Significant Differences In Permeability Research Articles

AN EXAMINATION OF MECHANISMS UNDERLYING THE SURVIVAL BENEFIT CONFERRED BY INTESTINESPECIFIC OVEREXPRESSION OF INTERLEUKIN-10

Background: We have shown that transgenic (TG) mice overexpressing IL-10 in the intestine have a significant survival advantage over their wildtype (WT) counterparts when challenged with cecal ligation and puncture (CLP). The mechanism underlying this survival advantage is unknown. Objective: To determine mechanisms responsible for the survival advantage conferred by intestine-specific overexpression of IL- 10. Methods: Given the documented role of IL-10 on systemic inflammation, the gut, and the lungs, each was examined in detail in septic TG and WT mice. TG (n=13) and WT (n=14) mice were subjected to CLP with a 1 by 27 injury. The animals were sacrificed 24 hours later and intestines, lungs, serum, and bronchoalveolar lavage (BAL) fluid were collected. The serum and BAL were spun down and assayed for cytokines IL-12, TNFa, IFN, MCP-1, IL-10, and IL-6 using cytometric bead analysis. Intestines and lungs were sectioned and stained by H&E. Intestines were assessed for epithelial apoptosis in 100 intact crypt-villus units while the lungs were assessed qualitatively. A piece of the intestine was also used to evaluate permeability utilizing the everted gut sac model. Results: IL-12 levels were lower (p <.05) in the serum of transgenic mice (5.1 +/− 0.5 vs. 6.7 +/− 0.5) with no significant differences in the other serum or BAL cytokines measured. There was no statistically significant disparity in intestinal apoptosis, and lung histology was unremarkable. Evaluation of clearance in the intestine revealed no significant difference in permeability. Conclusions: Intestinal production of IL-10, an anti-inflammatory cytokine, induces a minor downstream block of systemic IL-12 expression in septic animals but has no effect on other serum or BAL cytokines, gut permeability and apoptosis, and lung histology. The main mechanisms underlying the survival advantage conferred by intestinal overexpression of IL-10 remain to be determined.

The Influence of Intraocular Pressure on the Transscleral Diffusion of High-Molecular-Weight Compounds

To evaluate the effects of intraocular pressure on the permeability of the human sclera to high-molecular-weight compounds. Human transscleral permeability to FITC-albumin (70 kDa) and 70-kDa and 150-kDa FITC-dextran was determined at transscleral pressures from 0 to 60 mm Hg. For each compound at each pressure, six to eight experiments were performed. Scleral sections were mounted in a two-compartment perfusion chamber. Temperature was maintained at 37 degrees C. Fractions of choroidal perfusate were collected, and fluorescence was measured with a spectrofluorometer. From these data, scleral permeability K(trans) (in centimeters per second) was calculated. Permeability to FITC-albumin was decreased by approximately one half when pressure was elevated from 0 to 30 mm Hg (P < 0.05). No significant differences in permeability to 70-kDa FITC-dextran were observed at pressures from 0 to 60 mm Hg. Permeability to 150-kDa FITC-dextran decreased by a little more than one half when transscleral pressure was raised from 0 to 15 mm Hg and was approximately 10 times lower at 60 mm Hg than at 0 mm Hg (P < 0.01). Human sclera was permeable to compounds with a molecular weight of up to 150 kDa at transscleral pressures ranging from 0 to 60 mm Hg. Transscleral diffusion was relatively unaffected by the pressure gradient, although for 150-kDa FITC-dextran at 60 mm Hg a 10-fold decrease was observed compared with that at 0 mm Hg. These experiments suggest that high-molecular-weight compounds (e.g., immunoglobulins and oligonucleotides) could be effectively delivered transsclerally to the intraocular tissues under circumstances of physiological or elevated intraocular pressure.

Patterns of branch permeability with crown depth among loblolly pine families differing in growth rate and crown size

Patterns in branch permeability with crown depth and permeability at the top of the main stem were analyzed for loblolly pine (Pinus taeda L.) trees from families selected on the basis of growth rate (fast, slow) and crown size (large, small). Analysis of variance with levels of crown size nested within levels of growth rate was used to test for differences in main stem permeability. Permeability at the top of the stem averaged 2.0×10−12 m2. There were no significant differences in permeability between families selected for fast and slow growth, but permeability was significantly lower for families selected for large crowns than for families selected for small crowns. Branch permeability averaged 0.74×10−12 m2 and decreased significantly with crown depth. Large-crown families had higher overall branch permeability than small-crown families. Average permeability in branches did not differ significantly between fast- and slow-growing families. Large crown-families had significantly larger current leaf area: total leaf area ratios in the lower two-thirds of the crown, and a weak but significant association was found between permeability and current leaf area: total leaf area ratios for a given relative crown depth. Our results suggest that ecotypic and adaptive processes simultaneously affect the overall patterns of stem and branch permeability in loblolly pine families.

Modulation of caudal intestinal permeability in the rat during infection by the tapeworm Hymenolepis diminuta.

Bidirectional movement of solutes between the intestinal lumen and systemic circulation is restricted by tissue barriers that may be altered under conditions such as intestinal infection. In a study using an in vitro everted sac preparation to assess small intestinal permeability in a lumen-to-serosa direction, 51Cr-EDTA movement was compared regionally in the jejunum and ileum of rats infected and uninfected by tapeworms. Whereas jejunal segments showed no significant differences in permeability to 51Cr-EDTA at 6, 15, or 32 days postinfection (dpi), ileal segments displayed an increased permeability on 15 and 32 dpi, but not 6 dpi. The alterations in permeability were not reversed 1 wk after removal of the tapeworm from the intestine. In conclusion, the strictly lumen-dwelling tapeworm infection allows increased movement of molecules from the lumen into ileal, but not jejunal, tissues by 15 dpi.

Intestinal permeability testing using lactulose and rhamnose: a comparison between clinically normal cats and dogs and between dogs of different breeds

In the experiment reported here, the lactulose/rhamnose urinary excretion test was used to compare intestinal permeability between four breeds of healthy adult dogs and a group of healthy adult cats. A significant difference in permeability was found between dogs and cats (P<0·001) and between different breeds of dogs (P<0·005). The range of urinary lactulose/rhamnose ratios in the dogs in this study (0·07–0·61) was wider than previously reported (0·03–0·12). The mean value for dogs was 0·19. The range in cats was 0·41–1·25 and the mean 0·52. The results of this study suggest that breed or some other factor such as environment, diet or sexual status as well as species should be taken into account when assessing intestinal permeability using the lactulose/rhamnose urinary excretion test.

HIGH TEMPERATURE DRYING FROM THE THREE PRIMARY ORTHOGONAL SURFACES OF LOBLOLLY PINE

While several permeability studies have been performed, little information is available on the flow of water in wood along its three orthogonal axes during high temperature drying. Much southern yellow pine construction lumber is dried at temperatures above 100°C, thus how water moves in wood is of concern. In this experiment individual Loblolly pine (Pinus taeda) sapwood cubes were coated on two of their three orthogonal faces (longitudinal, radial, and tangential) and the effect of this sealing on the drying rate was determined. From these cubes, drying rates from each of the three primary planes were determined. The free water movement/evaporation between the radial and tangential faces was not statistically different, while the longitudinal rate was approximately three times faster. In commercial practice, the faster longitudinal rate is negated by the very small portion of transverse surface area relative to total lumber surface area. This partially explains why end checking and moisture variation in high temperature dried southern yellow pine lumber are not significant causes of degrade. There was no statistically significant difference in permeability across the seasons tested.

Type II cAMP-dependent Protein Kinase-deficientDrosophila Are Viable but Show Developmental, Circadian, and Drug Response Phenotypes

We identified a unique type II cAMP-dependent protein kinase regulatory subunit (PKA-RII) gene in Drosophila melanogaster and a severely hypomorphic if not null mutation, pka-RII(EP(2)2162). Extracts from pka- RII(EP(2)2162) flies selectively lack RII-specific autophosphorylation activity and show significantly reduced cAMP binding activity, attributable to the loss of functional PKA-RII. pka-RII(EP(2)2162) shows 2-fold increased basal PKA activity and approximately 40% of normal cAMP-inducible PKA activity. pka-RII(EP(2)2162) is fully viable but displays abnormalities of ovarian development and multiple behavioral phenotypes including arrhythmic circadian locomotor activity, decreased sensitivity to ethanol and cocaine, and a lack of sensitization to repeated cocaine exposures. These findings implicate type II PKA activity in these processes in Drosophila and imply a common role for PKA signaling in regulating responsiveness to cocaine and alcohol.

Measurement of uni-axial fiber angle in non-woven fibrous media

Fiber packing structure is known to affect properties of non-woven fibrous media such as paper and filter media. For a thin medium, such as paper, the fibers lay predominantly in a two-dimensional plane and angles are easily measured visually when viewed perpendicular to this plane. This two-dimensional plane is referred here as the X– Y plane. In thicker media, the fibers can have a three-dimensional orientation with a characteristic uni-axial angle measured relative to the Z-axis, where the Z-axis is perpendicular to the X– Y plane. A number of methods exist for measuring the three-dimensional structure of fibers in a non-woven medium. Many of the methods require expensive equipment. In this paper, a simple, relatively inexpensive visual method requiring moderate effort is presented that provides information on the distribution of fiber angles and the average fiber angle relative to the Z-axis. In the filtration industry extensive testing is done to characterize filter media and filter cakes. However, very few data are reported on the effect of fiber angle on filtration properties such as particle capture efficiency and permeability of filter media and filter cakes. In this work a method is developed to extend two-dimensional orientation data to obtain the three-dimensional fiber orientations. The method is used to characterize the average fiber angles of two filters formed of glass fibers with the only difference between the filters being the fiber structure. Filtration tests show significant differences in permeability and particle capture efficiency between the media of an average angle of 48° compared to the media of an average angle of 68°.

Permeation of sumatriptan through human vaginal and buccal mucosa.

Continued interest in the various routes by which sumatriptan may be administered prompted us to investigate its passage through buccal mucosa. Because human buccal mucosa is scarce, we proposed using the relatively abundant vaginal mucosa, which has been shown to have comparable diffusion rates for a number of widely varying molecules, as a model of buccal mucosa. In addition, by comparing these two tissues with respect to their permeability to sumatriptan, the human vaginal/buccal mucosa model could be further evaluated. Clinically healthy human vaginal and buccal mucosa specimens were used in the permeability studies. Permeability to sumatriptan was determined using a continuous flow-through diffusion system in the presence and absence of permeation enhancers. No statistically significant differences in permeability could be demonstrated for both mucosae toward sumatriptan. Flux values obtained in the absence and presence of glycodeoxycholate and lauric acid (1:1 molar ratio) to sumatriptan of buccal and vaginal mucosa, respectively, were not significantly different. The results obtained further support the hypothesis of the vaginal/buccal mucosal in vitro permeability model and suggest that this model may be used in conjunction with various absorption enhancers. Further studies on the buccal route of absorption of sumatriptan are thus warranted.

Geologically related variations in saturated hydraulic conductivity in the regolith of the western wheatbelt of Western Australia and its implications for the development of dryland salinity

This is the first systematic study of geology-related saturated hydraulic conductivity differences in the regolith of the wheatbelt of Western Australia. Except for 2 rock types studied, much lower permeability in the pallid zone than in the underlying aquifer, is substantiated. Higher permeability in major faults than in the surrounding granite is confirmed, and this extends into the pallid zone. Mafic dykes have no significant differences in permeability to granite in the saprolite aquifer but it is arguable that the permeability of dykes in the pallid zone is greater than granite. Permeability of the Tertiary valley filling sandstone aquifer is higher than of the underlying granite and much higher than of the overlying claystone aquiclude. The results presented in this paper provide a basis for groundwater models to take into account differences in permeability between major faults and granite and within Tertiary sediments, which is necessary in order to improve predictions of salinity extent and treatment effectiveness.

Permeability, morphologic and temperature changes of canal dentine walls induced by Nd: YAG, CO2 and argon lasers

The permeability, temperature and morphologic changes of the wall of the root canal induced by Nd:YAG, CO2 and argon lasers were studied. The changes were evaluated according to the presence or absence of a smear layer. Root canals of 140 human single-rooted teeth were enlarged using a step-back technique. Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. Temperature changes were measured using a thermovision system, and morphological changes were evaluated by scanning electron microscopy. Laser energy was delivered into the canal by means of a flexible optical fibre or metal tip. There were statistically significant differences in permeability between lased groups with and without a smear layer in the cervical third of the root canal following lasing. In the middle third of the root canal, all three laser types induced permeability increases in groups with a smear layer. In the apical third, statistically significantly decreases in permeability were observed among CO2 laser and Nd:YAG compared with control group (P < 0.01). Rises in temperature ranged from a minimum of +10.1 degrees C (CO2 laser) to a maximum of +54.8 degrees C (argon laser). All three laser devices appeared capable of producing a glazed-like surface and craters.

Morphologic differences of the vascular buds in the vertebral endplate: scanning electron microscopic study.

Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts. To examine morphologic differences between vascular buds in two regions of the vertebral endplate (inner anular and nucleus pulposar). Vascular buds are specific structures present at the vertebral endplate that are important as nourishing channels. There is a significant difference in permeability between the lateral portion (inner anular) and the central portion (nucleus pulposar) of the endplate, the latter usually being permeable and the former being impermeable. Morphologic differences between vascular buds in the two regions have not been investigated previously. Eight 20-week-old rabbits were used. Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts. The vascular buds in the region of the inner anulus form simple loops, but those in the area near the nucleus pulposus exhibit swollen and complex coil-like loops. Although they differ structurally, the average number of vascular buds per area does not vary between the two regions. We suggest that the morphologic difference between the vascular buds in the two regions (inner anular and nucleus pulposar) plays a principal role in permeability at the endplate.

Transport across rat trachea in vitro after exposure to cytoskeleton-active drugs in vitro or to ozone in vivo.

Full-length tracheas from Sprague-Dawley rats were exposed to cytoskeleton-active drugs in short-term organ culture, and the permeability of the tracheal epithelium was measured by instilling radiotracers into the lumen and assay of the radioactivity appearing in the external bathing medium. In vitro treatment with cytochalasin D (cyto D, 2-10 x 10(-6) M) increased the rate of movement of [14C]mannitol across the epithelium. Exposure to vinblastine (VB, 10(-4) M) alone had no significant effect. However, VB in combination with cyto D increased the permeability in a dose-dependent manner. In vivo exposure to ozone (O3, 0.8 or 2.0 ppm, 2 h) had only a slight effect on the rate of movement of the tracer as measured in vitro immediately after exposure. At 24 h postexposure there was no significant difference in permeability between ozone- and air-exposed tracheas. Prior in vivo O3 exposure sensitized the tracheas to the in vitro effects of cyto D; treatment of O3-exposed tracheas with cyto D immediately after O3 exposure produced a greater than additive effect on permeability measured in vitro. VB at concentrations up to 10(-4) M had no enhancing effect on permeability in O3-exposed tracheas. Sham exposure to clean air did not affect permeability compared to untreated (shelf) controls. Electron microscopic studies demonstrated penetration of horseradish peroxidase into intercellular spaces in the tracheas treated in vitro with cyto D or cyto D plus VB. Cyto D is known to affect intracellular microfilaments that have attachments at or near the cell surface, while VB affects microtubules associated with internal cellular structures. Therefore, the synergistic effect on tracheal permeability observed with O3 and cyto D, but not with O3 and VB, suggests that O3 may change cell surface structures associated with the microfilamentous cytoskeleton.

Allopurinol Absorption from Different Sites of the Rat Gastrointestinal Tract

Allopurinol exhibits good bioavailability (78–90%) after administration of oral dosage forms to humans and rabbits; however, it is not absorbed rectally from any of the dosage forms to any significant extent. Oral administration of allopurinol in a polyethylene glycol suspension, to which allopurinol may be reversibly complexed, to rabbits has been shown to produce erratic and poor absorption of allopurinol. This suggests the possibility of differential absorption of allopurinol from various sites of the Gl tract. The mechanism of allopurinol absorption was investigated in rats using the in situ Levine technique. The allopurinol absorption rate was 0.56 ± 0.10 μ/min/cm from the upper portion of the small intestine and was 0.48 ± 0.12 μ/min/cm from the midgut. The absorption from the lower portion of the small intestine was 0.33 ± 0.14 μ/min/cm and from the upper and lower large intestine segments was negligible (0.04 ± 0.06 μ/min/cm). The normalization of these absorption rates for surface area yielded flux values (normalized absorption rate as μ/min/cm2) with significant differences in permeability between small and large intestine for allopurinol. The allopurinol absorption rate increased with increases in the dose, and there was a linear relationship between dose and absorption rate. Thus, allopurinol absorption, although specific to particular sites, is not dose dependent in the dose range from 0.25 to 2.5mg/mL. Differences in the rates of absorption may be due to anatomical differences of the various parts of the Gl tract or due to physicochemical properties of the drug itself.

Permeability of different experimental brain tumor models to horseradish peroxidase.

The permeability of different brain tumor models to horseradish peroxidase (HRP) was examined by determining the fraction of tumor that contained HRP after intravenous administration. The intracerebral tumor models studied were Avian Sarcoma Virus (ASV)-induced tumors and tumors from transplanted RG-2, S69-C1-5, and 9L cell lines. The average fraction of RG-2 tumors permeable to HRP was .95; of S69-C1-5 tumors, .699; of ASV-induced tumors. .63; and of 9L tumors, .52. Except for the RG-2 tumors, there was considerable regional variation in HRP permeability, which was most marked in the ASV-induced tumors. In ASV-induced tumors, HRP permeability did not correlate with tumor histological classification, size, or anatomic location within the brain. The subcutaneous tumor models studied were RG-2-, S69-C1-5, and 9L-transplanted tumors in rats, and human glioblastoma cell lines transplanted into nude mice. All were completely permeable to HRP. These results indicate that significant differences in permeability to HRP exist among brain tumor models when the tumors are intracerebral, and that all subcutaneous tumors from transplanted glial cell lines are completely permeable to HRP. These variables must be considered in future studies of permeability in experimental brain tumors. Care must be exercised in extrapolating results about permeability from one brain tumor model to another.

The effect of exposure to daylight and dark storage on protective clothing material permeability

To estimate the effects of daylight and dark storage on permeability, samples of protective clothing materials were placed in a window facing east at 39°2′ N. latitude or in a closed cabinet for 0, 1, 2, and 3 months. At the end of the storage period the permeability of the sample was determined after 60-minute exposure to each of two solvents. Test data were normalized to account for differences in sample material thickness. Statistical analysis of the data showed that no significant differences in permeability occurred as a result of dark storage; small differences in 3 of 12 cases were observed following daylight storage.

Permeability of chorion laeve in cases of normal and retarded fetal growth

The in vitro permeability of the human placenta to sucrose and urea is described. The conclusion from these membrane transport studies is that, per unit surface area of chorion laeve, there is no significant difference in permeability between placentas from cases of normal and retarded fetal growth.

The effects of polyamines on the replication of T4 rII mutants in Escherichia coli K12 (λ)

While rII mutants of bacteriophage T4 can replicate in Escherichia coli K12S, replication is blocked when this host is lysogenized by λ phage. Polyamines, Mg ++, and streptomycin increase the yield of rII deletion mutants in K12(λ) to varying degrees below the normal yield obtained with wild-type phage. Of a homologous series of diamines, 1,7-diaminoheptane is about 7 times more effective than 1,4-dia-aminobutane (putrescine) or Mg ++. The critical portion of the latent period for diamine stimulation is between 10 and 20 minutes after infection. In the absence of diamine, UV induction of λ replication permits subsequent rII replication; further stimulation by 1,7-diaminoheptane still occurs under these conditions. Diamines and Mg ++, unlike UV irradiation, do not bring about induction of λ phage. Uninfected cells of K12(λ) and K12S were found to contain nearly identical amounts of putrescine. Several independent methods were used to examine permeability differences between the two types of infected cells; in all cases, no significant differences in permeability to large or small molecules were found. Therefore, the inability of rII mutants to replicate in K12(λ) cannot be attributed to generalized leakage resulting from phage infection. Several alternatives are suggested for the mode of action of these substances.

Large - Scale Laboratory Investigation of Sand Consolidation Techniques

Abstract Large-scale sand consolidation tests were conducted in an effort to determine the reasons for the successes and failures of this method of sand control. Several different consolidating materials were used in treating both clean and bentonitic sands that were packed in a chamber having a capacity of 3.3 cu ft. The results were essentially the same for all of the different consolidating materials. The data show that low-viscosity consolidating materials pumped at a relatively slow rate gave the best results. Where the formation has produced sand, the treating fluids can compress the formation, thus permitting the channeling of fluids to another horizon. Pressure-packing these zones before attempting to consolidate is recommended. Sands containing more than 4 per cent of water-swelling clays are not good candidates for consolidation. It is indicated that loose sand, particularly when it is bentonitic, can be fractured during the placement of the treating fluids. Introduction Sand production in oil and gas wells has plagued the industry for many years, and numerous cures for this problem have been suggested. Most methods have been successful to a certain degree, but the great variety of well conditions that exist in the different areas has magnified the problem and limited the successful use of the various systems. Four review papers present a wealth of information concerning the degrees of success that have been obtained by the different sand-control methods. The bridging of sand grains by the use of gravel packs and screens has been quite successful. However, these methods do not leave the casing clear for all types of multiple completions, and the cure does not last for the production life of the well in some instances. The control of loose sands by sand consolidation with resins has never been as successful as desired. It has always been hoped that such a treatment would eliminate all sand problems for the life of the well, but initial applications, starting in the middle 1940's, were only moderately successful. Lott, et al, reported a success ratio of approximately 50 per cent and made the following conclusions: The highest percentage of successes were obtained where:Consolidation of a zone was made at the time of initial completion or prior to the production of sand.The interval treated was less than 12 ft in length.Between 30 and 50 gal plastic/ft of producing interval was displaced through the perforations. REASONS FOR SAND CONSOLIDATION FAILURES Our own experiences in the field of sand consolidation point toward the following conditions as the major reasons for the failure of sand consolidation attempts.Mud-plugged perforations and mud invasion of the formation.Sand in the casing covering all or part of the perforations. This sand could be either formation sand or one of the coarser sands used as propping agents in hydraulic fracturing.Holes in the casing.Channels behind the casing.Attempting to treat too long a perforated section.Too high a percentage of water-swelling clays in the formation.Formations that have produced sand. Recent attempts were made to treat perforated sections ranging from 10 to 30 ft, in wells that have produced sand, by using a straddle packer that was raised and lowered through the perforations as the consolidating material was being pumped. In most instances, the pressure required to pump fluid into the formation varied considerably as the tool was raised and lowered. This suggested the possibility that significant differences in permeability were present or that only part of the formation had produced sand. There were times when a sudden break in pressure indicated that a fracture was being formed. Research conducted several years ago concerning the problem of the control of water in air and gas drilling indicated that shale sections could be fractured quite easily. In addition, it was determined that it was easier to pump fluids into shale bodies by fracturing the shale itself, or the interface between the shale and sand, than to pump into a fluid-saturated formation. Formations that produce sand are usually adjacent to shale bodies and frequently have shale streaks of various thicknesses interbedded in the sand. JPT P. 1221^