Osmotic Pressure Levels Research Articles

Effects of osmotic pressure in the extracellular matrix on tissue deformation

In soft tissues, large molecules such as proteoglycans trapped in the extracellular matrix (ECM) generate high levels of osmotic pressure to counter-balance external pressures. The semi-permeable matrix and fixed negative charges on these molecules serve to promote the swelling of tissues when there is an imbalance of molecular concentrations. Structural molecules, such as collagen fibres, form a network of stretch-resistant matrix, which prevents tissue from over-swelling and keeps tissue integrity. However, collagen makes little contribution to load bearing; the osmotic pressure in the ECM is the main contributor balancing external pressures. Although there have been a number of studies on tissue deformation, there is no rigorous analysis focusing on the contribution of the osmotic pressure in the ECM on the viscoelastic behaviour of soft tissues. Furthermore, most previous works were carried out based on the assumption of infinitesimal deformation, whereas tissue deformation is finite under physiological conditions. In the current study, a simplified mathematical model is proposed. Analytic solutions for solute distribution in the ECM and the free-moving boundary were derived by solving integro-differential equations under constant and dynamic loading conditions. Osmotic pressure in the ECM is found to contribute significantly to the viscoelastic characteristics of soft tissues during their deformation.

A comparative study of lidocaine and lidocaine- mannitol in anesthetizing human teeth with inflamed pulps.

Failure to achieve adequate and profound anesthesia in teeth with acute pulp inflammation is a common condition during emergency visits in root canal therapy. Many different anesthetic solutions such as morphine and capsaicin have accordingly been examined. Mannitol- an alcoholic sugar with high osmotic pressure level- is applicated for reducing intracranial and post retinal pressure in medicine. It has also been used for its diuretic effect. In combination with local anesthetic solution, it increases permeability of the nerve fiber sheath and leads to influx of the local anesthetic through cytoplasmic membrane .The purpose of the present study was to compare the efficacy of routine local anesthesia with or without using mannitol in teeth with inflamed pulps. one hundred patients with acute dental pain in posterior teeth were selected. Vials with 3 ml anesthetic solution containing 2.5% lidocaine with 1/80000 epinephrine or 2.5% lidocaine with 1/80000 epinephrine and 0.5 mol mannitol were used for anesthesia. For each patient, the routine injection technique was applied, during the removal of decay and dentine. Depth of anesthesia was evaluated and the supplementary injection was done in case of pain feeling and then pulpotomy was done. The analysis of data was done using chi-square statistical test. The results showed that complete anesthesia after the first injection was obtained with lidocaine mannitol in 46% and with lidocaine alone in 38% of cases. However, the difference was not significant. These finding suggest that the addition of mannitol to the standard anesthetic solution could insignificantly increase the level of anesthesia in teeth with inflamed pulps.

Viability of Escherichia coli after combined osmotic and thermal treatment: a plasma membrane implication

This study investigates the influence of temperature ( T) and osmotic pressure ( Π) on the viability of Escherichia coli K12 during an osmotic treatment. Osmotic shock (dehydration and rehydration within 1 s) in liquid media at different temperatures (4, 10, 30 and 37 °C) and different levels of osmotic pressure (26, 30, 35, 40, 82 and 133 MPa) were realized. Results show that a sudden dehydration, below 40 MPa, destroyed up to 80% of the bacterial population for each tested temperature, whereas viability was greater than 90% for an osmotic pressure less than 26 MPa. The influence of T and Π on the membrane's physical structure is finally considered to explain the results in light of FTIR and electron microscopy study of the influence of temperature and osmotic pressure on E. coli membrane phospholipids conformation.

Osmotic destruction of Saccharomyces cerevisiae is not related to a high water flow rate across the membrane

Influence of the kinetics of osmotic pressure variation on yeast viability was related to the rate of water transfer across the yeast membrane. A very high value of membrane hydraulic permeability ( L p>6 × 10 −11 m s −1 Pa −1) of the yeast Saccharomyces cerevisiae implies the presence of aqueous pores in the yeast membrane and explains the yeast resistance to a very high osmotic flow. The high water flow rate can not explain, by itself, the cell mortality following an osmotic shock. Experiments performed at different osmotic pressure levels show that the yeast death under osmotic shifts was related to the coupled effects of the kinetics of osmotic pressure variation and of the total osmotic pressure level of the medium.

Shrinkage and Expansion of Blastocoel affect the Degree of Invagination in Sea Urchin Embryos

By immersing sea urchin embryos in seawater containing various concentrations of sucrose, we found that the level of osmotic pressure of blastocoel changed during gastrulation; the level was low around the onset of gastrulation and higher during secondary invagination. To learn how such changes in osmotic pressure related to invagination processes, embryos were shrunken or expanded by means of sucrose treatments, and the degree of invagination was monitored using Nile blue staining. The method elucidated that the cells invaginated during primary invagination occupied only top one third of archenteron at the end of secondary invagination, and that the cells constituting intestine and the posterior half of stomach were recruited into the archenteron after secondary invagination. When embryos were expanded, the degree of invagination was remarkably decreased, indicating that a higher level of expanding force hindered the fulfillment of invagination. On the other hand, shrinkage of blastocoel during secondary invagination increased the degree of invagination. Cell tracing experiments showed that the change in the degree of invagination estimated with Nile blue staining was accompanied with the change in the number of cells incorporated into the archenteron. When embryos were expanded, only the descendants of veg2 constituted the gut rudiment, while a considerable amount of the veg1 descendants were recruited into archenteron when embryos were shrunken. Obtained results suggest that change in the level of osmotic pressure of blastocoel would be necessary for the progress of gastrulation.

Is the use of albumin in colloid prime solution of cardiopulmonary bypass circuit justified?

Background. Albumin in the priming solution precoats the surface of the cardiopulmonary bypass circuit, supposedly causing delayed adsorption of fibrinogen and reduced activation and adhesion of platelets. This action may result in lower transoxygenator resistance. Because our institution uses a colloidal prime solution (Gelofusine), questions were raised about the value of albumin in the prime solution. We decided to focus on the clinical effects of transoxygenator resistance. Methods. Sixty adults undergoing elective cardiac operations were randomly divided into three groups: a group with 20-g albumin (n = 20), a group with 2-g albumin (n = 20), and a group with no albumin (n = 20) in the 1,600-mL colloidal prime. Patients older than 75 years and patients with a preoperative serum albumin level of 30 g/L or less were excluded. The transoxygenator resistance was measured throughout cardiopulmonary bypass. β-Thromboglobulin levels were used to study contact activation of platelets. Measures of prothrombin F1,2 fragments were used as a marker of thrombin generation. Body surface area, age, preoperative albumin, hematocrit, hemoglobin, fibrinogen, platelet count, and colloid osmotic pressure levels were compared between groups. Results. Base line characteristics and chosen control measurements were similar for all three populations. When comparing the observed transoxygenator resistance among the three different groups, no significant differences were noted. Prothrombin F1.2 fragments remained low for all the groups without significant differences. In the no-albumin group the level of β-thromboglobulin appeared to be higher, but the difference was not statistically significant. Conclusions. Addition of albumin to prime solution in a cardiopulmonary bypass circuit that already contains colloids does not affect the transoxygenator resistance of the COBE Duo flat sheet oxygenator and does not affect prothrombin F1.2 and β-thromboglobulin levels. Therefore additional costs for the albumin are not justified. Measurement of transoxygenator resistance is a reliable, simple method to determine the effects of a prime solution on the oxygenator surface in vivo.

The effect of osmotic pressure on the membrane fluidity of Saccharomyces cerevisiae at different physiological temperatures.

Membrane fluidity in whole cells of Saccharomyces cerevisiae W303-1A was estimated from fluorescence polarization measurements using the membrane probe, 1,6-diphenyl-1,3,5-hexatriene, over a wide range of temperatures (6-35 degrees C) and at seven levels of osmotic pressure between 1.38 MPa and 133.1 MPa. An increase in phase transition temperatures was observed with increasing osmotic pressure. At 1.38 MPa, a phase transition temperature of 12 +/- 2 degrees C was observed, which increased to 17 +/- 4 degrees C at 43.7 MPa, 21+/- 7 degrees C at 61.8 MPa, and 24 +/- 9 degrees C at an osmotic pressure of 133.1 MPa. From these results we infer that, with increases in osmotic pressure, the change in phospholipid conformation occurs over a larger temperature range. These results allow the representation of membrane fluidity as a function of temperature and osmotic pressure. Osmotic shocks were applied at two levels of osmotic pressure and at nine temperatures, in order to relate membrane conformation to cell viability.

Modification of fatty acid composition in halophilic antarctic microalgae

The major fatty acids in two Dunaliella isolates originating from Antarctic hypersaline lakes were 18:3 ω3, 16:0, 16:4 ω3. 18:1 ω9, 18:2 ω6, and 16:1 ω7. The relative amount of individual fatty acids was modified by partially or fully replacing ionic osmotic pressure (Na +, K + and Cl −) with molecular osmotic pressure (sorbitol) in the growth medium. The effects of sorbitol on the extent of cellular fatty acid unsaturation differed in the two isolates. The results suggest that the appropriate environment necessary for the growth of these halophilic species is a certain level of osmotic pressure in the medium, but that this can be provided by either ionic or molecular osmotic pressure, or a mixture of both.

Responses of melanin-concentrating hormone mRNA to salt water challenge in the rainbow trout.

Melanin-concentrating hormone (MCH) is a structurally conserved neuropeptide, produced in the hypothalamus of all vertebrates where it probably serves as a central neurotransmitter/neuromodulator. In teleost fish it is also a neurohypophysial hormone with peripheral effects on skin colour but its central effects are less well understood. In mammals, MCH mRNA abundance changes in response to salt-loading or dehydration, suggesting an involvement in salt or water balance. The present study has used in situ hybridization to investigate the response of the MCH neurons in the rainbow trout (Oncorhynchus mykiss) to progressive changes in ambient salinity. In trout, MCH perikarya are found in two hypothalamic sites: predominantly in the nucleus lateralis tuberis (NLT) and, to a lesser extent, in neurons above the lateral ventricular recess (LVR). Immersion in 50% salt water (SW) for 24 h had no effects on MCH transcripts, plasma osmotic pressure (OP) or cortisol concentrations, but after 24 h in 80% SW, plasma OP and cortisol were raised and MCH transcripts in the NLT were significantly increased (159% of controls, p < 0.01). LVR-MCH neurons remained unaffected. However, after 24 h in 100% SW, MCH mRNA was significantly reduced in both groups of neurons (NLT -62% of controls, p < 0.001; LVR -33% of control, p < 0.001). These responses were transient and were no longer apparent after 6 days in 100% SW, despite the fact that plasma OP and cortisol levels continued to rise. The relative importance of osmotic disturbance and stress on the differential responses of the 2 groups of MCH neurons to changing salinity is discussed, together with a consideration of the potential role of MCH in osmoregulation.

Yeast resistance to high levels of osmotic pressure: Influence of kinetics

Application of slow and progressive changes in osmotic pressure to cells of S. cerevisiae allowed the preservation of viability up to very high levels of osmotic pressure (125 MPa). Viability was examined in relation to water exit from the cell in terms of cell volume changes which were measured continuously using an on-line image analysis system. It has been shown that the high survival level of cells subjected to such progressive changes in osmotic pressure are due to physical factors alone and mainly to the water flow rate during the period just after the osmotic shift.

Effects of the kinetics of osmotic pressure variation on yeast viability

The variation rate of the osmotic pressure increase was found to have a great effect on the viability of yeasts subjected to hyperosmotic stress. A low intensity of the increase rate of osmotic pressure could maintain an important viability of the cells (about 90 to 100%) even for very high levels of osmotic pressure (about 10(8) Pa). The viability level was found to be highly dependent on the physiological state of the cells: Variations in the properties of the cell membrane were supposed to be involved in such a dependence.

Optimal composition of burn resuscitation fluids

The hemodynamic, renal, and hematologic responses to fluid resuscitation with four different hydrating solutions (lactated Ringer's and hypertonic salt solutions, with and without albumin) administered in equal quantities were compared in an ovine burn model. Forty-five animals, including a sham group, were studied. The burn (40%, flame) was inflicted under anesthesia, but the animals were then studied while in the awakened state. Fluid resuscitation was begun one hour after the burn. While all animals survived the burn and disclosed reasonable hemodynamic stability throughout the experiment, those that received lactated Ringer's with albumin (LRA) restored their cardiac output to preburn values, by 24 h postinjury demonstrated higher serum albumin and colloid osmotic pressure levels, experienced no electrolyte or acid-base imbalances, and maintained serum osmolality within normal limits. In contrast to the other solutions, LRA did not induce edema in unburned tissues, and seemed optimal for burn resuscitation.

Hemodynamic and hemorheological profiles in women with proteinuric hypertension of pregnancy and in pregnant controls

We obtained blood samples from 52 patients with pre-eclampsia and from 40 pregnant controls for measurement of plasma urate levels, hematocrit, white cell count and various hemorheological parameters. We also used impedance cardiography to measure cardiac output in both groups and from the results derived values for total peripheral resistance and oxygen transport. Central venous pressure was measured with a superior vena cava catheter in patients with pre-eclampsia but not in controls. Women with pre-eclampsia had significantly lower cardiac output and central venous pressure when compared with a control group. A modest correlation was observed between central venous pressure and cardiac output. The majority of pre-eclamptic patients had significantly raised hematocrit, leucocyte count, uric acid and red cell aggregation. Red cell deformability was significantly decreased in patients with pre-eclampsia. Most patients with severe pre-eclampsia (BP diast. greater than 100 mmHg) had a low Antithrombin III and colloid osmotic pressure level. The leucocyte count was raised when compared with the women with moderate pre-eclampsia. Oxygen delivery was reduced in patients with pre-eclampsia because of impaired rheological properties of their blood.

Plasma exchange using dextran 40‐electrolyte solution as the sole replacement fluid in malignant paraproteinemia

The relative safety of 3 percent Dextran 40-electrolyte solution alone as replacement fluid during plasma exchange is described. Using an automated blood cell separator, the authors exchanged 3.21 of plasma 64 times in 11 patients with paraproteinemia secondary either to Waldenström's macroglobulinemia or multiple myeloma (malignant paraproteinemia). Then they replaced the plasma with an equal volume of 3 percent Dextran 40-electrolyte solution. They administered no protein-containing solutions during or after the plasma exchanges. Despite marked hypoalbuminemia immediately after plasma exchange, the plasma colloid osmotic pressure level fell only slightly because of the high concentration of plasma low-molecular dextran. The hemostatic abnormalities were similar to those seen in patients whose plasma was replaced with albumin solution. The exchanges were tolerated well clinically and no serious complications occurred during or after exchange. The authors believe that the 3 percent Dextran 40-electrolyte solution can be used safely as the sole replacement fluid in intensive plasma exchange programs for patients with malignant paraproteinemia.

Differential Physiological Response of Sugarcane Varieties to Osmotic Pressures of Saline Media1

Exposure of sugarcane varieties to different levels of osmotic pressure in nutrient solution (by adding NaC1) emphasizes varietal differences in response to this pressure. Working with varieties H 37‐1933 (known to be sensitive to drought) and H 49‐3533 (known to be tolerant to drought), physiological responses to added amounts of osmotic pressure were measured. Differential responses between these two varieties were shown in growth, flowering (tasseling), formation of joints, uptake of phosphorus, uptake of sodium, and storage of sucrose. These experiments showed that, above a certain pressure, there is a withdrawal of sugars from the basal or older joints. Provided that they have not been exposed to osmotic pressure great enough to cause death, after removal of the added pressure the plants start returning sugar to those joints from which it was withdrawn during the period of osmotic stress.

A comparative study of water balance in three species of quail—II. Utilization of saline drinking solutions

1. 1. Bobwhite, California and Gambel's quail show a positive correlation between their ability to effectively utilize sodium chloride solutions and the degree of water shortage in the typical habitat of each species. 2. 2. Utilization of sodium chloride drinking solutions was evaluated with respect to drinking rates, body weight changes, ability to acclimate to high salt input, absorption of salt from the gut, plasma and urine sodium and osmotic pressure levels and kidney structure.

Effects of Nitrogen Level and Osmotic Pressure of the Nutrient Solution on Incidence of Puccinia graminis and Helminthosporium sativum Infection in Merion Kentucky Bluegrass1

SynopsisMerion bluegrass grown in solution culture produced lower yields of foliage under low levels of nitrogen and high levels of osmotic pressure than when treated with high nitrogen and low osmotic pressures. Turf was resistant to inoculation with Puccinia graminis Pers. at all treatment combinations. Numbers of Helminthosporium sativum Pammel, King, and Bakke lesions per leaf blade and average size of lesions increased with increasing levels of nitrogen and decreasing osmotic pressure.

EFFECTS OF NUTRITION, OSMOTIC PRESSURE, AND TEMPERATURE OF THE NUTRIENT SOLUTION ON PLANT GROWTH AND CHEMICAL COMPOSITION: I. SPRING WHEAT AT THE 4- TO 6-LEAF STAGE

Thatcher wheat at the 4- to 6-leaf stage was grown in nutrient solutions and subjected to five osmotic pressure levels of 0.5, 2.5, 5.5, 8.5, and 11 atmospheres with polyethylene glycol "Carbowax 4000". Root temperatures of 45°, 54°, 67°, and 80°F. and nitrogen treatments of 5, 25, 50, and 100 p.p.m. were also applied. Osmotic pressure and nitrogen treatments had only a small effect on dry matter production, whereas increasing root temperatures significantly increased dry matter in the shoots and roots. Treatment effects on nitrogen and phosphorus absorption and translocation are discussed.

THE RELATION OF UREA TO THE MOVEMENT OF WATER IN LIVER TISSUE

The purpose of this study has been to determine what conditions maintain the high level of osmotic pressure within liver cells present immediately after their removal from the body, to define the relation of water movement to this pressure, and to learn if intracellular osmotic pressure and water movement are changed when amino acids and related substances are transformed to produce urea. Significant information concerning the activity of liver or of kidney cells as osmometers is obtainable immediately after the tissue is removed from the body.1 With relation to a wide variety of electrolytes, liver cells acting as osmometers measure the osmotic pressure of solutions in accord with the molecular weight, valence, and ion-dissociation of each substance. Tables (Robinson and Stokes2) assembled from freezing point depression, vapor tension, electrical conductivity, and other colligative properties of electrolytes have made it possible to define the molar concentration of electrolyte solutions with the same osmotic pressure. A solution of sodium chloride isotonic for liver immediately after its removal from the body is approximately 0.34 molar and a similar solution for kidney, 0.23 molar. Water equilibrium is maintained by the tissue at these levels during 15 to 20 min. Electrolytes as varied as potassium chloride, with monovalent base, magnesium chloride, with bivalent base, and lanthanum chloride with trivalent base, are isotonic with liver or kidney tissue in solutions that have the same osmotic pressure as that of sodium chloride in solution isotonic with one or other of these tissues. The tissues, acting as osmometers, measure osmotic pressure with approximate accuracy. The plasma membrane of liver cells is evidently imperfectly semipermeable to solutions of electrolytes and with their entrance into the cell permeability to both electrolyte and water is increased. Maintenance of isotonicity in vitro is promoted by immersion in media with electrolytes similar to those of blood plasma, by temperature at 38? C and by an adequate supply of oxygen.5 Slices of liver tissue, weighing preferably from 60 to 90 mg, determined rapidly by means of a torsion balance, have been immersed in the Krebs3 modification of Ringer's solution much used for manometric measurement of oxygen consumption. The solution with electrolyte concentration of 0.154 molar has been buffered with potassium phosphate and treated with oxygen or buffered with sodium bicarbonate and gassed with oxygen, 95 per cent, and carbon dioxide, 5 per cent. The medium is hypotonic for liver tissue but when its molar concentration is increased two-fold by addition of sodium chloride isotonicity may be maintained during one or two hr.4 Water movement measured in per cent of weight before immersion varies widely with oxygen supply to the medium. With abundant oxygen under conditions that promote its diffusion throughout the medium and into the tissue, water enters rapidly during about one hr but later is lost and within 2 or 3 hr may be less than that before immersion. With anoxia caused by diminished oxygen supply or by substitution of nitrogen for oxygen, water intake during the first hr of immersion

Germination of Six Alfalfa Varieties at Three Levels of Osmotic Pressure1

Germination of Six Alfalfa Varieties at Three Levels of Osmotic Pressure¹