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https://www.readbyqxmd.com/read/29471144/intestinal-absorption-and-activation-of-decitabine-amino-acid-ester-prodrugs-mediated-by-peptide-transporter-pept1-and-enterocyte-enzymes
#1
Wenhui Tao, Dongyang Zhao, Mengchi Sun, Ziyu Wang, Bin Lin, Yu Bao, Yingying Li, Zhonggui He, Yinghua Sun, Jin Sun
Decitabine (DAC), a potent DNA methyltransferase (DNMT) inhibitor, has a limited oral bioavailability. Its 5'-amino acid ester prodrugs could improve its oral delivery but the specific absorption mechanism is not yet fully understood. The aim of this present study was to investigate the in vivo absorption and activation mechanism of these prodrugs using in situ intestinal perfusion and pharmacokinetics studies in rats. Although PEPT1 transporter is pH dependent, there appeared to be no proton cotransport in the perfusion experiment with a preferable transport at pH 7...
February 19, 2018: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/29470917/theoretical-studies-on-the-photophysics-and-photochemistry-of-5-formylcytosine-and-5-carboxylcytosine-the-oxidative-products-of-epigenetic-modification-of-cytosine-in-dna
#2
Jinlu Xing, Yuejie Ai, Yang Liu, Jia Du, Weiqiang Chen, Zhanhui Lu, Xiangke Wang
Cytosine methylation and demethylation play crucial roles in understanding the genomic DNA expression regulation. The epigenetic modification of cytosine and its continuous oxidative products-the "new four bases of DNA" including 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), 5-carboxylcytosine (5caC). However, compared to the abundant studies on the classical DNA bases, the photophysical and photochemical properties of those new bases have not yet aroused people's excessive attention...
February 22, 2018: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29470546/computer-simulations-reveal-changes-in-the-conformational-space-of-the-transcriptional-regulator-mosr-upon-the-formation-of-a-disulphide-bond-and-in-the-collective-motions-that-regulate-its-dna-binding-affinity
#3
Amanda Souza Câmara, Eduardo Horjales
M. tuberculosis oxidation sense Regulator (MosR) is a transcriptional regulator from Mycobacterium tuberculosis. It senses the environment oxidation and regulates the expression of a secreted oxidoreductase, thus defending the bacilli against oxidative stress from the phagosome. While most of the members of the Multiple antibiotics resistance Regulator (MarR) family are ligand-responsive, MosR may dissociate from its DNA site upon formation of an intrachain disulphide bond. However, the structure of MosR in its oxidized state is not known, and it is not clear how the formation of this disulphide bond would lead to the conformational changes required for dissociation of the DNA...
2018: PloS One
https://www.readbyqxmd.com/read/29470086/computational-study-on-n-n-homolytic-bond-dissociation-enthalpies-of-hydrazine-derivatives
#4
Yuanyuan Zheng, Wenrui Zheng, Jiaoyang Wang, Huifang Chang, Danfeng Zhu
The hydrazine derivatives have been regarded as the important building blocks in organic chemistry for the synthesis of organic N-containing compounds. It is important to understand the structure-activity relationship of the thermodynamics of N-N bonds, in particular, their strength as measured by using the homolytic bond dissociation enthalpies (BDEs). We calculated the N-N BDEs of 13 organonitrogen compounds by 8 composite high-level ab initio methods including G3, G3B3, G4, G4MP2, CBS-QB3, ROCBS-QB3, CBS-Q and CBS-APNO...
February 22, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29469657/direct-mass-spectrometric-characterization-of-disulfide-linkages
#5
Xiaoyan Guan, Le Zhang, Jette Wypych
Disulfide linkage is critical to protein folding and structural stability. The location of disulfide linkages for antibodies is routinely discovered by comparing the chromatograms of the reduced and non-reduced peptide mapping with location identification confirmed by collision-induced dissociation (CID) mass spectrometry (MS)/MS. However, CID product spectra of disulfide-linked peptides can be difficult to interpret, and provide limited information on the backbone region within the disulfide loop. Here, we applied an electron-transfer dissociation (ETD)/CID combined fragmentation method that identifies the disulfide linkage without intensive LC comparison, and yet maps the disulfide location accurately...
February 22, 2018: MAbs
https://www.readbyqxmd.com/read/29469090/sterically-controlled-mechanochemistry-under-hydrostatic-pressure
#6
Hao Yan, Fan Yang, Ding Pan, Yu Lin, J Nathan Hohman, Diego Solis-Ibarra, Fei Hua Li, Jeremy E P Dahl, Robert M K Carlson, Boryslav A Tkachenko, Andrey A Fokin, Peter R Schreiner, Giulia Galli, Wendy L Mao, Zhi-Xun Shen, Nicholas A Melosh
Mechanical stimuli can modify the energy landscape of chemical reactions and enable reaction pathways, offering a synthetic strategy that complements conventional chemistry. These mechanochemical mechanisms have been studied extensively in one-dimensional polymers under tensile stress using ring-opening and reorganization, polymer unzipping and disulfide reduction as model reactions. In these systems, the pulling force stretches chemical bonds, initiating the reaction. Additionally, it has been shown that forces orthogonal to the chemical bonds can alter the rate of bond dissociation...
February 21, 2018: Nature
https://www.readbyqxmd.com/read/29468998/effect-of-heat-induced-%C3%AE%C2%BA-casein-dissociation-on-acid-coagulation-of-milk
#7
Daiki Oka, Wataru Ono, Shintarou Ohara, Tomohiro Noguchi, Katsumi Takano
No abstract text is available yet for this article.
February 2018: Journal of Dairy Research
https://www.readbyqxmd.com/read/29468871/peptide-probe-for-multi-walled-carbon-nanotubes-electrophoretic-assessment-of-the-binding-interface-and-evaluation-of-surface-functionalization
#8
Tyler A Davis, Lisa Ann Holland
Non-covalent interactions of peptides and proteins with carbon nanotubes play a key role in sensing, dispersion and biocompatibility. Advances in these areas require that the forces which contribute to physical adsorption are understood in order that the carbon nanotubes present a degree of functionalization appropriate to the desired application. Affinity analyses of peptides are employed to evaluate the role of tryptophan and arginine residues on physical adsorption to carboxylated multi-walled carbon nanotubes...
February 22, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29468501/resolution-and-assignment-of-differential-ion-mobility-spectra-of-sarcosine-and-isomers
#9
Francis Berthias, Belkis Maatoug, Gary L Glish, Fathi Moussa, Philippe Maitre
Due to their central role in biochemical processes, fast separation and identification of amino acids (AA) is of importance in many areas of the biomedical field including the diagnosis and monitoring of inborn errors of metabolism and biomarker discovery. Due to the large number of AA together with their isomers and isobars, common methods of AA analysis are tedious and time-consuming because they include a chromatographic separation step requiring pre- or post-column derivatization. Here, we propose a rapid method of separation and identification of sarcosine, a biomarker candidate of prostate cancer, from isomers using differential ion mobility spectrometry (DIMS) interfaced with a tandem mass spectrometer (MS/MS) instrument...
February 21, 2018: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/29467651/functional-g-protein-coupled-receptor-gpcr-synthesis-the-pharmacological-analysis-of-human-histamine-h1-receptor-hrh1-synthesized-by-a-wheat-germ-cell-free-protein-synthesis-system-combined-with-asolectin-glycerosomes
#10
Yasuyuki Suzuki, Tomio Ogasawara, Yuki Tanaka, Hiroyuki Takeda, Tatsuya Sawasaki, Masaki Mogi, Shuang Liu, Kazutaka Maeyama
G-protein-coupled receptors (GPCRs) are membrane proteins distributed on the cell surface, and they may be potential drug targets. However, synthesizing GPCRs in vitro can be challenging. Recently, some cell-free protein synthesis systems have been shown to produce a large amount of membrane protein combined with chemical chaperones that include liposomes and glycerol. Liposomes containing high concentrations of glycerol are known as glycerosomes, which are used in new drug delivery systems. Glycerosomes have greater morphological stability than liposomes...
2018: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/29467632/dissociating-explicit-and-implicit-timing-in-parkinson-s-disease-patients-evidence-from-bisection-and-foreperiod-tasks
#11
Giovanna Mioni, Mariagrazia Capizzi, Antonino Vallesi, Ángel Correa, Raffaella Di Giacopo, Franca Stablum
A consistent body of literature reported that Parkinson's disease (PD) is marked by severe deficits in temporal processing. However, the exact nature of timing problems in PD patients is still elusive. In particular, what remains unclear is whether the temporal dysfunction observed in PD patients regards explicit and/or implicit timing. Explicit timing tasks require participants to attend to the duration of the stimulus, whereas in implicit timing tasks no explicit instruction to process time is received but time still affects performance...
2018: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/29467426/neuronal-avalanche-dynamics-indicates-different-universality-classes-in-neuronal-cultures
#12
Mohammad Yaghoubi, Ty de Graaf, Javier G Orlandi, Fernando Girotto, Michael A Colicos, Jörn Davidsen
Neuronal avalanches have become an ubiquitous tool to describe the activity of large neuronal assemblies. The emergence of scale-free statistics with well-defined exponents has led to the belief that the brain might operate near a critical point. Yet not much is known in terms of how the different exponents arise or how robust they are. Using calcium imaging recordings of dissociated neuronal cultures we show that the exponents are not universal, and that significantly different exponents arise with different culture preparations, leading to the existence of different universality classes...
February 21, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29467382/krab-type-zinc-finger-proteins-pita-and-pisa-specifically-regulate-p53-dependent-glycolysis-and-mitochondrial-respiration
#13
Shan Wang, Zhiqiang Peng, Siying Wang, Lihua Yang, Yuhan Chen, Xue Kong, Shanshan Song, Pei Pei, Chunyan Tian, Hui Yan, Peipei Ding, Weiguo Hu, Cui Hua Liu, Xin Zhang, Fuchu He, Lingqiang Zhang
Few p53 regulators participate in selective control of p53-mediated cellular metabolism. How p53-mediated aerobic and glycolytic pathways are negatively regulated remains largely unclear. Here, we identified two KRAB-type zinc-finger proteins, PITA (p53 inhibitor of TIGAR activation) and PISA (p53 inhibitor of SCO2 activation), as selective regulators of p53 in metabolic control. PITA and PISA interact with p53 and specifically suppress transcription of the glycolysis regulator TIGAR and the oxidation phosphorylation regulator SCO2, respectively...
February 21, 2018: Cell Research
https://www.readbyqxmd.com/read/29467306/gait-analysis-in-psp-and-nph-dual-task-conditions-make-the-difference
#14
Charlotte Selge, Florian Schoeberl, Andreas Zwergal, Georg Nuebling, Thomas Brandt, Marianne Dieterich, Roman Schniepp, Klaus Jahn
OBJECTIVE: To test whether quantitative gait analysis of gait under single- and dual-task conditions can be used for a differential diagnosis of progressive supranuclear palsy (PSP) and idiopathic normal-pressure hydrocephalus (iNPH). METHODS: In this cross-sectional study, temporal and spatial gait parameters were analyzed in 38 patients with PSP (Neurological Disorders and Stroke and Society for Progressive Supranuclear Palsy diagnostic criteria), 27 patients with iNPH (international iNPH guidelines), and 38 healthy controls...
February 21, 2018: Neurology
https://www.readbyqxmd.com/read/29466732/dissonant-representations-of-visual-space-in-prefrontal-cortex-during-eye-movements
#15
Xiaomo Chen, Marc Zirnsak, Tirin Moore
We used local field potentials (LFPs) and spikes to investigate representations of visual space in prefrontal cortex and the dynamics of those representations during eye movements. Spatial information contained in LFPs of the frontal eye field (FEF) was differentially distributed across frequencies, with a majority of that information being carried in alpha and high-gamma bands and minimal signal in the low-gamma band. During fixation, spatial information from alpha and high-gamma bands and spiking activity was robust across cortical layers...
February 20, 2018: Cell Reports
https://www.readbyqxmd.com/read/29466468/fluorescent-single-stranded-dna-binding-protein-from-plasmodium-falciparum-as-a-biosensor-for-single-stranded-dna
#16
Liisa T Chisty, Daniela Quaglia, Martin R Webb
Single-stranded DNA (ssDNA) is a product of many cellular processes that involve double-stranded DNA, for example during DNA replication and repair, and is formed transiently in many others. Measurement of ssDNA formation is fundamental for understanding many such processes. The availability of a fluorescent biosensor for the determination of single-stranded DNA provides an important route to achieve this. Single-stranded DNA binding proteins (SSBs) protect ssDNA from degradation, but can be displaced to allow processing of the ssDNA...
2018: PloS One
https://www.readbyqxmd.com/read/29466293/comparison-of-sf%C3%A2-and-cf%C3%A2-plasma-treatment-for-surface-hydrophobization-of-pet-polymer
#17
Matic Resnik, Rok Zaplotnik, Miran Mozetic, Alenka Vesel
The fluorination of the polymer polyethylene terephthalate in plasma created from SF₆ or CF₄ gas at various pressures was investigated. The surface was analysed by X-ray photoelectron spectroscopy and water contact angle measurements, whereas the plasma was characterized by optical emission spectroscopy. The extent of the polymer surface fluorination was dependent on the pressure. Up to a threshold pressure, the amount of fluorine on the polymer surface and the surface hydrophobicity were similar, which was explained by the full dissociation of the SF₆ and CF₄ gases, leading to high concentrations of fluorine radicals in the plasma and thus causing the saturation of the polymer surface with fluorine functional groups...
February 21, 2018: Materials
https://www.readbyqxmd.com/read/29466274/dissociated-time-course-of-recovery-between-strength-and-power-after-isoinertial-resistance-loading-in-rugby-union-players
#18
Rodney A Kennedy, David Drake
Kennedy, RA and Drake, D. Dissociated time course of recovery between strength and power after isoinertial resistance loading in rugby union players. J Strength Cond Res 32(3): 748-755, 2018-There is a substantial amount of research on the responses to isometric and eccentric loading. However, only a paucity of literature exists on the responses to isoinertial loading, especially in trained athletic populations using realistic loading protocols. The purpose of this study was to examine the acute neuromuscular response to a bout of isoinertial resistance loading in elite rugby players...
March 2018: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/29466009/interpreting-quasi-thermal-effects-in-ultrafast-spectroscopy-of-hydrogen-bonded-systems
#19
Ashley Marie Stingel, Poul B Petersen
Vibrational excitation of molecules in the condensed phase relaxes through vibrational modes of decreasing energy to ultimately generate an equilibrium state in which the energy is distributed among low-frequency modes. In ultrafast vibrational spectroscopy, changes in the vibrational features of hydrogen-bonded NH and OH stretch modes are typically observed to persist long after these high-frequency vibrations have relaxed. Due to the resemblance of the spectral changes caused by heating the sample, these features are typically described as arising from a hot ground state...
February 21, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29466003/electronic-structure-and-bonding-situation-in-m-2-o-2-m-be-mg-ca-rhombic-clusters
#20
Wan-Lu Li, Jun-Bo Lu, Lili Zhao, Robert Ponec, David L Cooper, Jun Li, Gernot Frenking
Quantum chemical calculations using ab initio methods at the CCSD(T) level and density functional theory have been carried out for the title molecules. The electronic structures of the molecules were analyzed with a variety of charge- and energy decomposition methods. The equilibrium geometries of the M2O2 rhombic clusters exhibit very short distances between the transannular metal atoms M = Be, Mg, Ca. The calculated distances are close to standard values between double and triple bonds but there are no chemical M-M bonds...
February 21, 2018: Journal of Physical Chemistry. A
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