scholarly journals Reversible Hydrogels with Switchable Diffusive Permeability

2021 ◽  
pp. 2100076
Author(s):  
Paola Nicolella ◽  
Daniel Lauxen ◽  
Mostafa Ahmadi ◽  
Sebastian Seiffert
Keyword(s):  
Diffusive Permeability

Permeability to albumin in isolated coronary venules

1993 ◽  
Vol 265 (2) ◽  
pp. H543-H552 ◽  
Author(s):  
Y. Yuan ◽  
W. M. Chilian ◽  
H. J. Granger ◽  
D. C. Zawieja
Keyword(s):  
Permeability Coefficient ◽  
Filtration Rate ◽  
Intraluminal Pressure ◽  
Apparent Permeability ◽  
Filtration Pressure ◽  
Diffusive Permeability ◽  
Apparent Permeability Coefficient ◽  
Chemical Conditions ◽  
Physical And Chemical ◽  
Intravascular Pressure

This study reports measurements of albumin permeability in isolated coronary venules. The isolated microvessel technique allows the quantification of transmural exchange of macromolecules under tightly controlled physical and chemical conditions. Transvenular exchange of albumin was studied in isolated coronary venules during alterations in filtration rate caused by changes in intravascular pressure. The apparent permeability coefficient of albumin (Pa) at an intraluminal pressure of 11 cmH2O was 3.92 +/- 0.43 x 10(-6) cm/s. Elevating intraluminal pressure to 16 and 21 cmH2O increased Pa to 5.13 +/- 0.57 x 10(-6) and 6.78 +/- 0.66 x 10(-6) cm/s, respectively. Calculation of the true diffusive permeability coefficient of albumin (Pd) at zero filtration rate was 1.54 x 10(-6) cm/s. The product of hydraulic conductance (Lp) and (1 - sigma), where sigma is the solute reflection coefficient, was 3.25 x 10(-7) cm.s-1 x cmH2O-1. At a net filtration pressure of 4-5 cmH2O, diffusion accounts for > 60% of total albumin transport across the venular wall. Transmural albumin flux is very sensitive to filtration rate, rising 6.7% for each cmH2O elevation of net filtration pressure. At 11 cmH2O net filtration pressure, convection accounts for nearly 70% of net albumin extravasation from the venular lumen. We suggest that the isolated coronary venule is a suitable preparation for the study of solute exchange in the heart.

Test of a two-pathway model for small-solute exchange across the capillary wall

1998 ◽  
Vol 274 (6) ◽  
pp. H2062-H2073 ◽  
Author(s):  
B. M. Fu ◽  
R. H. Adamson ◽  
F. E. Curry
Keyword(s):  
Tight Junctions ◽  
Sodium Fluorescein ◽  
Intracellular Camp ◽  
Pathway Model ◽  
Mean Values ◽  
Permeability Coefficients ◽  
Diffusive Permeability ◽  
Small Pore ◽  
Separate Pathway ◽  
Small Solute

We previously proposed a two-pathway model for solute and water transport across vascular endothelium (Fu, B. M., R. Tsay, F. E. Curry, and S. Weinbaum. J. Biomech. Eng. 116: 502–513, 1994) that hypothesized the existence of a continuous slit 2 nm wide along tight junction strands within the interendothelial cleft in parallel with 20 × 150-nm breaks in tight junctions. We tested this model by measuring capillary permeability coefficients ( P) to a small solute (sodium fluorescein, radius 0.45 nm), assumed to permeate primarily the 2-nm small pore, and an intermediate-sized solute (FITC-α-lactalbumin, radius 2.01 nm) excluded from the small pore. Mean values of the paired diffusive permeability coefficients, P sodium fluorescein and P FITC-α-lactalbumin, were 34.4 and 2.9 × 10−6 cm/s, respectively, after corrections for solvent drag and free dye ( n = 26). These permeabilities were accounted for by transport through the large-break pathway without the additional capacity of the hypothetical 2-nm pathway. As a further test we examined the relative reductions of P sodium fluorescein and P FITC-α-lactalbuminproduced by elevated intracellular cAMP. Within 20 min after the introduction of rolipram and forskolin, P sodium fluorescein and P FITC-α-lactalbumindecreased to 0.67 and 0.64 times their respective baseline values. These similar responses to permeability decrease were evidence that the two solutes were carried by a common pathway. Combined results in both control and reduced permeability states did not support the hypothesis that a separate pathway across tight junctions is available for solutes with a radius as large as 0.75 nm. If such a pathway is present, then its size must be smaller than that of sodium fluorescein.

Study of Diffusion and Water Vapor Permeability in Chitosan Films and Chitosan Emulsified Films

2012 ◽  
Vol 326-328 ◽  
pp. 170-175 ◽  
Author(s):  
Arlete Barbosa dos Reis ◽  
Cristiana Maria Pedroso Yoshida ◽  
Vera Solange Oliveira Farias ◽  
Wilton Pereira Silva
Keyword(s):  
Water Vapor ◽  
Lipid Analysis ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Oxygen Barrier ◽  
Water Vapor Barrier ◽  
Industry Waste ◽  
Diffusive Permeability ◽  
Hydrophobic Compound ◽  
Chitosan Films

Chitosan is an abundant, natural polysaccaride obtained from fishing industry waste and films of chitosan also provide an efficient oxygen barrier. However, they are a poor water vapor barrier, which can be improved by incorporation of a hydrophobic compound, forming a emulsified film. Chitosan films were produced with the addition of palmitic acid lipid analysis and then the process in parallel with the diffusive permeability to water vapor. The objective of this work was to characterize the diffusion and water vapor permeability behavior of chitosan films and chitosan emulsified films.

Continuous arterio-venous haemodiafiltration: hydraulic and diffusive permeability index of an AN-69 capillary haemofilter

1998 ◽  
Vol 36 (1) ◽  
pp. 43-50
Author(s):  
E. Akcahuseyin ◽  
W. A. van Duyl ◽  
H. H. Vincent ◽  
M. C. Vos ◽  
M. A. D. H. Schalekamp
Keyword(s):  
Permeability Index ◽  
Diffusive Permeability

A biomimetic tissue from cultured normal human urothelial cells: analysis of physiological function

2005 ◽  
Vol 289 (2) ◽  
pp. F459-F468 ◽  
Author(s):  
W. R. Cross ◽  
I. Eardley ◽  
H. J. Leese ◽  
J. Southgate
Keyword(s):  
Urothelial Cells ◽  
Functional Relationships ◽  
Basal Expression ◽  
Physiological Investigation ◽  
Cell Culture Systems ◽  
Diffusive Permeability ◽  
Normal Human ◽  
Sodium Ion Channels ◽  
Normal Human Urothelium

The urinary bladder and associated tract is lined by the urothelium. Once considered as just an impermeable epithelium, it is becoming evident that the urothelium not only functions as a volume-accommodating urinary barrier but has additional roles, including sensory signaling. Lack of access to normal human urothelium has hampered physiological investigation, and although cell culture systems have been developed, there has been a failure to demonstrate that normal human urothelial (NHU) cells grown in vitro retain the capacity to form a functional differentiated urothelium. The aim of this study was to develop a biomimetic human urothelium from NHU cell cultures. Urothelial cells isolated from normal human urothelium and serially propagated as monolayers in serum-free culture were homogeneous and adopted a proliferative, nondifferentiated phenotype. In the presence of serum and physiological concentrations of calcium, these cells could be reproducibly induced to form stratified urothelia consisting of basal, intermediate, and superficial cells, with differential expression of cytokeratins and superficial tight junctions. Functionally, the neotissues showed characteristics of native urothelium, including high transepithelial electrical resistance of >3,000 Ω·cm2, apical membrane-restricted amiloride-sensitive sodium ion channels, basal expression of Na+-K+-ATPase, and low diffusive permeability to urea, water, and dextran. This model represents major progress in developing a biomimetic human urothelial culture model to explore molecular and functional relationships in normal and dysfunctional bladder physiology.

Water and nonelectrolyte permeability of isolated rat hepatocytes

1986 ◽  
Vol 251 (6) ◽  
pp. C872-C882 ◽  
Author(s):  
G. Alpini ◽  
R. A. Garrick ◽  
M. J. Jones ◽  
R. Nunes ◽  
N. Tavoloni
Keyword(s):  
Plasma Membrane ◽  
Homogeneous Medium ◽  
Rat Hepatocytes ◽  
Bile Canaliculus ◽  
Isolated Rat Hepatocytes ◽  
Permeability Coefficients ◽  
Diffusive Permeability ◽  
Intracellular Medium ◽  
Tracer Molecules ◽  
Isolated Rat

We have measured the diffusive permeability coefficients of isolated rat hepatocytes to 3H2O, [14C]urea, [14C]erythritol, [14C]mannitol, [3H]sucrose, and [3H]inulin, employing a technique previously developed for erythrocytes (Redwood et al., J. Gen. Physiol 64:706-729, 1974). Diffusion coefficients for the tracer molecules were measured in packed hepatocytes, supernatant fluid, and intracellular medium (lysed hepatocytes) and were calculated assuming one-dimensional semi-infinite diffusion through a homogeneous medium. By applying the series-parallel pathway model, the following permeability coefficients (10(-5) cm/sec) for the hepatocyte plasma membrane were obtained. 3H2O, 98.6 +/- 18.4; [14C]urea, 18.2 +/- 5.3; [14C]erythritol, 4.8 +/- 1.6; [14C]mannitol, 3.1 +/- 1.4; [3H]sucrose, 0; [3H]inulin, 0. These results indicate that isolated rat hepatocytes are highly permeable to water and polar nonelectrolytes, when compared with other transporting epithelia. This relatively high cellular permeability is consistent with a model in which nonelectrolyte permeation is via an aqueous pathway of equivalent pore diameter of 8-12 A. The finding that [14C]erythritol and [14C]mannitol cross the hepatocyte plasma membrane indicates that these molecules enter the bile canaliculus through the transcellular route. Conversely, the failure of [3H]sucrose and [3H]inulin to permeate the hepatocyte in the isolated condition supports the concept that biliary entry of these large carbohydrates, at least that fraction which cannot be accounted for by a vesicular mechanism, must occur via the transjunctional shunt pathway.

Diffusive Permeability of Rabbit Peritoneum for Small Solutes in Vitro: Effect of Gentamicin and Insulin

2002 ◽  
Vol 25 (4) ◽  
pp. 290-296 ◽  
Author(s):  
B. Szary ◽  
K. Czyżewska
Keyword(s):  
Uric Acid ◽  
Glucose Transport ◽  
Ussing Chamber ◽  
In Vitro Study ◽  
Mean Values ◽  
Peritoneal Transport ◽  
Diffusive Permeability ◽  
Vitro Effect ◽  
Mass Transport Coefficient

The purpose of the in vitro study was to compare the diffusive transport of creatinine, uric acid and glucose, directed from the interstitial (I) to the mesothelial (M) side of the peritoneum and in the opposite direction, before (15–60min) and after (75–120min) application of gentamicin and insulin. The experiments were undertaken on the rabbit parietal peritoneum in a modified Ussing chamber. A mathematical model was used to calculate a diffusive permeability coefficient P (in cm/s) and a diffusive mass transport coefficient KH (in mL/min). In the basic experimental series without drugs, the dynamics of peritoneal transport for examined solutes remained constant and there were no differences between transport directions (I→ M and M→ I). Mean values of P±SEM (KH±SEM) were 3.06±0.32 (321.1±33.5), 2.09±0.29 (219.2±30.7) and 2.73±0.47 (286.7±49.6) for creatinine, uric acid and glucose, respectively. The introduction of gentamicin decreased glucose transport directed from the mesothelial to the interstitial side of the membrane by about 12%. After insulin application we observed the increase of creatinine and glucose peritoneal transport rate. For creatinine, the above augmentation was by about 31% for I→ M and 83% for M→ I direction. In these conditions, the glucose transport directed from the interstitial to the mesothelial side of membrane increased by about 24%. Generally, in vitro gentamicin decreases, but insulin increases the diffusive permeability of the peritoneum for some small solutes. We suppose that these findings may be important for the efficiency of peritoneal dialysis.

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