Osmotic strength

Figure 5. Inhibition of lysosomal enzyme release from neutrophils by increased osmotic strength. Cells were preincubated for 10 min at 37°C in regular buffer containing no additions (o), or containing sodium sulfate ( ), sodium HEPES ( ), or sucrose ( ) to increase the osmotic strength. Cells were treated with cyto-chalasin B (5 arid FMLP (10" M) and p-glucuronidase was...

The formulations should also be iso-osmotic with surrounding tissues, to avoid causing volume changes of cells. Because some excipients can penetrate the red cell, thus lowering osmotic strength outside, but raising it within the cell, the concept of isotonicity is distinguished from iso-osmoticity. An isotonic solution will not result... 

The ability of cells to receive and act on signals from beyond the plasma membrane is fundamental to life. Bacterial cells receive constant input from membrane proteins that act as information receptors, sampling the surrounding medium for pH, osmotic strength, the availability of food, oxygen, and light, and the presence of noxious chemicals, predators, or competitors for food. 

Caridi, A., Crucitti, P., and Ramondino, D. (1999). Winemaking of musts at high osmotic strength by thermotolerant yeasts. Biotechnol. Lett. 21,617-620. 

Only extremely dilute solutions (in which there are no interactions between particles or particles and solvent) obey the relationship ttV =nRT. Yet, relatively concentrated solutions must be used to obtain good measurements of TT. Usually, the observed value of tt must be corrected for nonideality. This is accomplished by plotting ir/C (the reduced or specific osmotic strength) against C, and extrapolating to zero C. The MW is then calculated from ... 

Water, salt, and blood pressure are related. The blood volume is closely related to the blood pressure. A loss in blood volume can occur with water deficiency or because of extensive bleeding. The lack of enough blood to fill up the vessels of the circulatory system leads to a drop in blood pressure. A severe drop in blood pressure results in the inability of the heart to pump vital nutrients to the brain and other tissues. A loss in blood volume can also result from sodium deficiency. The concentrations of sodium and its counterion chloride must be maintained to maintain the osmotic strength of the blood plasma. Osmotic strength is expressed by the term osmolality. Osmolality is equal to the sum of the molarities of the separate particles (ions or molecules) in a liquid. For example, a solution of 1 mole of NaCl in 1 liter has an osmolality of 2.0 osmol/liter. Na and Cl ions dissociate completely in solution. Osmotic pressure develops when two solutions of differing osmolalities are placed in contact with each other but separated by a semiperme-able membrane. The walls of capillaries are semipermeable membranes. The renal... 

The most common materials used to generate density gradients are sucrose, Ficoll, and Cs salts. Sucrose solutions can be as concentrated as 65% w/w, with a maximum density of 1.32 g/cm3 at 4 °C however, concentrated solutions of sucrose have high osmotic strength and viscosity. Ficoll is a brand name for a synthetic polysaccharide with an average MW of 400,000 and a maximum density in aqueous solution of 1.23. It is very useful to separate osmotically sensitive particles, like mammalian cells. 

Sodium is the major cation of extracellular fluid. Because it represents approximately 90% of the 154mmol of inorganic cations per liter of plasma, Na is responsible for almost one half the osmotic strength of plasma. It therefore plays a central role in maintaining the normal distribution of water and the osmotic pressure in the extracellular fluid compartment. The normal daily diet contains 8 to 15 g (130 to 260 mmol) of NaCl, which is nearly completely absorbed from the gastrointestinal tract. The body requires only 1 to 2 mmol/day, and the excess is excreted by the kidneys, which are the ultimate regulators of the amount of Na" (and thus water) in the body. 

Galloway, S. M., Deasy, D. A., Bean, C. L., Kraynak, A. R., Armstrong, M. J., and Bradley, M. O. (1987). Effects of high osmotic strength on chromosome aberrations, sister-chromatid exchanges and DNA strand breaks, and the relation to toxicity. Mutat Res 189, 15-25. 

As would be expected, the combination of thermal and osmotic shocks has been shown to have a large effect on the osmotic strength of anion resins.This is illustrated in Fig. 27, where the decrease is shown to be over 15% in just 150 cycles. The important processing point to remember from this is that if the regeneration of a resin is performed at a temperature more than 20°C different from the temperature of the operating (loading) stream, it is advisable first to adjust the temperature of the resin with distilled water until it is at the temperature of the regenerant. 

Figure 27. The effect of thermal and osmotic cycling on the osmotic strength of a strong base anion resin, AV-17. (1) Effect of thermal cycling (2) effect of osmotic cycling (3) effect of thermal and osmotic cycling (cold alkali to hot acid) (4) effect of thermal and osmotic cycling (hot alkali to cold acid).f J...

MQ Original mass of mitochondria in cell = Y0 fM0, mg/1 BQ Osmotic strength of buffer, Os/kg... 

Osmotic concentration or osmolarity is the term used to describe the osmotic strength of a solution. It depends only on the ratio of the number of solute particles to the number of solvent particles. Thus the chemical nature and size of the solute are not important, only the concentration, expressed in molarity. For instance, a 2 M solution of glucose (a sugar of molecular weight 180) has the same osmolarity as a 2 M solution of albumin (a protein of molecular weight 60,000). 

Tables of osmotic and activity coefficients of sugar have been published by Robinson and Stokes ( 4). These should aid the food technologist in calculating osmotic strengths.

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