Apparent Permeability
Mostrando 13-24 de 169 artigos, teses e dissertações.
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13. Quantificação da influencia da composição de terpolimeros de polietilenotereftalato nas propriedades termicas, na morfologia e no comportamento de deformação, durante o sopro
PET terpolymers properties were never determined in a complete way. quantification of the relationship between the molecular weight and the comonomers content is practically inexistent. The objective of that study is, starting from 14 different PET terpolymer types, to quantify the thermal properties of stretching and the morphologic structure formed during
Publicado em: 2002
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14. Ritmo diario da secreção de insulina por ilhotas pancreaticas isoladas de rato : correlação com permeabilidades a potassio e calcio
This thesis examines the insulin secretion and the t<" and Ca2+ effluxes in pancreatic islets at different times of the day. Insulin secretion was measured during a 60 min incubation (37°C) of islets from fed or 48 h-starved rats. The t<" and Ca2+ effluxes were determined by measuring the rate of Rb + and Ca2+ efflux, respectively, from islets preloaded wit
Publicado em: 1998
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15. Proton and hydroxide ion permeability of phospholipid vesicles.
The apparent permeability of H+ through phospholipid bilayers was determined by measuring H+ efflux from large unilamellar phospholipid vesicles with internal space buffered at pH 4. The value obtained is about 10(-9) cm/sec at room temperature, five orders of magnitude lower than was recently reported for the combined permeability for H+ and OH- [Nichols, J
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16. Interaction between Osmotic- and Pressure-induced Water Flow in Plant Roots
When the pressure gradient across a root alters, there is often an apparent change in the permeability of the root to water. Fiscus (Plant Physiol. 1975. 55: 917-922) has suggested that this can be explained by a simple two-compartment model which takes into account rates of solute uptake into the xylem. A method of testing actual data against the Fiscus mod
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17. Lack of Influence of Phytochrome on Membrane Permeability to Tritiated Water 1
The water permeability of tissues was investigated by measuring the efflux of 3HHO from previously loaded (in darkness) etiolated bean buds (Phaseolus vulgaris L. var. Red Kidney), pea epicotyl segments (Pisum sativum L. var. Alaska), and oat coleoptile segments (Avena sativa L. var. Garry). Red light, far red light, or darkness was applied at the time of tr
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18. Active and Passive Bile Acid Absorption in Man. PERFUSION STUDIES OF THE ILEUM AND JEJUNUM
Absorption of the major human bile acids was studied in 12 healthy volunteers by steady state perfusion of the ileum in 112 experiments and of the jejunum in 48 experiments. Use of a randomized order of four perfusions on 1 day of study and use of up to 4 consecutive days of study in a subject allowed important comparisons of data from the same individuals.
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19. Proton-hydroxide permeability of liposomes.
Liposome permeability to net proton-hydroxide flux was compared under two conditions that have produced extreme values in previous studies. In the first [Nichols, J.W. & Deamer, D.W. (1980) Proc. Natl. Acad. Sci. USA 77, 2038-2042] small pH gradients were permitted to decay near pH 7 and permeability coefficients in the range of 10(-4) cm/sec were obtained.
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20. The permeability of gamma-aminobutyric acid-gated chloride channels is described by the binding of a "cage" convulsant, t-butylbicyclophosphoro[35S]thionate.
The "cage" convulsant t-butylbicyclophosphoro[35S]thionate ([35S]TBPS) binds with high affinity to sites at or near a gamma-aminobutyric acid (GABA)-gated chloride channel according to current hypothesis. We now report that the potencies of a series of anions in enhancing [35S]TBPS binding correlated highly with their relative permeabilities through GABA-gat
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21. Bacteriophage Mu-1-induced permeability mutants in Escherichia coli K-12.
Apparent permeability mutations were produced in Escherichia coli K-12 by bacteriophage mu-1 mutagenesis. They are pleiotropic mutations showing sensitivity to a number of detergents and unrelated antibiotics, and presumably they affect cell wall or membrane biosynthesis. One of the mutations was genetically mapped at a site in or near the acrA and mtc loci
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22. Treatment of early diabetic retinopathy with cyclandelate.
In order to assess the effect of cyclandelate on the abnormal permeability of the blood-retinal barrier which occurs in diabetic patients before any other lesions are apparent in the retina a well-controlled, double blind, and paired trial was carried out in 22 patients. The treatments were randomised. The permeability of the blood-retinal barrier was assess
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23. Permeability of Pseudomonas aeruginosa outer membrane to hydrophilic solutes.
Pseudomonas aeruginosa is usually resistant to a wide variety of antibacterial agents, and it has been inferred, on the basis of indirect evidence, that this was due to the low permeability of its outer membrane. We determined the permeability of P. aeruginosa outer membrane directly, by measuring the rates of hydrolysis of cephacetrile, cephaloridine, and v
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24. Anomalous mole fraction effect induced by mutation of the H5 pore region in the Shaker K+ channel.
Mutagenesis of the H5 region of the Shaker K+ channel has provided strong evidence that these amino acids form a major portion of the ionic pore. We have previously observed that a single-site mutation (T441S) in this region increased the apparent relative permeability of the channel to NH4+. We now report that this increased relative permeability to NH4+ is