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At least 55 records · Page 3Linked to original sources
PubMed2006

Diffusion-induced water movement within resin-dentin bonds during bonding.

It is thought that water-filled channels and nanovoids in resin-dentin bonds represent potential sites for degradation of bonds or hydrolysis of collagen or both. How water gains access to bonded interfaces is not clear. This study evaluated the diffusion-induced water uptake through resin-dentin interfaces during bonding. Two light-cured total-etch adhesive systems (Excite and One-Step Plus) and a chemical-cured adhesive (Amalgambond Plus) were used in this study. Dentin disks were placed in a split-chamber device, and the fluid movement across dentin was measured, with and without a physiological pressure, during bonding procedures and 24 h after bonding. For light-cured adhesives in the experimental groups, a 6 min interval of dark storage was conducted prior to light-curing, to evaluate the diffusion of water through the uncured resin monomers, and to test the effect of prolonged infiltration time of adhesives on water permeability of bonds. Prolonged adhesive infiltration reduced the water permeability of resin-dentin bonds for light-cured adhesives. Water gradients produced by bonding systems contribute to water movement across the dentin-adhesive interfaces during bonding procedures. Differences in chemical formulations for adhesive systems may lead to differences in the extent of diffusion-induced water movement and the amount of water within the resin-dentin bonds.

Dentin↗
PubMed1988

The relation of anatomy to water movement and cellular response in young barley leaves.

Young barley (Hordeum vulgare L. cv Arivat) leaves were examined anatomically and physiologically to infer the pathway of transpirational water movement and to explain why the growing region is more responsive to osmotic stress than the expanded blade. Vessels with open lumens extend from the intercalary meristem to the expanded blade, and all vessels are clustered in five vascular bundles that are separated by 20 closely packed mesophyll cells. Heat pulse transport data confirmed the anatomical suggestion that water moves through the growing region in vessels and not intercellularly, and also showed that stress reduces xylem water transport within 1 minute while transpiration remained unaffected. Water equal in volume to twice that expected in the xylem, and which exchanges more readily with water in the nutrient solution than with most water in tissues, can be extracted easily from growing tissues. It is hypothesized that this water is xylem plus cell wall water, that osmotic stress will quickly reduce its in situ water potential, and that stress causes growth to stop because cells in the growing region can respond rapidly to changes in water potential around them. In the expanded blade, bundles containing vessels are three and eight cells away from the closest and next substomatal cavities. This allows xylem water loss to occur predominantly through the closest stomata, and the expanded blade is believed to be less responsive because effects of stress on xylem water potential are confined largely to cells immediately around the vessels.

Journal Article↗
PubMed2003

Aquaporin proteins in murine trophectoderm mediate transepithelial water movements during cavitation.

Mammalian blastocyst formation is dependent on establishment of trophectoderm (TE) ion and fluid transport mechanisms. We have examined the expression and function of aquaporin (AQP) water channels during murine preimplantation development. AQP 3, 8, and 9 proteins demonstrated cell margin-associated staining starting at the 8-cell (AQP 9) or compacted morula (AQP 3 and 8) stages. In blastocysts, AQP 3 and 8 were detected in the basolateral membrane domains of the trophectoderm, while AQP3 was also observed in cell margins of all inner cell mass (ICM) cells. In contrast, AQP 9 was predominantly observed within the apical membrane domains of the TE. Murine blastocysts exposed to hyperosmotic culture media (1800 mOsm; 10% glycerol) demonstrated a rapid volume decrease followed by recovery to approximately 80% of initial volume over 5 min. Treatment of blastocysts with p-chloromercuriphenylsulfonic acid (pCMPS, > or =100 microM) for 5 min significantly impaired (P < 0.05) volume recovery, indicating the involvement of AQPs in fluid transport across the TE. Blastocysts exposure to an 1800-mOsm sucrose/KSOMaa solution did not demonstrate volume recovery as observed following treatment with glycerol containing medium, indicating glycerol permeability via AQPs 3 and 9. These findings support the hypothesis that aquaporins mediate trans-trophectodermal water movements during cavitation.

4-Chloromercuribenzenesulfonate↗
PubMed1987

Water movement during channel opening and closing.

By applying the osmotic stress of a nonpenetrating polymer, we have measured the change delta nu in polymer-inaccessible internal water volume of a voltage-gated ionic channel. The voltage-dependent anion channel (VDAC) from mitochondrial outer membranes shows a delta nu comparable in magnitude to the full channel volume estimated from solute penetrability, single-channel conductance, or image reconstruction. It thus appears that channel "gating" involves significant structure reorganization and water movement rather than the minimal changes caused by a local constriction or blockade. Hydration of the inner channel surface may be an important factor in channel gating as is the hydration of molecular surfaces in controlling macromolecular interaction in solution.

Body Water↗
PubMed2004

Water movement in the hybrid layer after different dentin treatments.

UNLABELLED: The aim of this study was to examine the morphology of the hybrid layer (HL) of bonded water-stored specimens after different chemical pre-treatments of dentin. MATERIALS AND METHODS: Twenty-seven recently extracted human molars were selected. Fifty-four dentin disks in middle/deep dentin were obtained with a slow speed saw with a diamond-impregnated disk under water lubrication. Smear layers were created with 180 grit silicon carbide under running water for 1 min. Different pre-treatments of dentin were: Group (1) no treatment; Group (2) 35% H3PO4 etch for 15 s followed by 10% glutaraldehyde for 120 s; Group (3) 37% H3PO4 etch for 15 s followed by 5% NaOCl for 120 s. Three dentin bonding agents (DBAs), Prime and Bond NT (P and B), AdmiraBond (AB), and Clearfil SE Bond (SEB) were applied in association with a resin composite following the manufacturers' directions. Each specimen was then longitudinally sectioned and polished with wet SiC papers (up to #4000 grit). Impressions of the polished dentin were immediately taken with a silicone impression material. Bonded specimens were then stored for 3 or 12 h in deionized water. Further impressions of stored specimens were taken after air-drying of specimens for 10 s. Positive replicas were obtained using a polyether impression material. All the replicas and the original specimens were inspected by SEM. RESULTS: A line of droplets (0.5-4 microm in diameter) was observed along the region of the adhesive-HL junction in all replicas of specimens stored in water, except in group 3, when P and B and AB were used. When SEB was used in each group the droplet were found in all groups except the zone of droplets was thinner. No differences in droplets dimensions were seen between 3 or 12 h water storage, or between the different dentin treatments. CONCLUSIONS: The replica procedure used in this study was able to detect water trapped in the adhesive-HL region that was released during the setting of the impression material. The droplets observed in this region support the hypothesis that there can be bidirectional water movement within the adhesive-HL complex.

Acid Etching, Dental↗
PubMed1993

Glucose-induced water movement from the intracellular to the extracellular space and its influence on calculations of glucose metabolism.

The osmotic effect of intravenous glucose was investigated in eight healthy volunteers. Increases in plasma glucose can induce water movement from the intracellular to the extracellular space. Serum choline esterase was used as an endogenous marker of serum dilution. Intravenous tests with 5, 15, 30 and 35 g of glucose showed that the water shift was proportional to the amount infused. The respective dilutions of choline esterase were 1.3 +/- 0.7%, 3.3 +/- 0.9%, 6.3 +/- 0.8% and 7.8 +/- 0.5%. The effect on extracellular water was maintained when plasma glucose remained elevated (inhibition of insulin secretion with a somatostatin analogue). In comparison to glucose, infusion of 10 g of a mixture of amino acids produced a less pronounced effect than expected. The acute water shift after intravenous glucose dilutes serum components including glucose (8% of total extracellular glucose at 35 g). This can be misinterpreted as glucose clearance when calculating metabolic rates. For estimated amounts a proportional correction should be made (3.5% per 5 mmol l-1 increase). A measured plasma glucose of 22.2 mmol l-1 should be corrected to 24.8 mmol l-1, while a plasma glucose value of 5.0 mmol l-1 needs no correction.

Blood Glucose↗
PubMed2006

Xylella fastidiosa infection and ethylene exposure result in xylem and water movement disruption in grapevine shoots.

It is conventionally thought that multiplication of the xylem-limited bacterium Xylella fastidiosa (Xf) within xylem vessels is the sole factor responsible for the blockage of water movement in grapevines (Vitis vinifera) affected by Pierce's disease. However, results from our studies have provided substantial support for the idea that vessel obstructions, and likely other aspects of the Pierce's disease syndrome, result from the grapevine's active responses to the presence of Xf, rather than to the direct action of the bacterium. The use of magnetic resonance imaging (MRI) to observe the distribution of water within the xylem has allowed us to follow nondestructively the development of vascular system obstructions subsequent to inoculation of grapevines with Xf. Because we have hypothesized a role for ethylene produced in vines following infection, the impact of vine ethylene exposure on obstruction development was also followed using MRI. In both infected and ethylene-exposed plants, MRI shows that an important proportion of the xylem vessels become progressively air embolized after the treatments. The loss of xylem water-transporting function, assessed by MRI, has been also correlated with a decrease in stem-specific hydraulic conductivity (K(S)) and the presence of tyloses in the lumens of obstructed water conduits. We have observed that the ethylene production of leaves from infected grapevines is greater than that from healthy vines and, therefore, propose that ethylene may be involved in a series of cellular events that coordinates the vine's response to the pathogen.

Ethylenes↗
PubMed1979

Water movement in red cells from burned patients. Its relationship to sodium retention and red cell filtrability.

Nine burned patients were investigated. Urinary sodium retention was associated with low red cell water and reduced red cell filtrability. The red cells from patients who recovered lost less water than normal cells when suspended in hypertonic NaCl solution but the proportionality of water loss or gain found for normal cells was maintained. The red cells from fatally burned patients lost proportional behaviour in hypertonic or hypotonic media. The abnormalities are not related to the area of the burn and may be the result of varying therapy. The monitoring of red cell water and water movement under tonicity stress is a convenient measure of the metabolic state of the cell.

Adolescent↗
PubMed1997

Correlation between transepithelial Na+ transport and transepithelial water movement across isolated frog skin (Rana esculenta).

In the present work the coupling under short-circuited conditions between the net Na(+)-influx across isolated frog skin and the transepithelial transport of water was examined i.e., the short-circuit current (Isc) and the transepithelial water movement (TEWM) were measured simultaneously. It has been shown repeatedly that the Isc across isolated frog skin is equal to the net transepithelial Na+ transport. Furthermore the coupling between transepithelial uptake of NaCl under open-circuit conditions and TEWM was also measured. The addition of antidiuretic hormone (AVT) to skins incubated under short-circuited conditions resulted in an increase in the Isc and TEWM. Under control conditions Isc was 9.14 +/- 2.43 and in the presence of AVT 45.9 +/- 7.3 neq cm-2 min-1 (n = 9) and TEWM changed from 12.45 +/- 4.46 to 132.8 +/- 15.8 nL cm-2 min-1. The addition of the Na+ channel blocking agent amiloride resulted in a reduction both in Isc and TEWM, and a linear correlation between Isc and TEWM was found. The correlation corresponds to that 160 +/- 15 (n = 7) molecules of water follow each Na+ across the skin. In another series of experiments it was found that there was a linear correlation between Isc and the increase in apical osmolarity needed to stop the TEWM. The data presented indicate that the observed coupling between the net transepithelial Na+ transport and TEWM is caused by local osmosis.

Animals↗
PubMed1977

Ouabain-insensitive salt and water movements in duck red cells. I. Kinetics of cation transport under hypertonic conditions.

Duck red cells in hypertonic media experience rapid osmotic shrinkage followed by gradual reswelling back toward their original volume. This uptake of salt and water is self limiting and demands a specific ionic composition of the external solution. Although ouabain (10(-4)M) alters the pattern of cation accumulation from predominantly potassium to sodium, it does not affect the rate of the reaction, or the total amount of salt or water taken up. To study the response without the complications of active Na-K transport, ouabain was added to most incubations. All water accumulated by the cells can be accounted for by net salt uptake. Specific external cation requirements for reswelling include: sufficient sodium (more than 23 mM), and elevated potassium (more than 7 mM). In the absence of external potassium cells lose potassium without gaining sodium and continue to shrink instead of reswelling. Adding rubidium to the potassium- free solution promotes an even greater loss of cell potassium, yet causes swelling due to a net uptake of sodium and rubidium followed by chloride. The diuretic furosemide (10(-3)M) inhibits net sodium uptake which depends on potassium (or rubidium), as well as inhibits net sodium uptake which depends on sodium. As a result, cell volume is stabilized in the presence of this drug by inhibition of shrinkage, at low, and of swelling at high external potassium. The response has a high apparent energy of activation (15-20 kcal/mol). We propose that net salt and water movements in hypertonic solutions containing ouabain are mediated by direct coupling or cis-interaction, between sodium and potassium so that the uphill movement of one is driven by the downhill movement of the other in the same direction.

Animals↗
PubMed1992

Plasma membrane water permeabilities of human oocytes: the temperature dependence of water movement in individual cells.

Membrane water permeability values were measured in individual fresh human pre-ovulatory oocytes using real time microscopy in a microscope diffusion chamber. The cells were exposed to anisosmotic conditions, their volume responses measured, and from these data the Lp values were computed employing the Kedem-Katchalsky analyses of irreversible thermodynamics. Lp values were measured at four temperatures for each oocyte between 37 degrees C and 10 degrees C, and the temperature-related Arrhenius activation energy (Ea) calculated. It was apparent that individual oocytes exhibited a wide range of Lp values; at 37 degrees C Lp values ranged between 0.33 and 1.80 microns/atm/min. However, each oocyte exhibited the expected inverse linear correlation between Lp and temperature, with high linear correlations (R2 values between 0.73 and 0.96). A mean value for Ea of 8.61 +/- 5.11 Kcal/mol was computed. It is apparent that pre-ovulatory human oocytes express a range of biological diversity in terms of membrane water transport, and this fact needs to be considered when attempting to formulate cryopreservation protocols for storage of these oocytes.

Cell Membrane Permeability↗
PubMed1977

Ouabain-insensitive salt and water movements in duck red cells. III. The role of chloride in the volume response.

This paper describes the effect of external chloride on the typical swelling response induced in duck red cells by hypertonicity or norepinephrine. Lowering chloride inhibits swelling and produces concomitant changes in net movements of sodium and potassium in ouabain-treated cells, which resemble the effect of lowering external sodium or potassium. Inhibition is the same whether chloride is replaced with gluconate or with an osmotic equivalent of sucrose. Since changes in external chloride also cause predictable changes in cell chloride, pH, and water, these variables were systematically investigated by varying external pH along with chloride. Lowering pH to 6.60 does not abolish the response if external chloride levels are normal, although the cells are initially swollen due to the increased acidity. Cells deliberately preswollen in hypotonic solutions with appropriate ionic composition can also respond to norepinephrine by further swelling. These results rule out initial values of cell water, chloride, and pH as significant variables affecting the response. Initial values of the chloride equilibrium potential do have marked effect on the direction and rate of net water movement. If chloride is lowered by replacement with the permeant anion, acetate, E(Cl) is unchanged and a normal response to norepinephrine, which is inhibited by furosemide, is observed. Increasing internal sodium by the nystatin technique also inhibits the response. A theory is developed which depicts that the cotransport carrier proposed in the previous paper (W.F. Schmidt and T.J. McManus. 1977b. J. Gen. Physiol. 70:81-97) moves in response to the net electrochemical potential difference driving sodium and potassium across the membrane. Predictions of this theory fit the data for both cations and anions.

Animals↗
PubMed1985

Effect of temperature on transcapillary water movement in isolated cat hindlimb.

Capillary filtration coefficient (CFC) was measured in the isolated cat hindlimb preparation, perfused at 20 ml X min-1 X 100 g muscle-1 with a perfusate containing 6 g/dl albumin and normal electrolyte concentrations, to which were added 50 ml of the cat's blood and 6 micrograms of the vasodilator isoproterenol. CFC was determined three to six times in an initial control period during which the tissue temperature (measured by a 5-mm disk thermistor implanted in a thigh muscle) was controlled near 37 degrees C. Tissue temperature was decreased to 5-10 degrees C by lowering perfusate and ambient air temperatures. About 50 min were required for tissue temperature equilibration. CFC was measured at low temperature and then again at 37 degrees C. For nine experiments, the ratio of CFC at low temperature to that in the 37 degrees C control periods averaged 87% of the ratio of water viscosity at 37 degrees C to that at low temperature. The activation energy for water calculated from these data was 5.0 kcal/mol. These results may be explained by all transcapillary water flow moving by diffusion through narrow pores or by about 90% moving by convection, with the remainder going through a lipid pathway. However, the results may be entirely due to a direct effect of temperature on the geometry of the transcapillary pathway for water movement.

Animals↗
PubMed1981

Effect of atropine on bile-oleic acid-induced alterations in dog jejunal hemodynamics, oxygenation, and net transmucosal water movement.

The effects of intraluminal bile-oleic acid on jejunal blood flow, oxygen uptake, net transmucosal fluid flux, and mucosal ultrastructure were studied in isolated autoperfused jejunal segments before and after cholinergic blockage with atropine. Bile-oleic acid increased jejunal blood flow (40%), decreased oxygen extraction (24%), and increased oxygen uptake (15%). Cholinergic blockade did not abolish the bile-oleic acid-induced changes in these parameters. Bileoleic acid induced net fluid secretion or significantly depressed absorption. Cholinergic blockade reversed net volume secretion to absorption or attenuated the depression of absorption produced by bile-oleic acid. Ultrastructural analyses of tissue samples taken during bile-oleic acid-induced secretion indicate major structural damage to the mucosal membrane which was not affected by cholinergic blockade. The physiologic and ultrastructural data acquired in this study suggest that: (a) the effects of bile-oleic acid on net transmucosal water movement are reversed by cholinergic blockade and (b) the hyperemia, increased oxygen consumption, and morphologic alterations induced by bile-oleic acid are not affected by cholinergic blockade. The results of this study may have important implications in steatorrheal diseases in that, atropine may alleviate the diarrhea induced by the presence of excess lipid in chyme without compromising the intestinal hyperemia and enhanced oxygen delivery required to meet the increased metabolic demands during nutrient absorption.

Animals↗
PubMed2005

[Research progress on unsaturated and saturated soil water movement in forest catchments].

This paper reviewed the studies on the movement ways, i. e., infiltration, phreatic evaporation, ground water recharge and interflow, of unsaturated and saturated soil water in forest catchments, and introduced the present advances in soil hydraulic parameters, including soil water characteristic curve, and unsaturated and saturated soil hydraulic conductivity. Research directions in the future were also proposed.

Models, Theoretical↗