Read by QxMD icon Read

ph responsive

Tathyana Mar Amorim Franco, Subray S Hegde, John S Blanchard
The biosynthetic pathway of the branched-chain amino acids is essential for M. tuberculosis growth and survival. We report here the kinetic and chemical mechanism of the pyridoxal 5'-phosphate (PLP)-dependent branched-chain aminotransferase, IlvE, from M. tuberculosis (MtIlvE). This enzyme is responsible for the final step of the synthesis of the branched-chain amino acids isoleucine, leucine and valine. As seen in other aminotransferases, MtIlvE displays a ping-pong kinetic mechanism. pK values were identified from the pH dependence on V as well as V/K, indicating that the phosphate ester of the PLP cofactor, as well as the α-amino group from L-glutamate and the active site Lys204, play roles in acid-base catalysis and binding, respectively...
October 25, 2016: Biochemistry
Dae Woo Park, Andrea Sebastiani, Choon Hwai Yap, Marc A Simon, Kang Kim
Mechanical and structural changes of right ventricular (RV) in response to pulmonary hypertension (PH) are inadequately understood. While current standard biaxial testing provides information on the mechanical behavior of RV tissues using surface markers, it is unable to fully assess structural and mechanical properties across the full tissue thickness. In this study, the mechanical and structural properties of normotensive and pulmonary hypertension right ventricular (PHRV) myocardium through its full thickness were examined using mechanical testing combined with 3D ultrasound speckle tracking (3D-UST)...
2016: PloS One
Jeng-Haur Chen, Weiyi Xu, David N Sheppard
Cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-gated Cl(-) channel defective in the genetic disease cystic fibrosis (CF). The gating behaviour of CFTR is characterized by bursts of channel openings interrupted by brief, flickery closures, separated by long closures between bursts. Entry to and exit from an open burst is controlled by the interaction of ATP with two ATP-binding sites, sites 1 and 2 in CFTR. To understand better the kinetic basis of CFTR intraburst gating, we investigated the single-channel activity of human CFTR at different intracellular pH (pHi ) values...
October 25, 2016: Journal of Physiology
Christoph Töpper, Cathérine Louise Steinbach, Christoph Dorn, Alexander Kratzer, Sebastian G Wicha, Michael Schleibinger, Uwe Liebchen, Frieder Kees, Bernd Salzberger, Martin G Kees
BACKGROUND: Standard doses of linezolid may not be suitable for all patient groups. ICU patients in particular may be at risk of inadequate concentrations. This study investigated variability of drug exposure and its potential sources in this population. PATIENTS AND METHODS: Plasma concentrations of linezolid were determined by HPLC in a convenience sample of 20 ICU patients treated with intravenous linezolid 600 mg twice daily. Ultrafiltration applying physiological conditions (pH 7...
October 24, 2016: Therapeutic Drug Monitoring
Min-Ju Seo, Woo-Ri Kang, Kyung-Chul Shin, Deok-Kun Oh
The reaction conditions for the production of 7S,8S-dihydroxy-9,12(Z,Z)-octadecadienoic acid from linoleic acid by recombinant Escherichia coli expressing 7,8-linoleate diol synthase from Glomerella cingulata were optimized using response surface methodology. The optimal reaction conditions were pH 7.0, 18.6 °C, 10.8% (v/v) dimethyl sulfoxide, 44.9 g/L cells, and 14.3 g/L linoleic acid, with agitation at 256 rpm. Under these conditions, recombinant cells produced 7,8-dihydroxy unsaturated fatty acids in the range of 7...
October 25, 2016: Journal of Agricultural and Food Chemistry
Mthulisi Khuphe, Clare S Mahon, Paul D Thornton
The glucoseamine-initiated ring-opening polymerisation of amino acid N-carboxyanhydrides and O-carboxanhydrides to yield amphiphilic block copolymers that are capable of self-assembly in aqueous solution to form well-defined, glucose-presenting, particles is reported. The particles formed are susceptible to enzyme-mediated (lipase and protease) and pH-induced degradation, and can selectively bind the lectin concanavalin A. Consequently, such glycoparticles are of significance for the controlled release of payload molecules in response to an acidic environment, for instance cancerous tissue, and upon interaction with target enzymes...
October 25, 2016: Biomaterials Science
Wanda Montalvo, Mary W Byrne
Objective. The aim of this study was to describe and analyze the correlations between mentoring functions and political skill development among nurses who have earned or are candidates for a Ph.D. or doctorate of nursing practice (DNP) degree. Background. The healthcare system is in flux; future generations of Ph.D. and DNP nurse leaders will be required to demonstrate political acumen. Political skill to navigate organizational politics has had limited research within nursing. Methods. A cross-sectional research design using a web-based survey of 222 nurses who have earned or are candidates for a Ph...
2016: Nursing Research and Practice
Bin Cheng, Yiwei Meng, Yanbing Cui, Chunfang Li, Fei Tao, Huijia Yin, Chunyu Yang, Ping Xu
Halomonas sp. Y2 is a halotolerant alkaliphilic strain from Na+-rich pulp mill wastewater with high alkalinity (pH >11.0). Transcriptome analysis of this isolate revealed this strain may use various transport systems for pH homeostasis. Especially, the genes encoding four putative Na+/H+ antiporters were differentially expressed upon acidic or alkaline conditions. Further evidence, from heterologous expression and mutant studies, suggested that Halomonas sp. Y2 employs its Na+/H+ antiporters in a labor division way to deal with saline and alkaline environments...
October 24, 2016: Journal of Biological Chemistry
Man Zhang, Rui Wang, Zhenqiang Shi, Xuelian Huang, Weifeng Zhao, Changsheng Zhao
A novel family of multi-responsive, tough, and reversible hydrogels were prepared by the combination of dipole-dipole interaction, hydrogen bonding interaction and slightly chemical cross-linking, using monomers of acrylonitrile, sodium allylsulfonate and itaconic acid. Reversible gel-sol transition was achieved by the flexible conversion of the dipole-dipole interactions between acrylonitrile-acrylonitrile and acrylonitrile-sodium thiocyanate, and the hydrogels could freely form desired shapes. The dipole-dipole and hydrogen bonding interactions improved the mechanical strength of the hydrogels with a compressive stress of 2...
October 11, 2016: Journal of Hazardous Materials
Jing Xu, Yuyang Long, Dongsheng Shen, Huajun Feng, Ting Chen
Untreated leachate membrane concentrates are a threat to the environment. In our study, effective removal of contaminants in pre-coagulated leachate membrane concentrates was achieved using the Fenton process. The Fenton process was optimized using the response surface method, and the maximum total organic carbon (TOC), chemical oxygen demand (COD), and chromaticity reduction efficiencies reached 68.9%, 69.6%, and 100% under the conditions pH 2, H2O2 concentration 1mol/L, and Fe(2+) concentration 17.5mmol/L...
October 15, 2016: Journal of Hazardous Materials
Varsha B Gujar, Divya Ottoor
Behavior of Amiloride (AMI) as a metal ion sensor in anionic surfactant assemblies of varying concentrations at different pH is depicted in this work. From a non-sensor fluorophore, AMI has been transformed in to a tunable fluorosensor for Cu(2+) ions in various SDS concentrations. At premicellar concentration of SDS, ion-pair complex is expected to be formed between AMI and SDS due to electrostatic interactions between them. However at CMC concentrations of SDS, fluorescence intensity of AMI is greatly enhanced with red shift in emission, due to the incorporation of AMI molecule in the hydrophobic micellar interface...
October 18, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Shaw D Bamber, Stig Westerlund
Sub-sea geological storage of carbon dioxide (CO2) provides a viable option for the Carbon Capture and Storage (CCS) approach for reducing atmospheric emissions of this greenhouse gas. Although generally considered to offer a low risk of major leakage, it remains relevant to establish the possible consequences for marine organisms that live in or on sediments overlying these storage areas if such an event may occur. The present study has used a series of laboratory exposures and behavioral bioassays to establish the sensitivity of Arctica islandica to simulated leakages of CO2...
October 11, 2016: Aquatic Toxicology
Yu Zhang, Yifei Lu, Feng Wang, Sai An, Yujie Zhang, Tao Sun, Jianhua Zhu, Chen Jiang
Inflammation has been reported as one significant hallmark of breast cancer in relation to tumor development, metastasis, and invasion. The bradykinin receptor 1 (B1R) is highly expressed on inflammatory breast tumor cells thus providing a promising targeting site for tumor recognition and sufficient receptor mediated endocytosis. In this study, the authors evaluate the targeting efficiency of l-form and d-form [des-Arg(10) ]kallidin both in vitro and in vivo. To further improve the drug delivery efficiency, the authors establish a dandelion like nanoparticle by combining the polymeric drug conjugates and aptamer complex together...
October 24, 2016: Small
Xiao-Ling Wang, Zhong-Yang Ding, Gao-Qiang Liu, Hailong Yang, Guo-Ying Zhou
Triterpene acids (TAs) are the major bioactive constituents in the medicinal fungus Ganoderma lingzhi. However, fermentative production of TAs has not been optimized for commercial use, and whether the TAs isolated from G. lingzhi submerged culture mycelia possess antitumor activity needs to be further proven. In this study, enhanced TA yield and productivity were attained with G. lingzhi using response surface methodology. The interactions of three variables were studied using a Box-Benhnken design, namely initial pH, dissolved oxygen (DO) and fermentation temperature...
October 20, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Yuji Mikata, Risa Ohnishi, Risa Nishijima, Hideo Konno
The tetrakisquinoline ligand HT(6-MeO8Q)HPN (N,N,N',N'-tetrakis(6-methoxy-8-quinolylmethyl)-2-hydroxy-1,3-propanediamine) exhibited Zn(2+)-induced fluorescence enhancement with high specificity and sensitivity (IZn/I0 = 57 and ICd/IZn = 6% in the presence of 2 equiv of Zn(2+); LOD (limit of detection) = 15 nM). This ligand also exhibited fluorescence enhancement specific to inorganic phosphate (PO4(3-)) in DMF-HEPES buffer (50 mM HEPES, 100 mM KCl, pH = 7.5) (1:1) in the presence of 2 equiv of Zn(2+). The structure of the unprecedented tetranuclear zinc complex with a μ4-PO4 bridge was elucidated by X-ray crystallography as the key species responsible for fluorescence enhancement...
October 24, 2016: Inorganic Chemistry
Zhigang Li, Chao Zu, Can Wang, Jianfeng Yang, Huan Yu, Huasong Wu
Soil microorganisms have important influences on plant growth and health. In this study, four black pepper fields consecutively monocultured for 12, 18, 28 and 38 years were selected for investigating the effect of planting age on rhizosphere and non-rhizosphere soil microbial communities and soil physicochemical properties. The results revealed that the relative abundance of the dominant bacterial phyla in rhizosphere soil increased considerably with long-term consecutive monoculture but decreased in non-rhizosphere soil with a significant decline in Firmicutes...
October 24, 2016: Scientific Reports
Matthew Urich, Alan R Denton
Microgels are soft colloidal particles that, when dispersed in a solvent, swell and deswell in response to changes in environmental conditions, such as temperature, concentration, and pH. Using Monte Carlo simulation, we model bulk suspensions of microgels that interact via Hertzian elastic interparticle forces and can expand or contract via trial moves that allow particles to change size in accordance with the Flory-Rehner free energy of cross-linked polymer gels. We monitor the influence of particle compressibility, size fluctuations, and concentration on bulk structural and thermal properties by computing particle swelling ratios, radial distribution functions, static structure factors, osmotic pressures, and freezing densities...
October 24, 2016: Soft Matter
Ganna Gryn'ova, Michelle L Coote, Clemence Corminboeuf
The electronic configuration of the molecule is the foundation of its structure and reactivity. The spin state is one of the key characteristics arising from the ordering of electrons within the molecule's set of orbitals. Organic molecules that have open-shell ground states and interesting physicochemical properties, particularly those influencing their spin alignment, are of immense interest within the up-and-coming field of molecular electronics. In this advanced review, we scrutinize various qualitative rules of orbital occupation and spin alignment, viz...
November 2015: Wiley Interdisciplinary Reviews. Computational Molecular Science
Clara Morita-Imura, Yoshiro Imura, Takeshi Kawai
Amidoamine derivative C18AA forms a highly viscous oil-in-water (O/W) emulsion, called an "emulsion gel." Previously, it was showed that the viscosity sensitively changes with the C18AA concentration, temperature, pH changes, and salt addition. In this work, C18AA concentration in the continuous aqueous phase ([C18AA]w) was investigated at different compositions, and it was found that a threshold concentration value of 16.5 wt% was required to obtain a highly viscous emulsion gel below 45°C. C18AA formed micellar networks in the aqueous phase, and stimuli or additives increase the value of [C18AA]w, so that the C18AA micellar network could grow in the continuous aqueous phase...
October 21, 2016: Journal of Oleo Science
Gheorghe Fundueanu, Marieta Constantin, Sanda Bucătariu, Iuliana Stoica
Double hydrophilic thermo-responsive pullulan-g-poly(N-isopropylacrylamide) (P-g-pNIPAM) copolymers with two different molecular weight of thermosensitive grafts were synthesized and used for preparation of indomethacin-loaded nanoparticles by dialysis and nanoprecipitation method. The polymers form aggregates in aqueous solution at a concentration of 10g/L, above their critical aggregation concentration (3.36g/L) and below the lower critical solution temperature (LCST). After indomethacin loading, nanoparticles with compact and uniform structure were formed below the LCST...
October 20, 2016: International Journal of Biological Macromolecules
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"