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https://www.readbyqxmd.com/read/28738657/a-new-strategy-for-fabrication-of-water-dispersible-and-biodegradable-fluorescent-organic-nanoparticles-with-aie-and-esipt-characteristics-and-their-utilization-for-bioimaging
#1
Dazhuang Xu, Meiying Liu, Hui Zou, Jianwen Tian, Hongye Huang, Qing Wan, Yanfeng Dai, Yuanqing Wen, Xiaoyong Zhang, Yen Wei
Fluorescence probes play a crucial role in optical imaging for visualization of complex biological processes. As compared with conventional organic fluorogens, the probes with aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics show significant advantages in high quantum yield at concentrated and aggregated state, large Stokes shift and low cytotoxicity. However, the synthesis of AIE-active fluorescent probes through the ESIPT mechanism has received only very limited attention...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738309/irradiation-by-blue-light-in-the-presence-of-a-photoacid-confers-changes-to-colony-morphology-of-the-plant-pathogen-colletotrichum-gloeosporioides
#2
Ron Simkovitch, Oren Gajst, Einat Zelinger, Oded Yarden, Dan Huppert
We used the photoacid 8-hydroxy-1,3,6-pyrenetrisulfonate (HPTS) that converts blue photons to acidic protons in water, with an efficiency of close to 100%, and determined that this treatment conferred changes to colony morphology of the plant pathogen Colletotrichum gloeosporioides. The time elapsed until hyphal collapse is noticed depends on both the laser intensity in mW/cm(2), and the concentration of HPTS in the Agar hydrogel. The time elapsed until hyphal collapse is noticed varies by only ±8% at HPTS concentrations of 500μM and at lower concentrations of HPTS the variance increases as the inverse of the concentration...
June 28, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28737941/unveiling-the-catalytic-role-of-b-block-histidine-in-the-n-s-acyl-shift-step-of-protein-splicing
#3
Jon I Mujika, Xabier Lopez
Protein splicing is a post-translational modification that involves the excision of a segment denoted as intein and the joining of its two flanking segments. The process is auto-catalytic, making inteins appealing for many applications in biotechnology, bioengineering, or medicine. The canonical mechanism of protein splicing is composed of four sequential steps, and is initialized by an N-S or N-O acyl shift to form a linear ester. It is well established that a histidine, the most conserved amino acid in all inteins catalyzes this initial step, even though its role remains to be understood...
July 24, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28737940/defining-the-structural-basis-for-allosteric-product-release-from-e-coli-dihydrofolate-reductase-using-nmr-relaxation-dispersion
#4
David Oyen, R Bryn Fenwick, Phillip C Aoto, Robyn L Stanfield, Ian A Wilson, H Jane Dyson, Peter E Wright
The rate-determining step in the catalytic cycle of E.coli dihydrofolate reductase is tetrahydrofolate (THF) product release, which can occur via an allosteric or an intrinsic pathway. The allosteric pathway, which becomes accessible when the reduced cofactor NADPH is bound, involves transient sampling of a higher energy conformational state, greatly increasing the product dissociation rate compared to the intrinsic pathway that obtains when NADPH is absent. Although the kinetics of this process are known, the enzyme structure and the THF product conformation in the transiently formed excited state remains elusive...
July 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28737924/linking-ph-temperature-and-k-concentration-for-dna-i-motif-formation
#5
Tra Nguyen, Claudette Fraire, Richard D Sheardy
The conformation a particular DNA segment assumes depends upon its sequence context and the environment under which it is prepared. To complement our findings with G-rich sequences related to the human telomere, we have been investigating the pH induced transition from single strand to i-motif for sequences related to the human telomere C-rich strand. We have carried out titrations of (CCCTAA)4 from pH 7.0 to pH 5.0 at temperatures ranging from 15 to 45 (o)C at 115 mM K(+) and at K(+) concentrations ranging from 15 to 315 mM at 25 (o)C...
July 24, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28737922/disentangling-the-complex-vibrational-spectrum-of-the-protonated-water-trimer-h-h2o-3-with-two-color-ir-ir-photodissociation-of-the-bare-ion-and-anharmonic-vscf-vci-theory
#6
Chinh H Duong, Olga Gorlova, Nan Yang, Patrick J Kelleher, Qi Yu, Anne B McCoy, Joel M Bowman, Mark A Johnson
Vibrational spectroscopy of the protonated water trimer provides a stringent constraint on the details of the potential energy surface (PES) and vibrational dynamics governing excess proton motion far from equilibrium. Here we report the linear spectrum of the cold, bare H(+)(H2O)3 ion using a two-color, IR-IR photofragmentation technique and follow the evolution of the bands with increasing temperature. The key low energy features are insensitive to both D2-tagging and internal energy. The D2-tagged D(+)(D2O)3 spectrum is reported for the first time, and the isotope dependence of the band pattern is surprisingly complex...
July 24, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28737919/proton-detected-nmr-spectroscopy-of-nanodisc-embedded-membrane-proteins-mas-solid-state-vs-solution-state-methods
#7
Nils-Alexander Lakomek, Lukas Frey, Stefan Bibow, Anja Böckmann, Roland Riek, Beat H Meier
The structural and dynamical characterization of membrane proteins in a lipid bilayer at physiological pH and temperature and free of crystal constraints is crucial for the elucidation of a structure/dynamics - activity relationship. Towards this aim, we explore here the properties of the outer-membrane protein OmpX embedded in lipid bilayer nanodiscs using proton-detected magic angle spinning (MAS) solid-state NMR at 60 and 110 kHz. [1H,15N]-correlation spectra overlay well with the corresponding solution-state NMR spectra...
July 24, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28737914/dft-study-on-the-complexation-of-nota-as-a-bifunctional-chelator-with-radiometal-ions
#8
Fatima Y Adeowo, Bahareh Honarparvar, Adam A Skelton
1,4,7 triazacyclononane-1,4,7 triacetic acid (NOTA) is a key bifunctional chelator utilized for the complexation of metal ions in radiopharmaceutical applications; the ability of these chelators depends on the strength of their binding with ions. The focus of the present work is to evaluate the complexation of Cu2+, Ga3+, Sc3+ and In3+ radiometal ions with NOTA using density functional theory (B3LYP functional) and 6-311+G(2d,2p)/DGDZVP basis sets. The significant role of ion-water interactions in the chelation interaction energies in solution reflects the competition between ion-water and NOTA-ion interaction in the chelation process...
July 24, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28737893/uncondensed-graphitic-carbon-nitride-on-reduced-graphene-oxide-for-oxygen-sensing-via-a-photoredox-mechanism
#9
James E Ellis, Dan C Sorescu, Seth C Burkert, David L White, Alexander Star
Melon, a polymeric, uncondensed graphitic carbon nitride with a two-dimensional structure has been coupled with reduced graphene oxide (rGO) to create an oxygen chemiresistor sensor that is active under UV photoactivation. Oxygen gas is an important sensor target in a variety of areas including industrial safety, combustion process monitoring, as well as environmental and biomedical fields. Due to the intimate electrical interface formed between melon and rGO, charge transfer of photoexcited electrons occurs between the two materials when under UV (λ=365 nm) irradiation...
July 24, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28737810/ionic-diffusion-and-proton-transfer-in-aqueous-solutions-of-alkali-metal-salts
#10
Giuseppe Cassone, Fabrizio Creazzo, Paolo V Giaquinta, Jiri Sponer, Franz Saija
We report on a series of ab initio molecular dynamics investigations on LiCl, NaCl, and KCl aqueous solutions under the effect of static electric fields. We have found that although in low-to-moderate field intensity regimes the well-known sequence of cationic mobilities μ(K(+)) > μ(Na(+)) > μ(Li(+)) (i.e., the bigger the cation the higher the mobility) is recovered, from intense field strengths this intuitive rule is no longer verified. In fact, field-induced water molecular dissociations lead to more complex phenomena regulating the standard migration properties of the simplest monovalent cations...
July 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28737803/concerted-transfer-of-multiple-protons-in-acid-water-clusters-hcl-h2o-2-and-hf-h2o-4
#11
I Zakai, M E Varner, R B Gerber
Molecular dynamics simulations using directly ab initio potentials are carried out for the ionically bonded clusters [(Cl(-))(H3O(+))]2 and [(F(-))(H3O(+))]4 to explore their transitions to the hydrogen-bonded [(HCl)(H2O)]2 and [(HF)(H2O)]4 structures during the first picosecond of simulation. Both the ionic and the H-bonded structures that are formed are highly symmetric. It is found that proton transfers are concerted in all trajectories for [(Cl(-))(H3O(+))]2. For [(F(-))(H3O(+))]4, the fully concerted mechanism is dominant but partially concerted transfers of two or three protons at the same time also occur...
July 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28737516/pre-therapy-neural-state-of-bilateral-motor-and-premotor-cortices-predicts-therapy-gain-after-subcortical-stroke-a-pilot-study
#12
Carmen M Cirstea, Phil Lee, Sorin C Craciunas, In-Young Choi, Joseph E Burris, Randolph J Nudo
OBJECTIVE: The aim of the study was to examine whether neural state of spared motor and premotor cortices captured before a therapy predicts therapy-related motor gains in chronic subcortical stroke. DESIGN: Ten survivors, presenting chronic moderate upper limb impairment, underwent proton magnetic resonance spectroscopy, magnetic resonance imaging, clinical, and kinematics assessments before a 4-wk impairment-oriented training. Clinical/kinematics assessments were repeated after therapy, and motor gain was defined as positive values of clinical upper limb/elbow motion changes and negative values of trunk motion changes...
July 22, 2017: American Journal of Physical Medicine & Rehabilitation
https://www.readbyqxmd.com/read/28737451/long-term-quality-of-life-outcomes-following-nissen-versus-toupet-fundoplication-in-patients-with-gastroesophageal-reflux-disease
#13
Rebecca L Gunter, Amber L Shada, Luke M Funk, Xing Wang, Jacob A Greenberg, Anne O Lidor
INTRODUCTION: Laparoscopic fundoplication is the gold standard treatment for gastroesophageal reflux disease (GERD) refractory to medical management. Although many studies have compared Nissen fundoplication (NF) to Toupet fundoplication (TF), it is unclear which operation provides the best long-term reflux control. The objective of this study was to evaluate long-term quality-of-life (QoL) outcomes after NF versus TF. METHODS: Clinical data from our single academic institutional foregut database were used to identify patients who underwent NF or TF (June 2010 to May 2016)...
July 24, 2017: Journal of Laparoendoscopic & Advanced Surgical Techniques. Part A
https://www.readbyqxmd.com/read/28736766/feasibility-studies-of-a-new-event-selection-method-to-improve-spatial-resolution-of-compton-imaging-for-medical-applications
#14
E Draeger, S Peterson, D Mackin, H Chen, S Beddar, J C Polf
A Compton imaging method for medical applications that includes new energy determination and data filtering techniques has been tested using several point sources with known emission lines. Using a prototype Compton camera, a distance-of-closest approach technique has been employed to determine the initial energy of the incoming γs and to ensure the reconstructed source position is within an acceptable distance from the known γ source location. Further analysis is done by implementing a Compton line filtering technique, keeping only those interactions whose deposited energy in the first interaction matches the theoretical energy deposition predicted by the Compton equation...
July 2017: IEEE transactions on radiation and plasma medical sciences
https://www.readbyqxmd.com/read/28736379/-preparation-of-nanoparticles-for-sustained-insulin-release-using-poly-ethylene-glycol-poly-%C3%AE%C2%B5-caprolactone-poly-n-n-diethylamino-2-ethylmethaerylate
#15
Lei Wu, Wen-Ting Zhu, Jun Wang, Jie Liu, Qing-Bing Zeng
OBJECTIVE: To prepare an insulin-loaded nanoparticle assembled using pH-sensitive poly(ethylene glycol)-poly(ε-caprolactone)-poly(N,N-diethylamino-2-ethylmethaerylate) (mPEG-PCL-PDEAEMA) and investigate its performance of sustained insulin release in vitro and its hypoglycemic effects in diabetic rats. METHDOS: mPEG-PCL-PDEAEMA triblock copolymers with different hydrophobic lengths were synthesized by ring opening polymerization (ROP) combined with atom transfer radical polymerization (ATRP)...
July 20, 2017: Nan Fang Yi Ke da Xue Xue Bao, Journal of Southern Medical University
https://www.readbyqxmd.com/read/28736106/in-vivo-magnetic-resonance-approach-to-trimethyltin-induced-neurodegeneration-in-rats
#16
Ladislav Baciak, Zdenka Gasparova, Tibor Liptaj, Ivo Juranek
Trimethyltin (TMT) is commonly used to induce neurodegeneration in mice and rats; however, only scarce data of in vivo MR spectroscopy and imaging characterizing TMT neurotoxicity are available. Our aim was to assess brain metabolite changes and brain atrophy by in vivo MR in the rat model of neurodegeneration induced by TMT. Adult male Wistar rats exposed to TMT (8 mg/kg, i.p.) were used in the study. Proton MRS was applied on the dorsal hippocampus to reveal changes in neurochemical profile and MRI was used to assess the volume of the entire hippocampus, ventricles and whole brain...
July 20, 2017: Brain Research
https://www.readbyqxmd.com/read/28735835/effect-of-scheduled-second-look-endoscopy-on-peptic-ulcer-bleeding-a-prospective-randomized-multicenter-trial
#17
Soo Jung Park, Hyojin Park, Yong Chan Lee, Chang Hwan Choi, Tae Joo Jeon, Jun Chul Park, Jie-Hyun Kim, Young Hoon Youn, Yu Jin Kim, Jae Hak Kim, Kwang Jae Lee, Sun Gyo Lim, Hyung Gil Kim, Byoung Wook Bang
BACKGROUND AND AIM: This study aimed to investigate the effectiveness of scheduled second-look EGD with endoscopic hemostasis on peptic ulcer rebleeding and sought to identify the risk factors related to the need for second-look EGD. METHODS: We prospectively randomized patients who had endoscopically confirmed bleeding peptic ulcer with stigmata of active bleeding, visible vessel, or adherent clot into 2 groups between August 2010 and January 2013. Hemoclip application or thermal coagulation, and/or epinephrine injection were allowed for initial endoscopic therapy...
July 20, 2017: Gastrointestinal Endoscopy
https://www.readbyqxmd.com/read/28735379/multidisciplinary-management-of-clival-chordomas-long-term-clinical-outcome-in-a-single-institution-consecutive-series
#18
Petter Förander, Jiri Bartek, Michael Fagerlund, Hamza Benmaklouf, Ernest Dodoo, Alia Shamikh, Pär Stjärne, Tiit Mathiesen
OBJECTIVE: Chordomas of the skull base have high recurrence rates even after radical resection and adjuvant radiotherapy. We evaluate the long-term clinical outcome using multidisciplinary management in the treatment of clival chordomas. METHODS: Between 1984 and 2015, 22 patients diagnosed with an intracranial chordoma were treated at the Karolinska University Hospital, Stockholm, Sweden. Sixteen of 22 were treated with Gamma Knife radiosurgery (GKRS) for tumour residual or progression during the disease course...
July 22, 2017: Acta Neurochirurgica
https://www.readbyqxmd.com/read/28735113/characterisation-of-the-secondary-neutron-field-generated-by-a-compact-pet-cyclotron-with-mcnp6-and-experimental-measurements
#19
D Alloni, M Prata
The production of the most common used PET radioisotope Fluorine-18 with commercial cyclotrons is obtained from the (18)O(p,n)(18)F nuclear reaction when (18)O-enriched water is bombarded with a proton beam. We present the characterization of the secondary neutron field spectra produced by this reaction in different locations around the cyclotron, through a comparison between MCNP6 Monte Carlo simulation results and experimental data obtained with Neutron Activation Analysis (NAA) of thin target foils of different materials...
July 17, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28734933/photosystem-ii-cyclic-electron-flow-powers-exceptional-photoprotection-and-record-growth-in-the-microalga-chlorella-ohadii
#20
Gennady Ananyev, Colin Gates, Aaron Kaplan, G Charles Dismukes
The desert microalga Chlorella ohadii was reported to grow at extreme light intensities with minimal photoinhibition, tolerate frequent de/re-hydrations, yet minimally employs antenna-based non-photochemical quenching for photoprotection. Here we investigate the molecular mechanisms by measuring Photosystem II charge separation yield (chlorophyll variable fluorescence, Fv/Fm) and flash-induced O2 yield to measure the contributions from both linear (PSII-LEF) and cyclic (PSII-CEF) electron flow within PSII. Cells grow increasingly faster at higher light intensities (μE/m(2)/s) from low (20) to high (200) to extreme (2000) by escalating photoprotection via shifting from PSII-LEF to PSII-CEF...
July 19, 2017: Biochimica et Biophysica Acta
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