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partition coefficient

Alice Strohmeier, Gesche Först, Philipp Tauber, Rolf Schubert
The interaction of liposomal membranes composed of soybean phosphatidylcholine with the bile salts (BSs) cholate (Ch), glycocholate (GC), chenodeoxycholate (CDC), and glycochenodeoxycholate (GCDC) was studied. The BSs differed with regard to their lipophilicity, pKa values, and the size of their hydrophilic moiety. Their membrane interactions were investigated using Laurdan as a membrane-anchored fluorescent dye. The apparent membrane/water partition coefficient, D, at pH 7.4 was calculated from binding plots and compared with direct binding measurements using ultracentrifugation as a reference...
October 18, 2016: Biophysical Journal
Prabodh Chander Sharma, Mona Piplani, Harish Rajak
In the present study, a novel strategy was developed to construct lipid prodrug of norfloxacin. N-Mannich base of norfloxacin was synthesized. The prodrug was obtained by covalently coupling this N-Mannich base with fatty acid hydrazide. The synthesized prodrug was characterized by spectral as well as other physical analysis. The hydrolytic studies of prodrug in buffers (pH 1.2 and 7.4), simulated gastric and intestinal fluid by HPLC analysis were undertaken. The studies revealed that prodrug liberates only about 2% of norfloxacin in HCl buffer (pH 1...
October 18, 2016: Current Drug Delivery
Mirela Enache, Ana Maria Toader, Madalin Iancu Enache
Mitoxantrone is a synthetic anticancer drug used clinically in the treatment of different types of cancer. It was developed as a doxorubicin analogue in a program to find drugs with improved antitumor activity and decreased cardiotoxicity compared with the anthracyclines. As the cell membrane is the first barrier encountered by anticancer drugs before reaching the DNA sites inside the cells and as surfactant micelles are known as simple model systems for biological membranes, the drugs-surfactant interaction has been the subject of great research interest...
October 13, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Martin May, Wiebke Drost, Sabine Germer, Tanja Juffernholz, Stefan Hahn
BACKGROUND: Acute-to-chronic extrapolation is an important approach to predict acceptable no-effect levels from acute data which has some uncertainties, but is valuable for risk assessment of chemical substances. With regard to the still limited and heterogenic data of chronic fish tests, conclusions on aquatic hazard estimation need to be checked and the question arises whether the chronic toxicity to fish can be adequately derived from acute data. A comprehensive dataset including ecotoxicological studies of 203 substances was used to investigate acute-to-chronic ratios (ACR) for both fish and Daphnia...
2016: Environmental Sciences Europe
Mare Oja, Uko Maran
Human intestinal absorption is a key property for orally administered drugs and is dependent on pH. This study focuses on neutral and amphoteric compounds and their membrane permeabilities across the range of pH values found in the human intestine. The membrane permeability values for 15 neutral and 60 amphoteric compounds at pH 3, 5, 7.4 and 9 were measured using the parallel artificial membrane permeability assay (PAMPA). For each data series the quantitative structure-permeability relationships were developed and analysed...
October 17, 2016: SAR and QSAR in Environmental Research
Xiutang Yuan, Xiaolong Yang, Anguo Zhang, Xindong Ma, Hui Gao, Guangshui Na, Humin Zong, Guize Liu, Yongguang Sun
Spatial distribution, source apportionment, and potential ecological risks of sixteen polycyclic aromatic hydrocarbons (PAHs) and seven endocrine disrupting compounds (EDCs) in the intertidal sediment at the Shuangtaizi Estuary, Bohai Sea of China were analyzed. Results showed that the total PAH concentrations ranged from 28.79ngg(-1) dw to 281.97ngg(-1) dw (mean: 115.92ngg(-1) dw) and the total EDC concentrations from 0.52ngg(-1) dw to 126.73ngg(-1) dw (mean: 37.49ngg(-1) dw). The distribution pattern for the PAHs was generally different from that of the EDCs possibly due to their distinct sources and n-octanol-/water partition coefficients (KOW)...
October 10, 2016: Marine Pollution Bulletin
Ashley M Hopkins, Mahin Moghaddami, David Jr Foster, Susanna M Proudman, Richard N Upton, Michael D Wiese
Leflunomide's active metabolite teriflunomide inhibits dihydro-oroate dehydrogenase (DHODH), an enzyme essential to proliferation of T-lymphocytes. As teriflunomide must reach the target site to have this effect, this study assessed the distribution of teriflunomide into T-lymphocytes, as intracellular concentrations may be a superior response biomarker to plasma concentrations. CD3 MicroBeads (MiltenyiBiotec) were used to extract CD3(+) T-cells from the peripheral blood of patients with rheumatoid arthritis whom were taking a stable dose of leflunomide...
October 14, 2016: Drug Metabolism and Disposition: the Biological Fate of Chemicals
Arup K Ghose, Gregory R Ott, Robert L Hudkins
At the drug discovery stage, it is important to understand the design concepts of a CNS drug compared to a non-CNS drug. Previously we published on ideal CNS drug space and defined in detail the physicochemical property space distribution of CNS and non-CNS oral drugs, the application of radar charting (a graphical representation of multiple physicochemical properties used during CNS lead optimization) and a recursive partition classification tree to differentiate between CNS and non-CNS drugs. The objective of the present study was to further the understanding of differentiations between CNS and non-CNS oral drugs into the development and application of an effective CNS algorithm TEMPO (Technically Extended Multiparameter Optimization)...
October 14, 2016: ACS Chemical Neuroscience
Juan Francisco Morales, Sebastián Scioli Montoto, Pietro Fagilino, María Esperanza Ruiz
The blood brain barrier (BBB) is a physical and biochemical barrier that restricts the entry of certain drugs to the Central Nervous System (CNS), while allowing the passage of others. The ability to predict the permeability of a given molecule through the BBB is a key aspect in CNS drug discovery and development, since neurotherapeutic agents with molecular targets in the CNS should be able to cross the BBB, whereas peripherally acting agents should not, to minimize the risk of CNS adverse effects. In this review we examine and discuss QSAR approaches and current availability of experimental data for the construction of BBB permeability predictive models, focusing on the modeling of the biorelevant parameter unbound partitioning coefficient (Kp,uu) ...
October 13, 2016: Mini Reviews in Medicinal Chemistry
Peter M Bentler
Classical test theory reliability coefficients are said to be population specific. Reliability generalization, a meta-analysis method, is the main procedure for evaluating the stability of reliability coefficients across populations. A new approach is developed to evaluate the degree of invariance of reliability coefficients to population characteristics. Factor or common variance of a reliability measure is partitioned into parts that are, and are not, influenced by control variables, resulting in a partition of reliability into a covariate-dependent and a covariate-free part...
October 12, 2016: Psychometrika
Atousa Abdollahi, Anita Eng, Liisa M Jantunen, Lutz Ahrens, Mahiba Shoeib, J Mark Parnis, Tom Harner
This study aimed to characterize the uptake of organophosphate esters (OPEs) by polyurethane foam (PUF) and sorbent-impregnated polyurethane foam (SIP) disk passive air samplers (PAS). Atmospheric OPE concentrations were monitored with high-volume active air samplers (HV-AAS) that were co-deployed with passive air samplers. Samples were analyzed for tris(2-chloroisopropyl) phosphate (TCIPP), tri(phenyl) phosphate (TPhP), tris(2-chloroethyl) phosphate (TCEP), and tris(2,3-dichloropropyl) phosphate (TDCIPP). The mean concentration of ∑OPEs in air was 2650 pg/m(3) for the HV-AAS...
October 7, 2016: Chemosphere
Hamed Moradkhani, Mir-Shahabeddin Izadkhah, Navideh Anarjan
In this work, gas dispersion in a two-phase partitioning bioreactor is analyzed by calculating volumetric oxygen mass transfer coefficient which is modeled using a commercial computational fluid dynamics (CFD), code FLUENT 6.2. Dispersed oxygen bubbles dynamics is based on standard "k-ε" Reynolds-averaged Navier-Stokes (RANS) model. This paper describes a three-dimensional CFD model coupled with population balance equations (PBE) in order to get more confirming results of experimental measurements. Values of k L a are obtained using dynamic gassing-out method...
October 8, 2016: Applied Biochemistry and Biotechnology
Grzegorz Siudem, Agata Fronczak, Piotr Fronczak
In this paper, we provide the exact expression for the coefficients in the low-temperature series expansion of the partition function of the two-dimensional Ising model on the infinite square lattice. This is equivalent to exact determination of the number of spin configurations at a given energy. With these coefficients, we show that the ferromagnetic-to-paramagnetic phase transition in the square lattice Ising model can be explained through equivalence between the model and the perfect gas of energy clusters model, in which the passage through the critical point is related to the complete change in the thermodynamic preferences on the size of clusters...
October 10, 2016: Scientific Reports
YanQiu Liu, YiMin Ren, Hong Gao, Li Zeng, ShaoFeng Lin, KaiQiang Zhang
OBJECTIVE: This research studied the influence of different blood lipid components on the rate of alveolar-capillary uptake of sevoflurane. METHOD: 104 patients aged 20 - 50 years undergoing elective operations under general anesthesia were mechanically ventilated through endotracheal intubation after intravenous injections of midazolam, vecuronium, fentanyl, and etomidate. They inhaled 2% sevoflurane at an oxygen flow of 2 L/min, then the inspired concentrations (FI) and expired concentrations (FA of sevoflurane were recorded at 1, 3, 5, 7, 10, 15, 20, and 30 minutes...
October 10, 2016: International Journal of Clinical Pharmacology and Therapeutics
Youhan Lee, Roberta Poloni, Jihan Kim
We propose a novel biased Widom insertion method that can efficiently compute the Henry coefficient, KH , of gas molecules inside porous materials exhibiting strong adsorption sites by employing purely DFT calculations. This is achieved by partitioning the simulation volume into strongly and weakly adsorbing regions and selectively biasing the Widom insertion moves into the former region. We show that only few thousands of single point energy calculations are necessary to achieve accurate statistics compared to many hundreds of thousands or millions of such calculations in conventional random insertions...
October 8, 2016: Journal of Computational Chemistry
Helen Y Fan, Dew Das, Heiko Heerklotz
Interactions between detergents and model membranes are well described by the three-stage model: Saturation and solubilization boundaries divide bilayer-only, bilayer-micelle co-existence, and micelle-only ranges. An underlying assumption of the model is the equilibration of detergent between the two membrane leaflets. However, many detergents partition asymmetrically at room temperature due to slow flip-flop, such as sodium dodecyl sulfate (SDS) and lysolipids. In this work, we use isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) to investigate the solubilization of unilamellar POPC vesicles by 12:0 lysophosphocholine (12:0 LPC)...
October 7, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Jung-Hwan Kwon, So-Young Lee, Hyun-Joong Kang, Philipp Mayer, Beate I Escher
World wide, regulations of chemicals request short-term toxicity data for evaluating hazards and risks of chemicals. Current data requirements on the registration of chemicals are primarily based on tonnage and do not yet consider properties of chemicals. For example, short-term ecotoxicity data are required for chemicals with production volume greater than 1 or 10 ton/y according to REACH without considering chemical properties. Highly hydrophobic chemicals are characterized by low water solubility and slow bioconcentration kinetics, which may hamper the interpretation of short-term toxicity experiments...
October 7, 2016: Environmental Science & Technology
Luisa A Ferreira, Vladimir N Uversky, Boris Y Zaslavsky
Partition coefficients of non-ionic essentially nonpolar compounds between air and rat biological tissues and between blood and other tissues were examined and found to be linearly interrelated according to the previously established equation for partition coefficients of solutes in aqueous two-phase systems: log Kblood-tissue-1 = k0 + k1 log Kblood-tissue-2 + k2 log Kblood-tissue-3, where k0, k1, and k2 are constants. Analysis of partition coefficients of amphiphilic and ionizable drugs between blood and different tissues in rats in vivo showed that the above relationship holds for the blood-tissue partition coefficients of these compounds as well...
September 28, 2016: Molecular BioSystems
Dragana P C de Barros, Sara R R Campos, Ana M Azevedo, António M Baptista, M Raquel Aires-Barros
The present work aims to achieve an additional insight into the protein partitioning behavior in aqueous two phase systems (ATPSs), together with a study on the viability of a semi-empirical model based on continuum electrostatics to predict the protein partition characteristics. The partitioning behaviors of 14 globular proteins, with different properties, were explored in three polymer/polymer ATPSs. By the Collander equation, a linear correlation between protein partitioning coefficients in all systems was observed...
October 1, 2016: Journal of Chromatography. A
Graham E Jackson, Fatin M Elmagbari, Ahmed N Hammouda, Raffaele P Bonomo
Copper complexes have anti-inflammatory activity in the treatment of inflammation associated with rheumatoid arthritis (RA). The preferred route of administration is through the skin, so the rate of dermal absorption and bioavailability of copper is important. Based on previous studies, 3-amino-N-(pyridin-2-ylmethyl)-propanamide, [H(56)NH2], was designed as a potential chelator of copper. The stability constant measurements revealed that MLH-1 is the most stable species at the physiological pH of 7.4. The X-ray crystal structure of this species was solved and copper was found in a rectangular pyramidal geometry...
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
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