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991.
Dr. Zhoulong Fan Katherine L. Bay Dr. Xiangyang Chen Zhe Zhuang Han Seul Park Dr. Kap-Sun Yeung Prof. Dr. K. N. Houk Prof. Dr. Jin-Quan Yu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(12):4800-4807
A simple and efficient nitrile-directed meta-C−H olefination, acetoxylation, and iodination of biaryl compounds is reported. Compared to the previous approach of installing a complex U-shaped template to achieve a molecular U-turn and assemble the large-sized cyclophane transition state for the remote C−H activation, a synthetically useful phenyl nitrile functional group could also direct remote meta-C−H activation. This reaction provides a useful method for the modification of biaryl compounds because the nitrile group can be readily converted to amines, acids, amides, or other heterocycles. Notably, the remote meta-selectivity of biphenylnitriles could not be expected from previous results with a macrocyclophane nitrile template. DFT computational studies show that a ligand-containing Pd–Ag heterodimeric transition state (TS) favors the desired remote meta-selectivity. Control experiments demonstrate the directing effect of the nitrile group and exclude the possibility of non-directed meta-C−H activation. Substituted 2-pyridone ligands were found to be key in assisting the cleavage of the meta-C−H bond in the concerted metalation–deprotonation (CMD) process. 相似文献
992.
Da Hyeon Choi Jiwon Park Ju Kwang Choi Kyeong Eun Lee Won Hee Lee Jinho Yang Ju Yeon Lee Yoon Jeong Park Chan Oh Ho-Ryun Won Bon Seok Koo Jae Won Chang Yoon Shin Park 《Experimental & molecular medicine》2020,52(9):1564
Oral microbes have the capacity to spread throughout the gastrointestinal system and are strongly associated with multiple diseases. Given that tonsils are located between the oral cavity and the laryngopharynx at the gateway of the alimentary and respiratory tracts, tonsillar tissue may also be affected by microbiota from both the oral cavity (saliva) and the alimentary tract. Here, we analyzed the distribution and association of the microbial communities in the saliva and tonsils of Korean children subjected to tonsillectomy because of tonsil hyperplasia (n = 29). The microbiome profiles of saliva and tonsils were established via 16S rRNA gene sequencing. Based on the alpha diversity indices, the microbial communities of the two groups showed high similarities. According to Spearman’s ranking correlation analysis, the distribution of Treponema, the causative bacterium of periodontitis, in saliva and tonsils was found to have a significant positive correlation. Two representative microbes, Prevotella in saliva and Alloprevotella in tonsils, were negatively correlated, while Treponema 2 showed a strong positive correlation between saliva and tonsils. Taken together, strong similarities in the microbial communities of the tonsils and saliva are evident in terms of diversity and composition. The saliva microbiome is expected to significantly affect the tonsil microbiome. Furthermore, we suggest that our study creates an opportunity for tonsillar microbiome research to facilitate the development of novel microbiome-based therapeutic strategies.Subject terms: Comparative genomics, Metagenomics 相似文献
993.
994.
Jin Young Kim Kyung Hwa Cho Bo Young Jeong Chang Gyo Park Hoi Young Lee 《Experimental & molecular medicine》2020,52(7):1152
Rab coupling protein (RCP) is upregulated in head and neck squamous cell carcinoma (HNSCC) and is correlated with the progression and survival of patients. However, the role of RCP in one of the aggressive types of HNSCC, oral squamous cell carcinoma (OSCC), remains elusive. In the present study, we identified the important role of Zeb1 in RCP-induced OSCC epithelial-to-mesenchymal transition (EMT) and invasion. RCP induces Zeb1 expression, and silencing Zeb1 expression significantly inhibits RCP-induced OSCC invasion. In addition, Zeb1 upregulates MT1-MMP expression to promote OSCC EMT and invasion. Furthermore, we observed that the β1 integrin/EGFR/β-catenin signaling cascade mediates RCP-induced Zeb1 expression to promote OSCC invasion. Notably, we provide evidence that resveratrol (REV) strongly inhibits RCP-induced Zeb1 expression through blocking β1 integrin endosome recycling and EGFR activation, leading to suppression of RCP-induced OSCC invasion, demonstrating the important role of RCP in OSCC invasion and its reversion by REV. Collectively, the present study provides evidence for the first time that RCP aggravates OSCC invasion through increasing Zeb1 expression and subsequently upregulating MT1-MMP expression and that this process is reversed by REV, providing novel biomarkers and indicating the therapeutic potential of REV in OSCC.Subject terms: Oral cancer, Cell invasion 相似文献
995.
Kyung-Baeg Roh De-Hun Ryu Eunae Cho Jin Bae Weon Deokhoon Park Dae-Hyuk Kweon Eunsun Jung 《Molecules (Basel, Switzerland)》2020,25(23)
Rosacea is a common and chronic inflammatory skin disease that is characterized by dysfunction of the immune and vascular system. The excessive production and activation of kallikerin 5 (KLK5) and cathelicidin have been implicated in the pathogenesis of rosacea. Coptis chinensis Franch (CC) has been used as a medicinal herb in traditional oriental medicine. However, little is known about the efficacy and mechanism of action of CC in rosacea. In this study, we evaluate the effect of CC and its molecular mechanism on rosacea in human epidermal keratinocytes. CC has the capacity to downregulate the expression of KLK5 and cathelicidin, and also inhibits KLK5 protease activity, which leads to reduced processing of inactive cathelicidin into active LL-37. It was determined that CC ameliorates the expression of pro-inflammatory cytokines through the inhibition of LL-37 processing. In addition, it was confirmed that chitin, an exoskeleton of Demodex mites, mediates an immune response through TLR2 activation, and CC inhibits TLR2 expression and downstream signal transduction. Furthermore, CC was shown to inhibit the proliferation of human microvascular endothelial cells induced by LL-37, the cause of erythematous rosacea. These results demonstrate that CC improved rosacea by regulating the immune response and angiogenesis, and revealed its mechanism of action, indicating that CC may be a useful therapeutic agent for rosacea. 相似文献
996.
Hyoun Woo Kim Seung Hyun Shim Jong Woo Lee Jae Young Park Sang Sub Kim 《Chemical physics letters》2008,456(4-6):193-197
We introduce a simple method of synthesizing SnO2 nanowire-Bi2Sn2O7 nanoparticle composites based on the principle that SnO2 nanowires can be grown by using Bi as catalysts. A mixture of Bi and Sn powders was thermally evaporated, and the effects of growth temperature on the morphology and structure of the products were investigated. We obtained Bi2Sn2O7-tipped SnO2 nanowires at 700 °C through a vapor–liquid–solid (VLS) process, whereas particle-free SnO2 nanowires were produced at higher temperatures. We have investigated the oxygen sensing properties of the as-synthesized product. 相似文献
997.
Jinhwang Kim Hyeon-Min Cha Mikyung Park Dileep K. Singh Gi H. Bae Seong H. Kim Ikyon Kim 《Journal of heterocyclic chemistry》2020,57(9):3279-3293
A new chemical space was generated via C2-functionalization of 3-arylbenzofurans. Mannich reaction of 3-arylbenzofurans with secondary amines and formaldehyde allowed for installation of aminomethyl unit at C2 position of benzofurans. A formyl group at C2 site introduced as a result of Vilsmeier-Haack formylation of 3-arylbenzofurans was employed as a reacting partner for three-component Kabachnik-Fields reaction with various amines and triethyl phosphite to give a wide variety of aminomethylphosphonates. Furthermore, several benzo[d]oxazoles and pyrrolo[1,2-a]quinoxalines were prepared by using the formyl group. Biological screening of the synthesized compounds revealed that the benzofuran bearing a pyrrolo[1,2-a]quinoxaline moiety ( 5b ) most potently inhibited the viability of human blood cancer cells, but not solid tumor cells. Caspase activity assay, analysis of Annexin V-positive cells, and Western blot analysis indicated that 5b -induced death of human lymphoma U937 cells could result from its potential to induce the caspase-dependent apoptotic death of blood cancer cells with inhibition of ERK activation. 相似文献
998.
999.
Jijun Qiu Weidong Yu Xiangdong Gao Xiaomin Li Weizhen He Se-Jeong Park Hyung-Kook Kim Yong-Hwae Hwang 《Journal of Sol-Gel Science and Technology》2008,47(2):187-193
Silver nanoparticles well dispersed in a spherical Poly(vinylpyrollidone)(PVP) matrix were simply prepared by spray pyrolysis
of aqueous solutions of AgNO3 and PVP without any reducing agent. Highly monodisperse silver particles were obtained above the initial mass ratio of PVP/AgNO3 ∼ 1 and in a certain narrow temperature range. Below the critical mass ratio the silver particles grew to larger ones polydispersely.
As the ratio increased above it, they became smaller maintaining their monodispersity. The use of PVP considerably decreased
the reduction temperature of the silver nitrate from 450 °C to 250 °C under the same pyrolysis conditions, due to its reducing
nature. As the pyrolysis temperature increased above the decomposition temperature of PVP, the silver particles in the matrix
grew to merge to a single particle while their crystallite size did not increase as much. The spherical assemblies of the
silver nanoparticles were hardly disengaged even after severe washing off the matrix materials. The mechanism of the nanoparticle
growth was also discussed. 相似文献
1000.
Biodiesel is a fatty acid alkyl ester that can be derived from any vegetable oil or animal fat via the process of transesterification.
It is a renewable, biodegradable, and nontoxic fuel. In this paper, we have evaluated the efficacy of a transesterification
process for rapeseed oil with methanol in the presence of an enzyme and tert-butanol, which is added to ameliorate the negative effects associated with excess methanol. The application of Novozym 435
was determined to catalyze the transesterification process, and a conversion of 76.1% was achieved under selected conditions
(reaction temperature 40 °C, methanol/oil molar ratio 3:1, 5% (w/w) Novozym 435 based on the oil weight, water content 1%
(w/w), and reaction time of 24h). It has also been determined that rapeseed oil can be converted to fatty acid methyl ester
using this system, and the results of this study contribute to the body of basic data relevant to the development of continuous
enzymatic processes. 相似文献