 38.80 years) underwent comprehensive whole transcriptome sequencing. Differentially expressed genes (DEGs), mutational landscape, and immune infiltration were analyzed. A total of 217 CAYA-PTC patients (162 females and 55 males) with an average age of 14.38 ± 3.53 years (range 2-18) were included. Lymph node metastasis (LNM) was observed in 85.71%, of which 57.60% were in the lateral cervical compartment. Disease recurred in 28 of 217 (12.90%) patients with a median follow-up of 4.76 years. Multivariate logistic regression analysis revealed that age, bilateral disease, extrathyroidal extension, and coexisting Hashimoto's thyroiditis (co-HT) were independent risk factors for LNM, while co-HT was the only risk factor for recurrence. Using whole transcriptome sequencing of PTC tissues, we identified 301 DEGs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses showed that differences in immune mediators played important roles, based on the distributions of mutation frequencies, types, and expression levels between CAYA and adult patients. Based on the integrated data sets, we identified significantly mutated immune genes, cluster of differentiation 24 (), coagulation factor 12 (), coagulation factor 5 (), integrin subunit alpha 3 (), and retinoic acid early transcript 1L (), which were then verified by immunohistochemistry. Furthermore, resting mast cells, resting natural killer cells, plasma cells, and regulatory T cells were different in the CAYA-PTC group and correlated with the expression of immune checkpoints. There are considerable variabilities that may contribute to the different clinical presentations between CAYA and adult PTC patients, among which the decrease in protective immune cells may be a factor. Collectively, our results add to the possible biological mechanisms involved in CAYA-PTC.
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http://dx.doi.org/10.1089/thy.2021.0003DOI Listing
November 2021

Corrigendum: The Immune System in Transfusion-Related Acute Lung Injury Prevention and Therapy: Update and Perspective.

Authors:
Kai Guo Shuxuan Ma

Front Mol Biosci 2021 27;8:720653. Epub 2021 Aug 27.

Department of Transfusion Medicine, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China.

[This corrects the article DOI: 10.3389/fmolb.2021.639976.].
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http://dx.doi.org/10.3389/fmolb.2021.720653DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8430320PMC
August 2021

Crown ethers in hydrogenated graphene.

Phys Chem Chem Phys 2021 Sep 1;23(34):18983-18989. Epub 2021 Sep 1.

Department of Optical Engineering, Zhejiang A&F University, Hangzhou, Zhejiang, 311300, P. R. China.

Crown ethers could serve as hosts to selectively incorporate various guest atoms or molecules within the macrocycles. However, the high flexibility of crown ether molecules limits their applications in areas requiring a higher binding strength and selectivity. As an important graphene derivate, graphane, which is composed of entirely sp hybridized carbon atoms and possesses the characteristic of non-wrinkle in contrast to graphene, provides an ideal two-dimensional platform to rigidify crown ether molecules. In this work, using first principles calculations, we demonstrate that the embedment of various crown ethers with different cavity sizes in the graphane lattice are thermodynamically and kinetically stable. Compared with the corresponding crown ether molecules, the binding strength for alkali metal cations can be increased by up to ∼14 times, which may provide a good means in the field of alkali metal cation separation. Meanwhile, the electronic properties of graphane could be tuned in a range of 4.43-5.85 eV by controlling the densities of the crown ethers. These crown ether graphanes are also good candidates for the photolysis of water. Therefore, considering the easy synthesis and tunable crystal structures of graphane, we expect that our findings will trigger a new wave of research and applications of both crown ethers and graphane.
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http://dx.doi.org/10.1039/d1cp03069hDOI Listing
September 2021

Predicting Drug-Induced Liver Injury Using Machine Learning on a Diverse Set of Predictors.

Front Pharmacol 2021 18;12:648805. Epub 2021 Aug 18.

Department of Biomedical Sciences, University of North Dakota, Grand Forks, ND, United States.

A major challenge in drug development is safety and toxicity concerns due to drug side effects. One such side effect, drug-induced liver injury (DILI), is considered a primary factor in regulatory clearance. The Critical Assessment of Massive Data Analysis (CAMDA) 2020 CMap Drug Safety Challenge goal was to develop prediction models based on gene perturbation of six preselected cell-lines (CMap L1000), extended structural information (MOLD2), toxicity data (TOX21), and FDA reporting of adverse events (FAERS). Four types of DILI classes were targeted, including two clinically relevant scores and two control classifications, designed by the CAMDA organizers. The L1000 gene expression data had variable drug coverage across cell lines with only 247 out of 617 drugs in the study measured in all six cell types. We addressed this coverage issue by using Kru-Bor ranked merging to generate a singular drug expression signature across all six cell lines. These merged signatures were then narrowed down to the top and bottom 100, 250, 500, or 1,000 genes most perturbed by drug treatment. These signatures were subject to feature selection using Fisher's exact test to identify genes predictive of DILI status. Models based solely on expression signatures had varying results for clinical DILI subtypes with an accuracy ranging from 0.49 to 0.67 and Matthews Correlation Coefficient (MCC) values ranging from -0.03 to 0.1. Models built using FAERS, MOLD2, and TOX21 also had similar results in predicting clinical DILI scores with accuracy ranging from 0.56 to 0.67 with MCC scores ranging from 0.12 to 0.36. To incorporate these various data types with expression-based models, we utilized soft, hard, and weighted ensemble voting methods using the top three performing models for each DILI classification. These voting models achieved a balanced accuracy up to 0.54 and 0.60 for the clinically relevant DILI subtypes. Overall, from our experiment, traditional machine learning approaches may not be optimal as a classification method for the current data.
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http://dx.doi.org/10.3389/fphar.2021.648805DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8416433PMC
August 2021

Boosting Nitrogen Reduction to Ammonia on FeN Sites by Atomic Spin Regulation.

Adv Sci (Weinh) 2021 Oct 2;8(20):e2102915. Epub 2021 Sep 2.

College of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China.

Understanding the relationship between the electronic state of active sites and N reduction reaction (NRR) performance is essential to explore efficient electrocatalysts. Herein, atomically dispersed Fe and Mo sites are designed and achieved in the form of well-defined FeN and MoN coordination in polyphthalocyanine (PPc) organic framework to investigate the influence of the spin state of FeN on NRR behavior. The neighboring MoN can regulate the spin state of Fe center in FeN from high-spin (d d d ) to medium-spin (d d d ), where the empty d orbitals and separate d electron favor the overlap of Fe 3d with the N 2p orbitals, more effectively activating N≡N triple bond. Theoretical modeling suggests that the NRR preferably takes place on FeN instead of MoN , and the transition of Fe spin state significantly lowers the energy barrier of the potential determining step, which is conducive to the first hydrogenation of N . As a result, FeMoPPc with medium-spin FeN exhibits 2.0 and 9.0 times higher Faradaic efficiency and 2.0 and 17.2 times higher NH yields for NRR than FePPc with high-spin FeN and MoPPc with MoN , respectively. These new insights may open up opportunities for exploiting efficient NRR electrocatalysts by atomically regulating the spin state of metal centers.
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http://dx.doi.org/10.1002/advs.202102915DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8529464PMC
October 2021

Identifying Intermediates in Electrocatalytic Water Oxidation with a Manganese Corrole Complex.

J Am Chem Soc 2021 Sep 1;143(36):14613-14621. Epub 2021 Sep 1.

Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710119, People's Republic of China.

Water nucleophilic attack (WNA) on high-valent terminal Mn-oxo species is proposed for O-O bond formation in natural and artificial water oxidation. Herein, we report an electrocatalytic water oxidation reaction with Mn tris(pentafluorophenyl)corrole () in propylene carbonate (PC). O was generated at the Mn potential with hydroxide, but a more anodic potential was required to evolve O with only water. With a synthetic Mn(O) complex of , a second-order rate constant, (OH), of 7.4 × 10 M s was determined in the reaction of the Mn(O) complex of with hydroxide, whereas its reaction with water occurred much more slowly with a (HO) value of 4.4 × 10 M s. This large reactivity difference of Mn(O) with hydroxide and water is consistent with different electrocatalytic behaviors of with these two substrates. Significantly, during the electrolysis of with water, a Mn-peroxo species was identified with various spectroscopic methods, including UV-vis, electron paramagnetic resonance, and infrared spectroscopy. Isotope-labeling experiments confirmed that both O atoms of this peroxo species are derived from water, suggesting the involvement of the WNA mechanism in water oxidation by a Mn complex. Density functional theory calculations suggested that the nucleophilic attack of hydroxide on Mn(O) and also WNA to 1e-oxidized Mn(O) are feasibly involved in the catalytic cycles but that direct WNA to Mn(O) is not likely to be the main O-O bond formation pathway in the electrocatalytic water oxidation by .
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http://dx.doi.org/10.1021/jacs.1c05204DOI Listing
September 2021

Non-metal with metal behavior: metal-free coordination-insertion ring-opening polymerization.

Chem Sci 2021 Aug 15;12(32):10732-10741. Epub 2021 Jun 15.

State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University 30 Puzhu Road South Nanjing 211816 China

The "coordination-insertion" ring-opening polymerization (ROP) mechanism has so far been the monopoly of metal catalysts. In this work, we present a metal-free "coordination-insertion" ROP of trimethylene carbonate (TMC) and -caprolactone (ε-CL), as well as their sequential block copolymerization, with -trimethylsilyl-bis (trifluoromethanesulfonyl)imide (TMSNTf) as the non-metallic initiator/catalyst. TMSNTf was proposed to work through an unprecedented metal-free "coordination-insertion" mechanism, which involves the coordination of monomer to the Si atom of TMSNTf, the nucleophilic attack of the -NTf group on the coordinated monomer, and the cleavage of the acyl-oxygen bond of the monomer. The proposed metal-free "coordination-insertion" ROP was studied by NMR, SEC, and MALDI-TOF analyses. In addition, the TMSNTf-mediated ROP of TMC and ε-CL led to linear and cyclic polymers following two-stage first-order polymerization processes, as evidenced by structural analyses and kinetics study, which further demonstrated the metal-free "coordination-insertion" mechanism.
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http://dx.doi.org/10.1039/d1sc02551aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8372312PMC
August 2021

Detection of epidermal growth factor receptor () mutations from preoperative circulating tumor DNA (ctDNA) as a prognostic predictor for stage I-III non-small cell lung cancer (NSCLC) patients with baseline tissue mutations.

Transl Lung Cancer Res 2021 Jul;10(7):3213-3225

Department of Thoracic Surgery, Tangdu Hospital, Air Force Medical University, Xi'an, China.

Background: Plasma circulating tumor DNA (ctDNA) may be a surrogate, minimally invasive approach to tissue-based epidermal growth factor receptor () mutation detection in non-small cell lung cancer (NSCLC) patients. However, the predictive ability of preoperative ctDNA mutation test on long-term postoperative survival and tumor metastasis development has not been extensively investigated.

Methods: Stage I-III NSCLC patients with tissue mutations were enrolled in this study (n=174). The ctDNA mutations were identified in paired preoperative plasma samples. mutation testing was performed using Scorpion amplified refractory mutation system (ARMS) technology. The correlation between ctDNA mutation status and clinicopathologic parameters was analyzed. By combining at least 5 years of follow-up data, we assessed the relationship between ctDNA mutation status and disease-free survival (DFS) and overall survival (OS).

Results: Plasma-based ctDNA mutations were detected in 27 patients. The mutation types were exactly matched with those in paired tissue samples. Blood test sensitivity was closely associated with N stages, tumor-node-metastasis (TNM) stages and tumor differentiation (P<0.001). The overall 5-year survival rate was 18.5% versus 76.9% for ctDNA mutation-positive and ctDNA mutation-negative patients, respectively. For patients with ctDNA mutation positive, the median OS and DFS were 29.00±2.55 and 19.00±2.50 months, respectively, which were both significantly better than those in the ctDNA mutation-negative subgroup (P<0.001). ctDNA mutation was an independent risk factor of OS and DFS [hazard ratio (HR) 3.289, 95% confidence interval (CI), 1.816-5.956, P<0.001; HR, 4.860, 95% CI, 2.660-8.880, P<0.001]. For stage III patients with exon 19 deletion or L858R mutations in both tissue and plasma samples, tyrosine kinase inhibitor (TKI) therapy showed significantly better OS (P=0.025) and possible DFS benefit (P=0.060) than did chemotherapy.

Conclusions: mutation testing using the Scorpion-ARMS method in preoperative plasma could be a strong predictor for postoperative survival and metastasis of NSCLC patients. Thus, the subset of this population may be benefit from targeted strategies and management.
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http://dx.doi.org/10.21037/tlcr-21-530DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8350110PMC
July 2021

CD147 confers temozolomide resistance of glioma cells via the regulation of β-TrCP/Nrf2 pathway.

Int J Biol Sci 2021 13;17(12):3013-3023. Epub 2021 Jul 13.

Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710038, China.

Drug resistance is one of the biggest challenges in cancer therapy. temozolomide (TMZ) represents the most important chemotherapeutic option for glioma treatment. However, the therapeutic efficacy of TMZ remains very limited due to its frequent resistance in glioma, and the underlying mechanisms were not fully addressed. Herein, we demonstrate that the elevated expression of CD147 contributes to TMZ resistance in glioma cells, potentially through the post-translational regulation of Nrf2 expression. Cell-based assays of CD147 triggered drug resistance were performed through Edu-incorporation assay, CCK8 assay, TUNEL staining assay and flow cytometric assay. Luciferase reporter assay, protein stability related assays, co-immunoprecipitation assay were used to determine CD147 induction of Nrf2 expression through β-TrCP dependent ubiquitin system. Finally, the effect of the CD147/Nrf2 signaling on glioma progression and TMZ resistance were evaluated by functional experiments and clinical samples. Based on the analysis of clinical glioma tissues, CD147 is highly expressed in glioma tissues and positively associated with tumor malignancy. Suppression of CD147 expression increased the inhibitory effect of TMZ on cell survival in both U251 and T98G cells, whereas the gain of CD147 function blocked TMZ-induced ROS production and cell death. Mechanistic study indicates that CD147 inhibited GSK3β/β-TrCP-dependent Nrf2 degradation by promoting Akt activation, and subsequently increased Nrf2-mediated anti-oxidant gene expressions. Supporting the biological significance, the reciprocal relationship between CD147 and Nrf2 was observed in glioma tissues, and associated with patient outcome. Our data provide the first evidence that glioma resistance to TMZ is potentially due to the activation of CD147/Nrf2 axis. CD147 promotes Nrf2 stability through the suppression of GSK3β/β-TrCP dependent Nrf2 protein degradation, which results in the ablation of TMZ induced ROS production. As such, we point out that targeting CD147/Nrf2 axis may provide a new strategy for the treatment of TMZ resistant gliomas.
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http://dx.doi.org/10.7150/ijbs.60894DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8375226PMC
July 2021

Synthesis, Anticancer Activity, Structure-Activity Relationship and Mechanistic Investigations of Falcarindiol Analogues.

ChemMedChem 2021 Aug 20. Epub 2021 Aug 20.

Department of Medicinal Chemistry, School of Pharmacy, Southwest Medical University, Luzhou, 646000, China.

Forty samples of optically active falcarindiol analogues are synthesized by using the easily available C2 symmetric (R)- and (S)-1,1'-binaphth-2-ol (BINOL) in combination with Ti(O Pr) , Zn powder and EtI. Their anticancer activities on Hccc-9810, HepG2, MDA-MB-231, Hela, MG-63 and H460 cells are assayed to elucidate their structure-activity relationships. These results showed that the falcarindiol analogue (3R,8S)-2 i with the terminal double bond has the most potent anti-proliferation effect on Hccc-9810 cells with IC value of 0.46 μM. The falcarindiol analogue (3R,8S)-2 i can induce obvious Hccc-9810 cell apoptosis in a concentration-dependent manner by Hoechst staining and flow cytometry analysis. The proposed mechanism suggests that the falcarindiol analogue (3R,8S)-2 i increases LDH release and MDA content, and reduces the levels of SOD activity, which lead to the accumulation of oxidative stress and induce apoptosis in Hccc-9810 cells.
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http://dx.doi.org/10.1002/cmdc.202100377DOI Listing
August 2021

In situ three-dimensional spider web construction and mechanics.

Proc Natl Acad Sci U S A 2021 08;118(33)

Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;

Spiders are nature's engineers that build lightweight and high-performance web architectures often several times their size and with very few supports; however, little is known about web mechanics and geometries throughout construction, especially for three-dimensional (3D) spider webs. In this work, we investigate the structure and mechanics for a spider web at varying stages of construction. This is accomplished by imaging, modeling, and simulations throughout the web-building process to capture changes in the natural web geometry and the mechanical properties. We show that the foundation of the web geometry, strength, and functionality is created during the first 2 d of construction, after which the spider reinforces the existing network with limited expansion of the structure within the frame. A better understanding of the biological and mechanical performance of the 3D spider web under construction could inspire sustainable robust and resilient fiber networks, complex materials, structures, scaffolding, and self-assembly strategies for hierarchical structures and inspire additive manufacturing methods such as 3D printing as well as inspire artistic and architectural and engineering applications.
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http://dx.doi.org/10.1073/pnas.2101296118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8379916PMC
August 2021

Photomediated core modification of organic photoredox catalysts in radical addition: mechanism and applications.

Chem Sci 2021 Jul 10;12(27):9432-9441. Epub 2021 Jun 10.

College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University 30 Puzhu Rd S. Nanjing 211816 China +86 2558139901 +86 25581399301.

Dihydrophenazines and their analogues have been widely used as strong reducing photoredox catalysts in radical chemistry, such as organocatalyzed atom transfer radical polymerization (O-ATRP). However, when dihydrophenazines were employed as organic photoredox catalysts (OPCs) to mediate O-ATRP, the initiator efficiency was nonquantitative due to cross-coupling between dihydrophenazines and radical species. Here, a new kind of core modification for dihydrophenazines, phenoxazines and phenothiazines was developed through this cross-coupling process. Mechanistic studies suggested that the radical species would be more likely to couple with OPC' radical cations rather than the ground-state OPC. Core modification of OPCs could stabilize the radical ions in an oxidative quenching catalytic cycle. Significantly, core modifications of OPCs could lower the energy of light required for photoexcitation. Compared with their noncore-modified counterparts, all the core-modified dihydrophenazines and phenoxazines exhibited efficient performance in controlling O-ATRP for the synthesis of poly(methyl methacrylate) with higher initiator efficiencies under the irradiation of simulated sunlight.
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http://dx.doi.org/10.1039/d1sc02258jDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8279010PMC
July 2021
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