Stress induced permeability

R. J. Sokol, M. S. Straka, R. Dahl, M. W. Devereaux, B. Yemshalmi, E. Gumpricht, N. Elkins and G. Everson, Role of oxidant stress in the permeability transition induced in rat hepatic mitochondria by hydro-phobic bile acids, Pediatr. Res., 2001, 49(4), 519. 

Since flavonoids are able to bind to the BDZ binding site of the GABA-A receptor, they might well interact with the BDZ binding site of the mitochondrial permeability transition protein, thereby modulating oxidative stress-induced apoptosis. ... 

In the filterwell or Transwell , systems, cells are grown on a permeable membrane between two separated liquid phases (McCall et al, 1981). In this condition confluent epithelial cells can achieve their full polarized functional state without the stresses induced by doming of epithelial monolayers on glass or plastic surfaces (Rabito et al, 1980). Filterwell culture has proved valuable for modelling the epithelium of the human intestine (Hidalgo et al., 1989). This technique is rapidly becoming the preferred culture system for many studies using epithelial cultures. 

Occludin phosphorylation may provide a molecular mechanism to control barrier properties. Studies from our group have demonstrated that both VEGF and shear stress induce permeability across endothelial monolayers associated with a rapid phosphorylation of occludin (67,68). The occludin phosphorylation was attenuated by a non-hydrolyzable cAMP analog that also inhibits shear-induced permeability (68). This phosphorylation of occludin appears to be serine or threonine directed since immunoprecipitation of occludin and phosphotyrosine blotting did not reveal any evidence of occludin tyrosine phosphorylation in this cell system (unpublished observation). However, in epithelial cells, evidence of occludin tyrosine phosphorylation exists (69). In addition, others have identified occludin phosphorylation in response to histamine (70) and use of brain extracts has helped identify casein kinase II as an occludin kinase (71). Collectively, this work demonstrates a close association of occludin phosphorylation with permeability. Future studies identifying specific occludin phosphorylation sites, followed by mutational analysis, should reveal the functional significance of occludin phosphorylation. 

Skultetyova, L, Tokarev, D., and Jezova, D., Stress-induced increase in blood-brain barrier permeability in control and monosodium glutamate-treated rats. Brain Res. Bull, 45(2), 175, 1998. 

Stress-induced changes in fracture aperture can give rise to significant changes in the rock mass permeability, through a sensitive cubic relationship between fracture aperture and fracture flow. This section discusses how to determine this relationship for large-scale heterogeneous fractured media (characterized by fLm) from small-scale laboratory measurements. The determination is based on the assumptions that an equivalent... 

Stress induced permeability change is of crucial importance in various kinds of applications such as nuclear waste disposal in deep geological formations, geothermal energy utilization and underground excavations. In particular, coupling between the stress and permeability is a key element in understanding the nature of flow in the fractured rock (Rutqvist and Stephansson, 2003). This is because fractures, which are the main pathways of fluid flow in fractured hard rocks, are heavily dependent on the stress conditions for their deformations. 

Figure 1 presents the three basic mechanisms of stress induced permeability change in fractured rock (a) normal closure/opening, (b) shear dilation/contraction and (c) induced anisotropy due to different orientations of fractures and anisotropic stress condition. 

CHARACTERIZING IN THE LABORATORY PERMEABILITY CHANGES INDUCED BY DEVIATORIC STRESS IN CLAYEY ROCKS... 

Sharma, H. S., Nyherg, F, Cervos-Navarro, J., and Dey, P. K. (1992). Histamine modulates heat stress-induced changes in blood-brain barrier permeability, cerebral blood flow, brain oedema and serotonin levels An experimental study in conscious young rats. Neuroscience 50, 445-454. 

Modification of mechanical properties High aspect ratio glass fibers, mica, nanoclays, carbon nanotubes, carbon/graphite fibers, and aramid/synlhetic/natural fibers Low aspect ratio talc, CaC03, kaolin, wood fiour, wollastonite, and glass spheres Control of permeability Reduced permeability impermeable plate-like fillers mica, talc, nanoclays, glass flakes Enhanced permeability stress concentrators for inducing porosity CaCOj and dispersed polymers... 

L. Bueno, C. Beaufrand, V. Theodorou, and M.C.A. Delestrain, Influence of simethicone and alverine on stress-induced alterations of colonic permeability and sensitivity in rats Beneficial effect of their association, /. Pharm. Pharmac., 65, 567-573, 20f3. 

The lanthaninn teehnique was used to study the epithelial permeability in the rat small intestine (Madara and Trier 1982). Dense lanthanum precipitates in TJ and paracellular spaces were restricted to a subpopulation of villous goblet cells and were not found between villous absorptive cells. These TJ were also permeable to barium, but not to macromolecular tracers such as microperoxidase, eytochrome c and horseradish peroxidase. It was also shown that palmitoylcamitine (PCC) opens TJ in a monolayer of Caco-2 colon carcinoma cells this phenomenon appears to be responsible for the significant enhancement of the absorption of hydrophilic drugs across intestinal mucosa caused by PCC and other long-chain acylcamitines (Hochman, Fix et al. 1994).In an experiment on rats, it was demonstrated that immobilisation stress induced a significant (but reversible) increase in epithelial permeability to the lanthanum tracer (Mazzon, Stumiolo et al. 2002). 

This interaction is still at the origin of magnetostriction, i.e. a deformation of the material under the effect of the magnetic field. Conversly, a stress induces magnetization. In the case of a ceramic, internal stresses which appear during sintering are likely to decrease the effective permeability of the material. 

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