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https://www.readbyqxmd.com/read/28441493/systematic-study-on-hydrated-arginine-clear-theoretical-evidence-for-the-canonical-to-zwitterionic-structure-transition
#1
Hongbao Li, Andong Hu, Jun Jiang, Yi Luo
Extensive ab initio investigations have been performed to characterize the stable conformers of hydrated arginine (Arg-H2O). Many new low-energy canonical Arg-H2O conformers were identified and they are more stable than previous results. The large energy differences (more than 5.00 kcal mol(-1)) between the canonical and zwitterionic Arg-H2O isomers calculated by the composite CBS-QB3 method confirmed the dominance of the zwitterions. The micro effects of corrections of the zero-point energy and the basis set superposition error on the stability of hydrated isomers were carefully examined for the first time...
April 25, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28440650/comprehensive-computational-and-experimental-analysis-of-biomaterial-towards-the-behavior-of-imidazolium-based-ionic-liquids-an-interplay-between-hydrophilic-and-hydrophobic-interactions
#2
Reddicherla Umapathi, Suresh B Vepuri, Pannuru Venkatesu, Mahmoud E S Soliman
To provide insights into the aggregation behavior, hydration tendency and variation in phase transition temperature produced by the addition of ionic liquids (ILs) to poly(N-isopropylacrylamide) (PNIPAM) aqueous solution, systematic physicochemical studies, and molecular dynamic simulations were carried out. The influence of ILs possessing same [Cl]- anion and a set of cation [Cnmim]+ with increasing alkyl chain length such as 1-ethyl-3-methylimidazolium ([Emim]+), 1-allyl-3-methylimidazolium ([Amim]+), 1-butyl-3-methylimidazolium ([Bmim]+), 1-hexyl-3-methylimidazolium ([Hmim]+), 1-benzyl-3-methylimidazolium ([Bzmim]+), and 1- decyl-3-methylimidazolium ([Dmim] +) on the phase transition of PNIPAM was monitored by the aid of UV-visible absorption spectra, fluorescence intensity spectra, viscosity (ɳ), dynamic light scattering (DLS) and Fourier transform infrared (FTIR) spectroscopy...
April 25, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28440641/thermochemical-investigations-of-hydrated-nickel-dication-complexes-by-threshold-collision-induced-dissociation-and-theory
#3
Rebecca A Coates, Peter B Armentrout
The experimental bond energies of Ni2+(H2O)x complexes, where x = 4 - 11, are determined by threshold collision-induced dissociation using a guided ion beam tandem mass spectrometer with an electrospray ionization source. The electrospray ionization source produces a distribution of Ni2+(H2O)x complexes, where an in-source fragmentation technique is employed to access the x = 4 - 6 complexes and control the population of excited isomers. The kinetic energy dependent cross sections are modeled to yield 0 K bond energies for sequential loss of neutral water molecules, which are converted to 298 K binding energies...
April 25, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28440077/molecular-dynamics-simulations-of-the-standard-leonardite-humic-acid-microscopic-analysis-of-the-structure-and-dynamics
#4
Drazen Petrov, Daniel Tunega, Martin H Gerzabek, Chris Oostenbrink
Humic substances (HS) are abundant in the environment and play an important role in a number of biogeochemical processes including microbial activity, soil aggregation, plant growth, the retention and release of nutrients, the environmental fate of pollutants and carbon storage. They are flexible, relatively small molecules forming supramolecular structures through weak interactions. Despite the great importance of understanding their behavior at the atomic level, computational modeling, a premier high-resolution technique providing great level of detail, has been surprisingly little employed to study humic substances...
April 25, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28439845/a-systematic-review-of-the-clinical-presentation-diagnosis-and-treatment-of-small-bowel-obstruction
#5
REVIEW
Srinivas R Rami Reddy, Mitchell S Cappell
PURPOSE OF REVIEW: This study aimed to systematically review small bowel obstruction (SBO), focusing on recent changes in diagnosis/therapy. RECENT FINDINGS: SBO incidence is about 350,000/annum in the USA. Etiologies include adhesions (65%), hernias (10%), neoplasms (5%), Crohn's disease (5%), and other (15%). Bowel dilatation occurs proximal to obstruction primarily from swallowed air and secondarily from intraluminal fluid accumulation. Dilatation increases mural tension, decreases mucosal perfusion, causes bacterial proliferation, and decreases mural tensile strength that increases bowel perforation risks...
June 2017: Current Gastroenterology Reports
https://www.readbyqxmd.com/read/28439559/isolation-of-the-simplest-hydrated-acid
#6
Rui Zhang, Michihisa Murata, Atsushi Wakamiya, Takafumi Shimoaka, Takeshi Hasegawa, Yasujiro Murata
Dissociation of an acid molecule in aqueous media is one of the most fundamental solvation processes but its details remain poorly understood at the distinct molecular level. Conducting high-pressure treatments of an open-cage fullerene C70 derivative with hydrogen fluoride (HF) in the presence of H2O, we achieved an unprecedented encapsulation of H2O·HF and H2O. Restoration of the opening yielded the endohedral C70s, that is, (H2O·HF)@C70, H2O@C70, and HF@C70 in macroscopic scales. Putting an H2O·HF complex into the fullerene cage was a crucial step, and it would proceed by the synergistic effects of "pushing from outside" and "pulling from inside...
April 2017: Science Advances
https://www.readbyqxmd.com/read/28438887/a-systematic-review-of-strategies-to-prevent-cisplatin-induced-nephrotoxicity
#7
Daniel J Crona, Aimee Faso, Tomohiro F Nishijima, Kathleen A McGraw, Matthew D Galsky, Matthew I Milowsky
INTRODUCTION: Cisplatin, a platinum-based antineoplastic agent, is the cornerstone for the treatment of many malignancies. Nephrotoxicity is the primary dose-limiting toxicity, and various hydration regimens and supplementation strategies are used to prevent cisplatin-induced kidney injury. However, evidence-based recommendations on specific hydration regimens are limited. A systematic review was performed to evaluate clinical studies that have examined hydration and supplementation strategies to prevent cisplatin-induced nephrotoxicity...
April 24, 2017: Oncologist
https://www.readbyqxmd.com/read/28437715/parameterization-of-nmr-relaxation-curves-in-terms-of-logarithmic-moments-of-the-relaxation-time-distribution
#8
Oleg V Petrov, Siegfried Stapf
This work addresses the problem of a compact and easily comparable representation of multi-exponential relaxation data. It is often convenient to describe such data in a few parameters, all being of physical significance and easy to interpret, and in such a way that enables a model-free comparison between different groups of samples. Logarithmic moments (LMs) of the relaxation time constitute a set of parameters which are related to the characteristic relaxation time on the log-scale, the width and the asymmetry of an underlying distribution of exponentials...
April 13, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28436830/antimicrobial-activity-of-free-and-liposome-encapsulated-thymol-and-carvacrol-against-salmonella-and-staphylococcus-aureus-adhered-to-stainless-steel
#9
Juliana Both Engel, Caroline Heckler, Eduardo Cesar Tondo, Daniel Joner Daroit, Patrícia da Silva Malheiros
Antimicrobial activity of thymol, carvacrol and thymol/carvacrol liposomes (TCL) was evaluated against two bacterial pools, each one consisting of four strains of Staphylococcus aureus or Salmonella enterica. TCL were prepared using thin-film hydration, showing 270.20nm average diameter (polydispersity index of 0.33) and zeta potential of +39.99mV. Minimum inhibitory concentration (MIC) of thymol, carvacrol and TCL against S. aureus pool was 0.662mg/ml, while MIC for Salmonella pool was 0.331mg/ml for thymol and carvacrol, and for TCL was 0...
April 13, 2017: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/28436705/pharmacologically-increasing-collateral-perfusion-during-acute-stroke-using-a-carboxyhemoglobin-gas-transfer-agent-sanguinate%C3%A2-in-spontaneously-hypertensive-rats
#10
Marilyn J Cipolla, Italo Linfante, Abe Abuchowski, Ronald Jubin, Siu-Lung Chan
Similar to patients with chronic hypertension, spontaneously hypertensive rats (SHR) develop fast core progression during middle cerebral artery occlusion (MCAO) resulting in large final infarct volumes. We investigated the effect of Sanguinate™ (SG), a PEGylated carboxyhemoglobin (COHb) gas transfer agent, on changes in collateral and reperfusion cerebral blood flow and brain injury in SHR during 2 h of MCAO. SG (8 mL/kg) or vehicle ( n = 6-8/group) was infused i.v. after 30 or 90 min of ischemia with 2 h reperfusion...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28436518/solution-behaviour-of-poly-n-isopropylacrylamide-stereoisomers-in-water-a-molecular-dynamics-simulation-study
#11
G Paradossi, E Chiessi
The water affinity of poly(N-isopropylacrylamide), PNIPAM, is tuned by tacticity, since the hydrophobicity rises with the increase of the degree of isotacticity. On the basis of this experimental evidence, atomistic molecular dynamics simulations of pairs of PNIPAM stereoisomers in 1.6% w/w polymer aqueous solution, a condition intermediate between the dilute and semidilute regimes, were carried out to comparatively investigate the solution behaviour and hydration of atactic and isotactic-rich PNIPAMs, both below and above the lower critical solution temperature, LCST...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28436310/synthesis-and-characterization-of-poly-n-vinylcaprolactam-based-spray-dried-microparticles-exhibiting-temperature-and-ph-sensitive-properties-for-controlled-release-of-ketoprofen
#12
Simone F Medeiros, Milene V Lopes, Bartira Rossi-Bergmann, Maria Inês Ré, Amilton M Santos
Poly(N-vinylcaprolactam) (PNVCL) and poly(N-vinylcaprolactam-co-acrylic acid) (poly(NVCL-co-AA)) were synthesized by solution free radical polymerization and displayed thermo-responsive behavior, with lower critical solution temperatures (LCSTs) of 35°C and 39°C, respectively. The incorporation of AA unities made the poly(NVCL-co-AA) sensitive to both pH- and temperature. They were exploited in this work in preparing microparticles loaded with ketoprofen via spray-drying to modulate the drug release rate by changing pH or temperature...
April 22, 2017: Drug Development and Industrial Pharmacy
https://www.readbyqxmd.com/read/28435966/water-structuring-above-solutes-with-planar-hydrophobic-surfaces
#13
Udo Schnupf, John W Brady
Many important biological solutes possess not only polar and hydrogen bonding functionalities, but also weakly-hydrating, or hydrophobic, surfaces. Theories of the hydration of such surfaces predict that their solvent interactions will change from a wetting type interaction to a dewetting regime as a function of the solute size, with a gradual transition in behavior taking place around characteristic lengths of ∼1 nm. Aggregations of non-polar species over this size range will undergo a transition from being dominated by entropy to being dominated by enthalpy...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28435965/conformational-and-hydration-properties-modulate-ice-recognition-by-type-i-antifreeze-protein-and-its-mutants
#14
Sandipan Chakraborty, Biman Jana
The mechanism of ice recognition by antifreeze protein (AFP) is a topic of recent interest. Here, using equilibrium simulations and free energy calculations, we provide structural rationale to the observed experimental anomalies on type I AFP (wfAFP isoform HPLC6) and its mutants as well as probe the molecular origin of ice recognition by them. Our results clearly demonstrate that the interplay between the conformational and hydration properties dictates the ice binding ability of type I AFP and its mutants...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28435964/kinetics-of-co2-diffusion-in-human-carbonic-anhydrase-a-study-using-molecular-dynamics-simulations-and-the-markov-state-model
#15
Gong Chen, Xian Kong, Diannan Lu, Jianzhong Wu, Zheng Liu
Molecular dynamics (MD) simulations, in combination with the Markov-state model (MSM), were applied to probe CO2 diffusion from an aqueous solution into the active site of human carbonic anhydrase II (hCA-II), an enzyme useful for enhanced CO2 capture and utilization. The diffusion process in the hydrophobic pocket of hCA-II was illustrated in terms of a two-dimensional free-energy landscape. We found that CO2 diffusion in hCA-II is a rate-limiting step in the CO2 diffusion-binding-reaction process. The equilibrium distribution of CO2 shows its preferential accumulation within a hydrophobic domain in the protein core region...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28435742/immobilisation-induced-hypercalcemia-following-spinal-cord-injury-affecting-the-kidney-function-in-two-young-native-greenlanders
#16
Michael V Linstow, Fin Biering-Sørensen
INTRODUCTION: Immobilisation-induced hypercalcemia following SCI affecting the kidney function, is a rare but potentially serious condition. We report immobilisation-induced hypercalcemia affecting the kidney function in two young native Greenlanders with spinal cord injury (SCI). CASE PRESENTATIONS: Two 15- and 24-year-old male native Greenlanders, both with traumatic C5 SCI were admitted to our spinal cord unit. They were non-smokers without history of daily alcohol intake pre- or immediately post-injury...
2017: Spinal Cord Series and Cases
https://www.readbyqxmd.com/read/28435737/n-1-5-bromo-2-hy-droxy-phen-yl-ethyl-idene-isonicotinohydrazide-monohydrate-crystal-structure-and-hirshfeld-surface-analysis
#17
See Mun Lee, Nathan R Halcovitch, Mukesh M Jotani, Edward R T Tiekink
In the title isonicotinohydrazide hydrate, C14H12BrN3O2·H2O {systematic name: N'-[(1E)-1-(5-bromo-2-hy-droxy-phen-yl)ethyl-idene]pyridine-4-carbohydrazide monohydrate}, the central CN2O region of the organic mol-ecule is planar and the conformation about the imine-C=N bond is E. While an intra-molecular hy-droxy-O-H⋯N(imine) hydrogen bond is evident, the dihedral angle between the central residue and the benzene rings is 48.99 (9)°. Overall, the mol-ecule is twisted, as seen in the dihedral angle of 71...
April 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28435725/hydrazinium-2-amino-4-nitro-benzoate-dihydrate-crystal-structure-and-hirshfeld-surface-analysis
#18
James L Wardell, Mukesh M Jotani, Edward R T Tiekink
In the anion of the title salt hydrate, H5N2(+)·C7H5N2O4(-)·2H2O, the carboxyl-ate and nitro groups lie out of the plane of the benzene ring to which they are bound [dihedral angles = 18.80 (10) and 8.04 (9)°, respectively], and as these groups are conrotatory, the dihedral angle between them is 26.73 (15)°. An intra-molecular amino-N-H⋯O(carboxyl-ate) hydrogen bond is noted. The main feature of the crystal packing is the formation of a supra-molecular chain along the b axis, with a zigzag topology, sustained by charge-assisted water-O-H⋯O(carboxyl-ate) hydrogen bonds and comprising alternating twelve-membered {⋯OCO⋯HOH}2 and eight-membered {⋯O⋯HOH}2 synthons...
April 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28435247/delivery-of-curcumin-by-directed-self-assembled-micelles-enhances-therapeutic-treatment-of-non-small-cell-lung-cancer
#19
Wen-Ting Zhu, Sheng-Yao Liu, Lei Wu, Hua-Li Xu, Jun Wang, Guo-Xin Ni, Qing-Bing Zeng
BACKGROUND: It has been widely reported that curcumin (CUR) exhibits anticancer activity and triggers the apoptosis of human A549 non-small-cell lung cancer (NSCLC) cells. However, its application is limited owing to its poor solubility and bioavailability. Therefore, there is an urgent need to develop a new CUR formulation with higher water solubility and better biocompatibility for clinical application in the future. MATERIALS AND METHODS: In this study, CUR-loaded methoxy polyethylene glycol-polylactide (CUR/mPEG-PLA) polymeric micelles were prepared by a thin-film hydration method...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28434758/mallards-anas-platyrhynchos-and-wastewater-ponds-part-ii-developmental-physiological-morphological-and-behavioural-effects-of-ingestion-of-secondary-clarified-effluent-water
#20
K B Tierney, P O Welsh, M Mills, S Nason, D R Barreda, C A Paszkowski
Rather than migrating, mallard ducks may choose to overwinter in northern cities on open-water thermal refuges, such as municipal wastewater treatment ponds, which in Edmonton, Canada, stay ≥10°C during frigid winter months. Refuging mallards spend appreciable time daily on these ponds and hydrate using secondary clarified municipal wastewater (SCEW). We aimed to determine if SCEW ingestion affected mallard health. To this end, we gavaged newly hatched mallards (domesticated Pekin strain) over their first month with SCEW, as well as water representing negative and positive controls (municipal tap water, and the primary active ingredient from birth control pills, 17α-ethinyl estradiol (EE2), respectively)...
April 20, 2017: Ecotoxicology and Environmental Safety
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