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https://www.readbyqxmd.com/read/29787675/a-metal-stabilized-quinoidal-dibenzo-g-p-chrysene-fused-bis-dicarbacorrole-system
#1
Xian-Sheng Ke, Yongseok Hong, Vincent M Lynch, Dongho Kim, Jonathan L Sessler
We report here a metal complexation-based strategy that permits access to a highly stable expanded porphyrin-type quinoidal PAH. Specifically, double insertion of Pd(II) ions into a dibenzo[g,p]chrysene-fused bis-dicarbacorrole (bis-H3) gives rise to a bis-metalated species (bis-Pd) that undergoes a facile benzenoid-quinonoid transformation. In contrast to what is true for the corre-sponding mono-Pd(II) complex, which has organic radical character, well resolved 1H- and 19F NMR spectra are seen for bis-Pd. This complex is also electron paramagnetic resonance (EPR) silent over a range of temperatures...
May 22, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29786739/synthesis-of-pure-silica-mfi-zeolites-using-imidazolium-based-long-dications-a-comparative-study-of-structure-directing-effects-derived-from-a-further-spacer-length-increase
#2
Peng Lu, Luis Gómez-Hortigüela, Miguel A Camblor
Length-dependent structure direction of linear methylimidazolium-based dications towards MFI zeolite, previously known only for the tetramethylene spacer, has also been found for octamethylene and decamethylene spacers. This works only under highly concentrated conditions, whereas dilution always tends to favor TON, a default structure that is the only zeolite obtained with the other reported dications (with tri-, penta-, and hexamethylene spacers). The locations and conformations of the dications have been studied by molecular mechanics simulations...
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29775280/fluorine-meets-amine-reducing-microenvironment-induced-amino-activatable-nanoprobes-for-19f-magnetic-resonance-imaging-of-bio-thiols
#3
Pingsheng Huang, Weisheng Guo, Guang Yang, Huijuan Song, Yuqing Wang, Chun Wang, Deling Kong, Weiwei Wang
19F MRI is of great significance for non-invasive imaging and detection of various diseases. However, the main obstacle in the application of 19F MRI agents stems from the unmet signal sensitivity, due to the poor water-solubility and restricted mobility of segments with high numbers of fluorine atoms. Herein, we report a kind of intracellular reducing microenvironment-induced amino-activatable 19F MRI nanoprobe, which can be used for specific imaging of bio-thiols. In principle, the nanoprobe has an initial architecture of hydrophobic core, where the trifluoromethyl-containing segments are compactly packed and 19F NMR/MRI signals are quenched ("OFF" state)...
May 18, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29768458/burden-of-bacterial-meningitis-in-india-preliminary-data-from-a-hospital-based-sentinel-surveillance-network
#4
Yuvaraj Jayaraman, Balaji Veeraraghavan, Girish Kumar Chethrapilly Purushothaman, Bharathy Sukumar, Boopathi Kangusamy, Ambujam Nair Kapoor, Nivedita Gupta, Sanjay Madhav Mehendale
BACKGROUND: Worldwide, acute bacterial meningitis is a major cause of high morbidity and mortality among under five children, particularly in settings where vaccination for H. influenzae type b, S. pneumoniae and N. meningitidis is yet to be introduced in the national immunization programs. Estimation of disease burden of bacterial meningitis associated with these pathogens can guide the policy makers to consider inclusion of these newer vaccines in the immunization programs. A network of hospital based sentinel surveillance was established to generate baseline data on the burden of bacterial meningitis among children aged less than 5 years in India and to provide a platform for impact assessment following introduction of the Pentavalent and Pneumococcal Conjugate Vaccines (PCV)...
2018: PloS One
https://www.readbyqxmd.com/read/29752763/cofactor-biogenesis-in-cysteamine-dioxygenase-c-f-bond-cleavage-with-genetically-incorporated-unnatural-tyrosine
#5
Yifan Wang, Wendell P Griffith, Jiasong Li, Teruaki Koto, Daniel J Wherritt, Elizabe Fritz, Aimin Liu
Cysteamine dioxygenase (ADO) is a thiol dioxygenase whose study has been stagnated by ambiguity as to whether or not it possesses an anticipated protein-derived cofactor. Herein, we report the discovery and elucidation of a Cys-Tyr cofactor in human ADO, crosslinked between Cys220 and Tyr222 through a thioether (C-S) bond. By genetically incorporating an unnatural amino acid 3,5-difluoro-tyrosine (F2-Tyr) specifically into Tyr222 of human ADO, we identified an autocatalytic oxidative carbon-fluorine bond activation and fluoride release by mass spectrometry and 19F NMR spectroscopy...
May 11, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29719105/die-interhalogenkationen-br2f5-und-br3f8
#6
Sergei Ivlev, Antti Karttunen, Magnus Buchner, Matthias Conrad, Florian Kraus
Wir berichten über die Synthese und Charakterisierung der bislang einzigen Polyhalogenkationen, in denen verbrückende Fluoratome vorliegen. Das [Br2F5]+-Kation enthält eine symmetrische [F2Br-µ-F-BrF2]-Brücke, das [Br3F8]+-Kation enthält unsymmetrische µ-F-Brücken. Die Fluoronium-Ionen wurden in Form ihrer [SbF6]--Salze erhalten und Raman-, und 19F-NMR-spektroskopisch, sowie durch Röntgenbeugung am Einkristall untersucht. Quantenchemische Rechnungen, sowohl für die isolierten Kationen in der Gasphase, als auch für die Festkörper selbst, wurden durchgeführt...
May 2, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29714374/highly-hindered-2-aryl-di-tert-butylsilyl-n-methyl-imidazoles-a-new-tool-for-the-aqueous-19-f-and-18-f-fluorination-of-biomolecule-based-structures
#7
Marion Tisseraud, Jürgen Schulz, Delphine Vimont, Murielle Berlande, Philippe Fernandez, Philippe Hermange, Eric Fouquet
A new class of silicon-based fluoride acceptors with a C-linked heterocycle as the leaving group was synthesized in one step from commercial chemicals, and linked to biomolecules. The resulting conjugates were efficiently 19F-fluorinated in aqueous mixtures, and switching to 18F-labelling provided nucleoside- and peptide-based bioconjugates with excellent molar activities suitable for biological applications.
May 1, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29704399/design-synthesis-chalcone-derivatives-as-adipor-agonist-for-type-2-diabetes
#8
Panhu Zhu, Weijun Huang, Jiaming Li, Xiaodong Ma, Mengqi Hu, Yujun Wang, Qinlong Xu, Xianna Wang
Two structurally novel series of chalcone derivatives were designed and synthesized as potential agents against type 2 diabetes. As a result of the antidiabetic biological evaluation in streptozotocin (STZ) induced type 2 diabetes animal model, 13e, 13g and 19f showed more significant reduction in serum Glu, TG, TC levels by contrast to the positive control AdipoRon. In addition to upregulating the expression of AdipoR1 and AdipoR2, 13e and 19f treatment also increased expression of AMPK and PPAR-α. Taken together, these results suggested that 13e and 19f might be a promising compounds for type 2 diabetes treatment...
April 28, 2018: Chemical Biology & Drug Design
https://www.readbyqxmd.com/read/29701470/molecular-mechanism-of-loading-sulfur-hexafluoride-in-gamma-cyclodextrin-metal-organic-framework
#9
Liping Han, Tao Guo, Zhen Guo, Caifen Wang, Wei Zhang, Shailendra Shakya, Huanyu Ding, Hai Yan Li, Xu Xu, Yujie Ren, Jiwen Zhang
Gamma-cyclodextrin metal-organic framework (γ-CD-MOF) is a new type of highly porous carrier for potential loading of therapeutic or diagnostic gas like sulfur hexafluoride (SF6). Here, loading of SF6 into γ-CD-MOF was investigated for its mechanism by molecular simulation and quantitative determination of SF6 using quantitative nuclear magnetic resonance (qNMR). For the SF6 loading, γ-CD-MOF was first degassed to remove the air without thermal decomposition or loss of framework crystallinity, then placed in the copper tube and sealed to adsorb SF6 under 1...
April 27, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29698665/high-prevalence-of-multidrug-resistant-international-clones-among-macrolide-resistant-streptococcus-pneumoniae-strains-in-immunocompromised-patients-in-tunisia
#10
Anis Raddaoui, Farah Ben Tanfous, Yosra Chebbi, Wafa Achour, Rekaya Baaboura, Assia Benhassen
Macrolide resistant Streptococcus pneumoniae (S.pneumoniae) isolates increased considerably the last decade with important geographical variations among involved phenotypes and genotypes. The aim of this study was to investigate phenotypes, genotypes, serotypes and genetic relatedness of macrolide resistant S. pneumoniae strains isolated from immunocompromised Patients Antibiotic susceptibility was studied by disk diffusion method and minimum inhibitory concentrations (MIC) of erythromycin and clindamycin were determined by Etest (®Biomerieux)...
April 23, 2018: International Journal of Antimicrobial Agents
https://www.readbyqxmd.com/read/29689653/streptococcus-pneumoniae-distribution-of-serotypes-and-antimicrobial-susceptibility-in-patients-with-cancer
#11
Araceli Soto-Noguerón, María Noemí Carnalla-Barajas, Patricia Cornejo-Juárez, Patricia Volkow-Fernández, María Elena Velázquez-Meza, Gabriela Echániz-Aviles
OBJECTIVE: To describe the distribution of pneumococcal serotypes causing infectious diseases in patients with hematological malignancies and solid tumors and their antimicrobial susceptibility before and after introduction of pneumococcal conjugate vaccine (PCV7) in Mexico. MATERIALS AND METHODS: Consecutive pneumococcal isolates from hospitalized patients from the SIREVA-network were serotyped using the Quellung reaction and antimicrobial susceptibility was performed using the broth microdilution method...
January 2018: Salud Pública de México
https://www.readbyqxmd.com/read/29682654/a-unique-19-f-mri-agent-for-the-tracking-of-non-phagocytic-cells-in-vivo
#12
Shehzahdi S Moonshi, Cheng Zhang, Hui Peng, Simon Puttick, Stephen Rose, Nicholas M Fisk, Kishore Bhakoo, Brett W Stringer, Greg G Qiao, Paul A Gurr, Andrew K Whittaker
There is currently intense interest in new methods for understanding the fate of therapeutically-relevant cells, such as mesenchymal stem cells (MSCs). The absence of a confounding background signal and consequent unequivocal assignment makes 19F MRI one of the most attractive modalities for the tracking of injected cells in vivo. We describe here the synthesis of novel partly-fluorinated polymeric nanoparticles with small size and high fluorine content as MRI agents. The polymers, constructed from perfluoropolyether methacrylate (PFPEMA) and oligo(ethylene glycol) methacrylate (OEGMA) have favourable cell uptake profiles and excellent MRI performance...
April 23, 2018: Nanoscale
https://www.readbyqxmd.com/read/29676908/fluorine-grafted-cu7s4-au-heterodimers-for-multimodal-imaging-guided-photothermal-therapy-with-high-penetration-depth
#13
Jiabin Cui, Rui Jiang, Chang Guo, Xilin Bai, Suying Xu, Leyu Wang
We report the multifunctional nanocomposites (NCs) consisting of 19F-moieties grafted Cu7S4-Au nanoparticles (NPs) through click chemistry for sensitive and negligible background 19F-magnetic resonance imaging (19F-MRI) and computed tomography (CT) imaging guided photothermal therapy. The localized surface plasmon resonance (LSPR) peak can be reasonably tuned to the in vivo transparent window (800-900 nm) by coupling Au NPs (<10 nm, LSPR 530 nm) with Cu7S4 NPs (<15 nm, LSPR 1500 nm) into the Cu7S4-Au heterodimers...
April 20, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29663671/exposing-the-origins-of-irreproducibility-in-fluorine-nmr-spectroscopy
#14
Antonio Togni, Carl Philipp Rosenau, Benson J Jelier, Alvar D Gossert
Fluorine chemistry has taken a pivotal role in chemical reaction discovery, drug development, and chemical biology. NMR spectroscopy, arguably the most important technique for characterization of fluorinated compounds, is rife with highly inconsistent referencing of fluorine NMR chemical shifts, producing deviations larger than 1 ppm. Herein, we provide unprecedented evidence that both spectrometer design and the current unified scale system underpinning the calibration of heteronuclear NMR spectra has unintentionally led to widespread variation in the standardization of 19F NMR spectral data...
April 16, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29662989/group-3-metal-trihalide-complexes-with-neutral-n-donor-ligands-exploring-their-affinity-towards-fluoride
#15
Emily Curnock, William Levason, Mark E Light, Sajinder K Luthra, Graeme McRobbie, Francesco M Monzittu, Gillian Reid, R Nathan Williams
Fluorination of [ScCl3(Me3-tacn)] (Me3-tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) and [ScCl3(BnMe2-tacn)] (BnMe2-tacn = 1,4-dimethyl-7-benzyl-1,4,7-triazacyclononane) by Cl/F exchange with 3 mol. equiv. of anhydrous [NMe4]F in CH3CN solution yields the corresponding [ScF3(R3-tacn)] (R3 = Me3 or BnMe2). These are the first examples of scandium fluoride complexes containing neutral co-ligands. The fluorination occurs stepwise, and using a deficit of [NMe4]F produced [ScF2Cl(Me3-tacn)]. Attempts to fluorinate [YCl3(Me3-tacn)], [YI3(Me3-tacn)], [LaCl3(Me3-tacn)(OH2)] or [MCl3(terpy)] (M = Sc, Y or La; terpy = 2,2':6'2''-terpyridyl) using a similar method were unsuccessful, due to the Cl/F exchange being accompanied by loss of the neutral ligand from the metal centre...
April 17, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29659110/rapid-aqueous-late-stage-radiolabelling-of-gaf3-bnme2-tacn-by-18f-19f-isotopic-exchange-towards-new-pet-imaging-probes
#16
Francesco M Monzittu, Imtiaz Khan, William Levason, Sajinder Luthra, Gill Reid, Graeme McRobbie
A simple and rapid method for 18F radiolabelling of [GaF3(BnMe2-tacn)] by 18F/19F isotopic exchange is described. Using MeCN:H2O or EtOH:H2O (75:25) and 18F(aq) (up to 200 MBq) with heating (80 oC, 10 mins.), gives 66±4% 18F incorporation at 268 nM concentration and 37±5% 18F incorporation at even lower (27 nM) concentration, without the need for a Lewis acid promoter. An SPE purification method has been established, giving 99% radiochemical purity (RCP) of [Ga18F19F(BnMe2-tacn)] in an EtOH/H2O mixture...
April 16, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29601100/structural-analysis-of-a-galnac-t2-mutant-reveals-an-induced-fit-catalytic-mechanism-for-galnac-ts
#17
Ramon Hurtado-Guerrero, Matilde de Las Rivas, Helena Coelho, Ana Diniz, Erandi Lira-Navarrete, Ismael Compañón, Jesús Jiménez-Barbero, Katrine T Schjoldager, Eric P Bennett, Sergey Y Vakhrushev, Henrik Clausen, Francisco Corzana, Filipa Marcelo
The family of polypeptide GalNAc-transferases (GalNAc-Ts) orchestrates the initiating step of mucin-type protein O-glycosylation by transfer of GalNAc moieties to serine and threonine residues in proteins. Deficiencies and dysregulation of GalNAc-T isoenzymes have been found to be related to different diseases. Recently, we have demonstrated that an inactive GalNAc-T2 mutant (F104S), which is not located at the active site, induces low levels of high-density lipoprotein cholesterol (HDL-C) in humans. Here, we have deciphered the molecular basis for F104S mutant inactivation...
March 30, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29595201/a-genetically-encoded-19-f-nmr-probe-for-lysine-acetylation
#18
Feng Zhang, Qing Zhou, Guiwen Yang, Liguo An, Fahui Li, Jiangyun Wang
Advances in acetylated protein-protein/DNA interactions depend on the development of a novel NMR (nuclear magnetic resonance) probe to study the conformational changes of acetylated proteins. However, the method for detecting the acetylated protein conformation is underdeveloped. Herein, an acetyllysine mimic has been exploited for detecting the conformational changes of acetylated p53-protein/DNA interactions by genetic code expansion and 19F NMR. This 19F NMR probe shows high structural similarity to acetyllysine and could not be deacetylated by sirtuin deacetylase in vitro/vivo...
March 29, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29594281/in-vivo-drug-tracking-with-19-f-mri-at-therapeutic-dose
#19
Shaowei Bo, Yaping Yuan, Yongping Chen, Zhigang Yang, Shizhen Chen, Xin Zhou, Zhong-Xing Jiang
Tracking drugs with 19F MRI would be beneficial for developing theranostics and optimizing drug therapy. To this end, a fluorinated dendritic amphiphile with high 19F MRI sensitivity and biocompatibility has been developed for 19F MRI tracking of doxorubicin (DOX)-loaded liposomes in mice, which may provide an effective platform to in vivo trace various drugs with 19F MRI.
March 29, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29589912/%C3%AE-cyclodextrin-reverses-binding-of-perfluorooctanoic-acid-to-human-serum-albumin
#20
Mary Jo Weiss-Errico, Jaroslava Miksovska, Kevin E O'Shea
Perfluorooctanoic acid (PFOA), a persistent organic pollutant known to cause adverse health effects, strongly binds to human serum albumin (HSA). β-Cyclodextrin (β-CD), a non-toxic cyclic sugar, strongly complexes PFOA in a host-guest complex, and has been proposed for environmental remediation of PFOA. The interactions between HSA, PFOA, and β-CD were investigated in order to determine if β-CD can reverse the binding of PFOA to HSA, with potential therapeutic applications towards exposure to PFOA.19 F Nuclear magnetic resonance (NMR), circular dichroism, and fluorescence spectroscopies were used to study these interactions...
March 28, 2018: Chemical Research in Toxicology
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