scholarly journals Membrane solubility of chlorpromazine. Hygroscopic desorption and centrifugation methods yield comparable results

1984 ◽  
Vol 224 (3) ◽  
pp. 1023-1026 ◽  
Author(s):  
M Luxnat ◽  
H J Müller ◽  
H J Galla
Keyword(s):  
Partition Coefficient ◽  
Physical Properties ◽  
Partition Coefficients ◽  
Biological Membranes ◽  
Membrane Composition ◽  
Bilayer Membranes ◽  
Filtration Method ◽  
Centrifugation Method ◽  
Positively Charged

Binding of the positively charged drug chlorpromazine to artificial and erythrocyte bilayer membranes was investigated by the filtration method called hygroscopic desorption [Conrad & Singer (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 5202-5206] and by the conventional centrifugation method. Only minor differences in the partition coefficients were observed using the two methods. Our finding is not consistent with the observation of Conrad & Singer that amphipaths are completely excluded from biological membranes. However, the partition coefficient is dependent on membrane composition, which means dependent on the physical properties of a membrane.

Erythrocyte ghost – buffer partition coefficients of phenobarbital, pentobarbital, and thiopental support the pH-partition hypothesis

1979 ◽  
Vol 57 (3) ◽  
pp. 325-328 ◽  
Author(s):  
Klaus Korten ◽  
Keith W. Miller
Keyword(s):  
Partition Coefficient ◽  
Organic Solvents ◽  
Partition Coefficients ◽  
Biological Membranes ◽  
Erythrocyte Ghost ◽  
Red Cell ◽  
Data Support ◽  
Permeability Constants ◽  
Degree Of Association

The partition coefficient (λ) between red cell ghosts and buffer has been determined for three barbiturates over a range of pH. Experimental partition coefficients were linearly proportional to the calculated degree of association of the barbiturates. λ was 9.5 ± 0.52 for phenobarbital, 12.7 ± 0.91 for pentobarbital, and 27 ± 4.9 for thiopental in their acid forms. λ for all three barbiturates in their anionic forms was zero. Our data support the assumption of the pH-partition hypothesis that the dependence of λ on pH in biological membranes behaves essentially like that in organic solvents. However, the relative magnitudes of the erythrocyte partition coefficients correlate much more closely with the physiological permeability constants than do those of organic solvents, which tend to overestimate the differences between these compounds.

scholarly journals Physical properties of lipid bilayer membranes: relevance to membrane biological functions.

2000 ◽  
Vol 47 (3) ◽  
pp. 613-625 ◽  
Author(s):  
W K Subczynski ◽  
A Wisniewska
Keyword(s):  
Physical Properties ◽  
Lipid Bilayer ◽  
Plasma Membranes ◽  
Translational Motion ◽  
Biological Membranes ◽  
Fluid Phase ◽  
Spin Labeling ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Labeling Method

Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is AW. Using mainly the electron paramagnetic resonance (EPR) spin-labeling method, we obtained unexpected results, which are significant for the better understanding of the functioning of biological membranes. We have developed a new pulse EPR spin-labeling method for the detection of membrane domains and evaluation of lipid exchange rates. This review will be focused on our main results which can be summarized as follows: (1) Unsaturation of alkyl chains greatly reduces the ordering and rigidifying effects of cholesterol although the unsaturation alone gives only minor fluidizing effects, as observed by order and reorientational motion, and rather significant rigidifying effects, as observed by translational motion of probe molecules; (2) Fluid-phase model membranes and cell plasma membranes are not barriers to oxygen and nitric oxide transport; (3) Polar carotenoids can regulate membrane fluidity in a way similar to cholesterol; (4) Formation of effective hydrophobic barriers to the permeation of small polar molecules across membranes requires alkyl chain unsaturation and/or the presence of cholesterol; (5) Fluid-phase micro-immiscibility takes place in cis-unsaturated phosphatidylcholine-cholesterol membranes and induces the formation of cholesterol-rich domains; (6) In membranes containing high concentrations of transmembrane proteins a new lipid domain is formed, with lipids trapped within aggregates of proteins, in which the lipid dynamics is diminished to the level of gel-phase.

Partition Coefficient Ratios and Tumour Perfusion Studied with 85mKr and 133Xe

1987 ◽  
Vol 26 (06) ◽  
pp. 253-257
Author(s):  
M. Mäntylä ◽  
J. Perkkiö ◽  
J. Heikkonen
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Regional Blood Flow ◽  
Blood Perfusion ◽  
Compartmental Analysis ◽  
Malignant Tumour ◽  
Mean Value ◽  
Perfusion Rate ◽  
Biological Variables ◽  
The Mean

The relative partition coefficients of krypton and xenon, and the regional blood flow in 27 superficial malignant tumour nodules in 22 patients with diagnosed tumours were measured using the 85mKr- and 133Xe-clearance method. In order to minimize the effect of biological variables on the measurements the radionuclides were injected simultaneously into the tumour. The distribution of the radiotracers was assumed to be in equilibrium at the beginning of the experiment. The blood perfusion was calculated by fitting a two-exponential function to the measuring points. The mean value of the perfusion rate calculated from the xenon results was 13 ± 10 ml/(100 g-min) [range 3 to 38 ml/(100 g-min)] and from the krypton results 19 ± 11 ml/(100 g-min) [range 5 to 45 ml/(100 g-min)]. These values were obtained, if the partition coefficients are equal to one. The equations obtained by using compartmental analysis were used for the calculation of the relative partition coefficient of krypton and xenon. The partition coefficient of krypton was found to be slightly smaller than that of xenon, which may be due to its smaller molecular weight.

Interphase distribution of 2-furylethylenes

1985 ◽  
Vol 50 (8) ◽  
pp. 1642-1647 ◽  
Author(s):  
Štefan Baláž ◽  
Anton Kuchár ◽  
Ernest Šturdík ◽  
Michal Rosenberg ◽  
Ladislav Štibrányi ◽  
...  
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Transport Rate ◽  
Phase System ◽  
Two Phase ◽  
Interphase Distribution ◽  
Distribution Kinetics ◽  
System 1 ◽  
Kinetics Of

The distribution kinetics of 35 2-furylethylene derivatives in two-phase system 1-octanol-water was investigated. The transport rate parameters in direction water-1-octanol (l1) and backwards (l2) are partition coefficient P = l1/l2 dependent according to equations l1 = logP - log(βP + 1) + const., l2 = -log(βP + 1) + const., const. = -5.600, β = 0.261. Importance of this finding for assesment of distribution of compounds under investigation in biosystems and also the suitability of the presented method for determination of partition coefficients are discussed.

Phase Behavior and Physical Properties of Dimethyl Ether/Water/Heavy-Oil Systems Under Reservoir Conditions

SPE Journal ◽  
2021 ◽  
pp. 1-17
Author(s):  
Desheng Huang ◽  
Ruixue Li ◽  
Daoyong Yang
Keyword(s):  
Physical Properties ◽  
Phase Behavior ◽  
Dimethyl Ether ◽  
Heavy Oil ◽  
Partition Coefficients ◽  
Binary Interaction ◽  
Binary Interaction Parameter ◽  
Translation Strategy ◽  
Wide Range ◽  
Oil Mixtures

Summary Phase behavior and physical properties including saturation pressures, swelling factors (SFs), phase volumes, dimethyl ether (DME) partition coefficients, and DME solubility for heavy-oil mixtures containing polar substances have been experimentally and theoretically determined. Experimentally, novel phase behavior experiments of DME/water/heavy-oil mixtures spanning a wide range of pressures and temperatures have been conducted. More specifically, a total of five pressure/volume/temperature (PVT) experiments consisting of two tests of DME/heavy-oil mixtures and three tests of DME/water/heavy-oil mixtures have been performed to measure saturation pressures, phase volumes, and SFs. Theoretically, the modified Peng-Robinson equation of state (EOS) (PR EOS) together with the Huron-Vidal mixing rule, as well as the Péneloux et al. (1982)volume-translation strategy, is adopted to perform phase-equilibrium calculations. The binary-interaction parameter (BIP) between the DME/heavy-oil pair, which is obtained by matching the measured saturation pressures of DME/heavy-oil mixtures, works well for DME/heavy-oil mixtures in the presence and absence of water. The new model developed in this work is capable of accurately reproducing the experimentally measured multiphase boundaries, phase volumes, and SFs for the aforementioned mixtures with the root-mean-squared relative error (RMSRE) of 3.92, 9.40, and 0.92%, respectively, while it can also be used to determine DME partition coefficients and DME solubility for DME/water/heavy-oil systems.

Apparent octanol/water partition coefficients of pentachlorophenol as a function of pH

1982 ◽  
Vol 60 (16) ◽  
pp. 2104-2106 ◽  
Author(s):  
Klaus L. E. Kaiser ◽  
Ilze Valdmanis
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Partition Coefficient ◽  
Linear Function ◽  
Partition Coefficients ◽  
Extreme Values ◽  
Log P ◽  
Water Partition Coefficient ◽  
Non Linear ◽  
Good Agreement

The apparent 1-octanol/water partition coefficient (log PApp) of pentachlorophenol (PCP) varies in non-linear function with pH of the aqueous solution. In the range of pH 1.2 to 13.5 extreme values of log PApp 4.84 at pH 1.2 and log PApp 1.3 at pH 10.5 were observed. In the alkaline regime, log PApp increases strongly with the ionic strength. The ion-corrected partition coefficient of PCP was found to be log P 5.05 in good agreement with literature values.

Effects of physical properties of the breathing gas on decompression-sickness bubbles

1995 ◽  
Vol 79 (5) ◽  
pp. 1828-1836 ◽  
Author(s):  
M. E. Burkard ◽  
H. D. Van Liew
Keyword(s):  
Partition Coefficient ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Bubble Growth ◽  
Decompression Sickness ◽  
Inert Gases ◽  
Inert Gas ◽  
Half Time ◽  
Bubble Density ◽  
Mathematical Relationships

To explore the relative dangers of different inert gases, we developed mathematical relationships concerned with bubble growth, using equations that separate gas properties from other variables. Predictions for saturation exposures were as follows. 1) Peak volume of a bubble is proportional to solubility in tissue when bubble density is high and to the 3/2 power of the ratio of the permeation coefficient to the partition coefficient when density is low. 2) Bubble duration is inversely proportional to the partition coefficient for the inert gas. 3). Sizes and durations of bubbles for one inert gas relative to another depend on whether the tissue is aqueous or lipid but are independent of the magnitude of the decompression and tissue half time. 4). He should give smaller bubbles than N2, except in aqueous tissue with low bubble density; our prediction correlates qualitatively with relative dangers observed with animals but seems to overestimate the safety afforded by He. Numerical simulations illustrate how nonsaturation dives are less predictable because more variables are involved.

Partitioning of charged and neutral dextran-dye derivatives in biphasic cellulose nanocrystal suspensions

2008 ◽  
Vol 86 (6) ◽  
pp. 503-511 ◽  
Author(s):  
Stephanie Beck-Candanedo ◽  
David Viet ◽  
Derek G Gray
Keyword(s):  
Molecular Weight ◽  
Partition Coefficient ◽  
Cellulose Nanocrystals ◽  
Partition Coefficients ◽  
Virial Coefficient ◽  
Total Concentration ◽  
Second Virial Coefficient ◽  
Fluorescein Isothiocyanate ◽  
Blue Dextran ◽  
Molecular Weights

The partitioning behaviour of dye-labeled dextrans of high molecular weight in aqueous suspensions of native cellulose nanocrystals was studied. Cellulose concentrations lie in the isotropic–nematic coexistence region. Blue dextrans of various molecular weights and degrees of substitution of dye molecules (anionic Cibacron blue 3G-A) were investigated. Increasing the total concentration of blue dextran and degree of dye substitution led to increasing partition coefficients. Increasing dextran molecular weight resulted in higher partition coefficients, in agreement with theory. Partition coefficients were larger than predicted theoretically using a second virial coefficient approximation. Electrostatic and entropic contributions to the partition coefficient of blue dextran are discussed. Dextrans labeled with neutral fluorescein isothiocyanate did not partition preferentially in this system.Key words: partition coefficient, cellulose nanocrystals, dextrans, degree of substitution, polyelectrolyte.

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